On Nutrition by Ed Blonz

Which Coffee Filter is Best: Paper or Metal?

DEAR DR. BLONZ: A recent ad for pour-over coffeepots with reusable metal filters stated that the filters allow more of the “tasty and healthful oils” to come through, as compared to paper filters. Years ago, I read that paper filters reduced the amount of unhealthy cortisol oil in coffee. I’d appreciate your view on the use of paper filters versus metal. -- D.M., via email

DEAR D.M.: While you are correct that paper filters can trap oily substances drawn out of the ground coffee by hot water, there is no cortisol in those beans. What you may be referring to is “cafestol” or “kahweol,” two substances in coffee beans that can indeed be trapped by a paper filter.

Coffee consumption is associated with beneficial effects, but cafestol and kahweol can affect a cholesterol-regulating receptor, which gives coffee a bit of a split personality. (Ironically, those two compounds may also be associated with some of coffee’s benefits.) A paper in the September 2019 issue of Nutrients (see b.link/coffee24) suggests that intakes of up to two cups of coffee a day do not appear to cause problems.

The use of a paper filter reduces the risk from these substances. The single-serving method is also covered, as pods often include, or can be used with, a paper filter. Those with a blood cholesterol issue who drink lots of unfiltered coffee may want to reconsider their brewing method.

DEAR DR. BLONZ: What are the health risks in having a diet rich in potassium? All items on a list of high-potassium foods are ones that are necessary for maintaining healthy muscle and nerve function. So why would a low-potassium diet ever be recommended? -- L.K., Oakland, California

DEAR L.K.: Potassium is a key mineral that helps regulate water balance inside the cells. (Sodium, by contrast, regulates water balance outside the cells. I bring this up because a high salt intake causes a greater fluid volume in the bloodstream, and this contributes to the increased risk of high blood pressure.) Potassium is also involved in the transmission of nerve signals (it keeps the heart beating), muscle tone and in the body’s acid-base balance. Adults should consume about 4,700 mg of potassium per day from the foods they eat.

A healthful diet would be naturally full of potassium-rich foods, as potassium tends to be found in fruits, vegetables and other whole foods. It is difficult to overdo it on healthful foods. The best food sources for potassium include bananas, prunes, potatoes, beet greens, chard, tomatoes, citrus fruits and avocados.

But it is never good to have too much of anything, and potassium is no exception. There are certain health conditions and medications that can upset the body’s normal potassium balance. Some conditions or medications, such as those that might involve or affect the kidneys, might cause the body to eliminate sodium while holding on to its potassium. For example, some medications for high blood pressure do this. If this were the case, the dietary intake of high-potassium foods might need to be monitored.

If, on the other hand, potassium were low, your physician might tell you to adjust your diet, or to take a potassium supplement.

Send questions to: “On Nutrition,” Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.