Hair and nails.

If the first nutrient that comes to mind when you read those words is biotin you’re on the right track. Even the mass marketed corner drugstore supplements whose labels say they’re good for hair and nails contain biotin (or claim to anyway) so there must be something to it. Indeed this B vitamin is good for tresses and claws but there’s a world of other things in our bodies that benefit from biotin. 

Biotin a.k.a. vitamin B7 (and formerly called vitamin H in case you were wondering what happened to vitamins F through J – the “H” was for “Haar und Haut” German words for “hair and skin”) is a key ingredient for many metabolic pathways and processes involving all three macronutrients: protein fat and carbohydrates. It’s a cofactor for at least five carboxylase enzymes in mammals including acetyl-CoA carboxylase a key enzyme involved in fatty acid synthesis. 

Another biotin-dependent enzyme is pyruvate carboxylase which catalyzes the conversion of pyruvate into oxaloacetate (OAA) which can either be funneled into the Krebs cycle or be shunted toward gluconeogenesis instead. This may be why biotin is often recommended along with chromium for improving blood sugar regulation. Multiple studies support the use of this combination for improving blood glucose management in type 2 diabetics including those whose conditions don’t improve sufficiently with oral therapeutic agents alone. Biotin may help regulate insulin secretion in response to glucose and pancreatic cells from biotin-deficient rats have 50% reduced glucokinase activity which could also result in elevated blood glucose. In addition to improving fasting blood glucose and hemoglobin A1c the chromium/biotin dynamic duo has been shown to improve cardiovascular risk markers in type-2 diabetics such as the ratio of LDL to HDL and the important triglyceride-to-HDL-ratio. (The other biotin-dependent carboxylases are involved in the metabolism of branched chain amino acids and odd-chain fatty acids.)

Biotin is also a cofactor for elongase enzymes that convert polyunsaturated linoleic acid and alpha-linolenic acid (ALA) into longer-chain polyunsaturated fatty acids (PUFAs) such as arachidonic acid (from linoleic) and EPA and DHA (from ALA). Vegetarians but in particular vegans who eschew all animal foods should be sure to get sufficient biotin so they have an adequate supply in order to support the conversion of ALA into the longer-chain omega-3s EPA and DHA since they avoid eating seafood and eggs which would provide these critical long-chain PUFAs.

So what about hair? Is “vitamin H” all it’s cracked up to be for hair growth? Alopecia is a symptom of biotin deficiency but biotin deficiency certainly isn’t the only factor that can cause hair loss. The authors of a study assessing biotin levels in women complaining of hair loss said it perfectly: “Pharmacy aisles and Internet drugstores are full of nutritional supplements promising full thick luscious hair for prices that range from suspiciously cheap to dishearteningly exorbitant. The fact is that unless hair loss is due to a specific nutritional deficiency there is only so much that nutritional therapies can do to enhance hair growth and quality.” Their study did find that many of their subjects had suboptimal biotin levels: out of 503 subjects 38% were frankly deficient and 49% had suboptimal levels with just 13% having optimal levels. Unfortunately there isn’t much research supporting the efficacy of biotin supplements specifically for reversing hair loss—probably because biotin deficiency either isn’t a factor causing the issue or it’s not the primary one.

Because biotin is found in a wide variety of foods overt deficiency due to dietary inadequacy alone is rare. Biotin deficiency is more likely to result from illnesses causing increased need for biotin poor nutrient absorption or medications that interfere with biotin synthesis in the intestines. What are these illnesses and medications? And what are the best ways to assess biotin status?

Stay tuned for part 2!