NEW YORK, Nov 02 (Reuters Health) - Infants who receive the recommended daily dose of vitamin D may have a lower risk of developing type 1 diabetes, researchers report.
Babies who received at least 2,000 international units (IU) of vitamin D daily were nearly 80% less likely to develop type 1 diabetes over the next three decades compared with infants who had lower intakes of the vitamin, according to findings published in the November 3rd issue of The Lancet.
It is not clear how vitamin D may lower the risk of type 1 diabetes, which occurs when the body's own immune system destroys the insulin-producing cells of the pancreas. However, vitamin D has been shown to suppress certain cells of the immune system that may play a role in the development of the disorder.
"As type 1 diabetes is considered to be an autoimmune disease, it seems likely that vitamin D would be needed in enabling the optimal function of the immune system and in preventing too aggressive attacks against the body's own tissues," Dr. Elina Hypponen, the study's lead author, told Reuters Health.
Current guidelines recommend that infants receive 7.5 to 10 micrograms (mcg), or about 400 international units (IU) of vitamin D daily. Sources of vitamin D include fatty salt-water fish, fortified cows' milk, eggs and infant formulas.
Research on animals has shown an association between vitamin D and a reduced risk of type 1 diabetes. To investigate the relationship in humans, the researchers followed more than 10,000 women who were due to give birth in 1966 in northern Finland.
New mothers recorded whether they gave vitamin D supplements to their children and how much they provided, during the first year of life. Researchers tracked the number of children who developed type 1 diabetes over 31 years.
Nearly 12% of children were given vitamin D supplements occasionally during their first year of life, 88% received regular vitamin D supplements and less than 1% were not given vitamin D. Overall, 81 children were diagnosed with diabetes during the study.
"These findings bring hope that something can be done in order to prevent the disease," Hypponen, from the Institute of Child Health in London, UK, told Reuters Health in an interview.
But while the study may be good news for families with a history of type 1 diabetes, the results may not apply to children in countries that receive more natural sunlight. In northern Finland, there are just 2 hours of sun daily during the month of December.
Ultraviolet light triggers a reaction in the skin that helps the body synthesize its own vitamin D. People with darker skin need more sunlight than their paler counterparts.
In an accompanying editorial, Dr. Jill M. Norris from the University of Colorado in Denver adds that children who receive infant formula instead of breast milk, which contains inadequate amounts of vitamin D, may also be less likely suffer from a deficiency of vitamin D.
"The emphasis on breast-feeding, the advice to keep babies out of the sun, and the increase in use of sunscreen when infants and toddlers are in the sun may act together to decrease the intake and synthesis of the sunshine vitamin," Norris writes.
SOURCE: The Lancet 2001;358:1476-1478, 1500-1503.