Protein is, along with fat and carbohydrates, one of the three macronutrients that provide our body with energy. Proteins can be broken down into their smallest parts, the amino acids. These have countless functions in our metabolism. The formation of enzymes, support of detoxification processes and the immune system, muscle building and maintenance are only a few examples. Hair, skin and nails are also formed and held together by proteins among other things, and our DNA, which controls our genes, retrieves information about amino acids. It is obvious: high-quality protein sources are essential for everyones life. There are many foods containing protein - but which of them are well tolerated and suitable for sports nutrition?
Why do we need foods with protein?
Protein is only secondarily an energy carrier, which our body needs as fuel. Normally it falls back on fatty acids and sugar. So protein has many other vital functions. About 15 to 17% of our body mass consists of proteins1. The word protein is derived from the Greek word "Proteos", which means "first "2. This already says a lot about the importance of this nutrient: Proteins have a number of functions in the human and animal body, which will be discussed in more detail in the section after next.
There are numerous different proteins, which accordingly take over different tasks in our organism. First of all it should be made clear that proteins consist of amino acid chains. In nature there are several hundred different amino acids, but our body only needs 20 of them. The topic of amino acids will be followed by another blog article, because their individual components and specific functions should be described in more detail. However, it is important for the understanding of proteins to know that they are made up of chains of these 20 different amino acids that are relevant for us. Twelve of these amino acids can actually be produced by our organism if necessary, but the remaining eight must be taken in regularly through food. This clearly shows that food must be eaten whose proteins consist at least of these 8 essential amino acids.
Our body can convert amino acids into proteins and break down proteins into amino acids. Both serve to form substance complexes which the organism needs for numerous functions and structures. Thus, some proteins have the purpose of forming enzymes that are needed for many processes such as digestion. Numerous organs need amino acids to form the right substances that contribute to their functions. The liver needs the substances to detoxify, convert other substances or regenerate cells.
Structural proteins hold our muscles, tissue, bones, cartilage, hair and nails together. Proteins play a particularly important role in muscle building!
How is protein being digested?
When we eat something that contains protein, such as fish, meat or nuts, decomposition begins in the stomach. Strictly speaking, the food is reduced in size in the mouth by the teeth, but unlike carbohydrates, no enzyme is released into the saliva that can break down the proteins.
In the stomach, however, hydrochloric acid is formed by the cells of the stomach's mucous membrane, which breaks down the proteins in a first step. The hydrochloric acid also activates the enzyme pepsin, which splits the protein chains from each other3.
The next and last important station in protein digestion is the small intestine. There the smaller chains are broken down into amino acids, because ultimately only these small particles can pass through the intestinal mucosa and enter the bloodstream3. Only from there do the amino acids reach all the cells and organs where the body needs them.
What are good protein sources?
Actually, it seems quite simple: You just have to eat food that contains enough protein, which consists of the 20 different amino acids our body needs. One might think that it doesn't matter whether the source is animal or vegetable or whether it is partly found in industrially manufactured products.
But that is not the case! It is crucial in which form the protein is present, because not all protein structures can be digested well by our body. This is known as bioavailability, and it is better or worse depending on the food:
Animal protein sources and bioavailability of protein
The spatial structure of the protein sources plays an important role: tendons, bones and cartilage of meat are so interconnected that they are difficult for the gastrointestinal tract to break down4. It therefore makes more sense to cook them for a long time so that, for example, the valuable structures protein collagen from the resulting bone broth can be easily absorbed by the intestine. Tender and cooked or roasted meat is easier to digest than raw meat. Tatar, however, is still a qualitative animal protein source due to its finer structure.
In itself, what is most similar to our own body is also what contains the most important amino acids and is well absorbed. Therefore, many animal sources have a high bioavailability and a higher protein content than vegetable sources. However, this does not mean that you cannot also consume protein from plant sources. However, certain things should be taken into account.
Especially with animal protein sources, especially with meat but also for fish and eggs, the origin plays another role: meat should be organically produced, preferably from pasture-fed animals with outdoor access, without antibiotic treatment or genetically manipulated feed. Fish is best sourced from sustainable fishing. The smaller the fish, the better, because this also means a smaller food chain. Eggs have a much better nutrient content when they come from free-range hens that move around a lot and are fed naturally.
