Paleolithic diets are not without risks

High-protein diets, known as ''Paleolithic diets'', are popular. Using mouse models, scientists at the University of Geneva (UNIGE) have studied their impact. While effective in regulating weight and stabilizing diabetes, these diets are not without risks. Excess protein greatly increases ammonium production, overwhelming the liver. Excess ammonium can cause neurological disorders and, in severe cases, lead to coma. These results, published in the Journal of Biological Chemistry, suggest caution when following these diets.

Type 2 diabetes is a metabolic disease that is constantly increasing.

Due to a sedentary lifestyle and an excessively rich diet, the damaged pancreas struggles to regulate blood sugar levels.

While current treatments help control the progression of the disease, they do not cure diabetes.

Losing weight is often an essential part of the treatment.

''Diets rich in animal and/or plant proteins, known as Paleolithic diets, can be used to stabilize type 2 diabetes and regulate weight,'' explains Pierre Maechler, full professor at the Department of Cell Physiology and Metabolism at the UNIGE Faculty of Medicine, who led this research.

These diets are inspired by the meat-based diets of pre-agricultural time.

''But what impact do they have on the body? Are they harmless?

That's what we set out to find out.''

Liver under Pressure

Ammonium is a normal waste product of protein breakdown, essentially eliminated in the liver by the enzyme glutamate dehydrogenase (GDH). In the event of protein overload, the GDH enzyme comes under pressure.

To study the impact of high-protein diets, Pierre Maechler's team fed healthy mice and mice lacking the GDH enzyme in their liver a diet with a protein content mimicking the so-called Paleolithic diet.

Scientists observed that in healthy mice, although excess protein increased ammonium production, the liver managed this excess due to the action of the GDH enzyme, which detoxifies ammonium before it can cause damage.

''In contrast, in mice lacking the GDH enzyme, the liver is unable to eliminate the excess of toxic ammonium derived from proteins.

No need to wait for weeks or months; a change of diet lasting a few days is enough to observe major consequences,'' explains Karolina Luczkowska, a former PhD student at the Department of Cell Physiology and Metabolism at the UNIGE Faculty of Medicine, and the study's first author.

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Ancient 'chewing gum' reveals stone age diet

What did people eat on the west coast of Scandinavia 10,000 years ago? A new study of the DNA in a chewing gum shows that deer, trout and hazelnuts were on the diet. It also shows that one of the individuals had severe problems with her teeth.

Some 9,700 years ago, a group of people were camping on the west coast of Scandinavia, north of what is today Göteborg.

They had been fishing, hunting and collecting resources for food.

And some teenagers, both boys and girls, were chewing resin to produce glue, just after munching on trout and deer, as well as on hazelnuts.

Due to a bad case of periodontitis (severe gum infection that can lead to tooth loss and bone loss), one of the teenagers had problems eating the chewy deer-meat, as well as preparing the resin by chewing it.

We know this because an international research team has been working with the chewed resin from Huseby Klev for some time.

"There is a richness of DNA sequences in the chewed mastic from Huseby-Klev, and in it we find both the bacteria that we know are related to periodontitis, and DNA from plants and animals that they had chewed before," says Dr. Emrah Kırdök, from Mersin University Department of Biotechnology, who coordinated the metagenomic work on the Mesolithic chewing gum.

Emrah Kırdök started to analyse the material when he was a postdoc at the Department of Archaeology and Classical Studies at Stockholm University, but the study has grown much since then.

The site Huseby Klev on the island Orust was excavated 30 years ago.

Chewed resin was found together with remains of stone tools in a context dated to c. 9700 years ago.

The stone material also indicated a Mesolithic chronology. The chewed material from Huseby Klev has already generated a study on the human genetic data from three individuals, and the DNA in the material that was not of human origin has also been analysed and published.

Identifying the different species present in the kind of mix of DNA that was present in the Mesolithic chewing gum was challenging.

Dr Andrés Aravena, from the Department of Molecular Biology and Genetics at Istanbul University spent much time on the computer analysing the data together with Dr. Emrah Kırdök. "We had to apply several computational heavy analytical tools to single out the different species and organisms. All the tools we needed were not ready to be applied to ancient DNA; but much of our time was spent on adjusting them so that we could apply them," concludes Andrés Aravena.

Metagenomics on ancient DNA is an expanding area, but there have yet only been a few studies on this type of chewed material.

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Global diet study challenges advice to limit high-fat dairy foods

Unprocessed red meat and whole grains can be included or left out of a healthy diet, according to a study conducted in 80 countries across all inhabited continents and published today in European Heart Journal, a journal of the European Society of Cardiology (ESC).1 Diets emphasising fruit, vegetables, dairy (mainly whole-fat), nuts, legumes and fish were linked with a lower risk of cardiovascular disease (CVD) and premature death in all world regions. The addition of unprocessed red meat or whole grains had little impact on outcomes.

"Low-fat foods have taken centre stage with the public, food industry and policymakers, with nutrition labels focused on reducing fat and saturated fat," said study author Dr. Andrew Mente of the Population Health Research Institute, McMaster University, Hamilton, Canada. "Our findings suggest that the priority should be increasing protective foods such as nuts (often avoided as too energy dense), fish and dairy, rather than restricting dairy (especially whole-fat) to very low amounts. Our results show that up to two servings a day of dairy, mainly whole-fat, can be included in a healthy diet. This is in keeping with modern nutrition science showing that dairy, particularly whole-fat, may protect against high blood pressure and metabolic syndrome."

The study examined the relationships between a new diet score and health outcomes in a global population. A healthy diet score was created based on six foods that have each been linked with longevity. The PURE diet included 2-3 servings of fruit per day, 2-3 servings of vegetables per day, 3-4 servings of legumes per week, 7 servings of nuts per week, 2-3 servings of fish per week, and 14 servings of dairy products (mainly whole fat but not including butter or whipped cream) per week. A score of 1 (healthy) was assigned for intake above the median in the group and a score of 0 (unhealthy) for intake at or below the median, for a total of 0 to 6. Dr. Mente explained: "Participants in the top 50% of the population -- an achievable level -- on each of the six food components attained the maximum diet score of six."

Associations of the score with mortality, myocardial infarction, stroke and total CVD (including fatal CVD and non-fatal myocardial infarction, stroke and heart failure) were tested in the PURE study which included 147,642 people from the general population in 21 countries. The analyses were adjusted for factors that could influence the relationships such as age, sex, waist-to-hip ratio, education level, income, urban or rural location, physical activity, smoking status, diabetes, use of statins or high blood pressure medications, and total energy intake.

The average diet score was 2.95. During a median follow-up of 9.3 years, there were 15,707 deaths and 40,764 cardiovascular events. Compared with the least healthy diet (score of 1 or less), the healthiest diet (score of 5 or more) was linked with a 30% lower risk of death, 18% lower likelihood of CVD, 14% lower risk of myocardial infarction and 19% lower risk of stroke. Associations between the healthy diet score and outcomes were confirmed in five independent studies including a total of 96,955 patients with CVD in 70 countries.

Dr. Mente said: "This was by far the most diverse study of nutrition and health outcomes in the world and the only one with sufficient representation from high-, middle- and low-income countries. The connection between the PURE diet and health outcomes was found in generally healthy people, patients with CVD, patients with diabetes, and across economies."

"The associations were strongest in areas with the poorest quality diet, including South Asia, China and Africa, where calorie intake was low and dominated by refined carbohydrates. This suggests that a large proportion of deaths and CVD in adults around the world may be due to undernutrition, that is, low intakes of energy and protective foods, rather than overnutrition. This challenges current beliefs," said Professor Salim Yusuf, senior author and principal investigator of PURE.

