Allergies are not usually caused by a lack of certain vitamins, but by the interaction of genetic and environmental factors. Allergies are caused by an excessive immune response to certain substances and are usually characterized by itchy skin, bumps, pimples, sneezing and runny nose. Allergies are usually not significantly correlated with a vitamin deficiency, but rather with genetic and environmental factors. Some people are allergy-prone and develop allergies when they come into contact with allergens in the environment. Some people have low immunity due to fatigue or illness, and may also develop allergies after exposure to allergens. Allergies are difficult to cure, so it is important to identify allergens in daily life, avoid contact with allergens, and improve immunity through exercise.