Around 70% of the world population is deficient in vitamin D and guess what: low levels of vitamin D are linked to hair loss.
Vitamin D 101: Vitamin D is fat soluble and it is produced by keratinocytes (KC) in a UVB-light dependent manner. It also comes from our diet. Vitamin D acts as anti-inflammatory and maintains serum calcium and phosphorus levels. Vitamin D modulates the immune response. There are approximately 2,000 genes under the control of vitamin D (5% of our genome).
Vitamin D and hair growth, what do we know?
Hair follicles express the receptor for vitamin D (VDR). The highest expression of VDR happens during the anagen phase (hair growth depends on vitamin D).
Subjects with vitamin D-dependent rickets type II, a disease characterized by a mutation in the VDR (cells do not respond to vitamin D) show significant hair loss (total scalp and body alopecia.
A systematic review of the published literature (14 studies in total, Lee S. et al 2018) on alopecia areata (AA) and vitamin D showed that AA subjects had significantly lower levels of vitamin D in serum when compared to control groups (n=1255 subjects AA and 784 control subjects). Gade VKV et al (2018) reported that the severity of the hair loss was inversely correlated to vitamin D in serum. What does this mean? It means, the lower the level of vitamin D, the more hair loss. Dorach et al (2018) also observed the link between severity of AA and low levels of this vitamin. In addition, they also reported severe inflammation in the scalp areas that were low in VDR (remember Vitamin D is anti-inflammatory).
OK, so it seems that hair loss is linked to vitamin D levels in serum … so supplementation of vitamin D may help, isn’t it?
Well, Thompson JM et al (2016) published a study (n=55,929 female subjects) reporting that there WAS NO significant association between oral supplementation of vitamin D and the development of AA. What does this mean? We all agree that low vitamin D levels are linked to hair loss but supplementation does not help? So what should we do? Fortunately I heard Dr. Eva Simmons-O'brien and Dr. Orlinsky AKA: @ladydermdocs passionate conversation about vitamin D and hair loss in a recent clubhouse and I asked them to provide some light on the subject. Here are their comments:
“Vitamin D is more than a vitamin, it is a prohormone and every cell in our body has VDR”.
“Vitamin D is a value that rises slowly and falls quickly”.
(My comment: This may explain the lack of effect reported on clinical trials. We would need to take these supplements consistently for long periods of time (or forever!).
“Vitamin D supplementation is important for all skin types, especially for types 4-6. In these skin types vitamin D formation in the skin bypasses the rays from the sun”.
“We would like vitamin D levels between 40-60 ng/ml especially with hair loss. Depending on how low it is we prescribe vitamin D2 units until corrects and then we have patients on vitamin D3 2,000 units a day”.
“Take vitamin D with a healthy fat to improve absorption as well as take probiotic and magnesium to get and keep the best levels in the bloodstream”
Thanks so much to @ladydermdocs for their comments ... they are awesome!