哈佛研究
Moderate amounts of coffee are the best
Coffee has had a hot-and-cold reputation when it comes to health benefits.
Drinking two to five daily cups of coffee may protect against heart disease, diabetes, and some cancers, but too much can cause problems like anxiety, nervousness, and insomnia. Now, a review of existing research suggests that a moderate approach to coffee is the best medicine. The results were published July 23, 2020, in The New England Journal of Medicine.
Based on their review of 95 studies, the authors suggest limiting total caffeine consumption from all beverages, including coffee, to 400 milligrams per day. That's equal to about four to five 8-ounce cups of most regular coffees. This amount helps people get much of the benefit of coffee but with a lower risk of caffeine's side effects, according to the researchers.
Scientists can't say for sure why coffee is healthy.
Given that the benefits are more strongly related to coffee compared with other caffeinated drinks, they likely result from ingredients in coffee other than caffeine. Coffee also contains a combination of phytochemicals, magnesium, potassium, and vitamin B, all of which have shown to lower oxidative stress and improve metabolism.