Routinely drinking alcohol may raise blood pressure even in adults without hypertension

Even in adults without hypertension, blood pressure readings may climb more steeply over the years as the number of daily alcoholic drinks rise, according to an analysis of seven international research studies published today in Hypertension, an American Heart Association journal.

With the statistical power of seven international research studies, this analysis confirms for the first time there was a continuous increase in blood pressure measures in both participants with low and high alcohol intake. Even low levels of alcohol consumption were associated with detectable increases in blood pressure levels that may lead to a higher risk of cardiovascular events.

"We found no beneficial effects in adults who drank a low level of alcohol compared to those who did not drink alcohol," said senior study author Marco Vinceti, M.D., Ph.D., a professor of epidemiology and public health in the Medical School of the University of Modena and Reggio Emilia University in Italy and an adjunct professor in the department of epidemiology at Boston University's School of Public Health. "We were somewhat surprised to see that consuming an already-low level of alcohol was also linked to higher blood pressure changes over time compared to no consumption -- although far less than the blood pressure increase seen in heavy drinkers."

"Our analysis was based on grams of alcohol consumed and not just on the number of drinks to avoid the bias that might arise from the different amount of alcohol contained in 'standard drinks' across countries and/or types of beverages," said study co-author Tommaso Filippini, M.D., Ph.D., an associate professor of epidemiology and public health in the Medical School of the University of Modena and Reggio Emilia in Italy, and affiliate researcher at the University of California Berkeley School of Public Health.

Researchers reviewed the health data for all participants across the seven studies for more than five years. They compared adults who drank alcohol regularly with non-drinkers and found:
 

• Systolic (top number) blood pressure rose 1.25 millimeters of mercury (mm Hg) in people who consumed an average of 12 grams of alcohol per day, rising to 4.9 mm Hg in people consuming an average of 48 grams of alcohol per day. (In the U.S., 12 ounces of regular beer, 5 ounces of wine or a 1.5 ounce shot of distilled spirits contains about 14 grams of alcohol. Usual alcohol content differs in alcohol available in other countries.)
• Diastolic (bottom number) blood pressure rose 1.14 mm Hg in people consuming an average of 12 grams of alcohol per day, rising to 3.1 mm Hg in people consuming an average of 48 grams of alcohol per day. These associations were seen in males but not in females. Diastolic blood pressure measures the force against artery walls between heartbeats and is not as strong a predictor of heart disease risk in comparison to systolic.

"Alcohol is certainly not the sole driver of increases in blood pressure; however, our findings confirm it contributes in a meaningful way. Limiting alcohol intake is advised, and avoiding it is even better," Vinceti said.

Although none of the participants had high blood pressure when they enrolled in the studies, their blood pressure measurements at the beginning did have an impact on the alcohol findings.

"We found participants with higher starting blood pressure readings, had a stronger link between alcohol intake and blood pressure changes over time. This suggests that people with a trend towards increased (although still not "high") blood pressure may benefit the most from low to no alcohol consumption," said study co-author Paul K. Whelton, M.D., M.Sc., the Show Chwan Chair in Global Public Health in the department of epidemiology at Tulane University's School of Public Health and Tropical Medicine in New Orleans and president of the World Hypertension League. Whelton is also the chair of the American Heart Association's 2017 Hypertension Practice Guidelines and a member of the writing committee for the Association's 2021 Scientific Statement on Management of Stage 1 Hypertension in Adults.

According to American Heart Association recommendations, if you don't drink already, don't start. If you do drink, talk with your doctor about the benefits and risks of consuming alcohol in moderation. The Association also does not recommend drinking any form of alcohol to gain potential health benefits. Instead, follow the Association's lifestyle and health metrics for optimal cardiovascular health called Life's Essential 8: eat healthy food, be physically active, don't smoke, get enough sleep, maintain a healthy weight, and control cholesterol, blood sugar and blood pressure levels.

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Stop counting cups: There's an ocean of difference in our water-drinking needs

A new study of thousands of people reveals a wide range in the amount of water people consume around the globe and over their lifespans, definitively spilling the oft-repeated idea that eight, 8-ounce glasses meet the human body's daily needs.

"The science has never supported the old eight glasses thing as an appropriate guideline, if only because it confused total water turnover with water from beverages and a lot of your water comes from the food you eat," says Dale Schoeller, a University of Wisconsin-Madison emeritus professor of nutritional sciences who has been studying water and metabolism for decades. "But this work is the best we've done so far to measure how much water people actually consume on a daily basis -- the turnover of water into and out of the body -- and the major factors that drive water turnover."

That's not to say the new results settle on a new guideline. The study, published today in the journal Science, measured the water turnover of more than 5,600 people from 26 countries, ages ranging from 8 days to 96 years old, and found daily averages on a range between 1 liter per day and 6 liters per day.

"There are outliers, too, that are turning over as much as 10 liters a day," says Schoeller, a co-author of the study. "The variation means pointing to one average doesn't tell you much. The database we've put together shows us the big things that correlate with differences in water turnover."

Previous studies of water turnover relied largely on volunteers to recall and self-report their water and food consumption, or were focused observations -- of, say, a small group of young, male soldiers working outdoors in desert conditions -- of questionable use as representative of most people.

