Study: Staying Hydrated Might Be the Secret to Living Longer

Drinking water has its perks—it prevents dehydration, maintains a normal body temperature, and can often ease constipation. According to a new study, how much water you drink might also be linked to how quickly you age and your risk for developing chronic diseases. 

The adults in the study who were sufficiently hydrated appeared to be healthier, were less likely to show signs of aging, developed fewer chronic health conditions, and lived longer than adults who were not well-hydrated. 

Experts suggest the longevity perks of hydration appear to be tied to keeping sodium levels in check. When it comes to making sure you’re getting enough water to reap this benefit, there are a few things to keep in mind.

Higher Sodium Levels Linked to Health Problems

The National Institutes of Health (NIH) study looked at health data on more than 11,000 adults in the United States who were followed for about 25 years. The researchers had data from several points in time, including when the participants were in their 50s and when they were between the ages of 70 to 90.

To determine how hydrated the participants were, the research team measured the concentration of sodium (salt) in their blood. 

Natalia Dmitrieva, PhD, an author of the study and a researcher in the Laboratory of Cardiovascular Regenerative Medicine at the National Heart, Lung, and Blood Institute (NHLBI), told Verywell that decreased levels of water in the body is the most common factor that increases sodium in the blood.

While most of the participants had blood sodium levels that fell within a normal range—135 to 146 millimoles (mmol) per liter—the researchers found the people with sodium serum levels above 144 mmol had a 21% increased risk of dying younger compared to people who were better-hydrated.

The researchers also found that the people who had sodium serum levels higher than 142 mmol had a 39% increased risk of developing chronic illnesses like heart failure, dementia, lung disease, stroke, diabetes, and high blood pressure (hypertension).

Take the Study With a Grain of Salt

Since sodium levels can indicate hydration status, Dmitrieva said that’s why the researchers believe the study’s results “suggest that staying well-hydrated may slow down aging, prevent or delay development of chronic diseases, and therefore, prolong disease-free life.”

Even though staying hydrated is key to having a healthy, functioning body, some experts say that the study’s results do not show a causal effect—in other words, they do not prove that optimal hydration prevents serious disease or improves longevity.

“There’s just a lot of uncertainty because they did not control which fluids they might have been drinking and what their hydration status was at time other than when they had their serum sodium measured,” David Cutler, MD, a family medicine physician at Providence Saint John’s Health Center in Santa Monica, California, told Verywell.

Cutler cautions that people should consider the study’s limitations and not jump to make changes to their lifestyle based on its findings.

“I wouldn’t draw too many conclusions from this [study] saying more water in a lower sodium level is necessarily better,” said Cutler. “Anything in life can have both good and bad effects.”

How Hydration Keeps You Healthy

Eric Ascher, DO, a family medicine physician at Lenox Hill Hospital in New York City, told Verywell that people who stay well hydrated with water are also “more likely to have other healthy habits,” such as staying active, making nutritious food choices, and getting enough sleep.

Taking care of your physical health with regular exercise and quality sleep supports healthy aging and helps prevent chronic disease.

Ascher pointed out one example of how water helps you with these goals: hydration keeps your joints lubricated. If you can move without pain, it’s easier to exercise and lead a less sedentary lifestyle—habits that are great for your heart health.

When you’re dehydrated, Ascher said it can affect your blood pressure levels. High blood pressure can raise your risk for heart attacks and strokes.

“Hydration status affects more than just your thirst. Your body is in a constant state of trying to balance different vitamins, minerals, neurotransmitters, and hormones,” said Ascher. “If there is an imbalance that dehydration contributes to, you risk interrupting body processes that can lead to organ damage or chronic disease.”

Could Hydration Fight Aging?

Hydration also stimulates blood flow, which helps your body remove toxins. According to Ascher, fewer toxins and a healthier heart may help lead to a longer life.

Dmitrieva admits that more research is needed to understand how not being well-hydrated might accelerate aging and increase the risk of chronic disease—but they do have theories.

One idea Dmitrieva has is that low water intake and dehydration stimulate the secretion of hormones that negatively affect the kidneys, leading to the excretion of lower volumes of more concentrated urine.

“Elevated levels of these hormones also affect other tissues in the body, gradually undermining their proper functions and leading to accelerated aging,” she said.

How Much Water Should You Drink a Day?

The basic guideline has long been to drink eight eight-ounce glasses of water every day. There are organizations that provide a range—for example, the National Academy of Medicine recommends 13 eight-ounce cups of fluid daily for men and 9 cups for women.

While a lot of people try to focus on getting their eight eight-ounce glasses of water daily, a recent study found that there really can’t be a one-size-fits-all recommendation.

The reality is that fluid intake needs are not the same for everyone. Ascher said that daily water needs vary because of differences in age, sex, pregnancy status, body size, composition, activity level, and lifestyle habits, as well as factors like the temperature of the climate and surroundings.

“Everyone requires a different amount of fluids,” said Ascher. For example, “the more you sweat or exercise, the more you are likely to be dehydrated, therefore the more water you will need.”

You also need to take other foods and beverages you have in a day into account. The Centers for Disease Control and Prevention (CDC) notes that while most people get enough fluids by drinking plain water, foods with a high water content like fruits and vegetables can also help them meet their fluid needs.

Hydrate—But Not Too Much

Dmitrieva cautioned that it is possible to drink too much water. If you get overhydrated, your kidneys won’t be able to excrete the extra water. This can lead to a potentially dangerous condition where the sodium content in your blood gets diluted or drops (hyponatremia).

“There is no need to drink more than three liters per day if there is no excessive water loss due to exercise or prolonged heat exposure,” she said. “If someone drinks more than three liters per day and still feels thirsty, it could be an indication of a disease condition that results in pathologically increased water losses and requires clinical evaluation.”

In other words, if you’re feeling really thirsty all the time or you just don’t know how much water you should be drinking, talk to your provider.

How Can You Tell If You're Not Drinking Enough Water?

When you’re dehydrated, Cutler said it means your body is losing more fluids than it’s taking in. Here are a few signs that you may need to drink more water:

• You feel thirsty 
• You’re not sweating when it’s hot outside 
• You have dark yellow urine
• You have strong-smelling urine
• You’re going pee less than usual
• You feel tired, dizzy, or lightheaded
• You have a dry mouth, lips, and tongue 

Even if you feel fine, checking your pee once in a while can help you spot the visual cues that you’re not drinking enough.

“If your urine resembles a very pale yellow like a watered-down lemonade, your body is adequately hydrated, said Ascher. “Anything darker is a sign of dehydration, anything clearer may signify overhydration.”

Dmitrieva said that the key to staying well hydrated is to be aware of how much fluid you’re taking in every day and make sure that you’re consuming water on a regular basis.