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Drinking water is the key to a long and healthy life

People all over the world are living for longer and there is a focus on finding interventions to combat the chronic diseases that so often plague people as they age. It is known that people age at different rates and this is apparent even by mid-life. Therefore measures to slow down the rate of aging, when applied early enough, may have the effect of extending healthy life span and improving the quality of life. 

One factor that may have the potential to slow down aging is the amount of water we drink. Previous research has shown that mice with restricted access to water die six months earlier than mice with unrestricted access. This shortened lifespan was associated with degenerative changes within multiple organ systems in the dehydrated mice. Hypohydration (not drinking enough water) in mice and humans causes the body to engage multiple mechanisms to conserve water, such as producing concentrated urine and secreting hormones to prevent water loss. It is also associated with an increase in the concentration of sodium in the blood. 

Sodium is an essential mineral that we take in with our food. It is needed in the body for regulating blood pressure and fluid balance, and for maintaining healthy nerves and muscles. A normal blood sodium level is between 135 and 146 mmoles per liter, but levels that are too high or too low are not healthy. The concentration of sodium in our blood increases when we do not drink enough water, and decreases when we do. Therefore, hypohydration in humans goes hand-in-hand with high serum levels of sodium.

Scientists under the auspices of the National Institutes of Health have now investigated the links between the levels of sodium in the blood and a variety of markers of biological aging in a cohort of 11,255 adults. The participants gave information on variables such as their systolic blood pressure, and their cholesterol and blood sugar levels, at five medical visits. The first two visits took place when the participants were in their 50s, and the last took place when participants were between 70 and 90 years of age, more than 20 years. 

To allow for a fair comparison between how hydration correlated with health outcomes, researchers excluded adults who had high levels of serum sodium at the start of the study, as well as those with underlying conditions, like obesity, that could affect serum sodium levels. They also adjusted for factors, like age, race, biological sex, smoking status, and hypertension. The 15 biomarkers gave information on how each person’s cardiovascular, respiratory, metabolic, renal, and immune system was functioning. 

The results of the analysis, published in the online journal eBioMedicine, showed 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 or lower ranges. Adults with higher levels were also more likely to die at a younger age. This highlights the importance of remaining hydrated so that sodium concentrations in the blood remain at the lower end of the normal range.

“The results suggest that proper hydration may slow down aging and prolong a disease-free life,” said Natalia Dmitrieva, Ph.D., a study author and researcher in the Laboratory of Cardiovascular Regenerative Medicine at the National Heart, Lung, and Blood Institute (NHLBI), part of NIH.   

The study expands on previous research by the scientists, published in March 2022, which found links between higher ranges of normal serum sodium levels and increased risks for heart failure. These findings, along with the current ones, came from the Atherosclerosis Risk in Communities (ARIC) study, which includes sub-studies involving thousands of Black and white adults from throughout the United States. 

Adults with sodium levels above 142 mmol/l had a 10–15 percent higher risk of being biologically older than their chronological age, as assessed by their metabolic and cardiovascular health, lung function and inflammation. Those with levels of above 144 mmol/l showed a 50 percent increase in risk. Furthermore, participants with sodium levels of 144.5–146 mmol/l were associated with a 21 percent increased risk of premature death, when compared to those with concentrations of between 137 and 142 mmol/l.

Similarly, adults with serum sodium levels above 142 mmol/l had up to a 64 percent increased associated risk for developing chronic diseases like heart failure, stroke, atrial fibrillation and peripheral artery disease, as well as chronic lung diseasediabetes, and dementia. Conversely, adults with serum sodium levels between 138–140 mmol/l had the lowest risk of developing chronic disease.    
There is considerable variation in the amount of fluid people consume daily, but previous research has found that a large proportion of people worldwide do not take in the recommended amounts and are hypohydrated. According to the results of the current study, optimal hydration can potentially slow down the aging process and reduce the risk of developing serious health complications during aging. This will result in a longer, disease-free lifespan. 

“People whose serum sodium is 142 mmol/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 should consume around 6–9 cups (1.5–2.2 liters) of fluids daily and men 8–12 cups (2–3 liters). 

Some people may need medical guidance about water intake if they have 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 Manfred Boehm, M.D., a study author and director of the Laboratory of Cardiovascular Regenerative Medicine. “Doctors may also need to defer to a patient’s current treatment plan, such as limiting fluid intake for heart failure.”

“On the global level, this can have a big impact,” Dmitrieva added. “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.”  

Because this was a correlational study, the findings don’t prove a causal effect, the researchers noted. Randomized, controlled trials are necessary to determine if optimal hydration can promote healthy aging, prevent disease, and lead to a longer life. However, the associations can still inform clinical practice and guide personal health behavior.   

By Alison Bosman, Staff Writer

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