Adults who stay well-hydrated appear to be healthier, develop fewer chronic conditions, such as heart and lung disease, and live longer than those who may not get sufficient fluids, according to a study published in eBioMedicine.
Using health data gathered from 11 255 adults over a 30-year period, researchers analysed links between serum sodium levels (which increase with reduced fluid intake) and various indicators of health. They found that adults with serum sodium levels at the higher end of a normal range were more likely to develop chronic conditions and show signs of advanced biological aging than those with serum sodium levels in the medium ranges. Adults with higher levels were also more likely to die at a younger age.
“The results suggest that proper hydration may slow down aging and prolong a disease-free life,” said Natalia Dmitrieva, PhD, a study author and researcher at the National Heart, Lung, and Blood Institute (NHLBI).
The study expands on previous research from the scientists, which found links between high-normal serum sodium levels and increased risks for heart failure. Both findings came from the Atherosclerosis Risk in Communities (ARIC) study, which started in 1987.
For this latest analysis, researchers assessed information study participants shared during five medical visits – the first two when they were in their 50s, and the last between ages 70–90. Adults who had high levels of serum sodium at baseline check-ins or with underlying conditions, like obesity, that could affect serum sodium levels, were excluded.
The researchers then evaluated how serum sodium levels correlated with biological ageing, which was assessed through 15 health markers such as systolic blood pressure, cholesterol, and blood sugar. These provided insight about how well each person’s cardiovascular, respiratory, metabolic, renal, and immune system was functioning. They also adjusted for factors, like age, race, biological sex, smoking status, and hypertension.
They found that adults with higher levels of normal serum sodium, normallu between 135–146 milliequivalents per litre (mEq/L), were more likely to show signs of faster biological ageing. This was based on indictors like metabolic and cardiovascular health, lung function, and inflammation. For example, adults with serum sodium levels above 142mEq/L had a 10-15% associated increased odds of being biologically older than their chronological age compared to ranges between 137–142mEq/L, while levels above 144mEq/L correlated with a 50% increase. Likewise, levels of 144.5–146 mEq/L were associated with a 21% increased risk of premature death compared to ranges between 137–142mEq/L.
Similarly, adults with serum sodium levels above 142mEq/L had up to a 64% increased associated risk for developing chronic diseases like heart failure, stroke, atrial fibrillation and peripheral artery disease, as well as chronic lung disease, diabetes, and dementia. Conversely, adults with serum sodium levels between 138–140 mEq/L had the lowest risk of developing chronic disease.
The researchers caution that randomised, controlled trials are needed to prove an association between fluid intake and signs of ageing.
“People whose serum sodium is 142mEq/L or higher would benefit from evaluation of their fluid intake,” Dmitrieva said. She noted that most people can safely increase their fluid intake to meet recommended levels, which can be done with water as well as other fluids, like juices, or vegetables and fruits with a high water content. The National Academies of Medicine, for example, suggest that most women consume around 6-9 cups (1.5–2.2 litres) of fluids daily and for men, 8-12 cups (2–3 litres).
Others may need medical guidance due to underlying health conditions. “The goal is to ensure patients are taking in enough fluids, while assessing factors, like medications, that may lead to fluid loss,” said study author Manfred Boehm, MD, director of the Laboratory of Cardiovascular Regenerative Medicine at NHLBI. “Doctors may also need to defer to a patient’s current treatment plan, such as limiting fluid intake for heart failure.”
The authors also cited research that finds about half of people worldwide don’t meet recommendations for daily total water intake, which often starts at 6 cups (1.5 litres).
“On the global level, this can have a big impact,” Dmitrieva said. “Decreased body water content is the most common factor that increases serum sodium, which is why the results suggest that staying well hydrated may slow down the aging process and prevent or delay chronic disease.”
