So, should we all be taking our daily hair vitamins?

Thinking about popping hair growth pills? Here’s the long and short of the issue.

Lately, there’s been a smattering of evidence that shows biotin supplements may actually do more harm than good: Overdosing on biotin can result in slower insulin production, topical rashes, decreased vitamin C and B6 levels, and increased blood sugar levels. There’s also talk that these pills might just be placebos, because there’s not really any conclusive evidence that these vitamins actually do anything.

But hold up: People spend a whopping $176 million annually on supplements. What’s the appeal?

“They’re not made-up pills. Our bodies are already taking them in and they should be a part of our diet,” celeb stylist Devin Toth of New York City’s Salon SCK told Medical Daily.

Usually, the pills contain a mix of vitamin C, biotin, vitamin B3, and vitamin A—vitamins that are both necessary for hair growth and other bodily processes. And individually, each have functions that can assist in hair growth: Vitamin C helps produce collagen and increases the blood’s ability to absorb iron, while biotin helps create the amino acids that build up proteins like keratin and improves the strength and elasticity of the hair follicle’s cortex. Vitamin B3 keeps blood flowing to the scalp with abandon.

In 2012, Viviscal—a brand of hair growth supplements which contain biotin, vitamin C, and iron among other ingredients—did a blind study on its products that proved the pill encouraged hair growth in women with thinning hair after periods of three and six months. These results may be the first study that found that nutritional supplements actually work.

But before you run out and buy a medicine cabinet’s worth of biotin, note that these findings don’t mean that supplements are miracle vitamins.

“While vitamin deficiencies — notably iron and vitamin D — can contribute to hair shedding, there just isn’t data to support the efficacy of vitamin supplements, like biotin or Hairfinity. And people spend so much money on them,” Marie Leger, a dermatologist at NYU Langone Medical Center, told Medical Daily.

And sometimes, genetics are just to blame for thinning hair. Sadly, no amount of vitamins can fix that.

The moral of this story: Vitamins can help your locks reach their maximum potential, but if your end game is a ponytail as long as Rapunzel’s, well, you might just want to get some extensions.