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Is Coffee Really Bad for You?

Studies show that coffee drinkers are less likely to get heart failure or die of heart disease. Unfiltered coffee, though, is bad for you.

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. Increasingly, researchers are reporting that coffee drinkers are less likely to develop heart disease.

Could Coffee Help Control Cholesterol?

If coffee were actually bad for you, it would mess up your blood lipids and boost your chances of atherosclerosis. Some early studies showed that is exactly what happens with unfiltered coffee, where the grounds and the water boil together. (We have summarized that research below.)

A new study shows, however, that the story is more complicated and suggests one possible mechanism for benefit. The scientists found that caffeine lowers levels of an enzyme called PCSK-9 (Nature Communications, Feb, 9, 2022). This is the same compound targeted by cholesterol lowering drugs such as alirocumab (Praluent) or evolocumab (Repatha). In addition, caffeine from coffee boosts the activity of LDL receptors in the liver that take cholesterol out of circulation. This could result in lower levels of LDL cholesterol in the bloodstream.

Coffee with Milk Is Not Bad for You:

Do you drink your coffee black, or do you prefer a splash of milk? Some research suggests that black coffee can raise good HDL cholesterol (Journal of Multidisciplinary Healthcare, Nov. 2, 2020). But a new study suggests that milk in coffee offers unexpected anti-inflammatory benefits.

Danish scientists have analyzed two of the most important polyphenols in coffee, chlorogenic acid and caffeic acid (Journal of Agricultural and Food Chemistry, Jan. 30, 2023). When these polyphenols interact with the amino acid cysteine in test tubes, they form a chemical complex. In the laboratory, this combination significantly dampens inflammation in specially treated immune system cells.

The amino acid cysteine is found in milk and certain other dairy products, so the researchers wondered if this interaction would be relevant outside the laboratory. They confirmed that commercial coffee drinks with added milk do contain the complex (Food Chemistry, March 1, 2023). In addition, they suspect, that this type of beneficial interaction between polyphenols and amino acids likely occur in other foods such as smoothies with dairy products. Besides coffee polyphenols, foods such as berries, apples, pomegranates and nuts are rich in polyphenols that have anti-inflammatory activity.

Coffee and Tea Drinkers Less Likely to Suffer Strokes:

In one big study, scientists analyzed the UK Biobank data. The investigators found that both coffee and tea are linked to a lower likelihood of stroke or dementia.

If coffee were really bad for you, it might increase the chance of brain crises like strokes or dementia. Previous research has not shown that to be the case, however. In this study, more than 360,000 volunteers answered questions about their coffee and tea habits (PLOS Medicine, Nov. 16, 2021). Since it was conducted in the UK, where tea is extremely popular, it made sense to include that beverage as well.

During the following decade, 5,000 people were diagnosed with dementia and 10,000 had a stroke. Data analysis showed that people who customarily consumed 2 or 3 cups of coffee a day were less likely to be among those with dementia or stroke. So were those who usually drank 3 or 4 cups of tea daily. People who enjoyed both beverages—4 to 6 cups combined in a day—were 28% less likely to develop dementia and 32% less likely to have a stroke than people who drank neither beverage regularly. There was no impact on Alzheimer disease, though.

The researchers point out that such epidemiological studies cannot establish cause-and-effect relationships. Nonetheless, these results (and those from previous studies) should encourage those of us who love our hot beverages.

Research on Coffee and Heart Failure:

For years, cardiologists have warned heart patients about coffee. They were concerned that caffeine would raise blood pressure and cause palpitations. That would certainly be bad for you! But a study in the journal Circulation: Heart Failure has produced some intriguing results (Circulation: Heart Failure, Feb. 9, 2021). The researchers analyzed data from three large long-lasting cohort studies of heart health. More than 21,000 older people participated for a minimum of 10 years. (These studies were: the Framingham Heart Study, the Cardiovascular Heart Study and the Atherosclerosis Risk in Communities cohort.) In all three groups, people who drank at least two cups of caffeinated coffee daily were less likely to develop heart failure. This is a condition in which the heart has trouble pumping blood efficiently. Decaf coffee offered no protection.

Previous studies have found similar associations. Both Swedish and Finnish researchers have found that people drinking about 4 cups of coffee daily had the lowest risk of heart failure. The Scandinavian coffee cups are smaller than American cups, however. An accompanying editorial points out that these studies cannot establish a cause-and-effect relationship between drinking coffee and protection from heart failure (Circulation: Heart Failure, Feb. 9, 2021). On the other hand, they throw shade on earlier claims that coffee drinkers are taking their lives in their hands. Let’s look at some of that history.

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. Moreover, lots of people drank coffee from a percolator. No wonder so many doctors thought coffee was really bad for you!

A review of scientific studies on coffee and cholesterol (New England Journal of Medicine, July 23, 2020) noted:

“The concentration of the cholesterol-raising compound cafestol is high in unfiltered coffee such as French press, Turkish, or Scandinavian boiled coffee; intermediate in espresso and coffee made in a Moka pot; and negligible in drip-filtered, instant, and percolator coffee.”

