Health benefits, say some researchers, may range from helping prevent diabetes to lowering the risk of liver disease.
With over 400 billion cups of coffee thought to be consumed every year, coffee is one of the world's most popular drinks. But is it really healthful, or are there also risks?
1) Coffee and diabetes
Coffee may help protect against type 2 diabetes. Researchers at UCLA identified that drinking coffee increases plasma levels of the protein sex hormone-binding globulin (SHBG). SHBG controls the biological activity of the body's sex hormones (testosterone and estrogen) which play a role in the development of type 2 diabetes.4
Dr. Simin Liu, one of the authors of the study, said that an "inverse association" exists between coffee consumption and risk for type 2 diabetes.
Increased coffee consumption may reduce risk of type 2 diabetes - the Harvard School of Public Health (HSPH) researchers gathered data from three studies. In these studies, the diets of the participants were evaluated using questionnaires every 4 years, with participants who reported having type 2 diabetes filling out additional questionnaires. In total, 7,269 study participants had type 2 diabetes.
The researchers found that the participants who increased their coffee intake by more than one cup a day (on average, an increase of 1.69 cups per day) over a 4-year period had an 11% lower type 2 diabetes risk over the subsequent 4 years, compared with people who did not change their intake.
2) Coffee and Parkinson's disease
Researchers in the U.S. carried out a study that assessed the link between coffee consumption and Parkinson's disease risk. The authors of the study concluded that "higher coffee and caffeine intake is associated with a significantly lower incidence of Parkinson's disease".5
In addition, caffeine in coffee may help control movement in people suffering from Parkinson's, according to a study conducted at the Research Institute of the McGill University Health Centre (RI MUHC) that was published in the journal Neurology.6
3) Coffee and liver cancer
Italian researchers found that coffee consumption lowers the risk of liver cancer by about 40%. In addition, some of the results suggest that if you drink three cups a day, the risks are reduced by more than 50%.7
The lead author of the study, Dr. Carlo La Vecchia, from Milan's Istituto di Ricerche Farmacologiche Mario Negri, said "our research confirms past claims that coffee is good for your health and particularly the liver."
4) Coffee and liver disease
Regular consumption of coffee is linked to a reduced risk of primary sclerosing cholangitis (PSC), a rare autoimmune disease of the bile ducts in the liver.8
In addition, coffee consumption can lower the incidence of cirrhosis of the liver for alcohol drinkers by 22%, according to a study at the Kaiser Permanente Medical Care Program, California, USA.
The authors of the study concluded that the results "support the hypothesis that there is an ingredient in coffee that protects against cirrhosis, especially alcoholic cirrhosis."9
Research published in the journal Hepatology in April 2014, suggested that drinking coffee is linked to a decreased liver cirrhosis death risk. The researchers suggested that drinking two or more cups of coffee every day can reduce the risk of death from liver cirrhosis by 66%.16
A study published in the journal Hepatology indicates that drinking decaf coffee also lowers liver enzyme levels, suggesting the benefits are not linked to caffeine content.
5) Coffee and heart health
Researchers at Beth Israel Deaconess Medical Center (BIDMC) and Harvard School of Public Health, concluded that drinking coffee in moderation protects against heart failure. They defined 'in moderation' as 2 European cups (equivalent to two 8-ounce American servings) per day.10
People who drank four European cups on a daily basis had an 11% lower risk of heart failure, compared to those who did not.
The authors stressed that their results "did show a possible benefit, but like with so many other things we consume, it really depends on how much coffee you drink."
Other possible benefits
Studies have suggested that coffee may:
- help prevent premature death
- reduce mortality
- protect against cirrhosis
- reduce the risk ofmultiple sclerosis
- protect against colorectal cancer
Some of these claims need to be confirmed by further research.
Regular black coffee (without milk or cream) has a very low calorie count. A typical cup of black coffee only contains around 2 calories.
However, if you add sugar and milk, the calorie count can shoot up.
Coffee is the number one source of antioxidants in the U.S., according to researchers at the University of Scranton.
Joe Vinson, Ph.D., lead author of the study, said that "Americans get more of their antioxidants from coffee than any other dietary source. Nothing else comes close."2
The authors of the study emphasize moderation, stating that only one or two cups a day appear to be beneficial.
Caffeinated and decaffeinated versions provided nearly the same levels of antioxidants.
Coffee: Is it helpful or harmful?
Drinking too much coffee can result in some very unpleasant adverse effects. According to a study by researchers at the University of Oklahoma, "caffeine can cause anxiety symptoms in normal individuals, especially in vulnerable patients, like those with pre-existing anxiety disorders."13
In addition, "caffeine use is also associated with symptoms of depression due to either a self-medication theory, or a theory that caffeine itself causes changes in mood."Women who plan on becoming pregnant should be cautious. Researchers from the University of Nevada School of Medicine reported in the British Journal of Pharmacology that regular coffee may reduce a woman's chances of becoming pregnant.14
Medical News Today examined the positive and negative effects of drinking coffee in an article in July 2012, Drinking Coffee: More Good Than Harm?.
Other possible risks include:
- having a negative effect on cardiovascular health in young adults with mild hypertension
- disrupting the body clock
In one study, researchers detected the presence of mycotoxins in commercial coffee samples, leading to concerns about potential public health risks