Human skin and vitamin D

The source of vitamin d3 is sunlight. The 7-dehydrocholesterol is converted by UVB ultraviolet light in the skin to make vitamin d3. the amount of vitamin d3 produced is up to 20,000 IU in a few minutes without any harm. Toxicity may not occure since the production of vitamin d in the skin is self regulatory. Vitamin d is produced in the skin when the sun is high.

It is not just the exposure to sunlight that bring about the production of the vitamin but it is the presence of the UVB rays which occurs. At higher latitudes, the UVB rays may not be produced even when the sun is high. For example, residents in the US in the north of San Fransisco to Philadelphia (about 40 degrees of latitudes) will experience formation of less vitamin for about 3 to 6 months annually.
Therefore, in winter, vitamin d deficiency occurs in up to 10 to 20 % of population.

Those who stay indoors or in a shed at middays will be lacking in vitamin d even if daily intake of supplement as recommended by RDA is met.
Furthermore, as aresult of health awareness campaign to curb skin cancer in Australia and Newzealand, most people are less exposed to the UVB rays which produces vitamin d in the skin. Thus leading to vitamin d deficiency in the residents of these areas. The effect is more harder on the dark skinned people.

There are evidences that people with dark skin will suffer more frequently from lack of sufficient vitamin D. This is also evidenced in the UK, where dark skinned people suffer from osteomalacia and severe vitamin d deficiency.

The articles on this website should not be used as a basis for any form of diagnosis or treatment for any medical condition. Always seek professional medical advice.