How to know if we are well hydrated?
2:01
(CNN) --
You may know that proper hydration is important for everyday bodily functions like temperature regulation and skin health.
But drinking enough water is also associated with a significantly lower risk of developing chronic disease, dying prematurely or being biologically older than chronological age, according to a National Institutes of Health (NIH) study published Monday in the journal
eBioMedicine
journal
.
"The results suggest that adequate hydration can delay aging and prolong a disease-free life," Natalia Dmitrieva, study author and researcher in the Laboratory of Cardiovascular Regenerative Medicine at the National Heart, Lung and Institute, said in a news release. the Blood, a division of the NIH.
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Learning what measures can slow down the aging process is "a great challenge for preventive medicine," the authors say in the study.
This is because an epidemic of "chronic age-dependent diseases" is emerging as the world's population ages rapidly.
And prolonging a healthy life can help improve quality of life and reduce healthcare costs more than just treating disease.
The authors thought that optimal hydration could slow down the aging process, based on previous similar research done in mice.
In those studies, lifelong water restriction increased the mice's serum sodium by 5 millimoles per liter and shortened their life expectancy by six months, which is equivalent to about 15 years of human life, according to the new study.
Serum sodium can be measured in the blood and increases when we drink less fluids.
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Using health data collected over 30 years from 11,255 black and white adults in the ARIC (Atherosclerosis Risk in Communities) study, the investigators found that adults with serum sodium levels at the upper end of the normal range - between 135 and 146 milliequivalents per liter (mEq/L) - had worse health outcomes than those at the lower end of the range.
Data collection began in 1987, when participants were between the ages of 40 and 50, and the average age of participants at final assessment during the study period was 76 years.
Adults with levels above 142 mEq/L were 10% to 15% more likely to be biologically older than their chronological age compared with participants in the 137 to 142 mEq/L range.
Participants at highest risk of aging faster also had a 64% increased risk of developing chronic diseases such as heart failure, stroke, atrial fibrillation, peripheral artery disease, chronic lung disease, diabetes, and dementia.
And people with levels above 144 mEq/L had a 50% increased risk of being biologically elderly and a 21% increased risk of dying prematurely.
In contrast, adults with serum sodium levels between 138 and 140 mEq/L had the lowest risk of developing chronic disease.
The study had no information on the amount of water the participants drank.
"This study adds observational evidence reinforcing the potential long-term benefits of improved hydration in reducing long-term health outcomes, including mortality," said Howard Sesso, MD, associate professor of medicine at the Harvard Medical School and associate epidemiologist at Brigham and Women's Hospital in Boston, via email.
Sesso was not involved in the study.
However, "it would have been nice to combine their definition of hydration, based solely on serum sodium levels, with the actual fluid intake data from the ARIC cohort," Sesso added.
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Biological age was determined using biomarkers that measure the functioning of different organ systems and processes, including cardiovascular, renal (kidney-related), respiratory, metabolic, immune, and inflammatory biomarkers.
Elevated serum sodium levels weren't the only factor associated with risk of disease, premature death, and faster aging: the risk was also higher among people with low serum sodium levels.
This finding is consistent with previous reports of increased mortality and cardiovascular disease in people with regularly low sodium levels, which have been attributed to diseases that cause electrolyte problems, the authors noted.
The study followed the participants over a long period, but the findings do not prove a cause-and-effect relationship between serum sodium levels and these health outcomes, the authors noted.
More studies are needed, they added, but the findings may help doctors identify and target patients at risk.
"People whose serum sodium is 142 mEq/L or higher would benefit from an assessment of their fluid intake," Dmitrieva said.
Sesso noted that the study did not fully address accelerated aging, "which is a complicated concept that we are just beginning to understand."
"Two key reasons underlie this," Sesso said.
The study authors "relied on a combination of 15 measures for accelerated aging, but this is one of many definitions that exist for which there is no consensus."
Second, their data on hydration and accelerated aging were a 'snapshot' in time, so we have no way of understanding cause and effect."
Drink enough fluids each day
About half of the world's population does not meet the total daily water intake recommendations, according to several studies cited by the authors of the new research.
"Globally, this can have a huge impact," Dmitrieva said in a press release.
"Decreased body water content is the most common factor that increases serum sodium, so the results suggest that staying well hydrated may slow the aging process and prevent or delay chronic disease."
Our serum sodium levels are influenced by fluid intake from water, other fluids, and fruits and vegetables with a high water content.
"The most impressive finding is that this risk (for chronic disease and aging) is evident even in individuals who have serum sodium levels that are at the high end of the 'normal range,'" said Dr. Richard Johnson, professor from the University of Colorado School of Medicine, via email.
He did not participate in the study.
"This challenges the question of what is really normal, and supports the concept that as a population we probably aren't drinking enough water."
According to the Cleveland Clinic, more than 50% of the body is made up of water, which is also necessary for multiple functions, such as digesting food, creating hormones and neurotransmitters, and delivering oxygen throughout the body.
The National Academy of Medicine (formerly known as the Institute of Medicine) recommends that women consume 2.7 liters (91 ounces) of fluids per day and men 3.7 liters (125 ounces).
This recommendation includes all liquids and foods rich in water, such as fruits, vegetables, and soups.
Since the average ratio of fluid to food intake of water is approximately 80:20, this equates to a daily amount of 9 cups for women and 12 ½ cups for men.
People with health problems should consult their doctor about the amount of liquid they should ingest.
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"The goal is to make sure that patients are getting enough fluids, while also evaluating factors, such as medication, that can lead to fluid loss," said study co-author Dr. Manfred Boehm, director of the Laboratory. of Cardiovascular Regenerative Medicine, in a press release.
"Doctors may also need to defer to a patient's current treatment plan, such as limiting fluid intake for heart failure."
If you're having trouble staying hydrated, you may need help incorporating this habit into your regular routine.
Try leaving a glass of water by your bed to drink when you wake up, or drink water while you make your morning coffee.
Anchor your hydration habit to a place you are a few times a day, behavioral science expert Dr. BJ Fogg, founder and director of Stanford University's Behavioral Design Lab, previously told CNN.
CNN's Sandee LaMotte contributed to this article.
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