(RxWiki News) Antioxidants are believed to reduce airway inflammations. As such, it's not surprising that recent studies have shown that fruits and vegetables, which are high in antioxidants, may reduce allergy risks. However, new research puts into question such findings.
In a study of 2,447 Swedish children, Helen Rosenlund, Ph.D., of Karolinska Institutet, and her team set out to investigate the relationship between the fruit and vegetable consumption and allergic disease in eight-year-old children. The researchers obtained information on each child's allergies and fruit and vegetable intake through blood tests and parent questionnaires. About seven percent of the kids had asthma. Rates of hay fever and skin rashes were more than double the rate of asthma.
At first, Rosenlund and colleagues found that some produce (such as apples, pears, and carrots) might be helpful in reducing the odds of developing hay fever. However, after further analysis, the researchers found that half of the kids with hay fever were sensitive to birch tree pollen, a pollen that is similar to the proteins in apples and carrots.
"While the proteins in apples and carrots would seem to be different enough in structure to something that's not a food product, like birch pollen, the immune system responds to and recognizes certain protein sequences, not necessarily the entire molecule," says Joseph V. Madia, M.D. "In this case, a simple protein on birch pollen and apples may be similar enough that the immune system in an allergic child cannot tell the difference between the two, and cause a reaction".
When the researchers repeated their analysis while accounting for these food-related allergy symptoms, they no longer saw the previously observed reduction in hay fever symptoms.
The authors conclude by saying that their results confirm the relationship between fruit consumption and allergy symptoms founds in past studies. However, they add that their finding about birch tree pollen sensitivity may also have contributed to the findings of these previous studies.
Hay fever - an allergic inflammation of the nasal airways - affects an estimated 7.2 million (9.8 percent) children in the United States.
The study by Dr. Rosenlund's team is published in The Journal of Allergy and Clinical Immunology.