If there’s one concern that affects people profoundly, and which endocrinologists can sometimes help, but often don’t – it is hair loss. Since endocrinologists treat conditions where hair thinning is a clue toward a diagnosis, we often evaluate people seeking help for their hair - even if no endocrinology is involved.
So, what are the most common reasons for hair loss, and can an endocrinologist help? Vitamin D is often suggested to help - does it? Last newsletter, I reviewed these questions and more. You can read it by copying this link into your browser:
https://shoutout.wix.com/so/efNrfPVDB?languageTag=en#/main
When there's not an obvious Vitamin D deficiency, what other vitamin is recommended? Biotin. By everyone. It is supplemented in high amounts in every hair-skin-nail supplement. Let's face it, an easy to purchase, relatively inexpensive supplement is the first thing most of us turn to when confronted with a new condition.
What you need to know about biotin and hair loss:
1. Under what conditions is it helpful?
2. At what doses?
3. Are there side effects to look out for?
For answers, let's start with a summary of the science, followed by a deeper dive into the details.
Bottom line:
1. Biotin is needed to use energy from carbohydrates, fat, AND protein. Most of the biotin we need is made by bacteria in our intestines, which we then absorb.
2. If you have a biotin deficiency, have intestinal inflammation or malabsorption, or consume a lot of raw eggs (more on that below!), then biotin supplementation is probably more likely to increase hair growth. People on medication for seizures or have dependence on alcohol are more likely to have biotin deficiency. Pregnancy is also a time when mildly low levels are common, so supplementation is reasonable, especially since we're still learning how low biotin may impact fetal growth and development.
3. There is no Recommended Daily Allowance for biotin, so the Food and Nutrition Board of the National Academy of Sciences used the amount in normal infant milk and then increased the amount for older children and adults to account for body weight. These levels are defined by them to vary by age from 5-6 mcg in infancy to 12 mcg by preK to 20/25/30 mcg daily at 9/14/19+ years old, even though our intestinal bacteria make much of that needed amount. Research has shown our total need is likely 2-3 times the amount made in the intestines. Most supplements contain 10-200 times that amount.
If your multivitamin contains what is likely about 10-30 mcg, you're likely taking enough in to supply the building blocks for your basic needs. If you have some kind of intestinal condition, or have more significant hair concerns, consider a supplement 10x this to be sure you are supplementing effectively.
3. Thankfully, there don't appear to be concerns with overdose. BUT, many hormone tests - including the measurement of Vitamin D, testosterone, estrogen, and thyroid levels - are influenced if there is high dose supplementation taken in the previous few days. This does not mean that the hormones are affected - just their measurement! - so feel free to continue taking the supplement otherwise. However, because interference in hormone measurements can last up to 7 days from a high dose, I recommend all my patients halt biotin supplements one week prior to planned blood tests.
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And now for the deeper dive:
Biotin is a B-vitamin that attaches and activates five different carboxylases - enzymes that transfer CO2 to various kinds of fuel sources in the body - to both build up and use energy from carbohydrates, proteins and fat. Biotin also modifies histone proteins and transcription factor activity to regulate DNA and protein synthesis, and affects signaling within cells, as well.
Generally, individuals make biotin in the microflora of their intestines, and it has generally been considered that we need little beyond this. That said, we also absorb biotin from foods - including animal products, vegetables (especially the superfoods broccoli, sweet potato, and green leafy ones!), nuts and seeds. Most biotin is bound to proteins, with digestive enzymes breaking these down to release it into a free form, which is then absorbed in the small intestine to be stored in the liver.
Extremely rarely, newborns are identified with a deficiency in biotinidase or holocarboxylase synthase - the enzymes needed to absorb biotin. These children have thin and fragile hair, brittle fingernails, rashes around mucous membranes (mouth, eyes, and anus), seizures, infections, weakness and developmental delays. Deficiency is hard to measure, since biotin level fluctuate. As a result, they are identified via elevated urinary levels of a substance that a biotin-carboxylase is supposed to reduce (3-hydroxyisovaleric acid). Elevated urinary 3HIA is used as the most widespread appropriate measure of low biotin.
Other than that rare condition, those who take long-term or powerful antibiotics may destroy the intestinal flora that produces biotin. Of people who are alcohol dependent, 15% have low levels of biotin, likely due to alcohol's direct effect on biotin absorption and storage. Individuals who take seizure medications - like carbamazepine and phenytoin - appear to have reduced absorption and more rapid excretion of breakdown products of biotin. Importantly, an unclear but sizeable proportion of pregnant women have measures of mild biotin deficiency. One study showed that pregnant women who had intakes of 60 mcg - about double the usual adult dose - had urinary excretion of metabolites demonstrating at least mild deficiency. That said, there appears to be a different way pregnant women metabolize these substances, so more research needs to be done before concluding that pregnancy is a particularly vulnerable state.
