Health professionals just can’t seem to make up their minds about coffee. Is it good or really bad for you? They have been arguing about the pros and cons of coffee drinking for at least half a century.
Does Coffee Harm the Heart?
Investigators for the Boston Collaborative Surveillance Program concluded that heavy coffee drinkers had twice the risk of a heart attack compared to people who never drank coffee (Lancet, Dec. 16, 1972).
On the other hand, researchers with the Framingham Heart Study found that
“coffee drinking, as engaged in by the general population, is not a factor in the development of atherosclerotic cardiovascular disease” (New England Journal of Medicine, Oct. 24, 1974).
Both groups of scientists were based in Massachusetts. We don’t know whether the proximity made their argument more intense or not. Certainly, doctors continued to disagree about whether coffee is really bad for you over many years after that.
Coffee and Cholesterol:
One controversy centered on cholesterol. Do coffee drinkers have higher cholesterol? Could that affect their cardiovascular mortality? Moreover, does it matter how you make your coffee?
As it turns out, brewing method may make an important difference. “Cowboy style coffee” in which the grounds are added directly to a pot of boiling water can apparently raise cholesterol, especially bad LDL. Scandinavians apparently like to boil their coffee, too (Metabolism, Nov. 1987). Finnish scientists actually recruited 42 people with mildly elevated cholesterol and gave them eight cups a day of boiled coffee, filtered coffee or tea. The filtered coffee and tea did not raise cholesterol.
Researchers kept hunting for the explanation. They discovered that the cholesterol-raising factor in coffee does not get through paper filters (Arteriosclerosis and Thrombosis, May-June 1991).
Further research revealed that
“Consumption of unfiltered, but not filtered, coffee increases serum levels of total and LDL cholesterol” (American Journal of Epidemiology, Feb. 15, 2001).
In the 1970s, when this research began, through the 1990s, cholesterol was viewed as a primary driver of heart disease. No wonder so many doctors thought coffee was really bad for you!
A Modern Update on Coffee and the Heart:
Now a new study has picked up where the old research left off (European Journal of Preventive Cardiology, April 22, 2020). Norwegian researchers followed more than 500,000 adults for an average of twenty years. They collected information at the beginning of the study on whether people drank coffee or not. For coffee drinkers, they recorded information on whether they prepared it with a filter or without.
Preparation technique made a difference. According to the scientists, people drinking one to four cups of filtered coffee daily had the lowest mortality, including cardiovascular mortality. That was even lower than the mortality rate for people who didn’t drink coffee at all. Individuals who drank nine or more cups of unfiltered brew a day were the most likely to die.
This made much more of a difference for men than women, however. In addition, the people more likely to die of heart attacks when drinking unfiltered coffee were elderly men. Unfiltered coffee contains 30 times more cafestol and kahweol than filtered coffee. These compounds raise cholesterol.
Changing Coffee Technology:
The researchers note that Norwegian coffee drinking practices have changed over two decades. Very few people (about 10 percent) use a French press to make their coffee. In addition, only a few more (about 15 percent) use espresso.
Increasingly, however, filtered coffee and pods have gained ground on traditional boiled coffee. The authors speculate that older men might be less amenable to changing their method of making coffee than younger people. Those drinking nine cups or more a day of unfiltered coffee boosted their risk of ischemic heart disease by 9 percent.
This finding is consistent with a large meta-analysis published last year (European Journal of Epidemiology, Aug. 2019). The investigators analyzed 40 studies with nearly 4 million participants. People who drank 3.5 cups of coffee daily were least likely to die from anything during the study period. The lowest heart disease mortality was at 2.5 cups a day, and people drinking two cups daily had a lower chance of dying from cancer.
The authors concluded:
“Moderate coffee consumption (e.g. 2-4 cups/day) was associated with reduced all-cause and cause-specific mortality, compared to no coffee consumption.”
If you like coffee, this is good news. Just make sure you are using a filter to brew your favorite beans. Don’t drink a lot of unfiltered coffee, because that is, in fact, really bad for you.