The new research objectively measured the time it took water to move through the bodies of study participants by following the turnover of "labeled water." Study subjects drank a measured amount of water containing trackable hydrogen and oxygen isotopes. Isotopes are atoms of a single element that have slightly different atomic weights, making them distinguishable from other atoms of the same element in a sample.

"If you measure the rate a person is eliminating those stable isotopes through their urine over the course of a week, the hydrogen isotope can tell you how much water they're replacing and the elimination of the oxygen isotope can tell us how many calories they are burning," says Schoeller, whose UW-Madison lab in the 1980s was the first to apply the labeled-water method to study people.

More than 90 researchers were involved in the study, which was led by a group that includes Yosuke Yamada, a former UW-Madison postdoctoral researcher in Schoeller's lab and now section head of the National Institute of Biomedical Innovation, Health and Nutrition in Japan, and John Speakman, zoology professor at the University of Aberdeen in Scotland. They collected and analyzed data from participants, comparing environmental factors -- such as temperature, humidity and altitude of the participants' hometowns -- to measured water turnover, energy expenditure, body mass, sex, age and athlete status.

The researchers also incorporated the United Nations' Human Development Index, a composite measure of a country that combines life expectancy, schooling and economic factors.

Water turnover volume peaked for men in the study during their 20s, while women held a plateau from 20 through 55 years of age. Newborns, however, turned over the largest proportion daily, replacing about 28 percent of the water in their bodies every day.

Physical activity level and athletic status explained the largest proportion of the differences in water turnover, followed by sex, the Human Development Index, and age.

All things equal, men and women differ by about half a liter of water turnover. As a baseline of sorts, the study's findings expect a male non-athlete (but of otherwise average physical activity) who is 20 years old, weighs 70kg (154 pounds), lives at sea level in a well-developed country in a mean air temperature of 10 degrees C (50 Fahrenheit) and a relative humidity of 50%, would take in and lose about 3.2 liters of water every day. A woman of the same age and activity level, weighing 60 kg (132 pounds) and living in the same spot, would go through 2.7 liters (91 ounces).

Doubling the energy a person uses will push their expected daily water turnover up by about liter, the researchers found. Fifty kilograms more body weight adds 0.7 liters a day. A 50% increase in humidity pushes water use up by 0.3 liters. Athletes use about a liter more than non-athletes.

The researchers found "hunter-gatherers, mixed farmers, and subsistence agriculturalists" all had higher water turnover than people who live in industrialized economies. In all, the lower your home country's Human Development Index, the more water you go through in a day.

"That's representing the combination of several factors," Schoeller says. "Those people in low HDI countries are more likely to live in areas with higher average temperatures, more likely to be performing physical labor, and less likely to be inside in a climate-controlled building during the day. That, plus being less likely to have access to a sip of clean water whenever they need it, makes their water turnover higher."

The measurements will improve our ability to predict more specific and accurate future water needs, especially in dire circumstances, according to Schoeller.

"Look at what's going on in Florida right now, or in Mississippi -- where entire regions have been exposed by a calamity to water shortages," he says. "The better we understand how much they need, the better prepared we are to respond in an emergency."

And the better we can prepare for long-term needs and even notice short-term health concerns, the researchers believe.

"Determining how much water humans consume is of increasing importance because of population growth and growing climate change," says Yamada. "Because water turnover is related to other important indicators of health, like physical activity and body fat percent, it has potential as a biomarker for metabolic health."

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Beer hops compounds could help protect against Alzheimer's disease

Beer is one of the oldest and most popular beverages in the world, with some people loving and others hating the distinct, bitter taste of the hops used to flavor its many varieties. But an especially "hoppy" brew might have unique health benefits. Recent research published in ACS Chemical Neuroscience reports that chemicals extracted from hop flowers can, in lab dishes, inhibit the clumping of amyloid beta proteins, which is associated with Alzheimer's disease (AD).

AD is a debilitating neurodegenerative disease, often marked by memory loss and personality changes in older adults. Part of the difficulty in treating the disease is the time lag between the start of underlying biochemical processes and the onset of symptoms, with several years separating them. This means that irreversible damage to the nervous system occurs before one even realizes they may have the disease. Accordingly, preventative strategies and therapeutics that can intervene before symptoms appear are of increasing interest.

One of these strategies involves "nutraceuticals," or foods that have some type of medicinal or nutritional function. The hop flowers used to flavor beers have been explored as one of these potential nutraceuticals, with previous studies suggesting that the plant could interfere with the accumulation of amyloid beta proteins associated with AD. So, Cristina Airoldi, Alessandro Palmioli and colleagues wanted to investigate which chemical compounds in hops had this effect.

To identify these compounds, the researchers created and characterized extracts of four common varieties of hops using a method similar to that used in the brewing process. In tests, they found that the extracts had antioxidant properties and could prevent amyloid beta proteins from clumping in human nerve cells. The most successful extract was from the Tettnang hop, found in many types of lagers and lighter ales. When that extract was separated into fractions, the one containing a high level of polyphenols showed the most potent antibiotic and aggregation-inhibiting activity. It also promoted processes that allow the body to clear out misfolded, neurotoxic proteins. Finally, the team tested the Tettnang extract in a C. elegans model and found that it protected the worms from AD-related paralysis, though the effect was not very pronounced. The researchers say that although this work may not justify drinking more bitter brews, it shows that hop compounds could serve as the basis for nutraceuticals that combat the development of AD.

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