Vitamin D 'reduces risk of diabetes'

Sunlight is an important source of vitamin D

Vitamin D has been linked to a reduced risk of developing type 1 diabetes.

A Finnish study following over 12,000 babies born in 1966 found those who were given the recommended amounts of vitamin D supplement had an 80% reduced risk of developing diabetes.

Researchers followed the children until 1997, and found 81 had been diagnosed with diabetes during the study.

They say: "We suggest that ... health workers ensure that all infants are receiving at least the amount of vitamin D indicated in the current recommendations."

We suggest that ... health workers ensure that all infants are receiving at least the amount of vitamin D indicated in the current recommendations

Dr Elina Hyppönen, of the Institute of Psychiatry London

Patients with type 1 diabetes, also known as insulin-dependent or immune-mediated diabetes need to take insulin to control blood sugar levels.

Nutrition experts recommend children under six months have 8.5 microgrammes a day (mcg), and 7mcg a day from seven months to three years.

But diabetes experts warn the Finnish study is inconclusive, and say people should not take vitamin D supplements unless they have been clinically diagnosed with a deficiency.

Rickets link

In the research, children were monitored for their vitamin D intake in the first year, and classed as below, within or above the recommended amount.

It was found children who took any amount of vitamin D had a lower rate of diabetes than those who did not.

Children who were given supplements regularly saw a reduced risk of 80%.

And those who had rickets - which is linked to vitamin D deficiency - in the first year of life had a three-fold risk of developing diabetes.

The link between a lack of vitamin D and diabetes has already been suggested in tests on animals and a retrospective study of children's health.

This is the first large-scale study to follow children's diet and their later development of diabetes

Exactly what causes the destruction of insulin secreting cells in the pancreas, and therefore the development of type 1 diabetes is not known.

However, vitamin D is known to be an immunosuppressive agent.

Type 1 diabetes is an autoimmune disease, where the immune system destroys its own cells.

Vitamin D is believed to act as an immunosuppressant agent.

The researchers believe it may prevent an overly aggressive response from the immune system.

High rates

Finland has the highest reported incidence of type 1 diabetes in the world.

In north Finland, there are only two hours of sunlight - a key source of vitamin D - every day in December.

This study is interesting, but still requires further research.

Mairi Benson, Diabetes UK

The researchers say vitamin supplements are therefore probably more important in that population, but say the study shows all infants should receive at least the recommended daily amount.

Dr Elina Hyppönen, of the Institute of Psychiatry London who led the research, told BBC News Online: "Our biggest hope is that something could be done in order to prevent diabetes.

"Vitamin D is also easily accessible and useful in terms of general health."

In a commentary piece in the Lancet, Dr Jill Norris, of the University of Colorado Health Sciences, adds "The potential role of vitamin D in the pathogenesis of type 1 diabetes is intriguing and deserves follow-up.

"Prospective studies in which biomarkers of vitamin D are measured at various times before the diagnosis of diabetes are necessary to resolve issues about timing and dose - such information would be important in the design of intervention trials."

Mairi Benson, a spokesperson for Diabetes UK said: "This study is interesting, but still requires further research.

"The causes of Type 1 diabetes are believed to be both genetic and environmental in basis, but the environmental triggers are not known.

"This research is at too early a stage to say conclusively whether a lack of vitamin D is one such environmental trigger.

"Diabetes UK does not recommend that people take supplements unless clinically diagnosed with a deficiency.

"The safety of taking various dosages of supplements, such as vitamin D, and taking them for a prolonged period of time must be rigorously tested."

The research was published in the Lancet.