Study shows reduced inflammation in residents after adding trees to their neighborhoods

The University of Louisville's groundbreaking Green Heart Louisville Project has found that people living in neighborhoods where the number of trees and shrubs was more than doubled showed lower levels of a blood marker of inflammation than those living outside the planted areas. General inflammation is an important risk indicator for heart disease and other chronic diseases.

The Christina Lee Brown Envirome Institute launched the first-of-its-kind project in 2018 in partnership with The Nature Conservancy, Washington University in St. Louis, Hyphae Design Laboratory and others to study whether and how living among more densely greened surroundings contributes to better heart health. The design of the study closely mirrors clinical trials which test whether medical treatments are effective. The team applied the treatment -- the addition of large trees and shrubs -- to some participants' neighborhoods but not to others. They then compared residents' health data to see how the addition of the trees affected their health.

"The Green Heart Louisville Project is an excellent example of how our university's innovative and collaborative researchers are working to improve lives in our community and far beyond," UofL President Kim Schatzel said. "Trees are beautiful, but these results show that the trees around us are also beneficial to individual and community health. Through this and many other projects, the Envirome Institute is improving health at the community level, not just for individuals, but for everyone living in a neighborhood."

To understand the state of community's health at the start of the study, researchers took blood, urine, hair and nail samples and documented health data from 745 people living in a four-square-mile area of south Louisville. The researchers also took detailed measurements of tree coverage and levels of air pollution in the area.

Following this baseline data collection, the Envirome Institute worked with The Nature Conservancy and a host of local partners and contractors to plant more than 8,000 large trees and shrubs in designated neighborhoods within the project area. Those living in the greened area were considered the treated population and the results obtained from this population were compared with residents of adjacent neighborhoods, where the project team did not plant any trees.

After the plantings, the research team reassessed residents' health. They found that those living in the greened area had 13-20% lower levels of a biomarker of general inflammation, a measure called high-sensitivity C-reactive protein (hsCRP) than those living in the areas that did not receive any new trees or shrubs. Higher levels of hsCRP are strongly associated with a risk of cardiovascular disease and are an even stronger indicator of heart attack than cholesterol levels. Higher CRP levels also indicate a higher risk of diabetes and certain cancers.

A reduction of hsCRP by this percentage corresponds to nearly 10-15% reduction in the risk of heart attacks, cancer or dying from any disease.

"These results from the Green Heart Louisville Project indicate that trees contribute more to our lives than beauty and shade. They can improve the health of the people living around them," said Aruni Bhatnagar, director of the Envirome Institute and UofL professor of medicine. "Although several previous studies have found an association between living in areas of high surrounding greenness and health, this is the first study to show that a deliberate increase in greenness in the neighborhood can improve health. With these results and additional studies that we hope to report soon, we are closer to understanding the impact of local tree cover on residents' health. This finding will bolster the push to increase urban greenspaces."

As more is known about the health impacts of increased tree cover, increased greening in cities may emerge as a key method to improve public health.

"Most of us intuitively understand that nature is good for our health. But scientific research testing, verifying and evaluating this connection is rare," said Katharine Hayhoe, chief scientist of The Nature Conservancy. "These recent findings from the Green Heart Project build the scientific case for the powerful connections between the health of our planet and the health of all of us."

Earlier in August, the Green Heart Louisville Project was awarded an additional $4.6 million in funding from the National Institute of Environmental Health Sciences to support continued research over the next five years.

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Your baby's gut is crawling with unknown viruses

Babies tumble about with more than 200 previously unknown viral families within their intestines. This large number comes as a surprise to researchers from the University of Copenhagen and COPSAC, who closely studied the diapers of 647 Danish babies and made the first mapping of its kind. These viruses most likely play an important role in protecting children from chronic diseases.

Viruses are usually associated with illness. But our bodies are full of both bacteria and viruses that constantly proliferate and interact with each other in our gastrointestinal tract. While we have known for decades that gut bacteria in young children are vital to protect them from chronic diseases later on in life, our knowledge about the many viruses found there is minimal.

A few years back, this gave University of Copenhagen professor Dennis Sandris Nielsen the idea to delve more deeply into this question. As a result, a team of researchers from COPSAC (Copenhagen Prospective Studies on Asthma in Childhood) and the Department of Food Science at UCPH, among others, spent five years studying and mapping the diaper contents of 647 healthy Danish one-year-olds.

"We found an exceptional number of unknown viruses in the faeces of these babies. Not just thousands of new virus species -- but to our surprise, the viruses represented more than 200 families of yet to be described viruses. This means that, from early on in life, healthy children are tumbling about with an extreme diversity of gut viruses, which probably have a major impact on whether they develop various diseases later on in life," says Professor Dennis Sandris Nielsen of the Department of Food Science, senior author of the research paper about the study, now published in Nature Microbiology.

The researchers found and mapped a total of 10,000 viral species in the children's faeces -- a number ten times larger than the number of bacterial species in the same children. These viral species are distributed across 248 different viral families, of which only 16 were previously known. The researchers named the remaining 232 unknown viral families after the children whose diapers made the study possible. As a result, new viral families include names like Sylvesterviridae, Rigmorviridae and Tristanviridae.

Bacterial viruses are our allies

"This is the first time that such a systematic an overview of gut viral diversity has been compiled. It provides an entirely new basis for discovering the importance of viruses for our microbiome and immune system development. Our hypothesis is that, because the immune system has not yet learned to separate the wheat from the chaff at the age of one, an extraordinarily high species richness of gut viruses emerges, and is likely needed to protect against chronic diseases like asthma and diabetes later on in life," states Shiraz Shah, first author and a senior researcher at COPSAC.

