Some like it hot, some like it iced, and some just don’t like it at all. Until recently, coffee was on the list of habits to break if you really wanted to be healthy.
Not anymore. Systematic reviews of the research – the most powerful method to weigh up scientific evidence – judge the current evidence as mostly in favour of drinking coffee. Coffee drinking is linked to a decreased risk of premature death, type 2 diabetes and some types of cancer.
However, some people will need to be cautious of the amount. Heavy coffee intake has been linked to an increased risk of lung cancer and can exacerbate heart problems.
Coffee drinkers live longer. A review of 20 studies including more than 970,000 people found those who usually drank the most coffee had a 14% lower risk of dying prematurely from any cause, compared with those who drank the least.
Even drinking just one to two cups a day conferred an 8% lower risk.
Decaffeinated coffee drinkers who had two to four cups a day still had a 14% lower relative risk of premature death than those who didn’t drink coffee at all. (Post continues after gallery.)
Coffee drinkers, particularly men, have a lower risk of liver cancer. This is important as liver disease is the sixth-most-common cancer in the world and is more common in men.
Results from six studies, based on the total number of cups of coffee drunk per day, found the relative risk of liver cancer was 14% lower for every extra cup.
Research shows that naturally occurring coffee components, including kahweol and cafestol, have direct cancer-protection and anti-inflammatory properties. Coffee appears able to up-regulate biochemical pathways in the liver that protect the body from toxins, including aflatoxin and other carcinogenic compounds.
Type 2 diabetes
Coffee drinkers have a lower risk of type 2 diabetes. Across 28 studies of more than one million adults, those who drank three or more cups of coffee a day had a 21% lower relative risk of developing type 2 diabetes compared to those who never or rarely drank it.
For those drinking six or more cups a day, the risk was lowered by 33%.
Interestingly, the risk was lower for both regular and decaffeinated coffee drinkers. For each cup of regular caffeinated coffee there was an extra 9% lower relative risk of developing diabetes and a 6% lower risk for each cup of decaffeinated coffee.
The active components of coffee help reduce oxidative stress, the imbalance between free radicals and antioxidants. Coffee contains chlorogenic acid, which has been shown to improve glucose metabolism and insulin sensitivity, and caffeic acid, which increases the rate muscles use up blood glucose, as well as having immune-stimulating and anti-inflammatory properties.
Coffee drinkers have a lower risk of prostate cancer. Across 13 studies that included more than 530,000 men, those who drank the most coffee had a 10% lower relative risk of developing prostate cancer than those who drank the least.