The human body has different life characteristics at different ages, and the nutritional requirements to sustain these lives are not the same. When the human body enters the pre-geriatric period (i.e., from the age of 45), muscle tissue tends to atrophy, daily exercise gradually decreases, basal metabolism becomes lower, and the demand for energy decreases, but the need for most nutrients does not decrease. The general tendency is that the quantity of food becomes less and the quality requirement becomes higher. Too much and not enough nutrients are not good for health. Protein is the most important raw material for human growth and development, renewal and repair of tissue cells, and is the basis for maintaining life, constituting various enzymes, hormones and antibodies, participating in material metabolism and regulating physiological functions, improving immunity, and protecting the body from aggression. Whole-body protein accounts for about 20% of body weight and is an essential element of the human body. There are two main types of protein needed by human beings from food sources: one is complete protein, also known as high quality protein, which contains all amino acids including essential amino acids, with a complete range, sufficient quantity and appropriate ratio. The amino acids it contains are close to the needs of the human body, so its nutritional value is high. Animal proteins such as milk, meat, eggs and fish and shrimp proteins are in this category. The other is incomplete (or semi-complete) protein, which contains insufficient amounts of amino acids and lacks certain essential amino acids. Plant proteins such as rice, pasta and potatoes contain proteins of this kind, so their nutritional value is not as good as the former. Plant-based proteins such as soybeans contain 30 to 40 percent of high quality protein. Animal proteins such as meat skins and hoof tendons are incomplete proteins. The elderly should ensure the supply of adequate amounts of protein, protein supply per person per day 1.0 to 1.5 grams per kilogram of body weight, accounting for about 15% of the total calories, as much as possible to high-quality protein, which should generally account for 40% to 50% of the total protein. The elderly have reduced digestive and absorption functions, reduced detoxification functions of the liver and reduced ability of the kidneys to remove waste. If excessive intake of protein will lead to indigestion and increased burden on the liver and kidneys, it will also cause adverse consequences and damage the health of the body. Whether the protein intake is sufficient and appropriate depends on the amount of various amino acids absorbed and utilized after the protein is digested and the ratio between them, whether it can meet the physiological needs of the body, and whether it can adequately supply various amino acids, especially the need for “essential amino acids”.