A Modern Update on Coffee and the Heart:

A large study 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.

How Does Instant Coffee Rate?

Q. When you write about coffee, does instant coffee automatically qualify? I drink instant and worry I may be missing benefits. Is it good or bad for you?

A. Many studies showing that coffee can help the heart, for example, don’t separate instant coffee from other preparation techniques. However, a recent analysis found that instant and decaf coffee both provide liver protection similar to that from regular brewed coffee (BMC Public Health, June 22, 2021).

Instant coffee, like filtered coffee, has very little kahweol and cafestol, compounds that can raise cholesterol if consumed in large quantities. That makes instant coffee a reasonable choice for the heart and arteries as well as the liver.

What About Coffee Made from Pods?

As we mentioned above, technology using pods to make single servings of coffee has been taking over the market. Some readers have wondered whether such coffee is bad for you.

Q. I’m one of the people whose cholesterol goes up when I drink unfiltered coffee. Will the Keurig or other coffee machines that use pods do the same?

A. Unfiltered coffee, such as the kind you get when you use a French press, could raise cholesterol. Compounds in coffee such as cafestol and kahweol are thought to be the culprits.

Filters can remove these chemicals from coffee. Pods for single-serve coffee machines do contain filters made of abaca fiber. Brazilian scientists have found that if a filter traps the coffee grounds, it also holds on to the majority of the cafestol (Food Research International, Oct. 2017).

Another reader asks if coffee made with pods is bad for you:

Q. You’ve written about coffee raising cholesterol unless it is filtered to remove cafestol and kahweol. My brother has been using only Keurig coffee makers for the past 10 years. He is experiencing high cholesterol and memory problems. Do the Keurig devices raise cholesterol, since they do not have filters for the coffee grounds?

A. Keurig-type machines that use “K-cups” or “pods” to make a single serving of coffee have become extremely popular. If you take a K-cup apart, you will find a filter in it. We don’t know whether that filter removes cafestol and kahweol. Consequently, we can’t say with certainty that your brother’s coffee habit affects his cholesterol. We suspect, though, that it’s less likely than unfiltered coffee to pose problems.

Adding a Filter Made a Big Difference:

We heard recently from a reader who offered some personal experience regarding coffee and cholesterol.

Q. My husband’s cholesterol was going in the wrong direction. It was in the 180s to 190s for years, with his doctor making noises about statins. My husband and I both have family members who experienced a detrimental drop in brain function clearly linked to statins, so we wanted to avoid them.

Once his cholesterol hit 202, his doctor became insistent. Unfortunately, what we were trying wasn’t working. Then it hit 234. His doctor was not happy, to say the least.

Filtering French Press Coffee:

Then I finally read something online that sent me down a different research path. French press coffee can be a culprit. We decided to continue with our usual French press method, but we added a second step with Chemex paper filters and a pour-over cone. After six months of this, his cholesterol is now 179.

We are amazed and grateful that such an easy modification worked. And the coffee tastes even better with the addition of the filter.

This simple change could help a lot of folks. It doesn’t remove the importance of exercise, but most folks could easily make this change, especially if they brew at home.

A. Thanks for the fascinating report. Unfiltered coffee contains cholesterol-raising compounds called cafestol and kahweol. Any coffee-making technique that uses a filter removes them. (Many people would skip the French press step and simply use the cone and filters.) Great detective work!

Some readers have asked whether the coffee pods for a machine similar to a Keurig are filtered. The answer is yes, they are. No worries there.

In addition, people have inquired about instant coffee. Biochemists analyzing coffee have found that instant coffee has low levels of cafestol and kahweol, similar to filtered coffee (Journal of Food Science and Technology, Nov. 2016).

What About Metal Mesh Coffee Filters?

After we posted this article, we got a number of queries from readers. Many wanted to know about instant coffee or coffee pods, addressed above. In addition, quite a few people are environmentally conscious and use a metal mesh coffee filter rather than a single-use paper filter. Here is one reader’s question:

Q. You recently wrote about coffee raising cholesterol. Apparently, though, if you use a filter to brew your coffee it won’t be bad for you. My coffee klatch friends want to know if a reusable metal mesh filter works as well.

A. We have yet to find a study comparing metal mesh to paper filters with regard to cafestol and kahweol. These are the compounds in coffee that raise cholesterol.

Brazilian scientists found that very porous paper filters, especially those with micro-perforations, let through a lot more of these chemicals (Food Research International, June 2018).  Another study found that metal mesh filters used in India were just as effective as paper filters in removing cafestol and kahweol (Nutrition Journal, May 15, 2011).  We conclude that a fine metal mesh filter is probably a very reasonable substitute for paper filters when you make your morning brew.

There is one caveat about metal filters, though. Some readers like to add cinnamon to their coffee to lower blood sugar. Do not put cinnamon in a metal filter since the powdered spice can cause a gooey mess and is difficult to remove.

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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies..
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