Can coffee help prevent cancer?

By Morgan Wharton and Jessica Cote

 

Most Americans drink coffee every day.¹ The caffeine in coffee helps us stay alert but also may cause jitteriness and interfere with sleeping. A few studies suggest that decaffeinated coffee also has health benefits, perhaps because of antioxidants or acids in the coffee bean.²

What Are The Health Benefits Of Drinking Coffee?

For years medical experts advised people to drink less coffee, mostly because of research suggesting coffee might increase the risk of heart disease. However, numerous studies conducted recently have discovered coffee’s unexpected health benefits. Like all well-designed research, most of these studies considered the impact of age, sex, body mass index (BMI), physical activity, tobacco use, and whether family members had developed cancer. By controlling for those factors, researchers made sure they could separate coffee’s impact on health from the effects of people’s lifestyle, family history, and previous health problems.

Colorectal Cancer

Meta-analyses are a kind of statistics that combine data from several comparable studies to make one very large study. These results are usually more accurate than any one study can be. Taken together, three meta-analyses suggest that drinking about four or more cups of coffee per day may reduce the chances of getting colorectal cancer by 11-24%.³⁴⁵

Endometrial (uterine) Cancer

Using data from 67,470 women who participated in the Nurses’ Health Study, researchers found that women who drank four or more cups of coffee per day were 25% less likely to develop endometrial cancer than women who drank only one cup of coffee per day. Compared to women who did not drink any coffee, those who drank four cups or more per day were 30% less likely to develop endometrial cancer. Decaffeinated coffee was just as effective as caffeinated coffee, but caffeinated tea did not lower the risk of endometrial cancer.⁶

Liver Cancer And Cirrhosis (Scarring of the Liver/Chronic Liver Disease)

One study found people who drank one or two cups of coffee per day had a slightly lower risk of getting the most common type of liver cancer compared to non-drinkers, but people who drank three or four cups of coffee were about half as likely as non-drinkers to get this kind of liver cancer. Meanwhile, people who drank five or more cups per day had an even lower risk than that (about one-third the risk of non-drinkers).⁷

Similarly, a study in Japan found a 76% decrease in the risk of that type of liver cancer in people who drank at least five cups of coffee per day compared to those who did not drink coffee. The strongest benefit was seen in individuals with hepatitis C, a disease which increases a person’s risk of developing liver cancer, although the researchers were not sure why.⁸

A study of 120,000 Americans over an 8-year period found a 22% decrease in the chances of developing cirrhosis for each daily cup of coffee. In Norway, a 17-year study of 51,000 citizens found that those who drank two or more cups of coffee per day were 40% less likely to develop cirrhosis compared to those who did not consume coffee.⁹

Skin Cancer

Using data from two enormous studies, the Nurses’ Health Study and the Health Professionals Follow-up Study, researchers found that men and women who drank more than three cups of caffeinated coffee per month were 17% less likely to develop basal cell carcinoma compared to people who drank less than one cup per month. Basal cell carcinoma is the most common and least dangerous type of skin cancer. Drinking decaffeinated coffee did not affect basal cell carcinoma.¹⁰

A 2014 study in the Journal of the National Cancer Institute found that the more coffee participants drank, the less likely they were to develop malignant melanoma over a 10 year period. Melanoma is the most dangerous form of skin cancer. Almost 450,000 whites, aged 50-71, participated in the study. Researchers found that drinking four or more cups of coffee per day was linked to a 20% lower risk of getting malignant melanoma. Once again, drinkers of decaffeinated coffee lost out. Their risk of getting melanoma was no different from that of non-coffee drinkers. Coffee drinking, however, did not affect the least dangerous form of melanoma, called melanoma in situ.

Remember that no matter how much coffee with caffeine you drink, the best way to prevent skin cancer is still to limit your time exposed to the sun and ultraviolet light! ¹¹

Bottom line

For most people, drinking coffee seems to improve health more than harm it. Many of coffee’s health benefits increase with the number of cups per day, but even one cup a day lowers the risk of several diseases. However, women who want to get pregnant or already are pregnant and women over 65 should probably limit their coffee intake because, in their case, the risks may outweigh the health benefits.

You can read more about coffee’s benefits and risks on different diseases here. Even though many studies show coffee has benefits, it’s still not clear why. Until further research can solve that puzzle, most adults should continue to enjoy their cup (or two, or three) of Joe. Finally, remember that nearly all studies on coffee and health have been done on adults. Coffee may affect children and teens differently.