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Face of Anglo-Saxon teen VIP revealed with new evidence about her life

The face of a 16-year-old woman buried near Cambridge (UK) in the 7th century with an incredibly rare gold and garnet cross (the 'Trumpington Cross') has been reconstructed following analysis of her skull. The striking image is going on public display for the first time on 21st June,* with new scientific evidence showing that she moved to England from Central Europe as a young girl, leading to an intriguing change in her diet.

Forensic artist Hew Morrison created the likeness using measurements of the woman's skull and tissue depth data for Caucasian females. Without DNA analysis, Morrison could not be sure of her precise eye and hair colour, but the image offers a strong indication of her appearance shortly before she died.

Hew Morrison said: "It was interesting to see her face developing. Her left eye was slightly lower, about half a centimetre, than her right eye. This would have been quite noticeable in life."

New "you are what you eat" isotopic analysis of the young woman's bones and teeth conducted by bioarchaeologists Dr Sam Leggett and Dr Alice Rose, and archaeologist Dr Emma Brownlee, during PhD research at the University of Cambridge also reveals that she moved to England from somewhere near the Alps, perhaps southern Germany, sometime after she turned 7 years old.

Leggett and Rose also found that once the girl had arrived in England, the proportion of protein in her diet decreased by a small but significant amount. This change occurred close to the end of her young life, showing that the period between her migration and burial near Cambridge was tragically short.

Dr Leggett, now at the University of Edinburgh, said: "She was quite a young girl when she moved, likely from part of southern Germany, close to the Alps, to a very flat part of England. She was probably quite unwell and she travelled a long way to somewhere completely unfamiliar -- even the food was different. It must have been scary."

Previous analysis indicated that the young woman had suffered from illness but her cause of death remains unknown. She was buried in a remarkable way -- lying on a carved wooden bed wearing the cross, gold pins (also on display) and fine clothing.

Hers is one of only 18 bed burials ever uncovered in the UK. Her ornate cross, combining gold and garnets (third quarter of the 7th century), is one of only five of its kind ever found in Britain and identifies her as one of England's earliest converts to Christianity and as a member of the aristocracy if not royalty. The best known example of such a cross was found in the coffin of St Cuthbert.

In 597 AD, the pope dispatched St Augustine to England on a mission to convert the pagan Anglo-Saxon kings, a process which continued for many decades.

Dr Leggett said: "She must have known that she was important and she had to carry that on her shoulders. Her isotopic results match those of two other women who were similarly buried on beds in this period in Cambridgeshire.

"So it seems that she was part of an elite group of women who probably travelled from mainland Europe, most likely Germany, in the 7th century, but they remain a bit of a mystery. Were they political brides or perhaps brides of Christ? The fact that her diet changed once she arrived in England suggests that her lifestyle may have changed quite significantly."

Dr Sam Lucy, a specialist in Anglo-Saxon burial from Newnham College, Cambridge, who published the Anglo-Saxon excavations at Trumpington**, said:

"These are intriguing findings, and it is wonderful to see this collaborative research adding to our knowledge of this period. Combining the new isotopic results with Emma Brownlee's research into European bed burials really does seem to suggest the movement of a small group of young elite women from a mountainous area in continental Europe to the Cambridge region in the third quarter of the seventh century.

"Southern Germany is a distinct possibility owing to the bed burial tradition known there. Given the increasingly certain association between bed burial, such cross-shaped jewellery, and early Anglo-Saxon Christianity, it is possible that their movement related to pan-European networks of elite women who were heavily involved in the early Church."

Dr Jody Joy, the exhibition's co-curator, said: "The story of this young woman goes to the very heart of what our exhibition is all about -- new research making visible the lives of people at pivotal moments of Cambridgeshire's history. MAA holds one of Britain's most important collections of Early Medieval archaeology and the Trumpington bed burial is so important. It looks like it still has much more to teach us."

In the exhibition, the 'Trumpington Cross' will be displayed together with the delicate gold and garnet pins connected by a gold chain, which were found near the teenager's neck. These pins probably secured a long veil to an outer garment of fine linen. The pins would have caught the light as she moved.The burial bed's decorativeheadboard will also be exhibited.

* The image and artefacts from the mysterious woman's burial -- discovered in 2012 by the Cambridge Archaeological Unit at Trumpington Meadows on Cambridge's southern limits -- including her famous cross will be unveiled in a major new exhibition at Cambridge's Museum of Archaeology and Anthropology (MAA). 'Beneath Our Feet: Archaeology of the Cambridge Region' will run from 21st June to 14th April 2024.

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Ancient herbivore's diet weakened teeth leading to eventual starvation, study suggests

A team of researchers from the University of Bristol have shed light on the life of the ancient reptile Rhynchosaur, which walked the earth between 250-225 million years ago, before being replaced by the dinosaurs.

Rhynchosaurs are a little-understood group of roughly sheep-sized ancient reptiles that thrived during the Triassic Period, a time of generally warm climates and tough vegetation.

In the new study, the researchers studied specimens found in Devon and used CT scanning to see how the teeth wore down as they fed, and how new teeth were added at the backs of the tooth rows as the animals grew in size.

The findings, published today in Palaeontology, show that these early herbivores likely eventually starved to death in old age, the vegetation taking its toll on their teeth.

"I first studied the rhynchosaurs years ago," said team-leader Professor Mike Benton from Bristol's School of Earth Sciences, "and I was amazed to find that in many cases they dominated their ecosystems. If you found one fossil, you found hundreds. They were the sheep or antelopes of their day, and yet they had specialized dental systems that were apparently adapted for dealing with masses of tough plant food."

Dr Rob Coram, who discovered the Devon fossils, said: "The fossils are rare, but occasionally individuals were entombed during river floods. This has made it possible to put together a series of jaw bones of rhynchosaurs that ranged in age from quite young, maybe even babies, through adults, and including one particularly old animal, a Triassic old-timer whose teeth had worn right down and probably struggled to get enough nutrition each day."

"Comparing the sequence of fossils through their lifetime, we could see that as the animals aged, the area of the jaws under wear at any time moved backwards relative to the front of the skull, bringing new teeth and new bone into wear," said Thitiwoot Sethapanichsakul who studied the jaws as part of his MSc in Palaeobiology. "They were clearly eating really tough food such as ferns, that wore the teeth down to the bone of the jaw, meaning that they were basically chopping their meals by a mix of teeth and bone."

"Eventually, though, after a certain age -- we're not sure quite how many years -- their growth slowed down and the area of wear was fixed and just got deeper and deeper," added Dr Coram. "It's like elephants today -- they have a fixed number of teeth that come into use from the back, and after the age of seventy or so they're on their last tooth, and then that's that.

"We don't think the rhynchosaurs lived that long, but their plant food was so testing that their jaws simply wore out and presumably they eventually starved to death."

The rhynchosaurs were an important part of the ecosystems on land during the Triassic, when life was recovering from the world's greatest mass extinction, at the end of the preceding Permian Period. These animals were part of this recovery and setting the scene for new types of ecologies when first dinosaurs, and later mammals became dominant, as the modern world was being slowly constructed.

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Global warming puts whales in the Southern Ocean on a diet

In the month of June, when winter bites in the southern hemisphere and the sea around the Antarctic freezes over, right whales swim north. Many of them gather in the bay outside the town of Hermanus in South Africa.

Here, the warmer South African water is perfect for mating or raising newborn calves. However, there is no food for the whales, and all winter long the right whale mothers use up their fat reserves to produce milk for their calves.

