No, prenatal vitamins won't grow your hair and nails — and taking them when you're not pregnant can be harmful

• Viral TikTok videos claim that prenatal vitamins can help non-pregnant people grow long hair.
• A dietitian told Insider supplements won't help people who don't have deficiencies.

Some TikTok users claim prenatal vitamins can give your hair a "pregnancy glow" even when you're not about to have a baby — but a dietitian says the claim isn't backed by science.

Prenatal vitamins differ from multivitamins because they contain nutrients that are vital during pregnancy, including folic acid, iron, and calcium. Pregnant people need more iron, for instance, because it helps deliver oxygen to the fetus through blood. Folic acid reduces the chance of a baby having a neural tube birth defect, like spina bifida, by up to 70%.

Though prenatals are essential when a person is pregnant, some TikTok videos have garnered tens of thousands of views by purporting prenatal vitamins grow strong, long hair and nails even when you're not carrying a child.

"Even though I'm not pregnant, these vitamins have so much good stuff in them," TikTok user nikki_monique_ said. "Prenatal vitamins have so many benefits for hair."

But the claim is one of the many medical myths spread on the app without evidence or science to back it up, according to Jamie Pronschinske, a registered dietitian at Mayo Clinic Health System in Wisconsin — and taking prenatals when you aren't pregnant could even be harmful to your health.

"There are no supported benefits" to taking prenatals when a person is not pregnant, Pronschinske told Insider.

Taking prenatals when you aren't pregnant may be harmful

Though iron, one of the main vitamins in prenatals, is linked to hair and nail health, too much of it can be dangerous — especially for kids.

Pronschinske said prenatals contain 27 mg of iron per daily dose, the amount recommended during pregnancy. For people who aren't pregnant, dietitians recommend just 8 mg for men and 18 mg for women – which they recommend getting through food, not supplements.

Taking too much iron can lead to iron toxicity, which can corrode tissue in your gastrointestinal tract, Insider previously reported.

Though Pronschinske said adults rarely suffer from iron toxicity from prenatals, Mount Sinai warns children can suffer from "severe overdose" if they take prenatal supplements.

Toxicity isn't the only concern when taking unnecessary prenatals. Pronschinske said that even in adults too much iron can reduce zinc absorption and interact with prescription medications in your body in a way that's harmful. Iron carries a positive charge that can bind to and may block the absorption of antibiotics used to treat pneumonia and bladder infections, making them less effective.

A balanced diet supports your hair and nails more than any prenatal vitamin

Pronschinske said the best way to get nutrients needed for hair and nail growth is through food. Many meats, legumes, and fortified cereals are good sources of iron, she said, and eggs and dairy contain the zinc, protein, and biotin that are needed on a daily basis.

For people who want to fill the gaps in their diet, Pronschinske said to consider a regular daily multivitamin that fits your age and gender. Multivitamins that contain up to 100% of the daily value for nutrients are a better option than prenatal vitamins, Pronschinske said, because a non-pregnant body will not process the excess nutrients and simply pee them out.

If you are eating a balanced diet and still struggle with brittle hair or nails, Pronschinske said that medical conditions, hormones, age, genetics, and medications can also all impact the strength and rate of growth of your hair and nails.