Supplement Smarts: Best Ways to Take Different Vitamins

With hundreds of supplements available, it's hard to believe that not every nutrient in whole foods has been captured in a capsule. That's why eating a variety of healthy foods is the best way to meet your health needs. But if you're low on a certain vitamin or mineral, or just want to cover all bases with a daily MVM (multivitamin/mineral), these tips will help you get the most from it.

You can take your MVM any time you'd like. Your body absorbs some of its vitamins better with food, so you may want to take it with a meal or a snack. You'll also avoid the upset stomach that you can get when you take it on an empty stomach. Not a breakfast person? Have it with lunch or even dinner.

Water dissolves them, and your body doesn't store them, so most must be taken every day. They include C and the B’s: thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), folic acid (B9), and cobalamin (B12). Take them with or without food, with one exception: You'll absorb B12 better with a meal. If you also use vitamin C, put 2 hours between them. Vitamin C can keep your body from using B12.

Vitamins A, D, E, and K need to go with fat from a meal for your body to absorb and use them. But you don't need a lot of fat -- or any saturated fat. The healthy plant-based kind you find in foods like avocado or nuts will do just fine.

You absorb iron best on an empty stomach. Take it with water or, better yet, a citrus juice: Iron and vitamin C have a tag-team effect. If it makes you queasy, save it for right after a meal. But don't mix it with calcium or high-calcium foods -- these interfere with iron. You won't take in either one fully. Men and postmenopausal women should skip supplements with this mineral unless a doctor says otherwise. The average MVM has more than you need.

Large doses of minerals can compete with each other to be absorbed. Don't use calcium, zinc, or magnesium supplements at the same time. Also, these three minerals are easier on your tummy when you take them with food, so if your doctor recommends them, have them at different meals or snacks. Don't take any individual mineral at the same time as an MVM or an antioxidant vitamin formula, like one with beta-carotene and lycopene. Also see: What is silicon dioxide and how is it used in supplements?

Watch the amount of what's called preformed vitamin A. If you're pregnant, doses over 10,000 IU a day can cause birth defects. High levels of both A and the usually safe beta-carotene (a substance that the body coverts to vitamin A) may raise your chances of having lung cancer if you're a smoker, and maybe even if you're a former smoker.

Extra folic acid and iron are very important for a healthy baby. They can be found in most prenatal vitamins. But some prenatal vitamins can make nausea worse, mostly because of the iron. If this happens to you, pair your prenatal vitamins with a light snack before you go to bed. Talk to your doctor about the best prenatal formula for you.

Even essential nutrients can interfere with many common medications. If you take a traditional blood thinner like warfarin, just the small amount of vitamin K in an MVM can cut its strength. Taking more than 1,000 mg of vitamin E per day can raise your risk for bleeding. And if you take thyroid medication, taking calcium, magnesium, or iron within 4 hours can cut its strength. Ask your doctor about how best to time it.

RDA (recommended daily allowance) is the daily amount of a nutrient you should get, based on sex and age. DV (daily value) is the percentage of a nutrient that a supplement or food serving adds to the average daily diet for all ages. UL (upper limit) is the most of a nutrient you should get in a day. Side effects from big doses range from tiredness or diarrhea to kidney stones or organ damage.

There's no one standard MVM formula. Some have more nutrients than recommended. Others may come up short on some RDAs. For instance, the amount of calcium you need to meet the RDA is too much to fit into a tablet that you could easily swallow. Scan the full ingredients list so you know exactly what's in the supplement you're considering. This will also help you know if you need to time when you take it.

Another way to get more of the nutrients you need is to shop for formulas geared to your age and sex. For example, many vitamins for seniors have more calcium and vitamins D and B12 than younger people need. As you get older, your body doesn't do as good a job of absorbing B12. Women in particular often need extra calcium and vitamin D after menopause to protect bones. Men's formulas leave out the iron.

Opinions about gummy vitamins are mixed. One study found that people who take vitamin D in gummy form get more from it than from a tablet. On the other hand, gummies can have a lot of sugar and calories. And because they taste like candy, it's easy to go overboard and eat too many. They may even cause cavities. Also, not all brands contain all essential vitamins and minerals. Some may not even contain the amounts listed on the label.

Since the FDA doesn't regulate supplements, look for brands that have been "verified" by one of the three companies that test supplements in the U.S.: Pharmacopeia, Consumer Lab, or NSF International. These testing organizations verify that what's on the label is in the bottle in the right amounts.

If you keep a log, it can help you time out different supplements and keep track of how much you take every day. The National Institute of Health's Office of Dietary Supplements has a form called "My Dietary Supplement and Medicine Record" that you can print out and fill in. Bring it with you, along with your medication list, when you go to doctor visits.