According to Tan Xiao's health theory, the three treasures in water are lotus root, horseshoe and perch. Middle-aged and elderly people can nourish yin and moisten dryness to keep healthy. Lotus root is rich in starch and vitamins, which can moisturize the skin in cold weather. Horseshoe is not only rich in water and vitamins, but also has high nutritional value; On the other hand, perch can improve intelligence and brain activity.