Ninety percent of the viruses found by the researchers are bacterial viruses -- known as bacteriophages. These viruses have bacteria as their hosts and do not attack the children's own cells, meaning that they do not cause disease. The hypothesis is that bacteriophages primarily serve as allies:

"We work from the assumption that bacteriophages are largely responsible for shaping bacterial communities and their function in our intestinal system. Some bacteriophages can provide their host bacterium with properties that make it more competitive by integrating its own genome into the genome of the bacterium. When this occurs, a bacteriophage can then increase a bacterium's ability to absorb e.g. various carbohydrates, thereby allowing the bacterium to metabolise more things," explains Dennis Sandris Nielsen, who continues:

"It also seems like bacteriophages help keep the gut microbiome balanced by keeping individual bacterial populations in check, which ensures that there are not too many of a single bacterial species in the ecosystem. It's a bit like lion and gazelle populations on the savannah."

Shiraz Shah adds:

"Previously, the research community mostly focused on the role of bacteria in relation to health and disease. But viruses are the third leg of the stool and we need to learn more about them. Viruses, bacteria and the immune system most likely interact and affect each other in some type of balance. Any imbalance in this relationship most likely increases the risk of chronic disease."

The remaining ten percent of viruses found in the children are eukaryotic -- that is, they use human cells as hosts. These can be both friends and foes for us:

"It is thought-provoking that all children run around with 10-20 of these virus types that infect human cells. So, there is a constant viral infection taking place, which apparently doesn't make them sick. We just know very little about what's really at play. My guess is that they're important for training our immune system to recognise infections later. But it may also be that they are a risk factor for diseases that we have yet to discover," says Dennis Sandris Nielsen.

Could play an important role in inflammatory diseases

The researchers have yet to discover where the many viruses in the one-year-olds come from. Their best answer thus far is the environment:

"Our gut is sterile until we are born. During birth, we are exposed to bacteria from the mother and environment. It is likely that some of the first viruses come along with these initial bacteria, while many others are introduced later via dirty fingers, pets, dirt that kids put in their mouths and other things in the environment," says Dennis Sandris Nielsen.

As Shiraz Shah points out, the entire field of research speaks to a huge global health problem:

"A lot of research suggests that the majority of chronic diseases that we're familiar with -- from arthritis to depression -- have an inflammatory component. That is, the immune system is not working as it ought to -- which might be because it wasn't trained properly. So, if we learn more about the role that bacteria and viruses play in a well-trained immune system, it can hopefully lead us to being able to avoid many of the chronic diseases that afflict so many people today."

The research groups have begun investigating the role of gut viruses in relation to a number of different diseases that occur in childhood, such as asthma and ADHD.

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Five hours' sleep a night linked to higher risk of multiple diseases

Getting less than five hours of sleep in mid-to-late life could be linked to an increased risk of developing at least two chronic diseases, finds a new study led by UCL researchers.

The research, published in PLOS Medicine, analysed the impact of sleep duration on the health of more than 7,000 men and women at the ages of 50, 60 and 70, from the Whitehall II cohort study.

Researchers examined the relationship between how long each participant slept for, mortality and whether they had been diagnosed with two or more chronic diseases (multimorbidity) -- such as heart disease, cancer or diabetes -- over the course of 25 years.

People who reported getting five hours of sleep or less at age 50 were 20% more likely to have been diagnosed with a chronic disease and 40% more likely to be diagnosed with two or more chronic diseases over 25 years, compared to people who slept for up to seven hours.

Additionally, sleeping for five hours or less at the age of 50, 60, and 70 was linked to a 30% to 40% increased risk of multimorbidity when compared with those who slept for up to seven hours.

Researchers also found that sleep duration of five hours or less at age 50 was associated with 25% increased risk of mortality over the 25 years of follow-up -- which can mainly be explained by the fact that short sleep duration increases the risk of chronic disease(s) that in turn increase the risk of death.

Lead author, Dr Severine Sabia (UCL Institute of Epidemiology & Health, and Inserm, Université Paris Cité) said: "Multimorbidity is on the rise in high income countries and more than half of older adults now have at least two chronic diseases. This is proving to be a major challenge for public health, as multimorbidity is associated with high healthcare service use, hospitalisations and disability.

"As people get older, their sleep habits and sleep structure change. However, it is recommended to sleep for 7 to 8 hours a night -- as sleep durations above or below this have previously been associated with individual chronic diseases.

"Our findings show that short sleep duration is also associated with multimorbidity.

"To ensure a better night's sleep, it is important to promote good sleep hygiene, such as making sure the bedroom is quiet, dark and a comfortable temperature before sleeping. It's also advised to remove electronic devices and avoid large meals before bedtime. Physical activity and exposure to light during the day might also promote good sleep."

As part of the study, researchers also assessed whether sleeping for a long duration, of nine hours or more, affected health outcomes. There was no clear association between long sleep durations at age 50 and multimorbidity in healthy people.

However, if a participant had already been diagnosed with a chronic condition, then long sleep duration was associated with around a 35% increased risk of developing another illness. Researchers believe this could be due to underlying health conditions impacting sleep.

Jo Whitmore, senior cardiac nurse at the British Heart Foundation said: "Getting enough sleep allows your body to rest. There are a host of other ways that poor sleep could increase the risk of heart disease or stroke, including by increasing inflammation and increasing blood pressure.

"This research adds to a growing body of research that highlights the importance of getting a good night's sleep."

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