Types of multivitamins

Experts say that getting your vitamins and minerals from whole foods is better than relying on a pill or powder. That's because researchers still aren't entirely sure how synthetic supplements interact in the body. For example, large doses of folic acid, the synthetic form of folate, have been linked to an increased risk of prostate and colon cancer. Those who get a lot of folate from food sources don't have the same risk. As a result, some manufacturers are focusing on food-based ingredients rather than their synthetic counterparts. New Chapter Organics, Garden of Life and Nature's Way are just a few companies that have multivitamin lines with food-based ingredients.

Liquid and gummy multivitamins for adults generally get good reviews from users who have trouble swallowing pills, but not many of these are included in the latest round of testing. We found no evidence to suggest that liquid multivitamins are more effective than pill-based supplements, and ConsumerReports.org says studies show no difference in absorption rates between liquid and pill multivitamins.

Consider the following when shopping for multivitamins:

  • Talk to your doctor first. Multivitamins can interfere with prescription medications. Consult your physician before starting a new multivitamin regimen.
  • Buy a basic multi. Companies charge extra for formulas touting heart health, energy and weight loss, yet many of those claims are untested and aren't worth the extra cost.
  • Buy generic. Experts say store brands are just as effective as their pricier counterparts. Multivitamins such as Walmart's Equate, Costco's Kirkland Signature and Target's Up&Up contain the nutrients listed on the label and dissolve properly.
  • Choose a multivitamin that contains 100 percent of the daily value of most of the essential vitamins and minerals. Don't take a multi with excessively high levels of essential vitamins and minerals; at best, you'll just expel the excess through urine. At worst, you could suffer health complications.
  • Watch your intake of vitamin A. Vitamin A is increasingly included in other fortified foods, making it easy to reach the recommended daily upper limit. Even small excesses of vitamin A can cause health problems. Look for a maximum of 5,000 IU, although experts in men's health recommend no more than 2,500 IU in a multi. At least half of the vitamin A should be in the form of beta-carotene, a safer form than fat-soluble retinol.
  • Boost your vitamin D and calcium consumption. Recommendations for these two nutrients have been increased. If your current multi is low, consider switching or asking your doctor about additional supplementation.
  • Check your multi for 400 mcg of folic acid if you're female. Folic acid can help prevent neural tube defects that develop before most women know they're pregnant. Experts advise all women of childbearing age to take folic acid supplements. Once pregnant, women should bump up their intake to 600 mcg per day.
  • Compare similar products. Chewable, gummy and liquid multivitamins may not contain the same amount of nutrients that their pill-form counterparts do. Compare labels before you buy.
  • Buy children's vitamins for children. Kids have different nutritional needs than adults. Never give a child an adult multivitamin.
  • Check the  expiration date. Expiration dates are voluntary, but nearly all supplement manufacturers list them on the packaging. In recent months, the Council for Responsible Nutrition released new guidelines for determining expiration dates for multivitamins and supplements. The FDA will look for stability test data to back up expiration date claims, which should give these dates more credibility.
  • Ignore "pharmaceutical grade" labels. These supplements claim to have ultra-purified ingredients that are of higher quality because they're made in strictly controlled facilities that follow good manufacturing practices. However, we saw no evidence that pharmaceutical-grade supplements work any better than regular multivitamins. What's more, the FDA doesn't recognize this labeling or hold these companies to a higher standard.
  • Shop carefully if you're a vegetarian/vegan. Many store-brand and mainstream brands include fish oils or gelatin that's derived from pork or beef. Look specifically for brands labeled as suitable for vegans or vegetarians; if a brand isn't clearly marked, assume that it's not suitable for strict vegetarian or vegan diets.

Understanding the alphabet soup of RDA, DV, DRI and UL

Multivitamin ingredients are measured in terms of the daily value (DV). The recommended amount of each vitamin and mineral is established by the FDA and is based in part on the recommended dietary allowances (RDA). To add to the confusion, RDA and DV are used concurrently to describe nutrient recommendations. According to the National Institutes of Health, the RDA is the amount of a nutrient needed to meet the daily basic needs of healthy people. It's one of the factors used to determine daily values, the amounts recommended to help prevent disease that are often higher than the RDA. The DV is presented on food labels and the RDA is mainly used by health professionals.

The newest standard for nutrient requirements is Dietary Reference Intake (DRI). This system was developed by the U.S. National Academy of Sciences' Institute of Medicine in consultation with Health Canada and is used in both countries. DRI recommendations are made up of three components: the estimated average requirements (EAR), a level nutritionists say should meet the needs of 50 percent of the people in a defined age and gender group; the RDA or, where no RDA has been established, the adequate intake (AI); and the upper limit (UL), meaning the highest level that experts consider safe.

Confused? You're not alone. Even among research and nutrition professionals, there's considerable debate about optimal levels and safe upper limits. Part of the problem is that researchers don't yet understand completely how these substances work in the body.

For every study that links a supplement to a supposed health benefit, there's probably another study that links it to adverse health effects. So what's a person to do? Experts agree that getting your nutrients from whole foods is best -- you reap all the benefits of each individual vitamin without the risk of side effects seen when those same vitamins are taken in supplement form. The science on nutritional supplements is constantly evolving, but it's unlikely that a single dietary supplement or vitamin will ever be a silver bullet for our health woes. Your best bet is to ask your doctor whether specific supplements or multivitamins are necessary for your individual health condition.

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