Population aging makes chronic diseases the main challenge for healthcare. Recent studies have shown that insufficient water intake is linked to the risk of hypertension, diabetes, dementia, and premature death. Biological age, assessed by biomarkers, allows early signs of accelerated aging to be caught before diseases appear. This work sits alongside studies of cellular aging and DNA methylation, but stands out for its focus on a simple and cheap marker available in any clinic.
Two datasets were used: electronic health records from Leumit Healthcare Services in Israel (363,286 people) and the NHANES national survey in the United States (24,611 people). Serum sodium level served as an indicator of hydration: when water is lacking, its concentration rises. Biological age was calculated using the Klemera and Doubal method based on seven biomarkers: blood pressure, mean corpuscular volume, urea, creatinine, cholesterol, glucose (or glycated hemoglobin), and albumin. To test the robustness of the results, a model with four biomarkers was also used. The analysis was performed separately for men and women, with adjustment for age, and in NHANES the complex survey design was taken into account.
In the Israeli cohort, among women the difference in biological age between the groups with the lowest and highest sodium was 2.32 years, and among men 0.88 years. The effect was stronger in people under 50: in women under 30 the difference reached 3 years. In the American data, among men the difference was 1.92 years, while in women there was no significant effect, but in certain age groups (under 30 and 41-50 years) the differences reached a year. The association persisted after adjustment for body mass index and when biomarkers sensitive to hydration were excluded.
The work confirms that even mild chronic dehydration, in which sodium remains within the normal range, is linked to accelerated aging. Unlike neighboring studies that focus on cellular mechanisms or genetics, this one uses a routine clinical indicator, which makes the result immediately applicable. This is the first test of the association on a large sample from electronic health records outside a specialized study, which reduces the risk of selection bias.
The next step could be interventional studies: would increasing water intake change biological age? It is also important to study how long an optimal hydration level must be maintained to slow aging, and which organs are most sensitive to chronic water deficit.
The results could influence preventive medicine: a simple blood sodium test could become a screening tool for the risk of accelerated aging. They also support recommendations for sufficient water intake as a cheap public health measure.
Conduct a randomized controlled trial in which participants with high-normal sodium increase their water intake, and compare the change in biological age. It would also be useful to repeat the analysis in other populations with different levels of access to water.
The work addresses an unresolved problem: which modifiable lifestyle factors most strongly influence the rate of aging. Unlike genetics, hydration can be changed, and its contribution to biological age has now been quantified.
In Israel, the law prohibits medical organizations from denying membership based on health status, so the Leumit sample suffers almost no selection bias, which is common in voluntary studies.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.