How Much is Too Much Biotin?

How much better is a manicure and a blowout when you have smooth, unbreakable nails and split-end free hair to work with? You can potentially thank biotin for that. If you’ve looked at hair and nail supplements, you’ve probably seen biotin, a key B-vitamin, as the universal ingredient. But can it actually nourish your hair and nails the way they need to be? And what’s the correct biotin dosage for adults—how much biotin is too much?

Biotin (aka B7) is one of the many water-soluble B-vitamins that are necessary for your body to function. Its main role in the body is as an important cofactor that’s essential for metabolizing macronutrients in order to regulate your metabolism. Another key role of biotin is in the nervous system, by helping the brain transmit nerve signals. B vitamins in general protect your brain and improve your memory and concentration.

You can find biotin in a number of different food sources including some nuts and legumes, eggs, dairy, and certain meats and fish (more on the nutritional aspect later). After you digest foods containing biotin, it gets absorbed in the small intestines and stored in the liver. Biotin plays an important role in metabolizing glucose, fatty acids, and amino acids. Its role as an enzyme in the metabolism of amino acids is crucial for protein creation, which results in building strong healthy hair and nails.

While the research is limited, clinical trials suggest that it can help reduce brittle nails that easily split or crack. The same goes for healthy hair. Studies show that individuals with a biotin deficiency can benefit from supplementing biotin to help with hair growth. Hair is easily damaged by sun-exposure, over washing, and constant heat from the hairdryer or other styling tools. Biotin plays a role in building the protein that helps regrow healthy hair, which is why it has become such a popular hair and nail supplement.

Adults need at least 30 micrograms (mcg) of biotin per day. If you’re eating a well-balanced diet that includes lean protein and plant-based foods like veggies, nuts, and seeds, you’re likely hitting your base level. There’s no official upper limit for biotin because it’s water-soluble, which means your body only stores what it needs. The rest is excreted in your urine. The normal recommended biotin dosage for adults is 30 to 100 micrograms (mcg) per day.

But there’s no evidence of high levels of biotin being harmful or causing toxicity, which is why you’ll commonly see biotin supplements containing 5,000 to 10,000 mcg. (These levels ensure your body gets as much biotin as it needs and absorbs it in the small intestines.) So is more than 10,0000 mcg too much biotin? Or, is 15,000 mcg too much biotin? Not exactly. Research has suggested that even mega-doses of 300 mg (that’s 300,000 mcg) to help with treating multiple sclerosis have no adverse side effects.

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