It is therefore extremely important that the whales eat a lot and fatten up in the cold waters around the Antarctic throughout the summer. But it seems there is not enough food. The whales arriving at the coasts of South Africa are thinner than they used to be.

This is the result of new research from Aarhus University. Since the researchers started to measure right whales in the 1980s, the whales have become increasingly thinner. This is explained by Fredrik Christiansen, a senior researcher at the Department of Ecoscience at Aarhus University, who is behind the new results.

"Right whales are 25 per cent thinner than they were in the 1980s. This is bad for the whale population, because it means that the newborn whale calves have a higher risk of dying. Fortunately, the right whales in the Southern Ocean are not endangered, but if this continues, they could become so," he says.

When the ice melts, food disappears

When winter comes, and the cows leave the Antarctic and swim north, they have to cope for several months without food. Several months in which they eat into the fat reserves they have built up through the warm and light summer season.

Throughout the summer, right whales swim around beneath the sea ice, open their mouths to take in seawater, krill and water fleas. The baleen inside their mouth is a sort of a giant filter and it filters the small animals from the salt water. This allows the whales to eat huge amounts of food without using a lot of energy.

But the large shoals of krill are shrinking -- and this means that the whales can't fatten up before winter as they used to," explains Fredrik Christiansen.

"The shoals of krill live on phytoplankton, which thrive best in the cold waters around the Antarctic. Here -- like plants on land -- they transform sunlight into energy. Rising sea temperatures mean there is less phytoplankton, fewer krill and thus less food for the whales.

Instead, the whales forage for food further north, where there is another and less energy-rich form of krill.

"Further north, there's less food for these small crustaceans. Therefore, they're not as big and fat as the animals living beneath the Antarctic sea ice," he says.

How to weigh a whale

How exactly do scientists know that the whales have become thinner? Do Fredrik Christiansen and his colleagues lift the huge animals out of the water with oversized weighing scales? No, he explains. Instead, the researchers have invented a method to work out the weight of the whales based on photographs taken by drones.

"Right whales like to lie flat on the sea surface. This makes them easy to photograph from above. When the drone has taken some photographs -- and we know the height of the drone -- we can calculate the size of the animal," he explains.

However, in order to know the weight of the whale, it is necessary to know the volume of the whale -- not just the length and width. But because scientists like Fredrik Christiansen have observed many right whales rolling around on the sea surface over the years -- and thereby have been able to measure their size -- the scientists now know the relationship between length, width and volume of the whales.

"We calculate the volume using the drone photographs -- and when we know the volume, we more or less know the weight. In this way, we can see that the whales have become thinner over the past 30 years -- and that's serious. The weight of the mothers has a huge impact on their calves," he says.

Small and weak whale calves

Thirty to forty years ago, the southern right whale had calves every three years on average. But this is no longer true, explains Fredrik Oscar Christiansen.

"In the 1980s, researchers observed that the right whales off the coast of South Africa gave birth to a new calf every three years. But because it's now difficult for them to fatten up during summer, this has fallen to every five years. This means that the population is growing significantly more slowly.

And not only do the whale calves come more rarely. The calves born today are smaller and grow more slowly.

"The amount of fat on the whale mother is directly linked to how much energy she can give to her calf through her milk. When the mother is thin, the calf gets less energy and grows more slowly," he says.

The researchers have discovered that the northern right whales in the waters off Canada and the northern US are not growing quite as big as before. This is possibly because the calves are born smaller. According to the researchers' calculations, a whale born in 2019 will be one metre shorter on average when it is fully grown than a whale born in 1981.

"Small calves have a higher risk of dying. They're more vulnerable if a killer whale attacks."

Hunted close to extinction

Right whales were given their name because they were considered the "right" whales to catch. People began hunting the large whales as early as in the 14th century, and for hundreds of years, they were hunted fiercely in both northern and southern parts of the Atlantic.

Oil from the whales' fat was one of the most important sources of energy. Train oil, which the oil used to be called, became a fuel in lamps -- both for indoors and for street lights. The demand for train oil was also one of the most important reasons why Denmark colonised Greenland in the 18th century.

Around 1900, train oil was replaced by another more efficient energy source: crude oil. The black gold pumped up from the underground meant that whale hunting was no longer profitable.

The southern right whale is one of the species that benefitted from the end of whaling. For more than 100 years, the population has been allowed to grow large and healthy again. And this is not just good for the whales, but also for the entire Southern Ocean ecosystem.

Because the whales bring nourishment to areas of the sea with little food.

Extremely important for the marine ecosystem

The sea around the Antarctic where the right whales come to eat has more life than any other sea on the planet. Despite the fact that the area only contains five per cent of the Earth's sea water, 20 per cent of all marine life lives in the area.

The many hours of sunshine in the summer, turbulent sea currents and the low temperature are perfect for teeming life.

The light makes marine algae grow explosively. The sea currents swirl the algae and nourishment around so that krill and plankton can gorge themselves. When full, the small crustaceans reproduce and form gigantic swarms. In some places, there may be as many as 35,000 krill in one cubic metre of water.

The right whales -- and many other animals -- stuff themselves with the abundance of krill, but unlike many other species, the whales migrate thousands of kilometres north to overwinter.

"The whales are extremely important for the parts of the sea where there is not much food. When the whales die, their huge bodies sink to the bottom. In the depths, they become food for a whole ecosystem of eel, sharks, crabs, lobsters, worms and microorganisms," says Fredrik Christiansen.

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Sugar is processed differently in the brains of obesity-prone vs. obesity-resistant rats

On a diet? Perhaps you're avoiding sweets or carbs altogether or curbing late-night munchies. These are examples of behavior modifications and when it comes to food, avoiding those diet triggers can be pretty hard to do.

To understand what drives people to overeat, scientists are looking more closely at a brain structure involved in motivation, called the nucleus accumbens. This small region drives reward-seeking behaviors underlying the pursuit of sex, recreational drugs like nicotine and alcohol, and food.

"These brain motivation centers evolved to help us survive; finding food and having sex are essential to the survival of an individual and of a species," said Carrie Ferrario, Ph.D., associate professor in the Department of Pharmacology at U-M Medical School.

"What was advantageous when food was hard to find has become a disadvantage and unhealthy in the current food dense environment. This is compounded by the over-abundance of over-processed, low nutrition foods that may satisfy our taste but leave our bodies unnourished. People don't tend to find it difficult to turn down an extra serving of broccoli, but just one more french-fry or making room for a bit of chocolate dessert...that's a different story. The real challenge is overcoming these urges and changing our behavior when it comes to food," Ferrario added.

Given the immense toll obesity takes on virtually all body systems, Ferrario, Peter Vollbrecht, Ph.D., of Western Michigan University, and their colleagues are using rat models to understand potential brain differences between animals who are prone to over-eating and obesity and those who are not.

Previous research from Ferrario's lab pinpointed differences in the nucleus accumbens in obesity-prone and obesity-resistant rats. Their latest study, published in the Journal of Neurochemistry, tracked what was happening in real time in the brain when these animals were presented with glucose, a type of sugar, labeled with a tracer. The tracer allowed the researchers to measure this new sugar in the brain.

Sugar is the brain's main fuel source and once there, the molecule is broken down and used to create new molecules such as glutamine, glutamate, and GABA, each with an important role in influencing the activation of neurons in the brain and nervous system.

"Glucose that is consumed gets broken down and then its carbons get incorporated into neurotransmitters. We see those labelled carbons showing up in those molecules -- glutamate, glutamine, and GABA -- over time," explained Vollbrecht.

