The National Institutes of Health (NIH) study was published on January 2, 2022, in the journal eBioMedicine. “The results suggest that proper hydration may slow down aging and prolong a disease-free life,” said study author Natalia Dmitrieva, PhD, a researcher at the National Heart, Lung, and Blood Institute in Bethesda, Maryland, in a press release.
Staying Hydrated Can Help You Stay Healthy
In the short term, getting enough water can help prevent dehydration, a health issue that can cause your body to overheat, cloud your thinking and mood, and lead to constipation and kidney stones, per the Centers for Disease Control and Prevention (CDC). According to the agency, staying hydrated in the short term can also help lubricate and cushion joints, protect your spinal cord and other sensitive tissues in your body, and get rid of waste. RELATED: Hydration Calculator: How Much Water Do You Need to Drink a Day? Scientists know less about the long-term impact of hydration and dehydration. Existing evidence suggests that less-than-optimal hydration may increase the risk for disease and lead to early death, according to the authors. In research using mice, lifelong restriction of water intake shortened their life span by six months, which equals about 15 years of human life, according to research published in September 2019 in the journal JCI Insight.
How Do You Measure Biological Age and Hydration?
Given that the U.S. Census Bureau indicates the national median age continues to increase, and with chronic health conditions becoming more widespread, the NIH researchers designed their study to explore whether maintaining an optimal state of hydration might slow the aging process. Investigators used health data from 11,255 Black and white adults from the Atherosclerosis Risk in Communities study (ARIC), collected over a 30-year period. The first assessment was in 1987 when participants were in their forties or fifties; the average age of participants at the final assessment during the study period was 76 years old. The authors estimated biological age (how well the body works, versus a person’s chronological age) using biomarkers of different organ systems and processes, including cardiovascular, renal (relating to the kidneys), respiratory, metabolic, immune, and inflammatory measurements. Rather than try to track the fluid intake of participants, researchers used serum sodium level as an indicator of hydration status. Serum sodium level is a measurement of how much sodium is in your blood: The more hydrated you are, the lower your serum sodium will be. The test is typically performed as part of routine yearly blood work, and the normal range is between 135 to 146 milliequivalents per liter (mEq/L).
Being ‘Optimally Hydrated’ Was Associated With a Lower Risk of Chronic Disease
After adjusting for factors that could influence the findings, including age, race, biological sex, smoking status, and high blood pressure, the NIH scientists found that adults with serum sodium levels at the higher end of the normal range had worse health outcomes than those at the lower end of the range. Adults with levels above 142 mEq/L were 10 to 15 percent more likely to be biologically older than their chronological age compared with participants in the 137 to 142 mEq/L range. Those “faster aging” participants with higher levels of serum sodium also had a 64 percent higher risk for developing chronic diseases such as heart failure, stroke, atrial fibrillation, peripheral artery disease, chronic lung disease, diabetes, and dementia. People with levels above 144 mEq/L had a 50 percent higher risk of being biologically older and a 21 percent higher risk of dying early compared to people with a level between 137 to 142 mEq/L. The group with the lowest risk of developing chronic disease had a serum sodium levels between 138 to 140 mEq/L.
Drinking Less Water May Be Connected to Obesity
“There is a wide variation in how much water people are drinking, and also how much salt we are eating,” says Richard Johnson, MD, a professor of medicine, clinician, and researcher at the University of Colorado in Aurora, who was not involved in the NIH study. It has been known for a while that people who have obesity, or who are prone to have obesity, tend to drink less water and to eat more salt, both of which act to increase the sodium concentration in our blood, says Dr. Johnson. “Our experimental studies in laboratory animals have suggested that this process can actually activate processes that can cause obesity and diabetes. This paper appears to find evidence that this is the case in humans,” he says. Results of the NIH study suggest that the sodium concentration in the blood can predict the risk for chronic diseases and even aging, says Johson: “The striking finding is that sodium levels that are considered normal, but are on the high end, are predicting increased risk. This goes along with other data suggesting many of us are not hydrating very well.” It’s important to note that the findings don’t prove that optimal hydration reduces the risk of early death, the NIH researchers noted — an association between the two does not prove cause-and-effect — and randomized, controlled trials are needed. Even so, the study does reinforce the reasons that people should try to follow the existing recommendations for fluid intake, the authors wrote. RELATED: 6 Smart Tips for Staying Hydrated Throughout the Day Johnson agrees, saying that although a higher serum sodium is associated with higher risk, this study doesn’t prove that the serum level caused that risk. “However, studies in laboratory animals have identified biological mechanisms by which mild dehydration can cause obesity,” he says.
How Much Water Should You Drink Every Day?
How much water is enough? There is no concrete recommendation of how much water everyone should drink, according to the CDC, but research from the U.S. National Academies of Sciences, Engineering, and Medicine determined that an adequate daily intake is 15.5 cups of fluid for men and 11.5 cups for women. That includes all beverages (not just water) and even food — about 20 percent of your fluid intake comes from food. “I think it is a good idea to drink a glass of water with each meal, and to drink some water throughout the day. Targeting the National Academy of Medicine recommendations is a good idea,” says Johnson. Measuring your serum sodium might be helpful as well, he adds. Need a little extra help getting enough water? Erin Coates, RD, a health coach at Cleveland Clinic in Ohio, suggests putting five rubber bands around a 16-ounce water bottle every morning. Every time you finish a bottle, take one of the bands off, with the goal of removing all five bands by the time you go to bed. Note that some people should check in with their doctor before upping their fluid intake. “If you do have serious health issues, like heart failure, or a low serum sodium, I recommend discussing with your doctor before you drink a lot of water. Marathon runners can also hold onto too much water with extensive exercise, and this group should only drink when thirsty,” says Johnson.
