DEAR DR. BLONZ: I belong to an eating club, and we are all senior citizens interested in living a long life. Years ago, we had discussed how palm oil is a dietary no-no, but I would like to find out about hearts of palm. I enjoyed them when at a party during the holidays, and I now use them in salads quite frequently. I realize that they are part of the palm and I had mentioned this at the club. We debated the benefits and potential dangers of this at the meeting, and I said that I would find out more. This question is my attempt to provide the needed information. -- S.T., Chicago

DEAR S.T.: I like the concept of your healthful eating club. Hearts of palm come from the palm plant, but not from the oil-containing portion. A one-third cup serving of hearts of palm contains less than a half-gram of fat, 14 calories, 207 mg of sodium, 1.5 mg of iron and 1 gram of dietary fiber together with manganese and smaller amounts of vitamin C, folate and other nutrients. But why do you classify palm oil as a no-no? This undeserved reputation originated from the misplaced branding of palm oil and all other tropical oils as foods to avoid at all cost. These foods can play a minor role in any well-balanced diet.

DEAR DR. BLONZ: I am 81 years old and have been a vegetarian for over 25 years. I was advised by my doctor to go on a diet that is low in sugar and fat. The only sugar I had been eating was from fresh fruit. I purchased some “no sugar” low-fat ice cream. There are three grams of sugar per half cup. The carton reads “sugar alcohol seven grams per half cup.” What is “sugar alcohol,” and is this anything of concern? -- S.M., San Diego, California

DEAR S.M.: The term “alcohol” refers to a particular chemical structure, and while there are many different alcohols in nature, a reference to alcohol in food or drink usually refers to the compound known as “ethyl alcohol.” There is an exception to this, however, and that is the sugar alcohol. This is a family of carbohydrates that contain an “alcohol” structure, but you won’t need an ID to buy them. The sugar alcohols include sorbitol, mannitol and xylitol. They contain fewer calories per gram than other carbohydrates, and they are not absorbed as quickly. As a result, sugar alcohols don’t raise the blood sugar level as rapidly as other sugars, making them useful as a sugar substitute for diabetics and others looking to limit their sugar intake.

Our bodies metabolize sugar alcohols differently than other carbohydrates, and one beneficial aspect of this is they do not feed the acid-producing bacteria that live in our mouth. As such, sugar alcohols do not contribute to tooth decay. They are not considered “sugars” for food labeling purposes and don’t have to be declared on the food label, but they can be listed if desired. The FDA allows food sweetened only with sugar alcohols to be labeled “sugar free.” While they have their benefits, be careful not to overdo it. Sugar alcohols can cause abdominal gas and cramping, especially when consumed on an empty stomach.

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 question is about chicken meat and fat and the differences between the white and dark meats. I eat a healthy diet but must confess a slight bit of guilt in that when eating chicken, I prefer the taste of dark meat to white meat. I discard the skin and visible fat when cooking chicken thighs and breast pieces, but does dark meat still contain more fat than white? -- B.C., Concord, California

DEAR B.C.: Stored calories in chicken, otherwise known as chicken fat, are under the skin, but some is also deposited around the individual muscle groups. The larger breast muscle doesn’t do much work because chickens are flightless birds. Not so for those leg muscles. There are many different bundles of muscles, each requiring an efficient blood supply and available energy. As domestic chickens tend to hang around and eat all day, they tend to always be in a positive caloric balance. This favors the laying down of body fat, some of which gets stashed in and around the muscles. (The same thing happens to us!) With the working muscles of the legs, there are more opportunities for fat to hide, which explains why dark meat tends to have more fat than white meat.

The “dark” of dark meat doesn’t come from fat; it comes from myoglobin, an oxygen-carrying pigment that is present to a greater degree in working muscles. Breast meat is lighter because it contains lesser amounts of myoglobin. Consistent with this theme, the breast meat of birds that fly, such as duck or goose, is not considered “white meat.”

