Need more reason to stay better hydrated? A new study in The Lancet suggests that getting enough water may help slow the aging process. Yes, you read that right. Previous animal research has shown that restricting water intake in mice hastens degenerative changes in multiple organ systems and shortens lifespan.
With funding from the National Heart, Lung, and Blood Institute, the researchers of the new study tested their hypothesis in humans by analyzing data from the Atherosclerosis Risk in Communities study, which included nearly 16,000 middle-aged people (ages 45 to 66) tracked for more than 25 years. Fasting serum sodium—which goes up with lower fluid consumption—was used as a proxy for hydration status.
Participants who had a serum sodium value of more than 142 mmol/L (which is at the upper end of the normal 135–146 range) were more likely to develop chronic diseases (such as heart failure, stroke, diabetes, lung disease, and dementia) over the follow-up period, as well as die younger, compared to those with lower values. Moreover, those with serum sodium values above 142, and especially above 144, were found overall to be biologically older, with biological age assessed by the researchers using various biomarkers for chronic disease and premature death.
Some possible explanations for the pro-aging effects observed are that a chronic low hydration status (hypohydration) may increase inflammation within blood vessels, arrest normal cell growth, and cause DNA damage.
Though serum sodium values were measured only at two points early in the study, three years apart, this blood marker is “remarkably steady and constant under a healthy, steady state,” says Mario Corona, M.D., a nephrologist and member of our editorial board. Serum sodium is also a very reasonable test to use, given the lack of other easily available and reproducible measures, he adds. Other factors that could affect hydration status were also adjusted for in the study, including sex, race, smoking status, blood pressure levels, and use of blood pressure drugs.
A strength of the study is the long follow-up, such that participants went from middle age into their 70s to 90s. Still, as the researchers acknowledge, “interventional trials are needed to prove this link.”
According to surveys cited in the paper, more than 50 percent of people worldwide don’t drink enough fluids. Thus, the researchers concluded that their results “provide additional reasons for reinforcing already existent recommendations for optimal fluid intake.” Their findings also suggest that a sodium serum value above 142 could be used in clinical practice as a threshold to identify those at higher risk for poorer health outcomes. Such individuals should be evaluated to see why their hydration status is low—whether it’s due to medical conditions that increase water losses in the body or simply a low fluid intake.