Thursday, February 26, 2009

Calcium supplements: What kind of calcium is in that pill?

Calcium-rich foods give you calcium paired with natural organic acids, a combination that your body easily digests and absorbs.
The form of calcium most commonly found in supplements, however, is calcium carbonate, the kind of calcium that occurs naturally in limestone and oyster shells.
Calcium carbonate is a versatile compound. Not only does it build strong bones and teeth, but it also neutralizes stomach acid and relieves heartburn. Calcium carbonate antacids can be used as calcium supplements. They’re nutritionally sound and generally cost less than products designed solely as nutritional supplements. Some calcium supplements contain compounds that mix calcium with an organic acid. Calcium lactate is calcium plus lactic acid, the combination that occurs naturally in milk. Calcium citrate is calcium plus citric acid, an acid found in fruits. These compounds are easier to digest, but they’re sometimes more expensive than calcium carbonate products. Calcium carbonate is nearly half calcium, a very high percentage. But unless your stomach is very acidic, it’s hard for your digestive system to break the compound open and get at the elemental calcium (the kind of calcium your body can use). You can increase your absorption of calcium from calcium carbonate by taking the tablets with meals.
Because different calcium compounds yield different amounts of elemental calcium, the label lists both the calcium compound and the amount of elemental calcium provided, like this:
Calcium carbonate, 500 milligrams, providing 200 milligrams elemental calcium. Whenever you see the word calcium alone, it stands for elemental calcium.
The human body absorbs calcium most efficiently in amounts of 500 milligrams or less. You get more calcium from one 500-milligram calcium tablet twice a day than one 1,000-milligram tablet. If the 1,000-milligram tablets are a better buy, break them in half.
Warning: Not all antacids double as dietary supplements. Antacids containing magnesium or aluminum compounds are safe for neutralizing stomach acid, but they won’t work as supplements.
In fact, just the opposite is true. Taking magnesium antacids reduces your absorption of calcium, and taking aluminum antacids reduces your absorption of phosphorus. Because manufacturers sometimes change the ingredients in their products without notice, you always need to read the product label before assuming that an antacid can double as a calcium supplement

I’m looking for an iron supplement. What’s this “ferrous” stuff?

The iron in iron supplements comes in several different forms, each one composed of elemental iron (the kind of iron your body actually uses) coupled with an organic acid that makes the iron easy to absorb.
The iron compounds commonly found in iron supplements are:
  • Ferrous citrate (iron plus citric acid)
  • Ferrous fumarate (iron plus fumaric acid)
  • Ferrous gluconate (iron plus a sugar derivative)
  • Ferrous lactate (iron plus lactic acid, an acid formed in the fermentation of milk)
  • Ferrous succinate (iron plus succinic acid)
  • Ferrous sulfate (iron plus a sulfuric acid derivative)
In your stomach, these compounds dissolve at different rates, yielding different amounts of elemental iron. So supplement labels list the compound and the amount of elemental iron it provides, like this:

Ferrous gluconate 300 milligrams
Elemental iron 34 milligrams

This tells you that the supplement has 300 milligrams of the iron compound ferrous gluconate, which gives you 34 milligrams of usable elemental iron. If the label just says “iron,” that’s shorthand for elemental iron. The elemental iron number is what you look for in judging the iron content of a vitamin/mineral supplement.

People who need extra minerals

If your diet provides enough minerals to meet the RDAs, you’re in pretty good shape most of the time. But a restrictive diet, the circumstances of your reproductive life, and just plain getting older can increase your need for minerals. Here are some scenarios.

You’re a strict vegetarian
Vegetarians who pass up fish, meat, and poultry must get their iron either from fortified grain products such as breakfast cereals or commercial breads or naturally from foods such as seeds, nuts, blackstrap molasses, raisins, prune juice, potato skins, green leafy vegetables, tofu, miso, or brewer’s yeast. Because iron in plant foods is bound into compounds that are difficult for the human body to absorb, iron supplements are pretty much standard fare. Vegans — vegetarians who avoid all foods from animals, including dairy products — have a similar problem getting the calcium they need. Calcium is in vegetables, but it, like iron, is bound into hard-to-absorb compounds. So vegans need calcium-rich substitutes. Good food choices are soybean milk fortified with calcium, orange juice with added calcium, and tofu processed with calcium sulfate.