Interestingly, an protein called avidin that is at high levels and active in raw egg white, avidly (!) binds up biotin so that it doesn't get absorbed. As a result, people who eat raw eggs frequently are at significantly higher risk of low biotin.
All supplemented biotin in healthy people is absorbed, even if it is a megadose - and these megadoses have been used with fairly good success in case reports published in the medical literature. Unfortunately, none of these studies had groups where people didn't take biotin - just measuring effects of taking the biotin. That said, the positive effects ranged from subtle to dramatic, and there did not appear to be negative effects.
Studies supplementing biotin to children have almost all been performed in those with identified genetic or hair/nail disorders known to respond to biotin. As a result, we still don't know if general thinning responds to high dose biotin. Due to this, pediatric dermatologists - and physicians in general - tend to be divided in their advice. While it may not be harmful to supplement, it isn't clear that it's providing a benefit and may provide false hope and delay in care by a dermatologist of a more appropriate treatment to an underlying diagnosis.
Reassuringly and importantly, the high doses of biotin - some 500x the above recommended levels - don't appear to cause any bad side effects. So, while we don't know if those who improved were the ones with low biotin levels, it is clear that many with rashes and thinning hair improved with high doses - and the risk-benefit ratio encourages supplementation.
A particularly exciting therapeutic possibility for high dose biotin is in progressive multiple sclerosis, where nerves' axons are damaged. The damage is due to both inflammation of the protective myelin sheath, composed of fatty acids, and low oxygen levels in the neuron itself a separate contributor to their destruction. Biotin appears to stabilize and help strengthen the myelin sheath by encouraging fatty acid production, and is becoming a more recognized part of therapy in MS.
The only real problem with taking high doses of biotin (other than its cost and any false hope its supplementation provides) is the common use of biotin in laboratory measurement of various hormones - whose very low levels in the blood require extra sensitive testing. Using the streptavidin-biotin bond, similar to that mentioned above in the problem with eating too many raw egg whites - laboratories frequently use these agents, attached to antibodies against the hormone, to measure a reaction that they can visualize and measure precisely. As an endocrinologist, this is critical information to obtain, and a major reason why I review the brands and ingredients of vitamins used when recording a medication list.
Indeed, for thyroid hormones, biotin supplements falsely decrease measurements of TSH due to the SA/B sandwich assay, and falsely increase measurements of free T4 due to the SA/B competitive assay, and also affect estrogen, testosterone, and Vitamin D measurements accordingly, depending on the manner of SA/B assay used. Interfering biotin has caused people to have surgeries and take medications due to abnormal lab values! So, please just halt all biotin for one week prior to any scheduled lab studies - or tell any physician what you are taking for more urgent laboratory workup.
While this information was initially published in 2017, and is now generally known among endocrinologists, it is not in the general population, even among physicians.
But now YOU know, and you can help spread the word!
Next newsletter: Other nutrients - Hair and growth
I'd love to hear your feedback! Please send suggestions to: EndocrineExplainedNewsletter@gmail.com. I read every email I receive.
All my best!
SL
I hope this was interesting and useful. Please see the sources below for further reading:
Bowen R, Benavides R, Colón-Franco JM, Katzman BM, Muthukumar A, Sadrzadeh H, Straseski J, Klause U, Tran U, Best practices in mitigating the risk of biotin interference with laboratory testing, Clinical Biochemistry, Volume 74,2019,Pages 1-11,ISSN 0009-9120,
Mock DM. Biotin: From Nutrition to Therapeutics. J Nutr. 2017;147(8):1487-1492. doi:10.3945/jn.116.238956
Ostrowska M, Bartoszewicz Z, Bednarczuk T, Walczak K, Zgliczyński W, Glinicki P. The effect of biotin interference on the results of blood hormone assays. Endokrynol Pol. 2019;70(1):102-121. doi: 10.5603/EP.a2018.0084. PMID: 30855699.
Patel DP, Swink SM, Castelo-Soccio L. A Review of the Use of Biotin for Hair Loss. Skin Appendage Disord. 2017;3(3):166-169. doi:10.1159/000462981
Saleem F, Soos MP. Biotin Deficiency. [Updated 2021 Sep 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-.
