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.