Don’t sneeze at vitamin D

  • 1 Mar 2009
  • Reading time 2 mins
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Two years ago I predicted that vitamin D deficiency in the winter was an important contributory factor in increased colds. This week a study confirms the association between low vitamin D levels and increased incidence of colds. The study published in the Archives of Internal Medicine, involved 19,000 people and found that with the lowest average levels of vitamin D were about 40 per cent more likely to have a recent respiratory infection, compared to those with higher vitamin D levels.

Vitamin D is primarily made in the skin in the presence of sunlight but, in the UK, we just don’t get enough sunshine, or expose enough skin to the little we get. As a consequence most people are deficient. Also in the news recently was research that shows that having enough vitamin D during pregnancy switches off a gene that increases risk of multiple sclerosis. Vitamin D is not only vital for the brain, nervous system and immune system, with profound anti-cancer effects, it is also vitamin for healthy bones. The importance of vitamin D, beyond it’s role in bone health, came to be noticed when researchers investigated possible reasons why the prevalence of a number of disease, including many forms of cancer, MS and schizophrenia, increases in relation to distance from the Equator.

In the Special Report Vitamin D – You Are Almost Certainly Not Getting Enough I make it clear that the minimum level we need for optimal health is around 30mcg a day, although some say this is to low. If you expose yourself to moderate sunlight for half an hour a day, and eat eggs and especially oily fish such as mackerel, you might achieve 15mcg. Hence there is a good case to supplement 15mcg, especially if you live in the UK or equivalent. The RDA, which is desperately out of date, is a mere 5mcg. There are two forms of vitamin D - D2 is derived from plants and can substitute for D3 in the human body. D3 is the natural form found in foods and made by the skin when exposed to sunlight. In effect, we are solar powered, relying on plants to store the sun’s energy in carbohydrate, the body’s primary fuel. Both the vitamin D and essential fats are dependent on sunlight. Effectively, sunlight stored in plankton is passed up the food chain into oily fish, which deliver this energy source to the darker regions of the world, stored in fat for use during winter months. Decline in egg consumption due to mistaken fears about cholesterol, and decline in oily fish consumption have fuelled an epidemic if vitamin D deficiency.