Drinking water day in and day out can be kind of boring, leading plenty of people to sip on soda, fruit drinks, coffee, and other beverages. But two new studies found that overindulging in these drinks could raise your risk of stroke. 

The studies, which were conducted by the same researchers, were published in the Journal of Stroke and the International Journal of Stroke. The first study analyzed data from the Interstroke research project, which involved nearly 27,000 people in 27 countries. That study focused on the consumption of fizzy drinks and fruit juice and had some eye-opening findings. 

The researchers discovered that both sugar-sweetened and artificially sweetened fizzy drinks were linked with a 22% increased risk of stroke, with the risk rising sharply when people had two or more of them a day. Fruit juice was linked with a 37% higher risk of stroke, and the risk tripled when people had two or more servings of fruit juice a day. Also worth noting: People who drank more than seven cups of water a day had a lowered risk of stroke caused by a clot. 

The researchers also analyzed data from the Interstroke research project for the second study. They discovered that drinking more than four cups of coffee a day increased the risk of stroke by 37% (but there wasn’t a risk of stroke with drinking less than that). Drinking tea actually lowered the chance of stroke by up to 20%. 

If these drinks are in regular rotation in your diet, it’s understandable to have questions. Here’s what neurologists want you to know. 

What is stroke and what causes it?

A stroke can happen when blood flow to the brain is blocked or when there is sudden bleeding in the brain, according to the National Heart, Lung, and Blood Institute (NHLBI). 

The most common type of stroke is called an ischemic stroke — this is what happens when blood flow to the brain is blocked, per the NHLBI. As a result, the brain can’t get oxygen and nutrients from blood, and brain cells start to die within minutes. The other type of stroke is a hemorrhagic stroke, which happens when someone has sudden bleeding in the brain. 

“With a stroke, a portion of the brain is injured,” says Amit Sachdev, M.D., M.S., medical director in the Department of Neurology at Michigan State University. “While the brain can recover from that loss by finding pathways around the area, it is never quite as robust as it was before. Recovery is not a guarantee, can take a long time and can be very disruptive to a patient’s life.”

Why might fizzy drinks and fruit juice raise your risk of stroke?

It’s not entirely clear why fizzy drinks and fruit juice raise your risk of stroke — the study simply found a link. But there are a few theories on what could be behind this. 

“We suspect that fizzy drinks contain substances that may have adverse cardiovascular effects,” says Andrew Smyth, Ph.D., lead researcher for both studies and a professor of clinical epidemiology at the University of Galway. “Full sugar fizzy drinks will contain additional sugars that may impact caloric intake and potentially weight gain, but they may also contain other substances — e.g. sweeteners in artificially sweetened drinks — that could also impact health.”

Christopher Yi, M.D., a vascular surgeon at Memorial Orange Coast Medical Center in Fountain Valley, CA, also says that the sugar content in these drinks may play a role. “High sugar content in regular carbonated drinks can contribute to obesity, diabetes, and hypertension, all of which are major risk factors for ischemic stroke and hemorrhagic stroke,” he says. “Similarly, the sugar additives to fruit drinks can cause rapid spikes of blood sugar and insulin levels, which can promote inflammation.”

Why might four or more cups of coffee increase your stroke risk?

There are a few potential factors here. “Folks with this rate of coffee consumption could just enjoy this as a preferred beverage,” Sachdev says. “More frequently, there could be an underlying issue that affects overall body health that that person is trying to treat, such as a sleep disorder.” (Research has shown that having a sleep disorder like insomnia can also raise your risk of stroke, Sachdev points out.) 

But coffee also has caffeine, “and too much caffeine raises blood pressure,” Sachdev says, noting that high blood pressure is also a risk factor for stroke. 

How to lower your stroke risk

Based on his findings, Smyth recommends limiting how much coffee, fizzy drinks, and fruit drinks you have. “If you’re looking for a hot beverage, we suggest tea,” he says. “If you’re looking for a cold beverage, we suggest water.”

Sachdev also suggests doing your best to maintain a healthy lifestyle, aiming for at least 150 minutes of moderate-intensity exercise a week and eating a plant-forward diet. “Good body health is important for good brain health,” he says. 

But it’s also important to be aware of your family and personal health history, as well as steps to take from there. “If you have certain risk factors for stroke, such as a family history, diabetes, or smoking history, then you may want to discuss with your provider if primary prevention with low-dose aspirin could be a part of your health regimen,” Sachdev says.