They found that glucose was taking longer to get into the nucleus accumbens of obesity-prone animals.

Furthermore, when measuring the concentration of the glutamate, glutamine, and GABA, they discovered excess levels of glutamate, an excitatory neurotransmitter. This, said the team, implied a defect in a neurotransmitter recycling process, typically maintained in the nervous system by star-shaped cells called astrocytes.

Normally, astrocytes will pull glutamate out of the space between neurons, called the synapse, convert it into glutamine, and then shuttle it back to cells that produce GABA or glutamate. This sequence is crucial for turning neurons off and on. "The findings suggest that we're getting too much glutamate and it's not being taken out of the synapse," said Vollbrecht.

Ferrario added, "The balance between glutamate and GABA (the main inhibitory transmitter) is really important for brain function and will influence activity of the neurons in the nucleus accumbens."

This balance, and therefore brain activity, is different in obesity-prone vs. obesity-resistant rats.

The fact that these rats are either prone to obesity or not is important for disentangling cause and effect, says Vollbrecht. "It allows us to remove diet as one of the variables."

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Evolution of wheat spikes since the Neolithic revolution

Around 12,000 years ago, the Neolithic revolution radically changed the economy, diet and structure of the first human societies in the Fertile Crescent of the Near East. With the beginning of the cultivation of cereals -- such as wheat and barley -- and the domestication of animals, the first cities emerged in a new social context marked by a productive economy. Now, a study published in the journal Trends in Plant Science and co-led by the University of Barcelona, the Agrotecnio centre and the University of Lleida, analyses the evolution of wheat spikes since its cultivation began by the inhabitants of ancient Mesopotamia -- the cradle of agriculture in the world -- between the Tigris and the Euphrates.

The authors of the study are Rut Sánchez-Bragado and Josep Lluís Araus-Ortega, from the UB Faculty of Biology and Agrotecnio-UdL; Gustavo A. Slafer, ICREA researcher at the UdL School of Agrifood and Forestry Science and Engineering, and Gemma Molero, from the International Maize and Wheat Improvement Center in Mexico, currently a researcher at KWS Seeds Inc.

A cereal that changed human history

The cultivation of wheat -- a grass that became basic food -- represented a turning point in the progress of human civilisation. Today it is the world's most important crop in terms of food security, but EU data warn that the impact of climate change could significantly increase its price and modify its production process in certain areas of the world.

Throughout the domestication process of wheat, the plant phenotype has undergone both rapid (within a few hundred years) and slow (thousands of years) changes, such as the weakening of the rachis, the increase in seed size, and the reduction or disappearance of the awns. In particular, awned and awnless wheat varieties are found all over the world, although the latter tend to be abundant in regions with arid climates, especially during the final stages of cultivation in late spring, a condition typical of Mediterranean environments.

"It is important to conduct studies that show which wheat varieties are best adapted to different environmental growing conditions, especially in a context of climate change. Studying the past retrospectively can give us an idea of the evolution of wheat cultivation over the millennia since agriculture appeared in ancient Mesopotamia," says Rut Sánchez-Bragado, first author of the study, who got a PhD at the UB.

"Awns are organs of the spike that have traditionally been associated with the plant's adaptations to drought conditions," says Josep Lluís Araus, professor at the Department of Evolutionary Biology, Ecology and Environmental Sciences of the Faculty of Biology.

"However, archaeological and historical records show that the wheat spike has existed predominantly with awns for more than ten millennia after the domestication of wheat. It is not until the last millennium that evidence shows in many cases the absence of awns, indicating a selection by farmers -- probably in an undirected way -- against this organ," stresses Araus, one of the most cited authors in the world according to Clarivate Analytics' Highly Cited Researchers (2022).

"The role of wheat awns in their performance remains controversial despite decades of studies," says researcher Gustavo A. Slafer, corresponding author of the study.

Spike awns: beneficial for the plant?

Is the presence of awns on the spike beneficial for the plant and the crops? Although there is no scientific consensus, "everything suggests that in conditions where the plant does not suffer from water stress, the extra photosynthetic capacity of the awns does not compensate for other potential negative effects (reduced susceptibility to fungal diseases, limitation in the total number of large ones that an ear supports, etc.)," says Araus.

"However, in wetter climates the awns accumulate moisture and can promote the spread of diseases," says Rut Sánchez-Bragado. "So, as the world's population is continuously growing, it is necessary to investigate the role of the awned spikes in the changing conditions of our climate in order to meet the world's demand for a primary food commodity such as wheat."

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Why a high fat diet could reduce the brain's ability to regulate food intake

Regularly eating a high fat/calorie diet could reduce the brain’s ability to regulate calorie intake. New research in rats published in The Journal of Physiology found that after short periods of being fed a high fat/high calorie diet, the brain adapts to react to what is being ingested and reduces the amount of food eaten to balance calorie intake. The researchers from Penn State College of Medicine, US, suggest that calorie intake is regulated in the short-term by cells called astrocytes (large star-shaped cells in the brain that regulate many different functions of neurons in the brain) that control the signalling pathway between the brain and the gut. Continuously eating a high fat/calorie diet seems to disrupt this signalling pathway.

Understanding the brain’s role and the complex mechanisms that lead to overeating, a behaviour that can lead to weight gain and obesity, could help develop therapies to treat it. Obesity is a global public-health concern because it is associated with increased risk of cardiovascular diseases and type 2 diabetes. In England, 63% of adults are considered above a healthy weight and around half of these are living with obesity. One in three children leaving primary school are overweight or obese1.

Dr Kirsteen Browning, Penn State College of Medicine, US, said,

“Calorie intake seems to be regulated in the short-term by astrocytes. We found that a brief exposure (three to five days) of high fat/calorie diet has the greatest effect on astrocytes, triggering the normal signalling pathway to control the stomach. Over time, astrocytes seem to desensitise to the high fat food. Around 10-14 days of eating high fat/calorie diet, astrocytes seem to fail to react and the brain’s ability to regulate calorie intake seems to be lost. This disrupts the signalling to the stomach and delays how it empties.”

Astrocytes initially react when high fat/calorie food is ingested. Their activation triggers the release of gliotransmitters, chemicals (including glutamate and ATP) that excite nerve cells and enable normal signalling pathways to stimulate neurons that control how the stomach works. This ensures the stomach contracts correctly to fill and empty in response to food passing through the digestive system. When astrocytes are inhibited, the cascade is disrupted. The decrease in signalling chemicals leads to a delay in digestion because the stomach doesn’t fill and empty appropriately.

The vigorous investigation used behavioural observation to monitor food intake in rats (N=205, 133 males, 72 females) which were fed a control or high fat/calorie diet for one, three, five or 14 days. This was combined with pharmacological and specialist genetic approaches (both in vivo and in vitro) to target distinct neural circuits. Enabling the researchers to specifically inhibit astrocytes in a particular region of the brainstem (the posterior part of the brain that connects the brain to the spinal cord), so they could assess how individual neurons behaved to studying rats' behaviour when awake.

Human studies will need to be carried out to confirm if the same mechanism occurs in humans. If this is the case, further testing will be required to assess if the mechanism could be safely targeted without disrupting other neural pathways.

The researchers have plans to further explore the mechanism. Dr Kirsteen Browning said.

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Intermittent fasting may reverse type 2 diabetes

After an intermittent fasting diet intervention, patients achieved complete diabetes remission, defined as an HbA1c (average blood sugar) level of less than 6.5% at least one year after stopping diabetes medication, according to a new study published in the Endocrine Society's Journal of Clinical Endocrinology & Metabolism.

