How much protein do we need?
The reference values for the daily intake of proteins are continuously revised based on new knowledge. Reference ranges are determined statistically from examination results of healthy people. The researchers can use a number of studies to determine how many proteins per day are sufficient on average to ensure a healthy diet.
Proteins perform many functions in our body. They are not only building materials for cells, enzymes and hormones, but also help with the transport of nutrients and provide energy. Depending on age, the human body consists of an average of 7 to 13 kilograms of proteins. To build the proteins, 20 different amino acids are required, 9 of which are essential. The body cannot produce indispensable amino acids itself, but must be supplied with food. These are isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine and histidine for infants.
If these amino acids are not supplied regularly, deficiency symptoms can occur. The German Society for Nutrition (DGE) has evaluated new scientific data and revised the reference values for protein on this basis. Strictly speaking, there is no physiological need for protein, but only for the element nitrogen contained in the proteins and the essential amino acids.
The derived recommended protein intake for children aged one to four years is 1.0 g per kg body weight per day and falls to 0.8 g per kg body weight per day depending on age and gender. For adults, the reference value is derived from data from nitrogen balance studies. The recommended intake for 19 to 65 year olds is 0.8 g protein per kg body weight per day. This corresponds to 57 to 67 g of protein per day. This amount can be achieved by eating protein-rich foods. In the case of plant products, this primarily includes legumes such as soy, lentils and peas. Grain products such as bread and animal foods such as meat, fish, milk products and eggs also contribute to the protein supply.
For adults aged 65 years and over, an exact calculation of the appropriate protein intake is not possible based on the available data. A higher need is suspected, since physical functionality and function maintenance are extremely important in old age. For healthy, older people with normal weight, this results in an estimate of 1.0 g per kilogram of body weight per day.
Does the intake of protein have preventive effects on weight?
Higher protein intake is associated with greater satiety and therefore greater weight loss in a diet compared to lower protein intake. According to various studies, a short-term diet of 3 to 6 months with a high protein intake (compared to a lower protein intake) seems to lead to a greater weight reduction. With increasing duration of a protein-rich diet, the effect becomes smaller or disappears completely. Further investigations are necessary in this connection. (sb)