Flavonoids as complementary medicine for allergic diseases: current evidence and future prospects

Introduction During recent decades, various allergic diseases such as allergic rhinitis, asthma, atopic dermatitis and food allergy have become more prevalent globally. Dietary change has been proposed to be one of the environmental factors responsible for the increase in allergic diseases and worsening of allergic symptoms. If this continues to increase, complementary medicine or a preventive strategy for allergic diseases may be found in dietary management. In fact, complementary and alternative medicine in the form of natural products has been traditionally used worldwide, but no specific natural products or nutrients for any allergic diseases have been recommended yet. Flavonoids are low-molecular-weight polyphenolic secondary plant metabolites included in the daily diet. In addition, they are natural products with antioxidant, anti-inflammatory and anti-allergic properties as well as immune-modulating effects used as complementary and alternative medicine. Findings from numerous studies, both in vitro and in vivo, using allergic animal models have indicated the potential benefits of an appropriate intake of flavonoids as complementary medicine and a dietary strategy for the prevention of allergic diseases. The aim of this review was to discuss flavonoids as complementary medicine for allergic diseases. Conclusion Allergy is a disease of growing concern because of its already high and still increasing prevalence, and because it interferes with people’s social life, school performance and work productivity, therefore it constitutes a major burden for society.