Intermittent fasting diets have become popular in recent years as an effective weight loss method. With intermittent fasting, you only eat during a specific window of time. Fasting for a certain number of hours each day or eating just one meal a couple of days a week can help your body burn fat. Research shows intermittent fasting can lower your risk of diabetes and heart disease.

"Type 2 diabetes is not necessarily a permanent, lifelong disease. Diabetes remission is possible if patients lose weight by changing their diet and exercise habits," said Dongbo Liu, Ph.D., of Hunan Agricultural University in Changsha, China. "Our research shows an intermittent fasting, Chinese Medical Nutrition Therapy (CMNT), can lead to diabetes remission in people with type 2 diabetes, and these findings could have a major impact on the over 537 million adults worldwide who suffer from the disease."

The researchers conducted a 3-month intermittent fasting diet intervention among 36 people with diabetes and found almost 90% of participants, including those who took blood sugar-lowering agents and insulin, reduced their diabetes medication intake after intermittent fasting. Fifty-five percent of these people experienced diabetes remission, discontinued their diabetes medication and maintained it for at least one year.

The study challenges the conventional view that diabetes remission can only be achieved in those with a shorter diabetes duration (0-6 years). Sixty-five percent of the study participants who achieved diabetes remission had a diabetes duration of more than 6 years (6-11 years).

"Diabetes medications are costly and a barrier for many patients who are trying to effectively manage their diabetes. Our study saw medication costs decrease by 77% in people with diabetes after intermittent fasting," Liu said.

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Cravings for fatty foods traced to gut-brain connection

A dieter wrestling with cravings for fatty foods might be tempted to blame their tongue: the delicious taste of butter or ice cream is hard to resist. But new research investigating the source of our appetites has uncovered an entirely new connection between the gut and the brain that drives our desire for fat.

At Columbia's Zuckerman Institute, scientists studying mice found that fat entering the intestines triggers a signal. Conducted along nerves to the brain, this signal drives a desire for fatty foods. Published September 7, 2022, in Nature, the new study raises the possibility of interfering with this gut-brain connection to help prevent unhealthy choices and address the growing global health crisis caused by overeating.

"We live in unprecedented times, in which the overconsumption of fats and sugars is causing an epidemic of obesity and metabolic disorders," said first author Mengtong Li, PhD, a postdoctoral researcher in the lab of the Zuckerman Institute's Charles Zuker, PhD, supported by the Howard Hughes Medical Institute. "If we want to control our insatiable desire for fat, science is showing us that the key conduit driving these cravings is a connection between the gut and the brain."

This new view of dietary choices and health started with previous work from the Zuker lab on sugar. Researchers found that glucose activates a specific gut-brain circuit that communicates to the brain in the presence of intestinal sugar. Calorie-free artificial sweeteners, in contrast, do not have this effect, likely explaining why diet sodas can leave us feeling unsatisfied.

"Our research is showing that the tongue tells our brain what we like, such as things that taste sweet, salty or fatty," said Dr. Zuker, who is also a professor of biochemistry and molecular biophysics and of neuroscience at Columbia's Vagelos College of Physicians and Surgeons. "The gut, however, tells our brain what we want, what we need."

Dr. Li wanted to explore how mice respond to dietary fats: the lipids and fatty acids that every animal must consume to provide the building blocks of life. She offered mice bottles of water with dissolved fats, including a component of soybean oil, and bottles of water containing sweet substances known to not affect the gut but that are initially attractive. The rodents developed a strong preference, over a couple of days, for the fatty water. They formed this preference even when the scientists genetically modified the mice to remove the animals' ability to taste fat using their tongues.

"Even though the animals could not taste fat, they were nevertheless driven to consume it," said Dr. Zuker.

The researchers reasoned that fat must be activating specific brain circuits driving the animals' behavioral response to fat. To search for that circuit, Dr. Li measured brain activity in mice while giving the animals fat. Neurons in one particular region of the brainstem, the caudal nucleus of the solitary tract (cNST), perked up. This was intriguing because the cNST was also implicated in the lab's previous discovery of the neural basis of sugar preference.

Dr. Li then found the communications lines that carried the message to the cNST. Neurons in the vagus nerve, which links the gut to the brain, also twittered with activity when mice had fat in their intestines.

Having identified the biological machinery underlying a mouse's preference for fat, Dr. Li next took a close look at the gut itself: specifically the endothelial cells lining the intestines. She found two groups of cells that sent signals to the vagal neurons in response to fat.

"One group of cells functions as a general sensor of essential nutrients, responding not only to fat, but also to sugars and amino acids," said Dr. Li. "The other group responds to only fat, potentially helping the brain distinguish fats from other substances in the gut."

Dr. Li then went one important step further by blocking the activity of these cells using a drug. Shutting down signaling from either cell group prevented vagal neurons from responding to fat in the intestines. She then used genetic techniques to deactivate either the vagal neurons themselves or the neurons in the cNST. In both cases, a mouse lost its appetite for fat.

"These interventions verified that each of these biological steps from the gut to the brain is critical for an animal's response to fat," said Dr. Li. "These experiments also provide novel strategies for changing the brain's response to fat and possibly behavior toward food."

The stakes are high. Obesity rates have nearly doubled worldwide since 1980. Today, nearly half a billion people suffer from diabetes.

"The overconsumption of cheap, highly processed foods rich in sugar and fat is having a devastating impact on human health, especially among people of low income and in communities of color," said Dr. Zuker. "The better we understand how these foods hijack the biological machinery underlying taste and the gut-brain axis, the more opportunity we will have to intervene."

Scott Sternson, PhD, a professor of neuroscience at University of California, San Diego, who was not involved in the new research highlighted its potential for improving human health.

"This exciting study offers insight about the molecules and cells that compel animals to desire fat," said Dr. Sternson, whose work focuses on how the brain controls appetite. "The capability of researchers to control this desire may eventually lead to treatments that may help combat obesity by reducing consumption of high-calorie fatty foods."

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Long term high-fat diet expands waistline and shrinks brain

New research shows that fatty foods may not only be adding to your waistline but also playing havoc with your brain.

An international study led by UniSA neuroscientists Professor Xin-Fu Zhou and Associate Professor Larisa Bobrovskaya has established a clear link between mice fed a high-fat diet for 30 weeks, resulting in diabetes, and a subsequent deterioration in their cognitive abilities, including developing anxiety, depression and worsening Alzheimer's disease.

Mice with impaired cognitive function were also more likely to gain excessive weight due to poor metabolism caused by brain changes.

Researchers from Australia and China have published their findings in Metabolic Brain Disease.

UniSA neuroscientist and biochemist Associate Professor Larisa Bobrovskaya says the research adds to the growing body of evidence linking chronic obesity and diabetes with Alzheimer's disease, predicted to reach 100 million cases by 2050.

"Obesity and diabetes impair the central nervous system, exacerbating psychiatric disorders and cognitive decline. We demonstrated this in our study with mice," Assoc Prof Bobrovskaya says.

In the study, mice were randomly allocated to a standard diet or a high-fat diet for 30 weeks, starting at eight weeks of age. Food intake, body weight and glucose levels were monitored at different intervals, along with glucose and insulin tolerance tests and cognitive dysfunction.

The mice on the high-fat diet gained a lot of weight, developed insulin resistance and started behaving abnormally compared to those fed a standard diet.

Genetically modified Alzheimer's disease mice showed a significant deterioration of cognition and pathological changes in the brain while fed the high fat diet.

"Obese individuals have about a 55 per cent increased risk of developing depression, and diabetes will double that risk," Assoc Prof Bobrovskaya says.

