Older people can eat grains and cereals, fresh fruits and vegetables, meat, eggs and dairy products to boost their immunity. To summarize, the diet program should be nutritionally balanced. 1. Grains and cereals: common grains and cereals are corn, buckwheat, wheat, brown rice, etc., because it contains dietary fiber, vitamins and trace elements, can supplement the body’s daily nutritional needs. 2. Fresh fruits and vegetables: such as oranges, grapes, peaches, apples, greens, cabbage and so on. Fresh fruits and vegetables are rich in vitamin C, which plays a role in preventing diseases and improving immunity. 3. Meat and eggs: these foods contain a lot of protein, which can effectively enhance the immunity of the elderly. 4. Dairy products: Dairy products contain sufficient calcium, which can enhance the strength of the bones of the elderly, prevent fractures, osteoporosis, and improve the immunity of the elderly. In short, the elderly should do low-salt, low-fat and light diet and nutrition should be balanced.