allergyCarotenoids are antioxidant substances that are found in plants. They give color to produce. Many, but not all, carotenoids can be converted to vitamin A by the body.  They may help to relieve allergy symptoms. A cross-sectional study published in Public Health Nutrition (2006; 9(4): 472-9) looked at the relationship between carotenoid levels in the blood and symptoms of allergic rhinitis (hay fever) in 547 adults. They found an inverse relationship between carotenoid levels and the presence of allergic rhinitis. Levels of vitamin C and vitamin E were also measured, but did not seem to have a relationship to the development of allergic rhinitis.