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 email@example.com. Due to the volume of mail, personal replies cannot be provided.