Saturday, November 29, 2008

Taking extra vitamin during pregnancy

Keep in mind that “eating for two” means that you’re the sole source of nutrients for the growing fetus, not that you need to double the amount of food you eat. If you don’t get the vitamins you need, neither will your baby. The RDAs for many nutrients are the same as those for women who aren’t pregnant. But when you’re pregnant, you need extra
  • Vitamin D: Every smidgen of vitamin D in a newborn’s body came from his or her mom. If the mother doesn’t have enough D, neither will the baby. Are vitamin pills the answer? Yes. And no. The qualifier is how many pills, because although too little vitamin D can weaken a developing fetus, too much can cause birth defects. That’s why until new recommendations for vitamin D are issued, the second important d-word is “doctor.” As in, check with yours to see what’s right for you.
  • Vitamin E: To create all that new tissue (the woman’s as well as the baby’s), a pregnant woman needs an extra 2 a-TE each day, the approximate amount in one egg.
  • Vitamin C: The level of vitamin C in your blood falls as your vitamin C flows across the placenta to your baby, who may — at some point in the pregnancy — have vitamin C levels as much as 50 percent higher than yours. So you need an extra 10 milligrams vitamin C each day (1⁄2 cup cooked zucchini or 2 stalks of asparagus).
  • Riboflavin (vitamin B2): To protect the baby against structural defects such as cleft palate or a deformed heart, a pregnant woman needs an extra 0.3 milligrams riboflavin each day (slightly less than 1 ounce of ready-to-eat cereal).
  • Folate: Folate protects the child against cleft palate and neural tube (spinal cord) defects. As many as two of every 1,000 babies born each year in the United States have a neural tube defect such as spina bifida because their mothers didn’t get enough folate to meet the RDA standard. The accepted increase in folate for pregnant women has been 200 micrograms (slightly more than the amount in 8 ounces of orange juice). But new studies show that taking 400 micrograms folate before becoming pregnant and through the first two months of pregnancy significantly lowers the risk of giving birth to a child with cleft palate. Taking 400 micrograms folate each day through an entire pregnancy reduces the risk of neural tube defect.
  • Vitamin B12: To meet the demands of the growing fetus, a pregnant woman needs an extra 0.2 micrograms vitamin B12 each day (just 3 ounces of roast chicken).

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).

A special case: The continuing saga of vitamin C

In 1970, chemist Linus Pauling published Vitamin C and the Common Cold, a small book (just about 100 pages) made weightier by the fact that Pauling had not one, but two Nobel prizes on his shelf — one for chemistry and one for peace. Ever since, people have been fighting over Pauling’s message that very large doses of vitamin C — called gram doses because they provide more than 1,000 milligrams (1 gram) — prevent or cure the common cold or his later (unfounded) claim that these doses may also cure advanced cancer.
Over the past decade, the argument has switched to vitamin C’s reputed ability to protect heart health. For example, an April 2004 report in the Journal of the American College of Nutrition said vitamin C could lower blood levels of CRP, an inflammation-related protein that increases the risk of heart disease. University of California, Berkeley, researchers gave 160 healthy adult volunteers either 500 milligrams vitamin C or a mixture of antioxidant nutrients or a look-alike pill with no nutrients once a day for two months. In the end, the folks who got the vitamin C experienced a 24 percent drop in CRP blood levels versus a statistically insignificant 4.7 percent for the cocktail and no change at all for those on the placebo. Not surprisingly, UC epidemiologists thought vitamin C may become an important aid to heart health.
Unless, that is, you’re taking medicines to knock down your “bad” cholesterol and boost the “good” kind. As the American Heart Association (AHA) Council on Nutrition Physical Activity and Metabolism points out, when 20 volunteers in an HDL-Atherosclerosis Treatment Study were given vitamin C supplements along with their anti-cholesterol meds, they ended up with lowerthan-expected levels of heart healthy high density lipoproteins (HDLs). In another small study, women taking antioxidant vitamins along with post-menopausal estrogens were more likely than those taking look-alike pills to die from their heart disease.
Oh, well. Nothing’s perfect.

Vitamin Megadoses, Is it Dangerous?

