We went to a South African couple’s home for dinner the other night and they mentioned that I had given them their ever first bottle of Vitamin D pills during their first ever Swedish winter. Now they take them every winter.
I don’t mind the winter cold, or the snow. What gets to me is the darkness during November. Some Stockholm Novembers have around two hours of sunshine in total. The constant cloud cover and rain really causes a lot of people to feel exhausted. There is only twilight between the last week in October and the first week in March. You go wake up in darkness, go to work in the darkness, come home in the darkness. 3pm feels like midnight. All I want to do is sleep. I wonder constantly ‘is this what bears feel like when they want to hibernate? Vitamin D supplements are the only things that help lessen the constant fatigue.
We normally absorb Vitamin D through the skin from sunlight, but if there is no sunlight, you can develop a deficiency if you do not get enough through your diet.
Globally, vitamin D synthesis from the sun (UVB) is more important than the vitamin D we obtain from our diet. The larger the exposed skin surface, the more vitamin D is formed. After about 30 minutes in strong sun, about 10,000 IU is achieved. Then no further production takes place in the skin. However, at our Nordic latitudes we can only form vitamin D in the skin during the summer months. Because UVB is filtered out in the atmosphere when the sun is low, we cannot form any vitamin D in the skin during the winter months. In the Nordic countries, we thus have to rely primarily on food sources in winter.
Read more about Vitamin D deficiency here