The GP appointment
Vitamin D and hair: why the UK winter is a hair problem
Vitamin D is the least glamorous of the hair nutrients and the one most British mums are short of. Between the latitude, the cloud, the office, the pram under a rain cover and the sun cream, most of us make almost none for half the year. The follicle notices.
What vitamin D does at the follicle
Every follicle has a vitamin D receptor, and the receptor is involved in the signal that tells a resting follicle to begin a new growing cycle. Without enough of it, follicles rest for longer and restart more slowly. Severe deficiency causes a diffuse shed; mild, long-standing deficiency does something quieter: it lengthens every rest, so that over a year the head carries slightly fewer growing hairs than it should. It also sits alongside the immune system, which is why low vitamin D is found more often in women with alopecia areata.
Who is short of it
Almost everyone in the UK by February. More so if you have darker skin, which makes vitamin D less efficiently; if you cover your skin or wear high-factor sun cream daily; if you are pregnant or breastfeeding, because the baby takes a share; if you are carrying extra weight, because vitamin D is stored in fat and less circulates; and if you spend the day indoors, which describes most mums with young children in winter.
How to test
Ask the GP for 25-hydroxyvitamin D, or 25(OH)D. It is often added to a hair-loss blood panel with ferritin and thyroid without argument. The reporting thresholds are: under 25 nmol/L deficient; 25 to 50 insufficient; over 50 adequate. For hair, I like to see it above 75. If a GP declines, a fingerprick postal test is inexpensive and reliable.
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Twelve quick questions. We tell you what we think is going on, what to do about it, and we say so if it is something we cannot help with.
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Government advice is 10 micrograms (400 IU) a day for everyone through autumn and winter. That is a maintenance dose for someone who is not deficient. If your level is under 50, most GPs will suggest 25 to 50 micrograms (1,000 to 2,000 IU) daily for three months and then a retest; if it is under 25, a short higher-dose course is often prescribed. Vitamin D3 is better absorbed than D2, and it is fat-soluble, so take it with a meal that contains some fat. Do not take very high doses on your own initiative for months on end; it accumulates.
Food and sun
Oily fish, egg yolks and fortified foods contribute, but not enough on their own. Between April and September, ten to twenty minutes of midday sun on forearms and face without sun cream a few times a week is enough for most lighter-skinned people to make what they need; darker skin needs longer. From October to March the angle of the sun means no amount of British daylight will do it, which is why the supplement advice is seasonal.
Where it fits
Vitamin D, ferritin and thyroid are the three things to check before spending money on anything else, and the blood tests article covers how to ask for all three at once. If they are all corrected and the pattern — corners, parting, ponytail — is still there, the reason is at the follicle, and that is what the rest of this site addresses.
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Twelve questions. We tell you what we think is going on for you, and we say so if it is something a GP should see first.
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