Tea has long been associated with a lower risk of heart disease, stroke and dementia. A study published Wednesday in the Journal of Internal Medicine now suggests that the way people prepare and consume tea could influence its relationship with cardiovascular health.

Researchers analyzed information from more than 485,000 Chinese adults ages 30 to 79. Participants described how often they drank tea, which type they preferred, how strongly they brewed it and the temperature at which they consumed it.

During an average follow up of about nine years, researchers documented more than 14,800 cases of diseases affecting the heart and blood vessels. Those conditions included heart attacks, strokes and peripheral artery disease, which involves narrowed arteries supplying blood to the arms and legs.

One of the clearest findings involved drinking frequency. People who consumed tea at least three days a week had a roughly 11% lower risk of developing vascular disease than those who drank it less frequently.

That association remained after researchers accounted for factors including age, smoking, physical activity, body weight and existing medical conditions. Nonsmokers who habitually drank tea and had high levels of physical activity recorded the lowest cardiovascular risk.

Strength and tea type also appeared to matter. Moderate strength tea was associated with lower risk, while black tea was linked to reduced risks across more kinds of cardiovascular disease than green tea.

Temperature produced one of the study’s most striking results. Participants who said they drank tea at a burning hot temperature had a 16% higher risk of vascular disease than people who did not regularly consume tea.

By contrast, those who drank tea at room temperature or hot, but not scalding, had significantly lower risk than people who were not regular tea drinkers. The temperature finding, however, came with important limitations.

Participants reported their preferred drinking temperature rather than having it objectively measured by the study’s authors. What feels burning hot to one person may not match another person’s description, according to CNN wellness expert Dr. Leana Wen.

People who prefer extremely hot tea may also differ in dietary habits or other lifestyle factors that could influence cardiovascular risk. Researchers may not have been able to account fully for all of those differences.

Wen, an emergency physician and clinical associate professor at George Washington University, said tea contains naturally occurring compounds called polyphenols, including flavonoids. These compounds have properties that counter oxidation and inflammation.

The compounds may help protect cells lining the blood vessels while improving the ability of arteries to relax and expand. Those effects can lower blood pressure and reduce strain on the heart.

Previous studies have found that tea consumption can modestly improve blood pressure, cholesterol levels and other indicators of cardiovascular health. Such effects could help explain why regular tea drinkers have experienced lower rates of strokes, heart attacks and other serious cardiovascular consequences.

Tea may offer another benefit when people choose an unsweetened cup instead of soda, juice drinks or other sugary beverages. Replacing drinks containing added sugar with unsweetened tea reduces sugar intake, which can support weight management and metabolic health.

Black and green tea come from the same plant, Camellia sinensis, but differences in leaf processing produce different polyphenol compositions. Although black tea showed more consistent associations with lower cardiovascular risk in this study, green tea also showed benefits.

Wen did not advise green tea drinkers to switch to black tea, or the reverse. Either variety can fit into a heart healthy diet, particularly when it is consumed without added sugar.

Among participants who drank tea at least weekly, the lowest estimated vascular disease risk occurred at approximately six to eight cups daily. Risk began rising again at consumption levels exceeding that amount.

Caffeine is another reason to watch total intake. An 8 ounce cup of black tea typically contains about 30 to 50 milligrams of caffeine, while green tea usually contains less, though most varieties still contain caffeine unless their labels explicitly say otherwise.

The US Food and Drug Administration cites 400 milligrams of caffeine per day as an amount not usually associated with dangerous effects. Pregnant people are advised to limit daily caffeine intake to 200 milligrams, and children should not consume caffeinated drinks.

For practical purposes, Wen advised avoiding tea hot enough to burn the mouth or throat. Allowing tea to cool until it can be sipped comfortably can prevent burns and could help preserve its potential cardiovascular benefits.

Regular tea drinkers should also consider total caffeine intake, especially if they experience anxiety, sleep problems or palpitations. People who do not drink tea need not begin, since physical activity, avoiding smoking, maintaining healthy blood pressure and cholesterol levels, and eating a nutritious diet are also supported ways to reduce cardiovascular disease risk.