San Francisco, Jan 3 (IANS): 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, a new study has shown.

According to the US-based National Institutes of Health study published in eBioMedicine, researchers gathered data from 11,255 adults over a 30-year period and analysed links between "serum sodium levels" -- which go up when fluid intake goes down -- and various indicators of health.

The researchers 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 ageing than those with serum sodium levels in the medium range.

Adults with higher levels were also more likely to die at a younger age, according to the study.

"The results suggest that proper hydration may slow down ageing and prolong a disease-free life," said Natalia Dmitrieva, PhD, a study author and researcher at the US-based National Heart, Lung, and Blood Institute (NHLBI).

Moreover, the researchers discovered that adults with higher levels of normal serum sodium -- normal ranges between 135-146 milliequivalents per litre (mEq/L) -- were more likely to show signs of faster biological ageing.

Similarly, adults whose serum sodium levels exceeded 142 mEq/L were associated with up to 64 per cent higher risks of 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, said the study.

"People whose serum sodium is 142 mEq/L or higher would benefit from evaluation of their fluid intake," Dmitrieva said.

The National Academies of Medicine, an American non-profit organisation, 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).

The authors also cited research that found that roughly half of the people worldwide do not meet daily total water intake recommendations, which typically begin at 6 cups (1.5 litres), the study added.

"On the global level, this can have a big impact," Dmitrieva mentioned.

"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 ageing process and prevent or delay chronic disease," she added.