Children in a recent study who took vitamin D supplements early in life had a much lower risk of developing diabetes than those who didn't, say researchers in Finland.
As Finland has the highest incidence of insulin-dependent (type I) diabetes in the world, the researchers were looking for any remedial effects on diabetes as well as an association between rickets and type I diabetes.
The study started at birth and followed almost 11,000 children for more than a decade. The results showed that the incidence of diabetes was nearly 80 per cent lower in the children who took the recommended amount of vitamin D in their first year of life - 2000 IU (international units) a day, generally from cod liver oil - compared with those who did not.
It was also found that the children who developed rickets in the first year of life had three times the risk of developing type I diabetes compared with those who did not develop rickets.
Vitamin D is found in cod liver oil, saltwater fish and liver. An even more basic source is sunlight, which transforms cholesterol in the skin into the vitamin. It is thought that 90 per cent of blood vitamin D is synthesised in this way and around 15 minutes of exposure to sunlight three times a week is enough to provide the recommended dietary allowance of vitamin D.
The most common known symptom of vitamin D deficiency is rickets, a bone-weakening condition that was common in the smog-covered cities of the 19th and early 20th centuries. Rickets is also common in northern countries, where sunlight exposure may be less than in sunnier southern climates.
Vitamin D is also known to help prevent the destruction of the insulin-secreting cells of the pancreas, and this new study adds evidence to support previous studies linking supplementation to a lower incidence of diabetes in children (Lancet, 2001; 358: 1500-3, 1476-8).
* To underscore the importance of adequate vitamin D intake, Canadian researchers have determined that the recommended daily intake of vitamin D in that country is pegged too low.
Their study of more than 800 women found that, during the winter, many had insufficient blood levels of vitamin D despite diets which provided more than 5 mcg (micrograms) or 200 IU daily, the recommended intake for adults less than 50 years of age.
In Canada, the researchers say, daily intakes should be around 1000 IU to prevent deficiencies (Eur J Clin Nutr, 2001; 55: 1091-7).
vitamin D deficiency, rickets, insulin-dependent diabetes, type I diabetes