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Diet plays key role in ADHD symptoms in children

 Here's a good reason for children with attention deficit hyperactivity disorder (ADHD) to eat their fruits and vegetables: It may help reduce inattention issues, a new study suggests.

As part of a larger study, researchers asked parents of 134 kids with ADHD symptoms to complete a detailed questionnaire about the typical foods the children ate, including portion sizes, over a 90-day period.

Another questionnaire asked parents to rate symptoms of inattention -- a hallmark of ADHD -- in their kids, such as having trouble staying focused, not following instructions, difficulty remembering things, and difficulty regulating emotions.

Results showed that kids who consumed more fruits and vegetables showed less severe symptoms of inattention, said Irene Hatsu, co-author of the study and associate professor of human nutrition at The Ohio State University.

"Eating a healthy diet, including fruits and vegetables, may be one way to reduce some of the symptoms of ADHD," Hatsu said.

The study was published online recently in the journal Nutritional Neuroscience.

The data for this research was collected as part of the Micronutrients for ADHD in Youth (MADDY) Study, which examined the efficacy of a 36-ingredient vitamin and mineral supplement to treat symptoms of ADHD and poor emotional control in the 134 kids aged 6 to 12.

The study that evaluated the effectiveness of the supplement showed that children who took the micronutrients were three times as likely to show significant improvement in their ADHD and emotional dysregulation symptoms than those who took a placebo. That study was published last year in the Journal of the American Academy of Child and Adolescent Psychiatry.

Another study involving the same children, published earlier this year in the journal Nutrients, showed that kids whose families had higher levels of food insecurity were more likely than others to show more severe symptoms of emotional dysregulation, such as chronic irritability, angry moods and outbursts of anger.

The three studies all paint a similar picture, Hatsu said: A healthy diet that provides all the nutrients that children require can help reduce the symptoms of ADHD in children.

"What clinicians usually do when kids with ADHD start having more severe symptoms is increase the dose of their treatment medication, if they are on one, or put them on medication," Hatsu said.

"Our studies suggest that it is worthwhile to check the children's access to food as well as the quality of their diet to see if it may be contributing to their symptom severity."

Children in the MADDY study, all of whom met the criteria for ADHD, were recruited from three sites: Columbus, Ohio; Portland, Oregon; and Lethbridge, Alberta, Canada. The study took place between 2018 and 2020. Participants were either not taking medication or stopped using it two weeks before the study began.

The studies on fruit and vegetable intake and the role of food insecurity were based on data collected when the children were first enrolled in the study, before they began taking the micronutrient supplement or placebo.

Why may diet be so important in ADHD?

Researchers believe that ADHD is related to low levels of some neurotransmitters in the brain -- and vitamins and minerals play a key role as cofactors in helping the body make those important neurochemicals and in overall brain function, Hatsu said.

Food insecurity may play an additional role.

"Everyone tends to get irritated when they're hungry and kids with ADHD are no exception. If they're not getting enough food, it could make their symptoms worse," she said.

Also, the stress of parents who are upset about not being able to provide enough food for their children can create family tension that could lead to more symptoms for children with ADHD.

The MADDY study is one of the first to look at the relationship between ADHD symptoms and diet quality among children in the United States and Canada, Hatsu said.

That's important because Western diets are more likely than many others, such as the Mediterranean diet, to fall short on fruit and vegetable intake, she said.

"We believe clinicians should assess the food security status of children with ADHD before creating or changing a treatment program," Hatsu said.

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Diet type can increase potentially harmful gas in the gut

Published in Clinical Nutrition, researchers from the University of Minnesota Medical School looked at colonic hydrogen sulfide -- a toxic gas in the body that smells like rotten eggs -- production in people in response to animal- and plant-based diet interventions.

"Although the role of hydrogen sulfide has long been a subject of great interest in the pathogenesis of multiple important diseases -- such as ulcerative colitis, colon cancer, and obesity -- past investigations have not been able to link dietary data, microbiome characterization and actual hydrogen sulfide production," said Alexander Khoruts, MD, a gastroenterologist in the U of M Medical School and M Health Fairview. "This is what we have done here."

From a human cohort, the study supports the general hypothesis that hydrogen sulfide produced by the gut microbiota increases with an animal-based diet. However, the results also suggested the existence of gut microbiome enterotypes that respond differentially and even paradoxically to different dietary input.

The study found that:
 

• In the majority of participants, a plant-based diet resulted in a lower hydrogen sulfide production compared to an animal-based (i.e., western) diet.
• As expected, a plant-based diet contained more fiber, while an animal-based diet contained more protein.
• In some individuals, plant-based diets did not lower hydrogen sulfide production and even led to some increases in it.
• Preliminary results suggested the existence of different compositions of gut microbiota (enterotypes) that correlate with differential responsiveness to diet in terms of hydrogen sulfide production.

"The study was consistent with the general understanding that regular intake of fiber-containing foods is beneficial to gut health," said Dr. Levi Teigen, a nutrition researcher in the Division of Gastroenterology in the U of M Medical School. "Future analyses of the gut microbiome may help to individualize nutrition interventions."

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Eating protein from a greater variety of sources may lower risk of high blood pressure

Eating a balanced diet including protein from a greater variety of sources may help adults lower the risk of developing high blood pressure, according to new research published today in Hypertension, a peer-reviewed journal of the American Heart Association.

Nearly half of the U.S. population has hypertension, or high blood pressure -- one of the leading contributors to cardiovascular disease. When left untreated, high blood pressure damages the circulatory system and is a significant contributing factor to heart attack, stroke and other health conditions.

"Nutrition may be an easily accessible and effective measure to fight against hypertension. Along with fat and carbohydrates, protein is one of the three basic macronutrients," said study author Xianhui Qin, M.D., of the National Clinical Research Center for Kidney Disease at Nanfang Hospital, Southern Medical University in Guangzhou, China.

There is a strong association between poor diet quality and increased risk of cardiovascular disease and death from cardiovascular disease. In its 2021 dietary guidance to improve cardiovascular health, the American Heart Association advises people eat healthy sources of protein, mostly from plants and may include seafood and low-fat or fat-free dairy products, and, if desired, lean cuts and unprocessed forms of meat or poultry. The American Heart Association recommends eating one to two servings, or 5.5 ounces, of protein daily.

The study authors analyzed health information for nearly 12,200 adults living in China who were part of at least 2 out of 7 rounds of the China Health and Nutrition Survey from 1997 to 2015 (surveys taken every 2-4 years). Participants' initial survey was used as a baseline, while data from their last round was used as a follow-up for comparison. Participants were an average age of 41 years, and 47% were men. The survey measured dietary intake in three consecutive 24-hour dietary recalls and a household food inventory. A trained interviewer collected 24-hour dietary information over 3 days in the same week during each round of the survey.

Participants were given a protein "variety score" based on the number of different sources of protein eaten out of 8 reported: whole grains, refined grains, processed red meat, unprocessed red meat, poultry, fish, egg and legumes. One point was given for each source of protein, with a maximum variety score of 8. The researchers then evaluated the association for new onset hypertension in relation to the protein variety score.

New-onset hypertension was defined as systolic (top number) blood pressure greater than or equal to 140 mm Hg and/or diastolic (bottom number) blood pressure greater than or equal to 90 mm Hg, taking blood pressure-lowering medicine, or self-reporting that a physician diagnosed high blood pressure since their last survey visit. Average time to follow-up was 6 years.

