Drinking enough water is essential to keeping the body functioning properly and staying healthy. Water regulates temperature, maintains skin health, and carries nutrients to cells. But staying hydrated actually goes even beyond that, a new study found. It could also lower the risk of developing chronic diseases, dying early, or aging faster.

The researchers collected over 25 years of data from more than 11,000 adults in the US who attended medical visits at ages 45 to 66 and then returned to follow-ups at ages 70 to 90. The researchers looked at sodium levels in their blood as a proxy for hydration. Higher concentrations are a sign they weren’t consuming enough fluids — they weren’t hydrated enough.

All participants had blood-sodium levels in the normal range (135-146 milliequivalents per liter). But the findings showed that people at the higher end of that range (above 144) were 50% more likely to show signs of physical aging beyond what would be expected for their age. They also had a 20% higher risk of dying early.

Even participants with blood-sodium levels above 142 had a higher risk of developing chronic diseases such as stroke, atrial fibrillation, chronic lung disease, diabetes, heart failure, and dementia. They also had a 10% to 15% higher chance of aging earlier. Meanwhile, those in the 138-140 range had the lowest risk of developing diseases.

“The results suggest that proper hydration may slow down aging and prolong a disease-free life,” study author Natalia Dmitrieva, a researcher in the Laboratory of Cardiovascular Regenerative Medicine at the National Heart, Lung and Blood Institute, a division of NIH, said in a statement. “On the global level, this can have a big impact.”

Hydration and health

Just like proper nutrition and regular physical activity are considered important elements of a healthy lifestyle, evidence from this and other studies show consistent and good hydration can also make a difference, the researchers said. But they warned more research is still needed to better determine the health effects of good hydration. Similar studies on a broader population sample would also be useful to see how other aspects (like genetic makeup or age) tie into the process.

The findings of the study also don’t prove a causal effect — researchers observed a correlation but did not establish a cause-effect. Randomized and controlled trials will be necessary to establish whether optimal hydration promotes healthy aging, prevents disease, and leads to a longer life. However, the association can still guide personal health behavior, the researchers said, increasing fluid intake if necessary.

Over half of the people worldwide don’t meet recommendations for daily total water intake, according to studies the authors of the new research cited. The National Academies of Medicine suggests women consume around 6-9 cups (1.5-2.2 liters) of fluids daily and for men, 8-12 cups (2-3 liters). This includes all fluids and water-rich food.

Recent studies have also highlighted that it’s not entirely clear how much water we should drink in the first place; one recent study found that for adults, the actual need could vary wildly, with averages ranging from 1 to 6 liters.

The study was published in the journal eBioMedicine.