If you feel itchy in your mouth or ears, itchy throat, hives in your mouth, or swelling of your lips, mouth, tongue, or throat after eating Brazil nuts or other fresh fruits, raw vegetables or nuts, you may have food pollen allergy syndrome (PFAS), also called oral allergy syndrome (OAS). Brazil nuts are the second most common cause of nut allergy in the United Kingdom. We present the case of a 20-year-old woman with a documented allergy to Brazil nuts who developed generalized urticaria and mild dyspnoea after having sex with her boyfriend, who had previously consumed Brazil nuts. Skin puncture tests with the boyfriend's semen after consumption of Brazil nuts confirmed significant reactivity, while a sample prior to the consumption of nuts yielded negative results.
We believe this is the first case of a sexually transmitted allergic reaction. Brazil nut is a food that can cause allergy symptoms in sensitized people. Several allergenic proteins have been isolated from Brazil nut, including a globulin-like protein and a 2S albumin, which is an important allergen and has been shown to be resistant to digestion. Although Turkey produces the largest amount of hazelnuts in the world (and hazelnut allergy affects 1.7% of its population), in the United States, in addition to proteins and fats, Brazil nuts are an important source of selenium, an important antioxidant.
Brazil nuts share a cross-reaction protein with walnuts and serious reactions can occur even with skin allergy tests. A study also reports on a 20-year-old woman with a documented allergy to Brazil nuts who developed generalized hives and mild dyspnoea after having sex with her boyfriend, who had previously consumed Brazil nuts. Hazelnut allergy is common and can range from oral allergy syndrome with itchy mouth in patients with birch pollen allergy to more serious anaphylactic reactions. Not a true nut, the Brazilian nut is actually the seed of a giant tree native to the South American rainforest, which grows in clusters inside large woody pods.
The oil extracted from walnuts is commonly used in Peru and other South American countries to make soap and to illuminate, and the empty pods are used as implements and burned to repel insects. Brazil nuts contain a protein common to many seeds, similar to those found in cotton, cacao, sunflower seeds, rapeseed, castor beans, castor beans, walnuts, mustard seeds and sesame seeds. Brazil nut allergy is common, often starting in the first few years of life, usually persists and causes serious and potentially life-threatening allergic reactions. Cases of anaphylaxis due to Brazil nut have been reported, which can occur even without a history of ingesting this nut.
The many health benefits may be related to eating Brazil nuts, but they also contain 1000 times more radium, a radioactive agent, than any other food. Walnut-induced anaphylaxis has been described, with a cross-reactivity with hazelnut and walnut from Brazil.