DEAR DR. BLONZ: If I am cooking chicken thighs or breast pieces and remove the skin and underlying globs of fat, would the dark meat still have more fat than the white? -- B.B., San Diego
DEAR B.B.: The fat in chicken tends to be stored under the skin, with some being deposited around the individual working muscle groups. The larger breast muscle is the leanest meat because it's a muscle that doesn't do much work, given that the chicken is a flightless bird. The leg muscles contain many different bundles of muscles, each requiring an efficient blood supply and available energy. The routine of the chicken is to stand around and eat most of the day, and this favors the laying down of body fat, some of which gets stashed in and around the muscles. (The same thing happens to us!) The thigh and leg areas contain a number of muscle groups responsible for support and movement of the chicken, and fat can be stored in and around these working muscles. This helps explain why dark meat tends to have slightly more fat than white meat.
An interesting aside: The "dark" of dark meat doesn't come from fat; it comes from myoglobin, an oxygen-carrying protein pigment that is present to a greater degree in working muscles. Chicken breast meat is light because it contains lesser amounts of myoglobin. Consistent with this theme, the breast meat of birds that fly, such as ducks or geese, is not "white meat."
DEAR DR. BLONZ: I keep hearing about broccoli as an anticancer food because it contains sulforaphane, and wanted some information about what this is. I usually prepare my broccoli by steaming it on the stove, but sometimes in the microwave. I make a simple sauce or use a bit of butter. My question has to do with overcooking and how this might affect broccoli's benefits. Also, what is the relative nutritional value in the paler stems compared to the darker tops? -- P.P., San Francisco
DEAR P.P.: 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 vitamins A and C, and is also a source of vitamin K and dietary fiber. That paler fibrous stem you refer to contains less of those vitamins, but more fiber.
As you mention, broccoli does contains sulforaphane, a phytochemical associated with cancer-fighting properties. Young broccoli sprouts and seedlings are the richest source; the broccoli tops, called the florets, are the next best.
Of interest regarding cooking is the fact that there is an enzyme in broccoli that helps sulforaphane form, and this enzyme can be inactivated by excess heat. This means that uncooked or quickly cooked broccoli can offer more sulforaphane. This was confirmed by a study in the April 2007 issue of the British Journal of Nutrition. That 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 is that broccoli and other crucifers are healthful foods. To maximize sulforaphane, you should keep cooking to a minimum. But please understand the most important bottom line: Food is to be enjoyed, so be sure to prepare your broccoli in the way that's most pleasing to your palate.
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