Vitamin D Insufficiency in Canadian Women.




European Journal of Clinical Nutrition

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Vitamin D is known as the "sunshine" vitamin because it is formed in the body by the action of the sun's ultraviolet rays on the skin. The fat-soluble vitamin is converted in the kidneys to the hormone calcitrol, which is actually the most active form of vitamin D. The effects of this hormone are targeted at the intestines and bones. Vitamin D is important for the growth and development of bones and teeth. For this reason, vitamin D is an important growth nutrient for infants and children. Vitamin D plays a key role in supporting the immune system.

Rickets is the classical childhood vitamin D deficiency disease. Insufficient deposition of calcium phosphate into the bone matrix creates bones that are not strong enough to withstand the ordinary stresses and strains of weight bearing. In adults, vitamin D deficiency can result in osteomalacia and osteoporosis. Vitamin D deficiency can result from inadequate dietary intake, insufficient exposure to sunlight, which reduces the body's synthesis of vitamin D, and kidney or liver malfunctions, which inhibit the conversion of vitamin D to its metabolically active forms.

A recent study published in the European Journal of Clinical Nutrition examined the rate of vitamin D insufficiency in women during the winter. The study consisted of at least 42 young Canadian women each month throughout one year. The ages of these women ranged from 18 to 35 years. These women had their serum vitamin D levels tested and were given a questionnaire regarding their lifestyle and diet. The prevalence of low vitamin D levels was higher in non-black, non-white females. During the winter, the women tested showed that the occurrence of low levels was not affected by the intake of vitamin D. Low levels were found in 31% of women not taking vitamin D, 26% of women taking some, and 20% in the women taking high amounts. The authors of this study concluded that recommended levels of vitamin D are inadequate in insufficiency prevention.1


1. Vieth R., Cole DE. Wintertime vitamin D insufficiency is common in young Canadian women, and their vitamin D intake does not prevent it. EJCN. Dec 2001; ;55:1091-1097.