At the same time, foods rich in vitamin A don’t seem to protect against allergies, despite earlier studies suggesting they do.
Dr. Masayuki Okuda of Yamaguchi University in Ube and colleagues measured the levels of substances in the blood that showed how much of the two vitamins children were likely eating. They focused on asthma and eczema because both are allergy-related conditions.
Among 396 10- and 13-year-old children, 240 of whom had eczema, wheezing, or asthma, the researchers found no relationship between a child’s risk of any of the conditions and his or her blood levels of vitamin A-related compounds.
However, kids with the highest levels of vitamin E-related compounds were at 67 percent lower risk of eczema than those with the lowest. Even those with only moderately higher than average levels of the compound had a similarly lower risk.
Although the study does not prove there is any cause and effect at work, it was more precise than earlier research, the authors note, because previous studies relied on food questionnaires. Such surveys can be somewhat unreliable because they depend on memory.
Yellow, red and orange fruits are rich in vitamin A and related compounds, while vitamin E is found in vegetable oils, nuts, and whole grains.
There are no commonly agreed-upon standards for levels of such compounds in the blood, but the U.S. recommended daily allowance of vitamin A is 2,000 international units (IUs) for this age group. The recommended daily allowance of vitamin E in the same age group is about 16 IUs.
It’s not clear why vitamin E would lower the risk of eczema, but Okuda and his colleagues suggest that its antioxidant and immune-boosting effects might play a role.