A guide to buying multivitamins.

Still have questions about multivitamins? Here are the answers to some of the most common ones:

Q. Where should I buy my vitamins?

A: It doesn't matter. Whether you shop at a health food store, supermarket, drug store, or through the mail, you get essentially the same ingredients. That's because most vitamin companies buy their raw materials from the same small group of multinational manufacturers like Hoffmann LaRoche or Eastman Chemical Company.

What varies is how much of each nutrient you get, whether the tablet is properly made, and how many non-vitamin ingredients like choline, inositol, bioflavonoids, and herbs it contains. These extras are more likely to show up at a health food store...for a price. Since there's too little evidence to show that they make you healthier consider them optional "frills."

Q: How do I know if my supplement is well-made?

A: There are no federal standards that tell companies how to manufacture supplements. So you're probably safer with a major brand, whether it's made by a pharmaceutical company or a large vitamin-maker.

Some of the best bargains are major "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.

It's also worth looking for a claim like "Release Assured" on the label (it appears on most vitamins made by Leiner Health Products, the largest maker of store-brand supplements). The claim means that the tablets dissolve in a lab test designed to mimic what happens in your gut. But vitamins made by other manufacturers could be as good, even if they don't carry a similar assurance.

Another way to make sure that your vitamins disintegrate is to get a chewable brand. If you can't find one for adults, try a children's multivitamin. Adults who hate to swallow pills should also consider chewables. But check the ingredients carefully. Some are low in minerals. The extra sugar or NutraSweet they contain is negligible.

Q: Should I look for a special women's or men's or seniors' formula?

A: In theory, a special formula would more closely match your needs. But in the real world, you can't trust the manufacturer to rely on science - rather than marketing - to come up with those formulas. The bottom line: look at the ingredients, not the name on the label.

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 for handling food. For example, older people, who often secrete too little stomach acid, may not absorb much of the calcium in calcium carbonate supplements if they take them on an empty stomach. They absorb plenty with meals, however.

Another timing tip: If you're taking a calcium supplement and a multivitamin that contains iron, take them at two different meals...assuming you want the iron. High doses of calcium can impair your ability to absorb iron.

Q: Are "natural" vitamins better?

A: In general, no. It usually makes no difference if a vitamin is made by a plant or in a test tube. The one exception is vitamin E. Natural vitamin E appears to be slightly better absorbed and used by the body than synthetic E. That doesn't mean the synthetic is useless - only that the more expensive natural form is better.

But there's a catch. The word "natural" on the label is no guarantee that you're getting natural E in the bottle. Look for d-alpha tocopherol in the ingredient list. If the supplement contains dl-alpha. gamma, mixed, or other tocopherols, it may not be natural.

Q: Can I trust the claims that appear on many bottles?

A: Not entirely. Ever since a new law was passed in 1994, supplement labels have been allowed to make what are called "structure and function claims." They aren't supposed to be "health claims," which mention diseases like cancer or heart disease. Instead, they're supposed to describe what the nutrient does, just like a textbook would.

The problem is that many structure and function claims imply that the nutrient can help prevent or cure common health problems.

For example, the label of One-A-Day's Women's formula says: "Vitamin A is essential for the normal function of vision." That's technically true. You would go blind if you had a severe vitamin A deficiency. But taking vitamin A won't do a thing for the vision problems that occur in Americans.

Similarly, the same label says: "Vitamin B-1 plays a vital role in nerve function." True. But it doesn't mean that taking One-A-Day will calm your nerves or help treat neurological problems.

Q: How much should I pay for my vitamins?

A: You shouldn't have to spend more than about $1 0 a month. A 30-day supply of a no-frills supplement costs $1 to $4. Add another $1 to $3 a month each for calcium, vitamin E, and - for the 65-or-older set - vitamin B-12.

If you go the "complete coverage" route and choose a multivitamin like Natrol's four-a-day My Favorite Multiple (including the extra B-12 that seniors will need), you'll have to shell out around $20 a month (less if you find it in a discount catalog or outlet store). If you're spending more than that for your vitamins, you're overpaying.