<s>[INST] My kids are very skinny and one is prone to infection. How can i help his immunity fast and then help him to gain some fat. He has always been so skinny since he started school was fine up till 5-6 age. But has always caught strange infection. No docs r helping and am stressed out. Hes always ill. [/INST] there are no medicines to improve immunity. It is Innate and hereditary. Proper nutrition is the best way to keep the immunity going. Help your child with a lot of anti oxidant like fresh fruits and fruit juices. Also give a lot of fresh milk and other dairy products. Certain immunity boosters and provitamin preparations are available in the market which u can try(although not of much help).probiotics for proper digestion, good amount of proteins in form of meat and cereals, proper carb diet will help him go strong internally. Your child will acquire weight and height later on which we sometimes call as Catch up growth. </s>