Ask the Doc: Seasonal Allergies

Q: I have asthma and allergies that flare up in the spring and fall. Can diet changes help?

A: Nutrition plays a major role in asthma, and there’s increasing evidence that foods can affect seasonal allergies too. When you have asthma, your bronchial tubes constrict, which causes wheezing, chest tightness and difficulty breathing. If you have it, you’ve no doubt found that attacks can be triggered by allergens such as pollen, as well as by infections, stress, cigarette smoke and other factors.

For many years, people with asthma suspected that dietary changes might help. Many noticed that they had fewer episodes and needed less medication when they switched to vegetarian (especially vegan) diets. In the mid-1980s, anecdotal reports led researchers to put these observations to the test. In a one-year study, they found significant improvements in lung function and a major reduction in medication use when patients switched to a vegan diet. Then in 1994, investigators at Loma Linda University tracked how often medical treatments for ailments, including asthma, were needed in a group of nearly 28,000 people. Vegetarians were less likely to need treatment for asthma—females were even less likely than males.

Why do vegetarian and vegan diets help? Researchers first attributed these benefits to the absence of common food triggers, such as meat, dairy and eggs. After all, if you’re not eating troublesome foods, you can’t have an allergic reaction to them. But there’s probably more to it. Repeated studies have shown that people who eat more fruits and vegetables have reduced risk of asthma, presumably because these foods improve immune system functions.

Vegetarians are also thinner, which is surprisingly important in asthma. Harvard’s long-term Nurses’ Health Study (an ongoing project studying thousands of nurses for multiple health concerns) found that thin people have only one-third the risk of asthma compared to overweight participants. When heavy people begin a low-fat, vegetarian diet, they typically lose a significant amount of weight, which is likely to improve asthma.

One note of caution: A vegetarian diet does improve nutrition and help alleviate asthma, but it’s also possible to be allergic to some vegetarian foods, such as peanuts, soy or wheat.

If seasonal allergies trigger asthma for you, or if they leave you with itchy eyes and a runny nose, here are two nutritional additions to consider:

Vitamin E
Whether it comes from foods or supplements, vitamin E seems to help ward off seasonal allergy symptoms. You’ll find it in green leafy vegetables (spinach, kale, etc.), beans, apples, carrots, celery, wheat germ and nuts. Researchers suspect that vitamin E stops your immune system from overreacting to pollens or other allergens.

 

Butterbur
(Petasites hybridus, also called butterdock) is an herbal remedy that has been used for centuries to soothe respiratory complaints. For symptoms of seasonal allergies, it works surprisingly well. Butterbur proved as effective as the antihistamine cetirizine (Zyrtec) against seasonal allergy symptoms, reported a Swiss study published in 2002 in the British Medical Journal. And although antihistamines are sedating, the herbal treatment isn’t.

Nutritional factors may even help prevent allergies. In a three-year Italian study in the 1990s, new mothers breast-fed their infants and didn’t introduce commonly allergenic foods such as whole cows’ milk, eggs, fish and nuts during the child’s first year. They also limited dairy products and avoided eggs in their own diets. These simple steps in the first years of their babies’ lives dramatically reduced the likeli-hood that the children would develop allergic symptoms later.

Although we may not be able to eliminate asthma and allergies entirely, diet changes can clearly help. And if started early enough, they can help children avoid a great deal of misery.

Neal D. Barnard, MD, lives in Washington, DC, where a healthy diet allows him to enjoy the cherry blossoms without sneezing.

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