For decades, health experts have issued platitudes along the lines of “You don’t need vitamins if you eat a balanced diet.” But about 40 percent of Americans take a supplement, and it’s most likely to be a multivitamin/mineral. So who’s right?
It makes sense to take a supplement to ensure you get the Daily Values (formerly known as the recommended daily allowances, or RDAs) for most vitamins and minerals, just in case you don’t get them from food. That’s especially true for women because they tend to eat less food than men.
What’s more, many people run short on some key nutrients, possibly raising their risk of heart disease or birth defects (folic acid), weakened bones (vitamin D), or nerve damage (vitamin B12).
But the corollary of the health experts’ platitude should be taken seriously: You can’t expect a supplement to make up for a lousy diet. Vitamins or no vitamins, you still have to eat enough fruits and vegetables, beans, whole grains, and low-fat dairy, poultry and fish. And you still have to limit fatty meats and dairy products, pastries, fried foods and sweets.
But a healthy diet and a supplement may be the best of both worlds. The question is which supplement? Or supplements?
Know your elements
It’s not as simple as taking 100 percent of the Daily Value (or DV) for everything. We already get too much of some nutrients, and some others won’t fit into a multivitamin (unless you have to take six a day). Here’s how to select the good from the not-so-good.
1. Look for 100 percent of 10 vitamins plus some vitamin K. The best have at least 100 percent of the DV for vitamins A, B1 (thiamin), B2 (riboflavin), B6, B12, C, D, E, folic acid and niacin. The over-50 crowd should look for a multivitamin with 25 micrograms (mcg) of B12, about four times the DV.
Those minimums shouldn’t be hard to find. But many supplements supply little or no vitamin K, which may help strengthen bones. The best have more than 30 percent of the DV for K. If your diet is rich in vegetables–especially leafy green ones–you don’t need vitamin K in your multi. (Note that if you take blood-thinners like Coumadin, tell your doctor before taking any vitamin K.)
2. Get your minerals. Multis with 100 percent of the DV for zinc and copper are fairly easy to find, but chromium is not so common.
A single pill won’t be able to pack in 100 percent of the DV for magnesium. But you should hope for at least 25 percent of the magnesium value.
3. Consider taking calcium and selenium (a sulfur relative) separately. As with magnesium, the DV of calcium won’t fit into a single pill, and it’s easy to find a separate calcium supplement that has the right dose (1,000 to 1,500 mg per day, depending on age and sex).
It’s worth taking selenium separately because we couldn’t find a multi with 200 mcg of the same high-yeast selenium that appeared to reduce the risk of lung, colon, and prostate cancer (so far in only a single-but compelling-study). Any form of selenium may turn out to be as good, but so far, no one knows. The form used in the study is SelenoExcell. Don’t overdo it, though; selenium is toxic, possibly in doses as low as 1,000 mcg.
4. Avoid excess. Your pill should have no more than 500 mg of phosphorus (we already get too much from food), 200 mg of vitamin B6 (more may cause nerve damage), and 15,000 international units of beta-carotene (more may raise the risk of lung cancer in smokers).
Iron is more complicated, because there is no amount that’s right for everyone. Look for a supplement with no more than the DV (18 mg). But many people–men and post-menopausal women–should look for 0-10 mg to lower the risk of iron overload and (although evidence is weak) possible heart disease and cancer. Iron supplements also may cause constipation.
Where, when and how
Here are the answers to a handful of the most common questions.
Q: Where should I buy my vitamins?
A: It doesn’t matter. You get essentially the same ingredients. That’s because most companies buy their vitamins and minerals from the same few manufacturers.
What varies is how much of each nutrient you get, whether the tablet is properly made, and which extra non-vitamin ingredients like coenzyme Q10, bioflavonoids and herbs it has. Since the amounts of these non-vitamins are usually tiny and their benefits inconclusive, consider them optional.
Q: How do I know if the supplement is well made?
A: There are no federal standards for supplements. So you’re probably safer with a major brand.
Some of the best bargains are store brands that carry the names of large drug chains or retailers like Wal-Mart or Kmart. They’re big enough to demand top quality from vitamin-makers. The letters USP on a supplement label mean that the tablets meet the voluntary standards of the U.S. Pharmacopoeia, and that they dissolve in a lab test designed to mimic what happens in your digestive tract.
Another way to help your vitamins disintegrate is to get a chewable brand. If you can’t find one for adults, try a children’s multi.
Q: Does it matter when I take my multivitamin?
A: There isn’t much evidence one way or the other, but most experts recommend taking vitamins with meals. That’s because some nutrients are better absorbed when your digestive tract is geared up to handle food. Some people also suffer gastric distress when they take supplements on an empty stomach.
Another timing tip: High doses of calcium can impair absorption of iron. So if you’re taking calcium and a multi with iron, take them at two different meals.
And unless your doctor says otherwise, it’s a good rule of thumb to wait a few hours between taking any prescription medication and taking a multivitamin, because some nutrients in the multi could interfere with the drug.
Q: Are “natural” vitamins better?
A: In general, no. The one exception is natural vitamin E (d-alpha tocopherol), which appears to be slightly better retained and used by the body than synthetic E (dl-alpha tocopherol). As long as the E is labeled in international units (IU), you needn’t worry–100 IU of synthetic E will be as potent as the same amount of natural E, because of the measurement technique.
Q: Should I buy “chelated” minerals?
A: Chelate [KEY-late] means clawlike. In theory, if a mineral is chelated (it sits inside an amino acid “claw”), it may be better absorbed because it’s protected from things in food (like the phytic acid in grains or the oxalates in spinach) that can bind it.
In practice, it may not be worth the extra cost. Chelated calcium, for example, is absorbed 5 percent to 10 percent better than ordinary calcium, but it costs five times as much.
Q: What should kids take?
A: Children aged four and older can take the same multivitamin-mineral supplements as adults (though it might be worth looking for ones without food dyes, which may worsen the behavior of children with Attention Deficit Hyperactivity Disorder). In fact, if you check a CentrumKids Complete, you’ll notice that it’s similar to Centrum for adults. Children’s multis are often scored for easy breaking because children aged one to three should take only half a pill each day.
Q: How much should I pay for my multivitamins?
A: A 30-day supply can cost as little as $1 to $4. Designer brands can run $15 or more. Unless you want the extra calcium and selenium that they sometimes have, there’s no reason to pay that much.
