Ever heard someone say that their hair grows better in the summer or when away on holiday to a hot destination? Well this got me thinking and I wondered whether there is a possible correlation here with Vitamin D levels. Just in case you didn’t know, Vitamin D deficiency is a really common problem in the UK with more than half of the population having insufficient levels of Vitamin D. This has led to a massive campaign in recent years to raise awareness about Vitamin D deficiency as Vitamin D is important for good health, growth and strong bones. The most natural way of getting enough Vitamin D is by exposure to sunlight (UV-B radiation). So soaking up the sun responsibly is really our main source of vitamin D as food only provides very little Vitamin D naturally. Oh and by the way, a diet that cuts out fat may further reduce this small supply of Vitamin D (a fat soluble vitamin).
Healthy looking hair is a sign of excellent general health, as well as good hair care practices. There is some evidence to suggest that there is a link between Vitamin D deficiency and hair loss (alopecia). Vitamin D may play a role in the hair growth cycle. Hair on the scalp grows about half an inch each month and there are three stages of the hair growth cycle:
- Anagen - this is the growth phase which lasts two to six years. About 85 percent of hairs are in the anagen phase at one time.
- Catagen - transition phase which occurs when the anagen hair follicle receives a signal ending the growth phase.
- Telogen - this is the resting phase which lasts five to six weeks until the anagen phase is initiated again. Apparently if a hair follicle remains resting this could result in hair loss. There is really good explanation of the hair growth cycle on the Philip Kingley’s website.
There are limited studies that have been done in humans to evaluate the role of Vitamin D in the hair cycle. The role of Vitamin D in hair growth cycle is still not well understood. To complicate the matter further, extensive data from animal studies suggest that the key is the vitamin D receptor in the hair follicle and not just Vitamin D. The vitamin D receptors in hair follicles are thought to play an important role during the stages of the growth cycle.There are also a number of studies linking lower Vitamin D levels with higher risk of anaemia. You are probably asking what this has to do with hair. Well, the role of nutrition in hair health has been studied for several years and it has been observed that specific nutrients are necessary for healthy hair. One of these important nutrients is iron. The role of iron in hair has long been established, with hair loss being one of the most common symptoms of anaemia. We need iron for healthy blood which is transported via blood vessels to the hair follicle to provide nutrients to the growing part of the hair. It is currently unclear how Vitamin D affects red blood cells.
I appreciate that current evidence still leaves many unanswered questions like is it something special about the sun (everyone is happy when the sun shines right?) or is it Vitamin D that’s a contributing factor to better hair growth in the summer? I noticed that the studies are small in size and so there is a need for further studies – bigger and better quality.
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