Drinking Water May Lower Stroke Risk

Being well-hydrated has many benefits beyond quenching thirst. Hydration is necessary for your body to function properly, and you can’t survive more than about three days without hydration. Your brain is also highly dependent on water. Even slight dehydration can negatively impact mood, memory and concentration. 

Studies have shown a link between hydration status and blood flow. Essentially, when we’re dehydrated, our blood is thicker and doesn’t flow as easily through our blood vessels. This also increases the chances of it being “clumpy.” And clumpy blood has been linked to stroke and heart attacks, the No. 1 killer of American adults. Researchers also point out evidence that drinking enough water is associated with a reduced risk of hypertension, diabetes and obesity. Plus, there’s even a link between adequate water intake and lower levels of inflammation.

Researchers from China wanted to know if drinking enough plain water could reduce stroke risk, and if so, what threshold of water intake makes a difference. They took a closer look at data from a long-term American study, the National Health and Nutrition Examination Survey (NHANES), to find answers and published their findings in the Journal of Stroke and Cerebrovascular Diseases. Let’s break down what they found.

How Was This Study Conducted?

Researchers pulled data from the years 1999 to 2020 of NHANES. They included adults over the age of 20 at baseline, with an average age of 49. More than 29,000 people were included in this analysis, and about 48% were male. 

For NHANES, participants completed 24-hour diet recalls that included daily water intake. Since recalling what we ate the previous day leaves room for error, researchers took the average of two 24-hour recalls for increased accuracy. Participants were then placed into one of four quartiles (groups) based on their water intake. Those in quartile 1 (Q1) had the lowest water intake, and those in Q4 had the highest.

Information on stroke was gathered from participants answering the question, “Has a doctor or other health professional ever told you that you had a stroke?” Almost 1,300 participants answered yes. 

Variables that would be adjusted for during statistical analyses included age, sex, ethnicity/race, education and income levels, smoking status, alcohol intake, BMI, physical activity, calorie consumption, hydration consumption, high blood pressure, diabetes, high cholesterol and heart disease. 

What Did This Study Find?

After adjusting for all relevant demographic variables—plus total calorie and hydration consumption—the group that drank the most water had a 25% lower risk of stroke compared to those who drank the least. 

Researchers also found an association between stroke risk and the amount of plain water intake. Those who drank less than approximately 1,400 mL of water per day—which is equal to about 6 cups or 47 fluid ounces of water—had a significantly higher risk of stroke. 

Some limitations of this study include the 24-hour dietary recalls, which, as previously mentioned, leave room for error and bias in participants recalling what they ate. Also, because NHANES is an observational study, researchers cannot establish causation, just that there is an association between those who drink more plain water and a lower risk of stroke. Lastly, only plain water was considered, so it’s unknown if other types of water, like sparkling water, might have the same associations with stroke risk as plain water.

How Does This Apply to Real Life?

The amount of water needed for each person depends on several factors, including sex, age, activity levels and medications. And while it is person-dependent, there are some general guidelines to provide a framework for you. For example, the National Academies of Sciences, Engineering and Medicine recommends that men drink 15.5 cups of water per day and women drink 11.5 cups per day.

Eating hydrating foods can also add to your hydration status. Nosh on watermelon, cucumbers, apples, grapefruit, okra, tomatoes and plain Greek yogurt to help stay hydrated. 

If your blood sugar tends to run on the high side, consider your hydrating habits. When blood is thicker and more viscous, blood sugar is more concentrated. Drinking plenty of water helps thin it out and can help lower blood sugar levels. 

With that said, too much of a good thing is, well, too much, and you can overhydrate. Referred to as hyponatremia or water intoxication, flooding your body with too much water dilutes the body’s electrolytes. And while rare, it can lead to death. Some signs you might be over imbibing on the H2O include clear urine, bloating, nausea, brain fog, headache and confusion. 

Do an assessment of your water intake. It can help to track it over several days and take the average of them. Are you coming close to the recommended 11.5 to 15.5 cups a day? It also helps to assess the color of your urine. Ideally, it’s about the color of diluted lemonade. This color suggests that you’re getting enough water into you. If it’s dark yellow or amber, it’s a sign that you’re not and are dehydrated, so drink up. 

It’s important to note that certain medications, supplements and foods can affect urine color. For example, if you’ve eaten beets, your urine might be red-tinged. And supplements that contain B vitamins can give you bright yellow pee. 

One strategy to get you started is to swap one of your typical drinks for water. So if you tend to grab soda throughout the day, start by exchanging one soda a day with water. Next week, swap out two sodas and so on. 

If you can’t stomach all that plain water, try flavoring it with fruits, vegetables and herbs. Lemon, Cucumber and Mint Infused Water is clean and refreshing on the palate. Or add berries or a splash of 100% juice to up the flavor quotient of plain water. Another trick is to try the water at different temperatures. Some people can tolerate it better when it’s ice cold. 

Besides staying well-hydrated, there are other lifestyle factors that may help lower your stroke risk, too. Following a heart-healthy diet plan or an eating style like the Mediterranean diet will go a long way toward getting the nutrients you need for a healthy heart and brain. So stock up on plenty of fruits, veggies, whole grains, legumes, nuts, seeds, lean proteins and healthy fats. Engaging in regular physical activity, dealing with what’s stressing you out and getting plenty of quality sleep also play large, connected roles in preventing diseases like stroke. 

Our Expert Take

According to this study, drinking less than 6 cups a day of plain water increases your risk of stroke. It is unknown whether plain carbonated waters, like sparkling water, reduce stroke risk, but they do contribute to overall hydration. Flavor your water with fruit, veggies and herbs if you have a difficult time imbibing plain water. Also consider your whole-health picture and other lifestyle habits that contribute to heart and brain health, which play a role in stroke prevention.