T here are different types of non-immune reactions to food.
The most obvious example is simple toxicity. In severe cases these contaminants can make food poisonous and anyone eating them will suffer ill effects. Much less obvious are the adverse reactions of a few people who lack the enzymes necessary to digest certain foods. A common example is lactose intolerance. This is due to the lack of the enzyme lactose, which is essential for the digestion of the milk sugar lactose.