How Do Diet and Physical Activity Affect Allergies?

Patients with allergies may deal with uncomfortable reactions like hives, a runny nose, or watery eyes. Depending on the allergen and the severity of the allergy, they may also be at risk for more serious reactions like difficulty breathing and anaphylaxis.

Food allergies are among the most common forms of allergy, but is this the only way food plays a role in allergy development and reaction? In seeking ways to avoid allergic reactions, patients may look to factors such as diet and exercise. How can diet and physical activity affect a patient’s allergies, both positively and negatively?

How Can Diet Affect Allergies?

A person’s diet can affect their allergy risk and severity in a number of ways. Some foods, for example, may be more likely to cause inflammation.

Some patients may wonder if weight and body mass index (BMI) play a role in allergy severity. Different studies have led to inconsistent results on this topic. A 2016 study in the Journal of Clinical Immunology looked into a potential link between obesity and allergic rhinitis (also known as hay fever) and non-allergic rhinitis, with varying results.¹ While the researchers found obesity to be linked to increased risk of non-allergic rhinitis, obesity and central obesity (measured by waist circumference) were not found to have an association with allergic rhinitis.

Contact Allergy and Hay Fever

A 2022 study in Nutrients examined how different factors such as obesity and diet affect contact allergies (defined as allergies where itching or a rash is caused by contact with a substance) and hay fever.² The investigators likewise did not find a statistically significant association between obesity/high BMI and hay fever incidence; however, subjects with obesity were much more likely to have contact allergies than those without.

The researchers suggested that a diet high in fats may put patients at further risk for developing contact allergies, though they mentioned an “imbalanced” dietary fat intake can affect allergies as well. Consumption of dietary fats in a way that is rich in both omega-3 fatty acids and polyunsaturated fatty acids, the researchers noted, can affect lipid metabolism in such a way that may help improve or prevent contact allergies.

Maternal Diet and Allergies

It is possible that a mother’s diet while pregnant could affect allergy outcomes in children. The maternal diet index has weighted measures of the intake of foods including vegetables, yogurt, red meats, fried potatoes, and cold cereals. Researchers in Allergy found that yogurt and vegetable consumption were associated with overall allergy prevention.³ Other less healthy foods were linked to an increase.

This was also the case in a recent study in the Journal of Allergy and Clinical Immunology: In Practice. Comparing the maternal diet index to other maternal diet measures, the researchers concluded that it was the most accurate in terms of predicting childhood allergic diseases.⁴ The researchers also concluded that, overall, a healthier and more diverse maternal diet is linked to improved childhood allergy outcomes.

First Year Diet

Studies have examined how the health and diversity of a child’s diet in their first year can affect allergy likelihood in the future. A 2020 study in Frontiers in Pediatrics examined data on infant diets during the first year and concluded that introduction to solid foods, incorporation of a diverse array of healthy foods, and exposure to common allergenic solids such as peanuts are recommended with medical advisement.⁵

In their data, the researchers found that recent guidelines often recommend introduction to peanut, cooked egg, dairy, and wheat in the first year. However, these introductions should come under medical advisement, as conditions such as atopic dermatitis or eczema may affect when parents are recommended to start introducing their children to certain allergens. The researchers also found that introducing a wider diversity of healthy foods in the first year may help reduce allergy risk. Diet diversity refers to an increased intake of nutrients like omega-3 fatty acids and prebiotics.

How Can Physical Activity Affect Allergies?

Physical activity can impact allergies in multiple ways. Though rare, there is a disorder known as exercise-induced anaphylaxis in which an immune hypersensitivity occurs during physical activity and causes anaphylaxis. Occasionally, certain foods combined with exercise can cause this condition.⁶

For many people, though, physical activity can be beneficial for their allergies. Per the researchers of the aforementioned study in Nutrients, vigorous exercise (outdoor cycling in particular) can have protective effects against hay fever.² This is due in part to the effects physical activity has on obesity, which in turn affects the body’s lipid metabolism. Improved sleep duration is also protective against hay fever.

Reducing inflammation via exercise can also protect against allergies, particularly seasonal ones. According to a 2019 study in the International Journal of Environmental Research and Public Health, recreational outdoor exercise in moderately cold temperatures during the winter can help reduce allergic airway inflammation.⁷ Recreational activities such as hiking helped create sustainable improvements in study participants.

This article originally appeared on Clinical Advisor