Allergic Rhinitis and Antioxidants

Antioxidants are substances that deactivate free radicals, highly unstable molecules that can damage cell membranes and scramble the genetic information (DNA) in cells. A number of antioxidants have been studied alone or in combination as a treatment for allergies, including allergic rhinitis. These antioxidants include beta-carotene, vitamin C, vitamin E, flavonoids, oligomeric proanthocyanidins (OPCs), zinc, selenium and garlic (which contains antioxidants).

Foods such as fresh fruits and vegetables contain antioxidants. Antioxidants are also available in supplement form.

The “antioxidant hypothesis” states that antioxidants may help prevent or treat health challenges associated with excess free-radical activity. Antioxidants are believed to reduce symptoms of allergic rhinitis by various mechanisms, including controlling the release of histamines, the allergic substances targeted by anti-histamine medicines.

Read more details about Antioxidants.

The research evidence for using antioxidants to treat allergic rhinitis is modest at best. However, enthusiasm for this approach is high among health professionals who have seen success in their patients.

Test tube studies suggest that flavonoids—biologically active compounds found in many plants—may help reduce allergy symptoms.^2,3,4,5 A particular flavonoid, quercetin, seems to be one of the most active.^{6,7,8,9,10,11} Many texts on natural medicine claim that quercetin works like the drug cromolyn (Intal), by stopping the release of allergenic substances in the body. However, while we have direct evidence that cromolyn is effective, there have not been any published studies in which people were given quercetin and their allergic symptoms decreased.

Vitamin C is often suggested as a treatment for allergies, but the research results are preliminary and somewhat contradictory.^{13, 14, 15}

A sizable (112-participant) double-blind study of vitamin E at a dose of 800 mg daily for hay fever found modest benefits at best.⁴² A smaller study failed to find any benefits.⁴⁵

One study failed to find evidence of benefit with a mixture of antioxidants: beta-carotene (9 mg/day), vitamin C (1500 mg/day), vitamin E (130 mg/day), zinc (45 mg/day), selenium (76 mg/day), and garlic (150 mg/day).⁵³

Oligomeric Proanthocyanidins (OPCs) from grape seed or pine bark are also often said to be effective. However, an 8-week, double-blind trial of 49 individuals found no benefit from grape seed extract (dose not stated).¹²

There is no single strategy for using antioxidants to treat allergic rhinitis. The best strategy for you will be customized to your unique experience of allergic rhinitis. For more information, consider consulting a health professional who specializes in nutrition, and read the usage information for the individual antioxidants recommended for allergic rhinitis:

Vitamin C usage

Vitamin E usage

Quercetin usage

Beta-carotene usage

Zinc usage

Selenium usage

Nutritionists and other health professionals who specialize in nutrition--including some naturopaths, chiropractors, and physicians--may offer helpful information about using antioxidant supplements and antioxidant-rich foods to treat allergic rhinitis.

In a 2008 detailed review of 67 randomized trials involving 232,550 participants, researchers found no evidence that antioxidant supplements could reduce mortality in either healthy or diseased individuals. On the contrary, there was some evidence that vitamin A , beta-carotene, and vitamin E supplementation may actually increase mortality.⁷

It is highly unlikely that antioxidants are harmful in modest quantities, such as those recommended by the U.S. government (called upper intake levels, or ULs). Foods that are naturally rich in antioxidants are considered not only safe, but beneficial. For more information, see side effects and warning information for the antioxidants that may help treat allergic rhinitis:

Vitamin C side effects and warnings

Vitamin E side effects and warnings

Quercetin side effects and warnings

Beta-carotene side effects and warnings

Zinc side effects and warnings

Selenium side effects and warnings

In a 2008 detailed review of 67 randomized trials involving 232,550 participants, researchers found no evidence that antioxidant supplements could reduce mortality in either healthy or diseased individuals. On the contrary, there was some evidence that vitamin A , beta-carotene, and vitamin E supplementation may actually increase mortality.⁷

It is highly unlikely that antioxidants are harmful in modest quantities, such as those recommended by the U.S. government (called upper intake levels, or ULs). Foods that are naturally rich in antioxidants are considered not only safe, but beneficial. For more information, see side effects and warning information for the antioxidants that may help treat allergic rhinitis:

Vitamin C side effects and warnings

Vitamin E side effects and warnings

Quercetin side effects and warnings

Beta-carotene side effects and warnings

Zinc side effects and warnings

Selenium side effects and warnings

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