The most common food allergens include peanuts, milk, eggs, tree nuts, fish, shellfish, soy, and wheat — these foods account for about 90% of all allergic reactions. The most common food allergies in adults are shellfish, peanuts, tree nuts, fish, and egg.The most common food allergies in children are milk, eggs, peanuts, and tree nuts. Six to eight percent of children under the age of three have food allergies and nearly four percent of adults have food allergies.hen the symptoms are severe it is known as anaphylaxis. Food intolerance and food poisoning are separate conditions. Common foods involved include cow's milk, peanuts, eggs, shellfish, tree nuts, wheat, rice, and fruit. Which allergies are most common depends on the country.