Proteins are the elementary building material for our body. They make up a whole 15-17% of our body weight. Whether muscles, skin, hair, our hormones and antibodies, etc. - so is formed from proteins. In addition, proteins provide energy: four calories per gram are in them. That's why they are one of the macronutrients in our diet, along with carbohydrates and fats.
What is the structure of proteins?
Proteins consist of smaller building blocks called amino acids. There are 20 different ones, nine of which are essential. So we have to take these in through food, since the body cannot make them itself. When more than 100 amino acids have joined together, they are called proteins. Shorter compounds are called peptides. The structure of a protein is determined by the characteristic arrangement of the amino acids, which is formed by linkages between the chain elements. Joined complexes are formed, which are decisive for the function of the respective protein. Proteins are divided according to their properties into scleroproteins (fibrillar proteins) with a fibrous structure and spherical spheroproteins (globular proteins).
The functions of proteins
Proteins can be divided into different groups and assigned functions:
Acceleration of reactions, e.g. in metabolism
Transport and storage proteins
Transport and storage of substances
Involved in coordinated movements
Structural or supporting proteins
Mechanical support functions, i.e., movement, shape, and property of body structures such as skin, muscles, bones, etc.
Carriers and ion channels
Enable the membrane of cells to be crossed in order to take up or release substances
Defense and protective reactions
Recognition of foreign substances and formation of antibodies, important for our immune system
Among other things, important for signal transduction
Regulation of e.g. metabolism
Through all these functions, proteins are essential for regeneration, wound healing, our immune system, metabolic processes and much, much more.
Individual amino acids also function, for example, as energy suppliers, as substrates for gluconeogenesis and protein biosynthesis, and as regulators in the acid-base balance.
The digestion of proteins
Proteins saturate for a long time, which is also related to the digestion process. They linger for a long time in the stomach, where they are denatured by gastric acid, which means that their structures break down. Various enzymes start splitting the amino acid chains into smaller sections. This process continues in the small intestine until di- and tripeptides, i.e. chains of two or three amino acids, and free amino acids are present. These can then be absorbed through the intestinal wall. How easily proteins can be digested and absorbed by our body depends on their spatial structure, the preparation of the food, our individual state of health, and obstructive substances.
state of health, and obstructive substances such as tannins from legumes or tea.
Soybeans and products made from them, such as tofu
Cereal products, such as rice and oatmeal
Fish and seafood
Seitan (wheat gluten)
Nuts and seeds
Protein-rich foods include animal foods such as meat, fish, egg and dairy products, as well as plant foods such as legumes, nuts and seeds, and grains.
How much protein does it need to be? And is there such a thing as "too much"?
Per day, 0.8 g of protein per kilogram of your body weight is recommended (or 10-15% of your total calorie intake per day). At a weight of 70 kg, that's 56 g of protein. You can get this by
... a breakfast consisting of 200 g of yogurt with 50 g of oatmeal, 15 g of nuts and some fruit, and a cup of coffee with a little milk (about 20 ml).
... a lunch with 70 g lentils and 150 g green beans (e.g. curry, lentil dal, one-pot dish)
... and 50 g of wholemeal bread with a fried egg for dinner.
By distributing it throughout the day, the protein is available to your body at any time of the day, and it also satiates well. Therefore, it should be part of every meal. A one-time very high protein intake is not very useful, because the body can only use a limited amount at a time. In addition to the total amount and regular distribution throughout the day, it is also recommended to consume protein in the evening. Overnight, the body can devote itself to regeneration processes, for which sufficient building material is needed. Again and again one hears and reads that a high protein intake is harmful. In particular, many amateur and competitive athletes attach importance to a protein intake that is often more than twice the recommended amount. For healthy people this is not dangerous. However, sufficient fluid intake should be ensured so that urea produced can be excreted via the kidneys and urine. This is produced in the course of metabolizing protein. If the kidneys are damaged by a disease, the amount of protein that can be tolerated depends greatly on the type and stage of the disease. Here you should seek advice from your doctor and a nutritionist. A high protein intake is not recommended if it comes mainly from animal or highly processed products. It is not the amount of protein that is unhealthy, but the consumption of animal fats and substances used in the processing, such as curing salts, high amounts of preservatives and sweeteners, and sugar. Ideally, then, protein is consumed from predominantly plant-based and low-processed foods, such as lentils, chickpeas and other legumes, nuts and seeds, soy and grains.