There have been many studies on the health benefits of coffee, say, coffee drinkers had a lower risk of heart and liver disease

Which is more popular—coffee or tea?
    If you are on Team Coffee, your team may be ahead.
    The well-known U.S. coffee shop Starbucks just opened its largest store in the land of tea: China! The Shanghai Starbucks is 2,700 square meters and employs more than 400 people.
    But now for the health question: Is coffee good for us?
    There have been many studies on the health benefits of coffee. Recently, researchers at the University of Southampton’s Faculty of Medicine in Great Britain looked at results from 201 observational coffee studies and 17 clinical trials of coffee.
    With this "umbrella review," researchers wanted to find a clear answer on whether coffee is good for us or not. They discovered that coffee drinkers had a lower risk of heart and liver disease and some cancers. Coffee drinkers also had a lower risk of dying from stroke.
    However, their findings are uncertain. The researchers could not prove coffee was the cause of these lowered risks.
    One of the researchers of this umbrella review is Robin Poole. Poole’s team notes that their umbrella review included mainly observational data. Therefore, they could not prove any cause and effect relationship.
    The National Institutes of Health in the United States defines an "observational uncontrolled study" as a study where "researchers simply watch what happens to a series of people in one group." There is no control group.
    Still, researchers found that the benefits of moderate coffee drinking seem to outweigh the risks. Their report says that drinking coffee "was more often associated with benefit than harm."
    Poole calls these findings "headline benefits."
    "There are some headline benefits such as a lower risk of dying from any cause, a lower risk of dying from heart disease and stroke and a lower risk of developing heart disease in the first place. And for those outcomes, the maximum benefit was around three to four cups of coffee per day."
    Poole means that if people read only the headline, they may think that the results are simply positive. But he warns that the coffee story is much more complicated.
    He advises people to not drink more than four cups a day. And not everyone should drink so much coffee.
    Researchers found that:
      Too much coffee during pregnancy can be dangerous.
       People, especially women, whose bones break easily should limit how much coffee they drink.
       People with abnormal heartbeat patterns are advised to drink decaffeinated coffee. Healthy coffee is black coffee
    In addition, the scientists point out that the research was only about coffee. Yet many coffee drinkers don’t just drink coffee. They put sugar into it. They add milk or cream. They may have a baked treat on the side.
    Researcher Robin Poole warns that to get the full health benefits of coffee, keep it simple. Drinking it black is the healthiest. And skip the pastries.
    "It is not about the sugar and the syrups and the biscuits, cakes and pastries. And we would urge people who are already drinking moderate amounts of coffee—about the three or four cups per day mark—to enjoy it, but try and make it as healthy as possible because standard health messages still apply to those other things."
    The researchers found that the greatest benefit to drinking coffee seemed to be in fighting liver diseases. Based on that finding, they are planning a clinical test using coffee as a treatment for cirrhosis, a serious liver disease.
    But the final takeaway is the same as before: If you drink coffee, keep it simple and don’t eat the pastries or other baked treats that often come with a cup of coffee.
    And if you’re not a coffee drinker, you don’t need to start drinking coffee to be healthier.