The analysis found:
 

• More than 35% of the nearly 12,200 participants developed new-onset high hypertension during follow-up.
• Compared to participants with the lowest variety score for protein intake (less than 2), those with the highest variety score (4 or higher) had a 66% lower risk of developing high blood pressure.
• For each of the 8 protein types, there was a window of consumption amount where the risk of hypertension was lower. Researchers described this as the appropriate level of consumption.
• When total quantity of protein intake was considered, the amount consumed was divided into five categories (quintiles), from least to most intake. People who ate the least amount of total protein and those who ate most protein had the highest risk for new onset of hypertension.

"The heart health message is that consuming a balanced diet with proteins from various different sources, rather than focusing on a single source of dietary protein, may help to prevent the development of high blood pressure," Qin said.

A limitation of the study is its observational design. Because researchers used prior health information, they could not definitively prove protein intake of any kind or quantity caused or prevented new-onset hypertension.

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Brief 5:2 diet advice is as effective as traditional GP advice, but people like it better, according to new study

A clinical trial has found people prefer receiving information on the 5:2 diet than standard GP weight management advice despite both interventions achieving similar modest weight loss results.

The trial, funded by the Medical Research Council (MRC) and led by Queen Mary University of London, is the first randomised evaluation of the 5:2 diet, a popular type of intermittent fasting regime. Researchers studied the long-term effects of providing 5:2 diet instructions compared to traditional weight loss advice in 300 UK adults with obesity over a one-year period.

The findings show that long-term weight loss was similar for those who received 5:2 diet or standard weight management advice with 18 per cent and 15 per cent of participants respectively losing at least five per cent of their body weight at one year. However, when asked to rate each intervention, participants in the 5:2 diet group were more likely to recommend the intervention to others or be willing to continue with their diet.

Previous evidence suggests that peer support could be important for encouraging dieters to adhere to and realise the effects of the 5:2 diet. To test this, the researchers studied the impact of a weekly support group in addition to the simple 5:2 diet advice. They found that whilst initially face-to-face support generated better early effects and improved adherence to the 5:2 diet, these effects weakened over time.

Together, the findings suggest that providing brief advice on the 5:2 diet could extend the options clinicians can offer to patients.

Dr Katie Myers Smith, Chartered Health Psychologist and Senior Research Fellow at Queen Mary, said:"Here we've been able to provide the first results on the effectiveness of simple 5:2 diet advice in a real-life setting. We found that although the 5:2 diet wasn't superior to traditional approaches in terms of weight loss, users preferred this approach as it was simpler and more attractive. Based on these findings, GPs may consider recommending the 5:2 diet as part of their standard weight management advice."

The 5:2 diet is popular intermittent fasting weight loss intervention whereby dieters restrict their caloric intake on two non-consecutive days a week and then apply sensible eating on the remaining days. It first became popular in the UK through a BBC Horizon documentary and follow-up bestselling book.

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Diet restricted size of hunter-gatherer societies

Short growing seasons limited the possible size of hunter-gatherer societies by forcing people to rely on meat, according to a recent study by a team of international reseachers including McGill University professor Eric Galbraith.

After looking at population size for the roughly 300 hunter-gatherer societies which existed until quite recently, the researchers found that many of these groups were much smaller than might have been expected from the local ecosystem productivity. In regions with short growing seasons, hunter-gatherer groups had smaller populations per square kilometre than groups who depended on abundant plant foods throughout the year.

Need for meat limited population size

"Basically, if people had to live through long dry or cold seasons when plant food was scarce, in order to survive they had to depend on hunting a very limited number of animals," explains Galbraith, a professor in McGill's Department of Earth and Planetary Sciences and at the ICTA-UAB (Institut de Ciència i Tecnologia Ambientals of the Autonomous University of Barcelona), and a senior author on the paper published recently in the journal Nature Ecology & Evolution.

"This led to a seasonal bottleneck in the amount of food available, which then set the overall limit on the population size, no matter how much food there was during the plentiful times."

The team developed a mathematical model that simulates daily human foraging activities (gathering and hunting) and the resultant carbon (energy) flows between vegetation, animals, and hunter-gatherers in a realistic global environment.

"We were struck by the fact that -- despite a long list of unknowns -- a very strong result emerged from the model equations," says Galbraith. "Wherever growing seasons were short, hunter gatherers required meat to make up a high percentage of their diets. And -- just as in the modern world -- it took much more land to produce the same amount of meat as plant-based food."

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Researchers call for a focus on fitness over weight loss for obesity-related health conditions

The prevalence of obesity around the world has tripled over the past 40 years, and, along with that rise, dieting and attempts to lose weight also have soared. But according to a review article publishing September 20 in the journal iScience, when it comes to getting healthy and reducing mortality risk, increasing physical activity and improving fitness appear to be superior to weight loss. The authors say that employing a weight-neutral approach to the treatment of obesity-related health conditions also reduces the health risks associated with yo-yo dieting.

"We would like people to know that fat can be fit, and that fit and healthy bodies come in all shapes and sizes," says co-author Glenn Gaesser of the College of Health Solutions at Arizona State University. "We realize that in a weight-obsessed culture, it may be challenging for programs that are not focused on weight loss to gain traction. We're not necessarily against weight loss; we just think that it shouldn't be the primary criterion for judging the success of a lifestyle intervention program."

"This is especially important when you consider the physiological realities of obesity," says co-author Siddhartha Angadi of the School of Education and Human Development at the University of Virginia. "Body weight is a highly heritable trait, and weight loss is associated with substantial metabolic alterations that ultimately thwart weight loss maintenance."

Obesity is associated with a number of health conditions, including cardiovascular disease, diabetes, cancer, and problems with the bones and joints. But weight cycling, commonly called yo-yo dieting, is also associated with health problems, including muscle loss, fatty liver disease, and diabetes. The authors say that by focusing on fitness rather than weight loss, people can gain the benefits of exercise while avoiding the risks associated with weight cycling.

Current public health guidelines recommend that adults accumulate 150-300 minutes per week of moderate-intensity physical activity (the intensity equivalent to walking at casual-to-brisk pace) or 75-150 minutes per week of vigorous-intensity physical activity (the intensity equivalent to jogging or running). "But it's important to note that the benefits of exercise are dose dependent, with the biggest benefits coming from just moving out of the couch-potato zone to doing at least some moderate-intensity activity," Gaesser says. "It's also important to emphasize that physical activity can be accumulated throughout the day. For example, multiple short walks during the day (even as short as two to ten minutes each) are just as beneficial as one long walk for health benefits."

In the review, the authors cite recent research focused on the magnitude of mortality risk reduction associated with weight loss compared to that associated with an increase in physical activity or cardiorespiratory fitness. The risk reduction associated with increasing fitness and physical activity was consistently greater than that associated with intentional weight loss. They also looked at the magnitude of reduction in the risk markers of cardiovascular disease that are associated with either weight loss or increased physical activity. They used meta-analyses from several studies done over a range of time periods and across a broad geographical area. "Science has generally supported the main points proposed in Big Fat Lies, a book on this topic that I first published in 1996," Gaesser notes.

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Study reveals missing link between high-fat diet, microbiota and heart disease

A high-fat diet disrupts the biology of the gut's inner lining and its microbial communities -- and promotes the production of a metabolite that may contribute to heart disease, according to a study published Aug. 13 in the journal Science.

The discoveries in animal models support a key role for the intestines and microbiota in the development of cardiovascular disease, said Mariana Byndloss, DVM, PhD, assistant professor of Pathology, Microbiology and Immunology at Vanderbilt University Medical Center.

The intestines, she noted, have been relatively understudied by scientists seeking to understand the impact of obesity.

