Drinking 8 glasses of water a day may be key to healthy heart for decades

SOPHIA ANTIPOLIS, France — Drinking eight glasses of water a day is an age-old recommendation which doctors say keeps your entire body healthy. Now, a new study reveals getting enough water not only prevents dehydration, but may also keep your heart from failing decades later.

“Our study suggests that maintaining good hydration can prevent or at least slow down the changes within the heart that lead to heart failure,” says study author Dr. Natalia Dmitrieva of the National Heart, Lung, and Blood Institute, part of the National Institutes of Health, in a media release. “The findings indicate that we need to pay attention to the amount of fluid we consume every day and take action if we find that we drink too little.”

Health experts typically recommend that women drink anywhere from six to eight eight-ounce glasses of water each day. For men, that number stands between eight and 12 glasses. Despite this, surveys find many people don’t come anywhere near this range.

Study authors add that serum sodium provides scientists with a precise measure of how hydrated a person really is. When people drink less water, the concentration of serum sodium in their bodies goes up. The human body reacts to this by trying to conserve water, triggering biological processes which contribute to heart failure.

“It is natural to think that hydration and serum sodium should change day to day depending on how much we drink on each day. However, serum sodium concentration remains within a narrow range over long periods, which is likely related to habitual fluid consumption,” Dr. Dmitrieva explains.

Less water now may hurt your heart 25 years later

Researchers examined serum sodium levels in 15,792 adults from the Atherosclerosis Risk in Communities (ARIC) study during this project. All of the participants were between 44 and 66 years-old at the start and were evaluated five times over the next 25 years.

Study authors kept track of each person’s hydration and the thickening of the walls along the heart’s left ventricle — the main pumping chamber. This type of thickening (or left ventricular hypertrophy) is a common precursor to heart failure.

The team also divided the group into four categories, based on their average serum sodium concentrations at the start of the study. Those readings ranged between 135–139.5, 140–141.5, 142–143.5, and 144–146 mmol/l. Using these measurements, researchers looked at the number of participants who developed heart failure and left ventricular hypertrophy by year 25.

Their findings reveal higher serum sodium concentration during middle age displays a link to both heart failure and left ventricular hypertrophy later in life. The readings remained constant even after taking into account factors such as age, blood pressure, kidney health, cholesterol, blood glucose, body mass index, sex, and smoking habits.

Moreover, researchers find every 1 mmol/l increase in serum sodium concentration leads to a 1.20-percent higher chance of developing left ventricular hypertrophy and a 1.11-percent jump in the odds of suffering from heart failure.

Keep serum sodium below 142

Dr. Dmitrieva notes that the risk of both heart ailments in people between 70 and 90 years-old increases when their serum sodium levels rise above 142 mmol/l during midlife.

“The results suggest that good hydration throughout life may decrease the risk of developing left ventricular hypertrophy and heart failure. In addition, our finding that serum sodium exceeding 142mmol/l increases the risk of adverse effects in the heart may help to identify people who could benefit from an evaluation of their hydration level. This sodium level is within the normal range and would not be labelled as abnormal in lab test results but could be used by physicians during regular physical exams to identify people whose usual fluid intake should be assessed,” the NIH researcher concludes.

The team presented their findings at ESC Congress 2021.

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