  • Vitamin A 15,000 to 25,000 IU retinol a day for adults (2,000 IU or more for children) may lead to liver damage, headache, vomiting, abnormal vision, constipation, hair loss, loss of appetite, low-grade fever, bone pain, sleep disorders, and dry skin and mucous membranes. A pregnant woman who takes more than 10,000 IU a day doubles her risk of giving birth to a child with birth defects.
  • Vitamin D 2,000 IU a day can cause irreversible damage to kidneys and heart. Smaller doses may cause muscle weakness, headache, nausea, vomiting, high blood pressure, retarded physical growth, and mental retardation in children, and fetal abnormalities. Vitamin E Large amounts (more than 400 to 800 IU a day) may cause upset stomach or dizziness.
  • Vitamin C 1,000 mg or higher may cause upset stomach, diarrhea, or constipation.
  • Niacin Doses higher than the RDA raise the production of liver enzymes and blood levels of sugar and uric acid, leading to liver damage and an increased risk of diabetes and gout.
  • Vitamin B6 Continued use of 50 mg or more a day may damage nerves in arms, legs, hands, and feet. Some experts say the damage is likely to be temporary; others say that it may be permanent.
  • Choline Very high doses (14 to 37 times the adequate amount) have been linked to vomiting, salivation, sweating, low blood pressure, and — ugh! — fishy body odor.
You may not have to go sky-high on vitamin A to run into trouble. In January 2003, new data from a long-running (30-year) study at University Hospital in Uppsala (Sweden) suggested that taking a multivitamin with normal amounts of vitamin A may weaken bones and raise the risk of hip fractures by as much as 700 percent, a conclusion supported by data released in 2004 from the long-running Nurses’ Health Study. A high blood level of retinol — from large amounts of vitamin A from food or supplements — apparently inhibits special cells that usually make new bone, revs up cells that destroy bone, and interferes with vitamin D’s ability to help you absorb calcium. Of course, confirming studies are needed, but you can bet the debate about lowering the
amount of A in your favorite supplement will be vigorous. The new recommendations for vitamin A are 700 RE/2,300 IU of vitamin A for women and 900 RE/3,000 IU for men, but many popular multivitamins still contain 750–1500 RE/2,500–5,000 IU. Oooops?

Big trouble: Vitamin megadoses

Can you get too much of a good thing? Darn right, you can. Some vitamins are toxic when taken in the very large amounts popularly known as megadoses. How much is a megadose? Nobody knows for sure. The general consensus, however, is that a megadose is several times the RDA, but the term is so vague that it’s in neither my medical dictionary nor the dictionary on my computer.
  • Megadoses of vitamin A (as retinol) may cause symptoms that make you think you have a brain tumor. Taken by a pregnant woman, megadoses of vitamin A may damage the fetus.
  • Megadoses of vitamin D may cause kidney stones and hard lumps of calcium in soft tissue (muscles and organs).
  • Megadoses of niacin (sometimes used to lower cholesterol levels) can damage liver tissue.
  • Megadoses of vitamin B6 can cause (temporary) damage to nerves in arms and legs, fingers, and toes.
But here’s an interesting fact: With one exception, the likeliest way to get a megadose of vitamins is to take supplements. It’s pretty much impossible for you to cram down enough food to overdose on vitamins D, E, K, C, and all the Bs. Did you notice the exception? Right: vitamin A. Liver and fish liver oils are concentrated sources of preformed vitamin A (retinol), the potentially toxic form of vitamin A. Liver contains so much retinol that early 20th century explorers to the South Pole made themselves sick on seal and whale liver. Cases of vitamin A toxicity also have been reported among children given daily servings of chicken liver. On the other hand, even very large doses of vitamin E, vitamin K, thiamin (vitamin B1), riboflavin (vitamin B2), folate, vitamin B12, biotin, and pantothenic acid appear safe for human beings.