"Before COVID, obesity and metabolic syndrome were considered the pandemic of the 21st century. Right now, roughly 40% of the U.S. population is obese, and that percentage is predicted to climb," Byndloss said. "Our research has revealed a previously unexplored mechanism for how diet and obesity can increase risk of cardiovascular disease -- by affecting the relationship between our intestines and the microbes that live in our gut."

In previous studies, Byndloss and Andreas Bäumler, PhD, at the University of California at Davis, found that the epithelial cells lining the intestines and gut microbes share a mutually beneficial relationship that promotes a healthy gut environment. They wondered if diseases like obesity affect this relationship.

The collaborating research teams found that a high-fat diet causes inflammation and damages intestinal epithelial cells in animal models. The high-fat diet impairs the function of energy-generating mitochondria, Byndloss explained, causing the intestinal cells to produce more oxygen and nitrate.

These factors, in turn, stimulate the growth of harmful Enterobacteriaceae microbes, such as E. coli, and boost bacterial production of a metabolite called TMA (trimethylamine). The liver converts TMA to TMAO (trimethylamine-N-oxide), which has been implicated in promoting atherosclerosis and increasing the relative risk for all-cause mortality in patients.

"It was known that exposure to a high-fat diet causes dysbiosis -- an imbalance in the microbiota favoring harmful microbes, but we didn't know why or how this was happening," Byndloss said. "We show one way that diet directly affects the host and promotes the growth of bad microbes."

The researchers demonstrated that a drug currently approved for treatment of inflammatory bowel disease restored the function of intestinal epithelial cells and blunted the increase in TMAO in the animal models. The drug, called 5-aminosalicylic acid, activates mitochondrial bioenergetics in the intestinal epithelium.

"This is evidence that it's possible to prevent the negative outcomes associated with a high-fat diet," Byndloss said. A drug such as 5-aminosalicylic acid might be used in conjunction with a probiotic to both restore a healthy intestinal environment and boost beneficial microbe levels, she added.

"Only by fully understanding the relationship between the host -- us -- and gut microbes during health and disease are we going to be able to design therapies that will be effective in controlling obesity and obesity-associated outcomes like cardiovascular disease."

Byndloss and her team plan to extend their studies into animal models of cardiovascular disease. They also are exploring the role of the host-microbe relationship in the development of other diseases including colorectal cancer.

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Declining biodiversity in wild Amazon fisheries threatens human diet

A new study of dozens of wild fish species commonly consumed in the Peruvian Amazon says that people there could suffer major nutritional shortages if ongoing losses in fish biodiversity continue. Furthermore, the increasing use of aquaculture and other substitutes may not compensate. The research has implications far beyond the Amazon, since the diversity and abundance of wild-harvested foods is declining in rivers and lakes globally, as well as on land. Some 2 billion people globally depend on non-cultivated foods; inland fisheries alone employ some 60 million people, and provide the primary source of protein for some 200 million. The study appears this week in the journal Science Advances.

The authors studied the vast, rural Loreto department of the Peruvian Amazon, where most of the 800,000 inhabitants eat fish at least once a day, or an average of about 52 kilograms (115 pounds) per year. This is their primary source not only of protein, but fatty acids and essential trace minerals including iron, zinc and calcium. Unfortunately, it is not enough; a quarter of all children are malnourished or stunted, and more than a fifth of women of child-bearing age are iron deficient.

Threats to Amazon fisheries, long a mainstay for both indigenous people and modern development, are legion: new hydropower dams that pen in big migratory fish (some travel thousands of miles from Andes headwaters to the Atlantic estuary and back); soil erosion into rivers from deforestation; toxic runoff from gold mines; and over-exploitation by fishermen themselves, who are struggling to feed fast-growing populations. In Loreto, catch tonnages are stagnating; some large migratory species are already on the decline, and others may be on the way. It is the same elsewhere; globally, a third of freshwater fish species are threatened with extinction, and 80 are already known to be extinct, according to the World Wildlife Fund.

Different species of animals and plants contain different ratios of nutrients, so biodiversity is key to adequate human nutrition, say the researchers. "If fish decline, the quality of the diet will decline," said the study's senior coauthor, Shahid Naeem, director of Columbia University's Earth Institute Center for Environmental Sustainability. "Things are definitely declining now, and they could be on the path to crashing eventually."

To study the region's fish, the study's lead author, then-Columbia PhD. student Sebastian Heilpern, made numerous shopping trips to the bustling Belén retail market in the provincial capital of Iquitos. He also visited the city's Amazon River docks, where wholesale commerce begins at 3:30 in the morning. He and another student bought multiple specimens of as many different species as they could find, and ended up with 56 of the region's 60-some main food species. These included modest-size scale fish known locally as ractacara and yulilla; saucer-shaped palometa (related to piranha); and giant catfish extending six feet or more. (The researchers settled for chunks of the biggest ones.)

The fish were flown on ice to a government lab in Lima, where each species was analyzed for protein, fatty acids and trace minerals. The researchers then plotted the nutritional value of each species against its probability of surviving various kinds of ongoing environmental degradation. From this, they drew up multiple scenarios of how people's future diet would be affected as various species dropped out of the mix.

Overall, the biomass of fish caught has remained stable in recent years. However, large migratory species, the most vulnerable to human activities, comprise a shrinking portion, and as they disappear, they are being replaced by smaller local species. Most fish contain about the same amount of protein, so this has not affected the protein supply. And, the researchers found, many smaller fish in fact contain higher levels of omega-3 fatty acids, so their takeover may actually increase those supplies. On the other hand, as species compositions lean more to smaller fish, supplies of iron, zinc are already going down, and will continue to decline, they say.

"Like any other complex system, you see a tradeoff," said Heilpern. "Some things are going up while other things are going down. But that only lasts up to a point." Exactly which species will fill the gaps left when others decline is difficult to predict -- but the researchers project that the overall nutritional value of the catch will nosedive around the point where 40 of the 60 food species become scarce or extinct. "You have a tipping point, where the species that remain can be really lousy," said Heilpern.

One potential solution: in many places around the world where wild foods including fish and bush meat (such as monkeys and lizards) are declining, people are turning increasingly to farm-raised chicken and aquaculture -- a trend encouraged by the World Bank and other powerful organizations. This is increasingly the case in Loreto. But in a separate study published in March, Heilpern, Naeem and their colleagues show that this, too, is undermining human nutrition.

The researchers observed that chicken production in the region grew by about three quarters from 2010 to 2016, and aquaculture nearly doubled. But in analyzing the farmed animals' nutritional values, they found that they typically offer poorer nutrition than a diverse mix of wild fish. In particular, the move to chicken and aquaculture will probably exacerbate the region's already serious iron deficiencies, and limit supplies of essential fatty acids, they say. "Because no single species can offer all key nutrients, a diversity of species is needed to sustain nutritionally adequate diets," they write.

Besides this, chicken farming and aquaculture exert far more pressure on the environment than fishing. In addition to encouraging clearing of forests to produce feed for the animals, animal farming produces more more greenhouse gases, and introduces fertilizers and other pollutants into nearby waters, says Heilpern.

"Inland fish are fundamental for nutrition in many low-income and food-deficit countries, and of course landlocked countries," said John Valbo Jørgensen, a Rome-based expert on inland fisheries with the UN Food and Agriculture Organization. "Many significant inland fisheries, including those of Peru, take place in remote areas with poor infrastructure and limited inputs. It will not be feasible to replace those fisheries with farmed animals including fish."

Heilpern is now working with the Wildlife Conservation Society to produce an illustrated guide to the region's fish, including their nutritional values, in hopes of promoting a better understanding of their value among both fishermen and consumers.

Read more at Science Daily