A EuroPrevall review of factors affecting incidence of peanut allergy: priorities for research and policy (original) (raw)

The peanut (Arachis hypogaea), also known as the groundnut, earthnut, monkey nut or goober, is a legume (1). Archaeological records suggest it was first encountered and used by humans in Peru between 2500 and 300 bc (2, 3). At the time of the Spanish and Portuguese conquests of America, peanuts were being grown widely in the West Indies and South America. Nowadays, the peanut is widely distributed, with the most important producing countries being India, China, USA, Argentina, Western and Southern Africa, and Brazil (4). Arachis hypogaea has four main cultivars, known as Virginia, Peruvian Runner, Valencia and Spanish (believed to have originated from different locations in South America), though breeding programmes to improve yields and disease resistance have subsequently produced many different varieties [Maleki (5) numbers 14 000 of these]. Peanut seeds are nutritious, containing many important nutrients, such as vitamin E, niacin, folacin, calcium, phosphorus, magnesium, zinc, iron, riboflavin, thiamine and potassium. They are also a good source of protein and a rich source of edible oil. Furthermore, peanuts are cheap to produce-an important factor in the context of world hunger. On the negative side, the prevalence of food allergy related to peanuts has reportedly increased in recent decades, particularly in western countries (6). Peanuts are among the highest food producers of IgE-mediated allergic reactions following ingestion (7) and they are one of the most common foods that cause an allergic reaction, both in children and adults (8-14). Allergic reactions arise as a result of immunological responses to particular proteins: in peanuts these proteins are Ara h 1 (vicilin), Ara h 2 (conglutin-homologue protein), and Ara h 3/Ara h 4 (glycinin). These proteins are considered major allergens because they are recognized by over 50% of peanut-allergic patients in the USA (13, 15), although interestingly, Ara h 1 may be only a minor allergen for some European patients (16). More recently three additional minor allergens-Ara h 6 and Ara h 7 (both conglutin-homologue proteins) as well as Ara h 5 (the plant pan-allergen profilin)-have been identified (17). Recently, Mittag et al. (18) identified, Peanuts are extensively cultivated around the world, providing a foodstuff that is both cheap to produce and nutritious. However, allergy to peanuts is of growing global concern, particularly given the severity of peanut-allergic reactions, which can include anaphalaxis and death. Consequently, it is important to understand the factors related to the prevalence of peanut allergy in order to inform efforts to ameliorate or preempt the condition. In this article we review evidence for the relevance of factors hypothesized to have some association with allergy prevalence, including both genetic and environmental factors. Although our analysis does indicate some empirical support for the importance of a number of factors, the key finding is that there are significant data gaps in the literature that undermine our ability to provide firm conclusions. We highlight these gaps, indicating questions that need to be addressed by future research.