Thursday, November 13, 2008

Vitamin deficiencies

The good news is that vitamin deficiencies are rare among people who have access to a wide variety of foods and know how to put together a balanced diet. For example, the only people likely to experience a vitamin E deficiency are premature and/or low–birth weight infants and people with a metabolic disorder that keeps them from absorbing fat. A healthy adult may go as long as 10 years on a vitamin E–deficient diet without developing any signs of a problem. Aha, you say, but what’s this subclinical deficiency I hear so much about? Nutritionists use the term subclinical deficiency to describe a nutritional deficit not yet far enough advanced to produce obvious symptoms. In lay terms, however, the phrase has become a handy explanation for common but hard-to-pin-down symptoms such as fatigue, irritability, nervousness, emotional depression, allergies, and insomnia. And it’s a dandy way to increase the sale of nutritional supplements.
Simply put, the RDAs protect you against deficiency. If your odd symptoms linger even after you take reasonable amounts of vitamin supplements, probably something other than a lack of any one vitamin is to blame. Don’t wait until your patience or your bank account has been exhausted to find out. Get a second opinion as soon as you can. Table 10-2 lists the symptoms of various vitamin deficiencies.


Choline is not a vitamin, a mineral, a protein, a carbohydrate, or a fat, but it’s usually lumped in with the B-vitamins, so heeeeere’s choline! In 1998, 138 years after this nutrient first was identified, the Institute of Medicine (IOM) finally declared it essential for human beings. The IOM had good reasons for doing so. Choline keeps body cells healthy. It’s used to make acetylcholine, a chemical that enables brain cells to exchange messages. It protects the heart and lowers the risk of liver cancer. And new research at the University of North Carolina (Chapel Hill) shows that choline plays a role in developing and maintaining the ability to think and remember, at least among rat pups and other beasties born to lab animals that were given choline supplements while pregnant. Follow-up studies showed that prenatal choline supplements helped the animals grow bigger brain cells. True, no one knows whether this would also be true for human pups, er, babies, but some researchers advise pregnant women to eat a varied diet, because getting choline from basic stuff like eggs, meat, and milk is so easy. IOM’s Food and Nutrition Board, the group that sets the RDAs, has established an AI (Adequate Intake) for choline.

Pantothenic acid

Pantothenic acid, another B-vitamin, is vital to enzyme reactions that enable you to use carbohydrates and create steroid biochemicals such as hormones. Pantothenic acid also helps stabilize blood sugar levels, defends against infection, and protects hemoglobin (the protein in red blood cells that carries oxygen through the body), as well as nerve, brain, and muscle tissue. You get pantothenic acid from meat, fish and poultry, beans, whole grain cereals, and fortified grain products. As with biotin, the Food and Nutrition Board has established an Adequate Intake (AI) for pantothenic acid.

Understanding Biotin

Biotin is a B-vitamin, a component of enzymes that ferry carbon and oxygen atoms between cells. Biotin helps you metabolize fats and carbohydrates and is essential for synthesizing fatty acids and amino acids needed for healthy growth. And it seems to prevent a buildup of fat deposits that may interfere with the proper functioning of liver and kidneys. (No, biotin won’t keep fat from settling in more visible places, such as your hips.) The best food sources of biotin are liver, egg yolk, yeast, nuts, and beans. If your diet doesn’t give you all the biotin you need, bacteria in your gut will synthesize enough to make up the difference. No RDA exists for biotin, but the Food and Nutrition Board has established an Adequate Intake (AI), which means a safe and effective daily dose.

Understanding Vitamin B12

Vitamin B12 (cyanocobalamin) makes healthy red blood cells. Vitamin B12 protects myelin, the fatty material that covers your nerves and enables you to transmit electrical impulses (messages) between nerve cells. These messages make it possible for you to see, hear, think, move, and do all the things a healthy body does each day. In 2005, the Canadian Medical Association Journal reported that low blood levels of B12 in older people are linked to higher levels of homocysteine (a minor risk factor for heart disease).
Vitamin B12 is unique. First, it’s the only vitamin that contains a mineral, cobalt. (Cyanocobalamin, a cobalt compound, is commonly used as “vitamin B12” in vitamin pills and nutritional supplements.) Second, it’s a vitamin that can’t be made by higher plants (the ones that give us fruits and vegetables). Like vitamin K, vitamin B12 is made by beneficial bacteria living in your small intestine. Meat, fish, poultry, milk products, and eggs are good sources of vitamin B12. Grains don’t naturally contain vitamin B12, but like other B vitamins, it’s added to grain products in the United States.