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.

DEAR DR. BLONZ: I have a question about fasting as a means to help release toxins from the body. I have used fasting in the past to help jump-start my weight loss, but I have also read that it helps with toxins. Is this true? -- S.H., Seattle

DEAR S.H.: Some connect the way they feel during a fast as an affirmation that their body is casting off toxins. This can be misleading, as the lack of food can cause sensations that might be mistaken for such an effect.

It is a bumpy road to assume that fasting facilitates healing through the removal of toxins. Detoxification is an ongoing process in our bodies. Our digestive system is designed to keep nasty stuff from gaining entry, while the liver and excretory systems work to neutralize and get rid of “undesirables” in the body. Stopping the intake of healthful foods can handicap detoxification by curtailing the raw materials that facilitate the process. With no food coming in, metabolic priorities get reshuffled.

Humans evolved amidst unreliable food sources; we made it through such stresses thanks to our ability to use stored energy in different ways, and thus keep our brains working and muscles fueled until we could find new food sources and increase our chances for survival.

Fat storage cells in our body (adipocytes) shrink in size during a fast, as their contents provide energy for the body. Some types of toxins accumulate in the fat cells because many problematic toxins are fat-soluble, and our fat storage is our largest depot to dilute these contaminants. The body slowly eliminates toxins during the normal cell turnover, as all cells are routinely taken apart and remade.

During a fast, the blood levels of some toxins can rise. Think of this as putting a dirty sponge in a pan of water, where the water is slowly but continually refreshed. Over time, the dirty sponge gets rinsed clean. Now, think of how squeezing a dirty sponge in the pan would have an immediate effect on the water.

If the body could easily eliminate stored toxins, they wouldn’t have built up in the first place. Now, also consider that with a fast, your body no longer has the fuel and other nutrients to keep things going. Heavy metals, for example, can only be slowly eliminated from the body, and they create a problem if the intake is greater than our ability to eliminate them. They must get stashed away to keep them from causing metabolic harm. During a fast, the reduction of body mass can release more of these into the system.

The other aspect of fasting you mention is the “jump-start” phenomenon, and this deserves consideration. Here, one can use the fast as a transition period to jettison past practices before shifting to a new lifestyle -- ideally a more physically, emotionally and spiritually healthful one. There is potential here, as the fast might serve as a productive time of contemplation to review the status quo and make new plans. It can be a powerful tool as it defines a distinct separation from what was and what is to be. But it should be approached cautiously, especially if there are ongoing health considerations and medications, so be sure to check with your health professional.

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.

DEAR DR. BLONZ: My hair is thin and subject to frequent breakage. Someone suggested that taking Norwegian kelp will help. Will this remedy my symptoms and stimulate hair growth? What other natural products would you suggest? By the way, I’m African American, if that makes a difference. -- S.T., Tulsa, Oklahoma

DEAR S.T.: Kelp, a vegetable that grows in the sea, is primarily known for its iodine content. But it also contains lesser amounts of potassium, calcium, magnesium, sodium, folate, vitamin A, vitamin K and several other nutrients. An ounce of kelp provides 100% of the recommended daily intake of iodine (150 micrograms), but not much more than 5% of the daily requirement of other nutrients.

Iodine is an essential mineral that plays a role in the manufacture of the thyroid hormones, the substances that help regulate the body’s metabolism. There may be some logic to your friend’s recommendation, because dry, coarse and breaking hair, and hair loss, are among the host of symptoms of inadequate thyroid hormone (hypothyroidism). However, that does not mean that adding kelp can represent a solution in your particular case. Today, it is rare for anyone eating a varied diet to suffer from an iodine deficiency.

Iodine is plentiful in the ocean, but it is not well-distributed on land. Foods with natural iodine are limited to seafoods, crops grown in coastal areas, and dairy or meat foods from animals that have grazed on feed containing iodine. Starting in 1924, iodine was added to table salt in the U.S.

One’s genetic background, certain health conditions and medications can all have a range of influences on how hair looks and behaves. The quality of your diet is also a player. I would take a look at what you have been eating and aim for a good mix of fruits, greens and grains, as these provide the essential vitamins and minerals. Eggs provide many nutrients used in hair growth, and I would also suggest regular intakes of seafood and other sources of essential fatty acids. These are all regulars of healthful eating.

But keep in mind that regardless of what one eats, hair will always be affected by the products and treatments we use. A knowledgeable aesthetician or hairstylist might be able to recommend products well-suited to your particular situation.

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.