Go ahead and remove the visible fat as best you can, but even then, there will still be a bit more fat in the dark meat. But you mention that you eat a healthful diet; so why not consider discarding that guilt and simply sticking with the type of meat you enjoy?

DEAR DR. BLONZ: My wife and I love crab. When it is in season, we tend to have a family feast, but afterward, we tend to experience tiredness even into the next day. Is this some sort of coincidence or is there a chemical reason for this? -- C.D., San Diego, California

DEAR C.D.: It’s not likely the crab, at least not by itself. If, however, you tend to have a full plate, and you couple the crab with a high-carbohydrate side dish or a sweet dessert, the combination may be causing a seafood version of the protein-carbohydrate tiredness typically associated with a Thanksgiving feast. The relative amount of the amino acid tryptophan tends to be higher in crab than in other types of protein. When consumed as a part of a big meal that contains carbohydrates, this can give rise to increased production of serotonin in the brain that can contribute to relaxation. It is unclear how this would overflow to the next day unless a leftovers feast continued on the following day, or if the associated toils of the family event had interrupted your normal sleep pattern.

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: The label on the peanut butter states "no trans fat per serving," but under the ingredients’ column it lists partially hydrogenated vegetable oils. Is it possible that a food could contain partially hydrogenated vegetable oils but not trans fats? Thank you for your reply. -- S.F., San Jose, CA

DEAR S.F.: It is always good to check the ingredient list to find out more about the product you are considering. The hydrogenation process is one that saturates (solidifies) unsaturated oils that are typically liquid. Through “partial” hydrogenation, the manufacturer is able to make the fat the perfect consistency for their product, and also help extend shelf life by reducing the tendency of oil to oxidize. As helpful as this was to food processors, it was discovered that the “trans fats” that formed during partial hydrogenation, which can be thought of as a mid-step between being unsaturated and fully saturated, represented a health risk for the human body.

In 2006, after decades in the food supply, the U.S. Food and Drug Administration ruled that the level of trans fats had to be declared on the label. Later, in 2013, the FDA ruled that partially hydrogenated oils (and the trans fats they contain) are no longer GRAS, which means Generally Regarded As Safe. Only a fraction of the fats that undergo partial hydrogenation will become trans fats; that percentage based on the starting material, and the degree of hydrogenation requested by the food manufacturer. If there are no more than 0.5 grams of trans fat per serving, a product is legally entitled to be labeled “no trans fats.”

DEAR DR. BLONZ: Broccoli is a favorite vegetable, and it is appreciated for its healthful qualities.

I usually prepare my broccoli by steaming on the stove, but I sometimes do the steaming in the microwave. I make a simple sauce, or sometimes use a bit of butter. My question has to do with overcooking, and how this might affect broccoli’s benefits. Please pass on some information about cooking effects and a nutritional comparison of how cooking impacts vitamins, minerals and fiber so I can be sure I am getting the best. -- J.S., Tucson, AZ

DEAR J.S.: Broccoli is a member of the crucifer family, which also includes cauliflower, Brussels sprouts, kale, bok choi, turnips, rutabagas and cabbage. The vegetables in this family contain a number of healthful phytochemicals. Broccoli, in particular, is high in vitamin A and C, and is also a source of vitamin K and dietary fiber. The fibrous stem contains less of the nutrients but more fiber. Young broccoli sprouts and seedlings are the richest sources of sulforaphane, a phytochemical associated with anti-cancer properties, with the broccoli tops, called the florets, as next best.

Regarding cooking, there is an enzyme in broccoli that helps the sulforaphane form, and this enzyme can be inactivated by heat. This means that uncooked and quickly cooked broccoli will offer more sulforaphane. One study compared broccoli cooked in the microwave for 2 minutes (lightly cooked) with that cooked for 5.5 minutes (fully cooked). The study reported that the yield of sulforaphane was three times higher in the lightly cooked broccoli. The take-home message here is that broccoli and the other crucifers are healthful foods, and the important thing is to include them in your diet in a way that pleases the palate; but when possible, keep cooking to a minimum.

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.