New data suggest even paper-filtered coffee may raise “bad” LDL cholesterol.
In my video from more than a decade ago called Is Coffee Bad for You?, I explained that the “cholesterol-raising factor from…coffee does not pass [through] a paper filter.” As I discuss in my recent video Does Coffee Affect Cholesterol?, if you give people French press coffee, which is filtered but without paper, their cholesterol starts swelling up within just two weeks, as you can see below and at 0:22 in the video. But, if you switch them to paper-filtered coffee, their cholesterol comes right back down. It’s the same amount of coffee, just prepared differently.
The cholesterol-raising factor from coffee beans has since been identified as the fatty substances in the oil within coffee beans. One reason it took us so long to figure that out is that they didn’t raise cholesterol in rats, hamsters, or even in monkeys, but did in human beings, as you can see below and at 0:45 in my video.
But, the fatty substances apparently get stuck in the paper filter. “This explains why filtered coffee does not affect cholesterol, whereas Scandinavian ‘boiled,’ cafetiere [French press coffee], and Turkish coffees do.” As you can see below and at 1:07 in my video, espresso, which has 20 times more cafestol, the cholesterol-raising substance, than paper-filtered drip coffee, also raises cholesterol, though French press, Turkish, and boiled coffees are progressively worse. Instant and percolated coffee are pretty low, even though neither is prepared with paper filters, but still not as low as paper-filtered drip coffee. Note, however, that if you make drip coffee with a metal mesh filter common in many machines and do not add a paper filter in the cradle, it would presumably be just as bad as French press coffee.
The studies in general “appeared to consistently find” that this fatty component was filtered out by paper, but “a small number of studies suggested that filtered coffee may also increase cholesterol levels, and began to cast some doubt into what appeared to be a fairly clear picture.” So, yes, “although the cholesterol-raising effects brought about by the consumption of filtered coffee may not be as strong as those of the boiled coffee, it is important not to discard the possibility that filtered coffee may also play a small but important role in explaining the cholesterol-raising effects of coffee.”
I had known about a study that found that three cups a day of filtered coffee raised total cholesterol, but the increase in “bad” LDL cholesterol was not statistically significant, as you can see below and at 2:10 in my video. Researchers got the same results in another study, finding that subjects who stopped consumption of filtered coffee reduced their total cholesterol, which suggests that perhaps paper coffee filters only achieve partial cafestol removal. Had anyone ever just measured the levels of the cholesterol-raising compounds found in the paper filters?
Indeed, researchers investigated just that and found most of the cholesterol-raising cafestol was retained by the coffee grounds, rather than actually getting stuck in the paper filter itself. In other words, “the principal function” of the paper filter is not necessarily blocking the compound itself, but blocking any fine particles that are carrying the compound. This is similar to when you make French press coffee. When you depress that plunger with its fine mesh screen, you’ll still get a little sludge at the bottom of the cup. That sludge is made up of the tiny particles that pass through the screen and can carry some of the risk. So, a little cafestol does get through the filter. As you can see below and at 3:07 in my video, you can cut out more than 90 percent of cafestol by switching from a French press or coffee maker with a metal mesh filter to one with a paper filter. If you use coffee that starts out with a high level of the cafestol compound, you’re still clearing out about 95 percent with the paper filter, but could there still be enough left to bump up your LDL? You don’t know until you…put it to the test.
As you can see below and at 3:38 in my video, study subjects started out drinking a high-cafestol coffee, and after a month of drinking two cups a day, their LDL cholesterol increased significantly, even though the coffee was paper-filtered. So, if you have high cholesterol despite eating a healthy diet, you may want to try cutting out coffee and then getting retested. Or, you can try switching to a lower cafestol coffee. There are all sorts of variables that may affect cafestol levels, including roasting degree or grind size, and one can imagine a smaller particle size would allow for greater extraction. Since roasting appears to destroy some cafestol, a really dark roast should have less, but no significant difference was seen between the rise in cholesterol after a medium light roast versus a medium roast; both raised bad cholesterol.
In the chapters on liver disease, depression, and Parkinson’s in my book How Not to Die, I discussed the benefits of coffee for the liver, mind, and brain. Coffee drinkers do seem to live longer and have lower cancer rates overall, but coffee may worsen acid reflux disease, bone loss, glaucoma, and urinary incontinence. The bottom line is that I don’t recommend drinking coffee, but mainly because every cup of coffee is a lost opportunity to drink something even more healthful, such as a cup of green tea, which wouldn’t have the adverse cholesterol consequences.