8 Things You Don’t Know About Supplements

In early February, the New York Times reported that New York attorney general Eric T. Schneiderman launched an investigation into some of the largest supplement retailers. DNA testing revealed that 79% of supplements tested did not contain what the labels on their bottles claimed, though the industry criticized the testing methods used by the attorney general.

The wild, mysterious world of vitamins and dietary supplements is the subject of author Catherine Price’s new book Vitamania. Here’s what she thinks every American needs to know before popping another over-the-counter pill.

1. Vitamins and supplements are not required to undergo safety or efficacy testing before they’re sold. “I feel like people don’t really think about the implications of that,” says Price. “I could pretty much create something this afternoon in my kitchen and sell it and not have to do any kind of testing ahead of time.” That’s not to say all supplements are not safe; it’s just to say that the companies that make them don’t have to show evidence of their safety before they go to market.

2. There’s no regulatory definition for a “multivitamin.” “If you buy a multivitamin from Centrum, it could be totally different from a different company’s product,” says Price. That’s confusing if you’re trying to compare brands while you shop.

3. Vitamins and supplements are not the same thing. There are only 13 vitamins: vitamins A, C, D, E, K and eight B vitamins. Supplements are any substance you ingest by mouth that’s intended to supplement the diet. “While vitamins are dietary supplements, all dietary supplements are not vitamins,” says Price. “There are an estimated 85,000 dietary supplements in the U.S. marketplace.”

4. Most dietary supplement ingredients and vitamins are not made in America. Sometimes the pills may be manufactured in the U.S., but the raw ingredients typically come from out of the country. “A large percentage of the ingredients in dietary supplements come from China, and there are nearly no vitamin manufacturing plants in America,” says Price. “Considering how dependent we are on vitamins and fortified foods to meet our needs, it’s surprising how dependent we are on other countries to keep us healthy.”

5. It’s difficult to tell if a supplement is of good quality. “People ask me all the time, ‘How do I pick a good dietary supplement?'” says Price. “The unfortunate thing is that given the state of regulation right now, that is an extremely difficult question to answer.” Looking for evidence that the product has been tested by a third party can help. She recommends visiting sites like the subscription-based site ConsumerLab.com, which randomly tests products, and the similar company LabDoor. There are also two independent verification programs called United States Pharmacopeia (USP) and NSF International (NSF). “If you are a supplement user, you should really use these to help pick your brands,” says Price.

6. Dietary supplements can be spiked with prescription drugs. The three biggest categories where this can happen are weight loss, body building and sexual enhancement, Price says. “What I like to tell people is that if you think your Chinese herbal supplement is just as good as Viagra, it’s probably because it has Viagra in it,” she says with a laugh. You can read more about some of these cases here.

7. More is not better. Taking more vitamins or supplements does not provide extra benefit and could cause harm. Be sure to tell your doctor what you are taking, since supplements can negatively interact with your other medications, and respect the upper-limit dose suggestions on the bottle.

8. You probably ingest supplements even if you don’t realize it. “There’s so much fortification in our food supply that for most people you are probably getting a multivitamin just from the foods you are eating,” says Price. “Most people don’t need to get a separate multivitamin.” In some cases, supplements are needed. For instance, Price agrees with the recommendation that women of child bearing age take folic acid to prevent birth defects.