Common causes include foods such as peanuts, tree nuts, sesame, fish, shellfish, dairy products and eggs.

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Some common allergy triggers are milk, shellfish, legumes, sesame, eggs and tree nuts like almonds and walnuts.

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Owen, now 7, is allergic to peanuts and tree nuts, said his mother, Haylee Kellogg of Cedar Hills, Utah.

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The Mediterranean diets pushed either olive oil or tree nuts in addition to fatty fish, beans, tomato sauce, white meat and wine (for those already habitually drinking).

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He is allergic to dairy, peanuts, tree nuts and legumes.

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But for some people, ingesting something that even accidentally touched tree nuts or peanuts could result in anaphylaxis, a severe reaction that can lead to blocked airways, cardiovascular collapse, and even death.

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The recommendations are a U-turn from 2000, when the American Academy of Pediatrics issued guidelines that children should put off having milk until age 1, eggs until 2 and peanuts, shellfish, tree nuts and fish until 3.

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Since 2006, food manufacturers have been required to clearly label products that contain any of the most common allergens -- milk, eggs, fish, shellfish, peanuts, tree nuts, wheat and soy -- but some allergy experts say the labels should be more explicit.

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During her time in Ghana, Warren stumbled upon women who collect the fallen nuts from the shea tree, indigenous to sub-Saharan Africa.

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Ginkgo, made from the nuts and leaves of a tree, is a rich source of antioxidants - substances which it is thought can neutralise free radicals.

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