DEAR DR. BLONZ: I’m under the impression that vitamin D requires fat in order to be absorbed well. Does that mean they must be consumed at the same time? If I drink a glass of nonfat milk by itself, will I absorb less of its vitamin D? Also, is that why cod liver oil is one of the best ways to get vitamin D -- because of the fat in the oil? -- N.S., via email
DEAR N.S.: Meal conditions can affect nutrient absorption, and this is a good example. Vitamin D is a fat-soluble vitamin, and it requires some fat to facilitate its passage through the absorptive surface of the intestines. There are a number of studies in the scientific literature reporting that eating a meal that contains fat at the same time as taking a vitamin D supplement, or shortly after, does indeed result in significantly more absorption.
Cod liver oil does contain vitamin D and fat, but it can also contain a lot of vitamin A, which is harmful in large doses. Consult with your doctor, read labels, and be careful not to overdo it. (Read more about cod liver oil at b.link/pkyuv.)
DEAR DR. BLONZ: In a previous column, you wrote about aging, saying that some of the blame is on free radicals. The column then explained that whole grains and nutrient-rich whole foods could combat free-radical damage. What exactly do you mean by “whole foods”? Do you mean organic foods, foods with fiber, green vegetables or something else? -- B.B., Hayward, California
DEAR B.B.: “Whole foods” refers to fruits, vegetables and grains that are unprocessed or minimally processed, such as freezing or drying. These are foods as close to their “just picked” natural state as possible. Foods need not have been organically grown to qualify, though organic is an excellent choice when available. The idea is to have a regular intake of a variety of foods that have their full complement of healthful components. Some have fiber; others do not. Some may be green, but whole foods come in all colors.
To survive the rigors of nature, “whole foods” have had to evolve to make the substances they require to grow and reproduce, along with an arsenal of phytochemical components. Many of these compounds are essential, or at least beneficial, to our health as well -- but you have to eat the whole food to gain the benefit. As a general rule, whole foods are preferable to their highly processed counterparts, as processing can destroy delicate phytochemicals and leave with you lesser amounts of nutrients.
The final part of the picture is to acknowledge that not everything “natural” is beneficial. There are naturally occurring toxins as well as healthful whole foods. The reference to whole foods speaks to wholesome, traditional foods that have proven their safety and dietary worth over time.
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.