Dairy products, especially from cows, are less optimal protein sources. Although they may theoretically contain larger amounts of protein in some cases, they can promote inflammation in the intestines, which means that more pro-inflammatory substances enter the body2. This also means that the body digests many things more poorly and therefore generally has more difficulty absorbing more complex proteins.
Plant-based protein sources
Pulses, for example, have a very strong structure and unfortunately contain additional antinutrients that are actually there to protect the plant from pathogens. These inhibit some of our digestive enzymes and can thus hinder the absorption of micronutrients and the breakdown of proteins. They should therefore always be soaked in water and lemon for 8 to 12 hours and then rinsed well before being boiled in fresh water. This process optimizes compatibility and bioavailability.
Soya is supposedly often regarded as the vegetable super protein source. Especially tofu is currently very popular with vegans. Although the bean does indeed have a very high protein content, it contains many of the above-mentioned antinutrients, is usually contaminated with heavy metals as a result of washing in special tanks, may be genetically manipulated and also contains phytoestrogens. These are substances that act on our oestrogen receptors and thus upset our hormone balance. Should soy be considered nevertheless, the somewhat more optimal source would be Tempeh, as this product is better tolerated due to the special fermentation process.
Seitan is one of the most problematic meat substitutes!
The industrially produced food consists mainly of the protein gluten, which comes from cereals, especially cheap wheat. Gluten is one of the main allergens that can damage our intestines and, especially in large quantities, causes more and more intolerances. This vegetable protein source is therefore not a good option, because most people find it very difficult to digest the proteins and it also triggers inflammatory processes.
Highly recommended vegetable protein sources are quinoa, buckwheat, millet and rice. However, it should not be forgotten that they also have a higher carbohydrate content. Quinoa actually provides all 8 essential amino acids and contains 100g of 14g of protein and 60g of carbohydrates per 100g of protein. Meat has higher protein levels and contains no carbohydrates, so it is always a bit harder to meet protein requirements with vegetable products. Nuts are similar, although they have a relatively high protein content, but also contain a lot of fat, so they should only be eaten in small amounts, which reduces the amount of protein per portion.
For vegans it is recommended to consume protein in powder form. Rice, hemp or pea protein is very well tolerated and is filtered out of the respective products so that the carbohydrates are no longer present. Vegan produced amino acids are also recommended in a plant-based diet for protein requirements.
How much protein do you need?
Different recommendations are made depending on the source. The German Society for Nutrition says that at least 0.8g protein per kilogram of your body weight should be consumed daily. However, new findings show that the body is better supplied with more protein. Especially athletes and people who have more muscles or want to build them up should rather consume 1.5 to 2g of protein per kilogram of body weight. However, it is always important that the acid produced during the metabolism of protein can be neutralized by the body. A lot of vegetables can help here and calcium and vitamin D3 play another important role in the acid-base balance. This is because calcium neutralizes acid.
Protein is indispensable for our body. It needs the nutrient to carry out vital metabolic processes and to keep its components together. Therefore, sufficient protein should be consumed daily. The source plays an important role here. Animal protein sources in particular have a high bioavailability, but some plants such as quinoa, rice or nuts can also help to cover the protein requirement.
1 Doccheck Flexikon: Protein. [https://flexikon.doccheck.com/de/Protein; 15.08.2020].
2 Nischwitz, Dr. Dominik (2018): Ernährungsdesign nach Dr. Dominik Nischwitz.
Die Basis für ihre Gesundheit. Tübingen: DNA Health & Aesthetics. Zentrum für Biologische Zahnmedizin
Andreas Nischwitz Msc, Dr. Dominik Nischwitz.
3 Bütikofer, Markus; Hopf, Zensi; Rutz, Guido; Stach, Silke und Grigoleit, Andrea (2015): Humanbiologie 1: Grundlagen, Stoffwechsel und Abwehrsysteme. Zürich: Compendio Bildungsmedien.
4 Helmich, Ulrich (2020): Proteinverdauung. [http://www.u-helmich.de/el/04-Proteine/proteine06.html; 15.08.2020].