A new study suggests that children with vitamin D deficiencies are more likely to have both food allergies and outdoor allergies.

The study, published February 17 in the Journal of Allergy and Clinical Immunology, found that kids with low levels of vitamin D were 2.3 times as likely to have allergies to oak and 2.4 times as likely to be allergic to peanuts as kids with sufficient levels of the vitamin. Researchers also found a link between allergies to ragweed, dogs, cockroaches, shrimp and seven other allergens and vitamin D deficiencies.

In the study, tests showing the children had less than 15 nanograms of vitamin D per milliliter of blood qualified as a vitamin D deficiency. Kids with enough vitamin D showed more than 30 nanograms of the vitamin per milliliter of blood.

A previous study reported that the number of people who visit emergency rooms due to acute allergic reactions to food rises in the winter, the researchers said, citing a possible link to vitamin D. Vitamin D levels drop during the winter, because sunlight is necessary to generate the vitamin in the body.

Study researcher Dr. Michal Melamed, assistant professor of medicine and of epidemiology and population health at Albert Einstein College of Medicine in New York, said, "The latest dietary recommendations calling for children to take in 600 I.U. of vitamin D daily should keep them from becoming vitamin D deficient."

Other ways to get vitamin D on dark, winter days? The body does store vitamin D, so stocking up in summer months can help see you through winter's dim days. Vitamin D doesn't occur naturally in many foods, but mackerel, sardines, salmon, and fish liver oil are rich sources: three ounces of canned pink salmon, for example, contains about 600 I.U. of vitamin D. Vitamin-fortified cereals and dairy products are good options, as are dietary supplements of vitamin D.

However, there is some debate over how your body processes vitamin D from foods. "When you ingest vitamin D, only about 60 percent of it sticks to vitamin D-binding protein, but when you make vitamin D in your skin, 100 percent binds to the protein," said Michael F. Holick, director of both the general clinical research unit and the bone health care clinic at Boston University Medical Center in the US, in an MSN interview.