You live inland, away from the ocean
Now here’s a story of 20th century nutritional success. Seafood and plants grown near the ocean are exposed to iodine-rich seawater. Freshwater fish, plants grown far from the sea, and the animals that feed on these fish and plants are not exposed to iodine. So people who live inland and get all their food from local gardens and farms cannot get the iodine they need from food. American savvy and technology rode to the rescue in 1924 with the introduction of iodized salt. Then came refrigerated railroad cars and trucks to carry food from both coasts to every inland city and state. Together, modern salt and efficient shipment virtually eliminated goiter, the iodine deficiency disease, in this country. Nonetheless, millions of people worldwide still suffer from chronic iodine deficiency.

You’re a man
Just as women lose iron during menstrual bleeding, men lose zinc at ejaculation. Men who are extremely active sexually may need extra zinc. The trouble is, no one has ever written down standards for what constitutes “extremely active.” Check this one out with your doctor.
Men who take a daily supplement of 200 micrograms selenium seem to cut their risk of prostate cancer by two-thirds. The selenium supplement also produces an overall drop in cancer mortality, plus a significantly lower risk of prostate cancer, colon cancer, and lung cancer in both men and women.

You’re a woman
The average woman loses about 2 to 3 teaspoons of blood during each menstrual period, a loss of 1.4 milligrams of iron. Women whose periods are very heavy lose more blood and more iron. Because getting the iron you need from a diet providing fewer than 2,000 calories a day may be virtually impossible, you may develop a mild iron deficiency. To remedy this, some doctors prescribe a daily iron supplement.
Women who use an intrauterine device (IUD) may also be given a prescription for iron supplements because IUDs irritate the lining of the uterus and cause a small but significant loss of blood and iron.

You’re pregnant
The news about pregnancy is that women may not need extra calcium. This finding, released late in 1998, is so surprising that it probably pays to stay tuned for more — and definitely check with your own doctor. Meanwhile, pregnant women still need supplements to build not only fetal tissues but also new tissues and blood vessels in their own bodies. Animal studies suggest (but don’t prove) that you may also need extra copper to protect nerve cells in the fetal brain. Nutritional supplements for pregnant women are specifically formulated to provide the extra nutrients they need.

You’re breast-feeding
Nursing mothers need extra calcium, phosphorus, magnesium, iron, zinc, and selenium to protect their own bodies while producing nutritious breast milk. The same supplements that provide extra nutrients for pregnant women will meet a nursing mother’s needs.

Wow — You think that was a hot flash?
Then you need extra calcium. Both men and women produce the sex hormones testosterone and estrogen, although men make proportionately more testosterone and women, more estrogen. Testosterone builds bone; estrogen preserves it.
At menopause, a woman’s production of estrogen drops precipitously, and her bones rapidly become less dense. As men age and their testosterone levels drop, they’re also at risk of losing bone tissue, but the loss is less rapid and dramatic than a woman’s.

For both men and woman, severe loss of bone density can lead to osteoporosis and an increased risk of bone fractures, a condition more common among women of Caucasian and Asian ancestry. Estrogen supplements can help a woman maintain bone tissue, but taking the hormone may have serious side effects, including an increased risk of breast cancer. Twenty years ago, nutritionists thought it impossible to stop age-related loss of bone density — that your body ceased to absorb calcium when you passed your mid-20s. Today, medications such as alendronate (Fosamax) protect an aging woman’s bones without estrogen’s potentially harmful effects. Increasing your consumption of calcium plus vitamin D may also be helpful, regardless of your gender. But the most recent studies — by which I mean the study released in February 2006 as I am typing these words — says the value of extra calcium may not be as high as once believed. What can I say? Stay tuned for more on this one.