It is almost impossible to pick up a newspaper or magazine these days without reading an article on vitamin D – it really is the hot button issue in evidence-based nutrition at the moment. In the last two years alone, more than 4,000 scientific papers have been added to the medical and scientific literature, indicating a huge and sustained interest in vitamin D in university researchers. This three-part article synthesizes some of the most important new information on vitamin D, and its implications for your health.

What is vitamin D?

Vitamin D is a fat-soluble vitamin. It is needed for normal growth and the formation of bones and teeth, and for absorption and metabolism of bone-building minerals like calcium and phosphorus. Vitamin D, or to give it its chemical name, cholecalciferol, is manufactured in skin from a cholesterol derivative, 7-deyhdrocholesterol, when the skin is exposed to sunlight or artificial UV light. It can also be synthesized in the laboratory.

How common is vitamin D deficiency?

Deficiency of vitamin D is much more common than previously thought. Anyone can suffer from it, but it is especially common in elderly patients in Western countries. However, it also affects younger age groups, especially those with darker skin, who use sun block or cover up extensively while outdoors. Living in northerly countries (higher than 400 latitude) during the winter months puts everyone at risk of vitamin D deficiency.

Dark skinned individuals may need much higher exposure to sunlight – six to ten times as much – than white-skinned people to produce the same amount of the vitamin D. Therefore those with dark skin are particularly at risk of health problems associated with vitamin D deficiency, especially when they move from sun-rich environments to live in cooler climates.

Actually, even in sun rich countries, changing lifestyles mean more and more time is spent indoors – in front of the computer in offices or in air-conditioned apartments. Children spend more time watching TV or playing computer games and less time kicking a ball around the yard. So it is not surprising that concern for vitamin D deficiency is not confined to northern climates, but is becoming more frequent in places like the Middle East.

Genetic studies are also beginning to demonstrate that some people might be more sensitive to vitamin D deficiency than others. A recent study in the United Kingdom suggested that both low blood levels of vitamin D in combination with genes that control the binding of vitamin D to tissues increases the risk of breast cancer in white women [1].

Can we get enough vitamin D from food?

Very few foods naturally contain vitamin D. The ones that do include fish, liver, and egg yolks. Cod liver oil, a rich source of vitamin D, has been used in Europe to prevent rickets since the 17th century. Because in the past vitamin D deficiency was considered a public health issue, some foods are fortified with vitamin D, including milk products, margarine and some cereals. But the amount of vitamin D in these foods is low. For example, you would have to drink about 10 glasses of milk a day to obtain the current lowest recommended amount for osteoporosis prevention (1000 IU).

Read Part 2 – Vitamin D and disease, and the symptoms of vitamin D deficiency

Read Part 3 –  How to know if you’re getting enough Vitamin D — and ensure you do

Aileen Burford-Mason, PhD, is a biochemist, immunologist and cell biologist and a widely recognized expert in the field of vitamins and their appropriate use in health maintenance, healthy aging and the prevention and treatment of disease. Respected for her balanced and scientifically-based approach, Aileen is known for her ability to take the latest findings in diet and supplement research and translate them into practical evidence-based guidelines for both lay audiences and health professionals. A go-to person for radio, TV and print journalists, Aileen is in regular demand for media commentary on the latest research and controversies in the field of dietary supplements. She is the author of Eat Well, Age Better, with Judy Stoffman (2012, Thomas Allen Publishers). Learn more about Aileen at aileenburfordmason.ca.

References

(1). Lowe LC et al. Plasma 25-hydroxy vitamin D concentrations, vitamin D receptor genotype and breast cancer risk in a UK Caucasian population. Eur J Cancer. 2005 May;41(8):1164-9. Epub 2005 Apr 14