The truth is that our bodies tightly regulate levels of the vitamins and minerals we consume. If you don’t have a deficiency, consuming more of a particular vitamin or mineral through a supplement won’t necessarily lead to health benefits. That’s why supplement skeptics sometimes say, “You’re just paying for expensive pee” – since your body will excrete the excess.

For an example of the more-is-better myth, look at basically any vitamin C supplement. The packaging often prominently displays dosages that can reach 750 or 1,000 milligrams. But adults need only about 75 to 120 milligrams of vitamin C per day. Similarly, look at vitamin D supplements that can come in dosages of 5,000 IU, or international units – a fact also often prominently displayed on packaging. But adults should have no more than 4,000 IU daily. Again, it’s easy to exceed what we need.

Finally, the supplement industry likes to capitalize on the idea that doing something is better than doing nothing. This is the action bias. Taking action makes people feel like they have more control of a situation, which is especially powerful when it comes to health. “Even if I don’t need the extra vitamin C,” they might think, “I’ll take it just to be sure. What’s the harm?”

The examples in the last section show that supplements often contain many times the recommended daily intake of a particular vitamin or mineral. This assumes that taking that much of any of those particular substances is safe.

It is possible to have too much of a good thing. Too much vitamin C can lead to diarrhea, nausea, stomach cramps and more. Too much vitamin D can lead to conditions including nausea, vomiting and kidney stones. Supplements can also interact with prescribed medications. For example, St. John’s wort is famous for interacting with contraceptives, immunosuppressive drugs, statins and chemotherapy by exacerbating or dulling their effects. When it comes to supplements, taking them isn’t necessarily better than not.

Be on the lookout for these marketing messages – they aren’t necessarily correct or good for your health. And talk with your doctor before taking any supplements.

This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Katie Suleta, George Washington University

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Katie Suleta does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.