Hello, under a normal diet, the elderly should increase their intake of high-quality protein, such as lean meat, chicken, sea cucumber, seafood, eggs and milk. Yogurt is good. It is recommended that the elderly drink more, which can increase immunity. Eating more soy products and ensuring enough vegetables and fruits every day can improve immune function. Old people should eat less sweets, because too much sweets will cause decreased resistance. I hope I can help you.