People with very high blood pressure should drink less coffee

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In a study from the National Center for Global Health and Medicine in Tokyo, scientists found people with severely high blood pressure who drink two or more cups of caffeinated coffee each day could double their risk of dying from a heart attack, stroke, or other types of cardiovascular disease.

But drinking green tea or just one cup of coffee did not have the same effect.

The increased risk also did not apply to people with lower blood pressure levels who drank two or more daily cups of coffee.

Prior research suggests drinking one cup of caffeinated coffee per day may help people lower their death risk following a heart attack and help prevent heart attacks and strokes in healthy adults.

Some research suggests coffee can lower the risk for high blood pressure, also called hypertension, in people who don’t already have it.

But drinking too much coffee has been shown to raise blood pressure and lead to anxiety, heart palpitations and trouble sleeping.

The American Heart Association and American College of Cardiology define high blood pressure as a systolic (“top”) reading of 130 mmHg or higher or a diastolic (“bottom”) reading of 80 mmHg or higher.

In this study, researchers used five categories to classify blood pressure levels: optimal and normal (less than 130/85); high normal (130-139/85-89); grade 1 hypertension (140-159/90-99); grade 2 (160-179/100-109); and grade 3 (180/110 or higher).

People whose blood pressure was 160/100 or higher were considered to have severe hypertension.

The team tested 6,574 men and 12,035 women from 30 Japanese communities. Participants were ages 40 to 79 when they enrolled between 1988 and 1990. They were followed through 2009.

The team found that participants with severe hypertension who drank two or more cups of coffee each day doubled their risk of dying from cardiovascular disease, compared to those who didn’t drink coffee.

They also showed Drinking just one cup of coffee or any amount of green tea – regardless of blood pressure level – did not raise the risk.

Both drinks contain caffeine. An 8-ounce cup of coffee has 80 to 100 milligrams of caffeine, according to the Food and Drug Administration. An 8-ounce cup of green or black tea has 30 to 50 mg of caffeine.

The researchers suggested that polyphenols – micronutrients found in green tea that have antioxidant and anti-inflammatory properties – may partially account for why the drink was not linked to the increased death risk associated with high coffee consumption.

While the authors called for more research, researchers say these findings may support the assertion that people with severe high blood pressure should avoid drinking excessive coffee.

If you care about blood pressure, please read studies that black licorice could cause dangerous high blood pressure, and this common plant nutrient could help reduce high blood pressure.

For more information about blood pressure, please see recent studies that beetroot juice could help lower high blood pressure, and results showing cinnamon could help lower high blood pressure.

The study was conducted by Dr. Hiroyasu Iso et al and published in the Journal of the American Heart Association.

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