I have curly hair, so it gives the illusion of volume and thickness in its natural state. But when I actually blow it out, my hair immediately falls flat and its true thinness finally reveals itself to the world. As it turns out, many of my friends actually have fine hair, too, and some of them even take prenatal vitamins to try to get their hair thicker. That just seems a bit excessive to me, though, as I’m nowhere near ready to try to have a kid and the idea of anything “prenatal” gives me a panic attack. But I’ve also heard that biotin might help your hair get fuller — and help your nails grow. So, to figure out if that’s actually true, I consulted with two experts.
First of all, what is biotin? Biotin is actually a water-soluble B vitamin (which means it dissolves in water after entering the body). Dr. Margarita De L Teran-Garcia, an assistant professor of nutritional sciences at the University of Illinois, told me that biotin is basically the artist formerly known as vitamin B7 or vitamin H, and since it’s a vitamin, it’s necessary to live. It works by helping your body convert carbohydrates and fats from the foods you consume into energy that your body can use, according to Dr. Sarah E. Kelling, clinical assistant professor of pharmacy at the University of Michigan College of Pharmacy.
Where can I find biotin? Well, biotin actually occurs naturally in a ton of foods. You can find it in everything from meat to fish, vegetables, soy beans, egg yolks, yeast, mushrooms, swiss chard, and a lot of other things. In fact, biotin pops up so frequently in our diets, that it’s pretty uncommon to have any sort of deficiency of it.
How much biotin do I need? As it turns out, healthy adults only need very small amounts of biotin. The National Academy of Medicine recommends most adults take 30 micrograms each day, though that number spikes up to 35 micrograms for breastfeeding women, Dr. Kelling told me.
But what happens if I don’t get enough? Although it’s incredibly uncommon to be deficient in biotin, if a person doesn’t have enough of it, they may experience a rash around their eyes, nose, or throat, eye inflammation, hair loss, tiredness, hallucinations, and burning in their extremities, Dr. Kelling told me. Dr. Teran-Garcia added that, surprisingly, people can actually be at risk of biotin deficiencies if they eat a ton of egg whites — which contain a protein that binds to biotin and stops it from being absorbed in the body. But, this is important to note: A fact sheet about biotin from the University of Michigan states that up to half of pregnant women are at risk of deficiency, so it’s important for them to take something like a prenatal multivitamin that contains biotin.
So, can it help with my hair? According to Dr. Teran-Garcia, one of the first things scientists discovered about biotin is that it can promote growth — particularly when it comes helping to keep the skin healthy and strong. But unfortunately, even though you can find shampoos with biotin in it, there’s not much scientific evidence to support the theory that it can help promote hair growth. “It’s kind of tricky because there’s not too much evidence that only biotin is working for this. It’s not the only element that is necessary to have the hair be thicker or grow faster,” Dr. Teran-Garcia said.
What about nails? Actually, Dr. Kelling told me that there have only been a “few small studies” that looked at biotin’s effect on nails. Some preliminary evidence found that biotin could increase the thickness of finger nails and toe nails in people who have brittle nails — but there are a bunch of different causes of brittle nails that have nothing to do with biotin deficiencies, including excessive dryness or nail-polish exposure. “Right now there’s insufficient evidence to determine whether it’s helpful for people to use biotin for nails and hair,” Dr. Kelling said.