Saturday, November 29, 2008

Taking Extra Vitamins as Needed

Who needs extra vitamins? Maybe you. The RDAs are designed to protect healthy people from deficiencies, but sometimes the circumstances of your life (or your lifestyle) mean that you need something extra. Are you taking medication? Do you smoke? Are you on a restricted diet? Are you pregnant? Are you a nursing mother? Are you approaching menopause? Answer “yes” to any of these questions, and you may be a person who needs larger amounts of vitamins than the RDAs provide.

I’m taking medication
Many valuable medicines interact with vitamins. Some drugs increase or decrease the effectiveness of vitamins; some vitamins increase or decrease the effectiveness of drugs. For example, a woman who’s using birth control pills may absorb less than the customary amount of the B vitamins. For more about vitamin and drug interactions.

I’m a smoker
It’s a fact — you probably have abnormally low blood levels of vitamin C. More trouble: Chemicals from tobacco smoke create more free radicals in your body. Even the National Research Council, which is tough on vitamin overdosing, says that regular smokers need to take about 66 percent more vitamin C — up to 100 mg a day — than nonsmokers.

I never eat animals
On the other hand, if you’re nuts for veggies but follow a vegan diet — one that shuns all foods from animals (including milk, cheese, eggs, and fish oils) — you simply cannot get enough vitamin D without taking supplements. Vegans also benefit from extra vitamin C because it increases their ability to absorb iron from plant food. And vitamin B12–enriched grains or supplements are a must to supply the nutrient found only in fish, poultry, milk, cheese, and eggs.

I’m a couch potato who plans to start working out
When you do head for the gym, take it slow, and take an extra dose of vitamin E. A study at the USDA Center for Human Nutrition at Tufts University (Boston) suggests that an 800 milligram vitamin E supplement every day for the first month after you begin exercising minimizes muscle damage by preventing reactions with free radicals (parts of molecules) that cause inflammation. After that, you’re on your own: The vitamin doesn’t help conditioned athletes whose muscles have adapted to workout stress.

I’m breast-feeding
You need extra vitamin A, vitamin E, thiamin, riboflavin, and folate to produce sufficient quantities of nutritious breast milk, about 750 milliters (3⁄4 liter) each day. You need extra vitamin D, vitamin C, and niacin as insurance to replace the vitamins you lose — that is, the ones you transfer to your child in your milk.

I’m approaching menopause
Information about the specific vitamin requirements of older women is as hard to find as, well, information about the specific vitamin requirements about older men. It’s enough to make you wonder what’s going on with the people who set the RDAs. Don’t they know that everyone gets older? Right now, just about all anybody can say for sure about the nutritional needs of older women is that they require extra calcium to stem the natural loss of bone that occurs when women reach menopause and their production of the female hormone estrogen declines. They may also need extra vitamin D to enable their bodies to absorb and use the calcium. Gender Bias Alert! No similar studies are available for older men. But adding vitamin D supplements to calcium supplements increases bone density in older people. The current RDA for vitamin D is set at 5 micrograms/200 IU for all adults, but the new AI (Adequate Intake) for vitamin D is 10 micrograms/400 IU for people ages 51 to 70 and 15 micrograms/600 IU or more for people 71 and older. Some researchers suggest that even these amounts may be too low to guarantee maximum calcium absorption.
Check with your doctor before adding vitamin D supplements. In very large amounts, this vitamin can be toxic.

I have very light skin or very dark skin
Sunlight — yes, plain old sunlight — transforms fats just under the surface of your skin to vitamin D. So getting what you need should be a cinch, right? Not necessarily. Getting enough vitamin D from sunlight is hard to do when you have very light skin and avoid the sun for fear of skin cancer. Even more difficult is getting enough vitamin D when you have very dark skin, which acts as a kind of natural sunblock. When Centers for Disease Control and Prevention researchers surveyed the vitamin D status of more than 2,000 African American and Caucasian women ages 15 to 49, they found low body levels of vitamin D in 42 percent of the African American women and 4.2 percent of the Caucasian women. Based on these numbers, Boston University researchers suggest that the Recommended Dietary Amount for adults who don’t get enough sunlight may be as much as four times the current recommended amount. Check this out with your doctor; it’s very important news for women who are or hope to be pregnant and need extra vitamin D (check back a few paragraphs for this information).

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