Protein: role in the body, demand, products rich in protein

Protein deficiency symptoms

Author: Time S.A

Join the JeszCoLubisz diet program today, which will answer your individual nutritional needs. If you are on a vegan diet, take care of essential nutrients, including adequate protein. The menu of the vegan diet in the JeszCoLubisz program is a guarantee of a tasty and balanced menu using only plant-based products.

Dietary protein sources

Where to get protein? From what sources is it best to provide them so that the diet is wholesome and varied? Many people may associate rice with chicken and broccoli, especially in the gym. Yes, chicken is a good source of protein, but you should also include other meats and fish in your diet. It is best to use products that are as least processed as possible. We are then sure what we actually eat. The egg is also a great source of protein with a very high digestibility. For many years, ovalbumin was considered a standard protein - wholesome, containing all essential amino acids in the right proportion, which was used to compare the biological value of different proteins.

Dairy is a valuable source of protein, but it is worth noting that milk provides only 3.4 g of protein per 100 g of product, and natural yoghurt - 4.4 g / 100 g. they should not be a permanent element of a he althy diet due to the very high fat content.

Products rich in vegetable protein:

Animal proteins are better absorbed than vegetable proteins (meat - 96 percent, milk - 90.5 percent), because in terms of amino acid composition they are more similar to our proteins.

Of course, protein can also be obtained from plant sources, but it is more difficult to absorb due to the presence of fiber and digestion inhibitors. The best vegetable sources of protein are dry pulses. Large amounts of it can also be found in groats and nuts.

When composing your diet and choosing the type of protein, pay attention to its biological value, which is determinednumerically compared to the reference protein. Proteins can be divided into those of high biological value, i.e. wholesome, which include egg white, human milk, milk protein, cheese, meat of slaughter animals, poultry and fish. They provide all essential (exogenous) amino acids. Proteins with low biological value, i.e. deficient, contain an insufficient amount of one or several essential amino acids. The sources of deficient protein include grains, vegetables, nuts and potatoes. This does not mean that vegetarians are doomed to be protein deficient.

The best way to digest the protein from plant sources is soybean (90%), lentil (85%) and white beans (73%). You will increase this ability by properly combining products (cereals with dairy, vegetables with groats, rice or eggs).

When using a vegetarian diet, it is very important to correctly compose meals to supplement the amino acids limiting one product, diversifying the meal with another (a limiting amino acid is the essential amino acid that is present in the smallest amount in a given food in relation to the reference protein - it limits it is possible to use other amino acids for the synthesis of proteins in the body). This phenomenon is called protein complementarity. An example of this is the combination of rice with beans and corn, known from Mexican cuisine. Grain products are low in lysine, while legume seeds are rich in lysine. Combine cereal with dairy products such as kefir or natural yoghurt.

Where else to look for good combinations of protein sources?

• Legume seeds (beans, peas, lentils, soybeans) rich in isoleucine and lysine should be combined with cereals and their preparations: groats, rice, pasta, flour, bread, cereals, sunflower seeds, sesame seeds, pumpkin, walnuts. What dishes can be composed of these products? Corn tortilla with beans, lasagne with spinach and tofu, bread with humus or dumplings stuffed with lentils.
• Vegetables are low in methionine. It is good to supplement its amount with sesame, nuts, mushrooms, millet, rice and corn.To increase the use of amino acids from vegetables, just sprinkle salads with sesame and add corn to them or prepare a vegetable-rice mixture. The nutritional value of vegetables is also increased by eggs.

In order for the limiting amino acids to complement each other, it is not necessary to consume them in one meal. Proteins will be best utilized if consumed within 5-6 hours of each other, but consuming supplements are recommendedamino acids throughout the day.

Products rich in protein - TABLE

When is the best time to eat protein?

Protein can be eaten with every meal of the day. At breakfast, it's best to combine them with complex carbohydrates. This way you will compose a wholesome and filling meal. Dinner should consist of vegetables and a protein source. As a result, it is light, does not stay in the stomach for a long time and provides a small amount of calories. Protein speeds up metabolism and quickly gives a feeling of fullness, which is beneficial for people on a slimming diet.

The dangers of a high-protein diet

Very popular high-protein diets, such as the Dukan diet, on which you can lose weight quickly, are dangerous for the body in the long term. What exactly the term "extended use" means has not been specified, possibly because organisms are very different from one another. But experts agree that losing weight from obesity to normal weight with a high-protein diet is dangerous. High-protein or high-fat diets necessarily provide little carbohydrates, i.e. the main energy component for humans. The body is then forced to obtain energy from other sources, mainlyfrom fat.

It is said that fats are burned in the carbohydrate fire. What does it mean? That glucose is needed to completely oxidize fat. When there is not enough glucose, fats are burned incompletely and form ketone bodies. Their high concentration increases the acidity of the blood, which in turn leads to ketoacidosis, which disrupts the proper functioning of the body. In the case of glucose deficiency, ketone bodies become a source of energy. This condition is accompanied by the lack of hunger (highly appreciated by people on a diet), but also a decrease in concentration and a feeling of fatigue.

A high-protein diet greatly reduces the supply of fiber, vitamins, antioxidants and minerals obtained from plants. This results, for example, in unpleasant symptoms from the digestive tract, such as constipation. Chronic retention of food content in the intestines significantly extends the time of contact of intestinal cells with toxins from digested food. This increases the risk of colon cancer. It is worth noting that the recommended amount of energy from protein in the diet of a he althy person is 10-15%, for people who are slimming 20-25%, while the popular Dukan diet in the first two phases provides nearly 60%. It can be more dangerous than the paleo diet because it is more one-sided and rules out the consumption of fruit and vegetables for a long time.

Digestion of proteins

Proteins are digested under the influence of proteolytic enzymes that break down the peptide bond between amino acids. Digestion of proteins begins in the stomach. The acidic environment of gastric juice causes protein denaturation (change of structure and loss of biological properties), as well as swelling of collagen, elastin and keratin. This allows for easier penetration of proteolytic enzymes into the protein structures. Pepsin works in the stomach, which only at a low pH changes into its active form and breaks peptide bonds in the middle of the protein chain.

Digested food passes into the duodenum, where the pancreatic juice contains the enzymes trypsin, chymotrypsin and elastase, which work in an alkaline environment. During multi-stage processes, the protein is digested in the duodenum and the further part of the small intestine into free amino acids. Absorption of digested protein components takes place in the small intestine. From the cells of the small intestine, amino acids pass into the blood of the portal vein and then into the liver. Protein digestion products are carried by the blood to all tissues and are used to synthesize body proteins. Undigested and unabsorbed digestive components are excreted from the body.

In order for the protein to be properly broken down, it is necessarythere is a low acidic pH which is normal and necessary for the stomach. It is worth knowing that antacids in the stomach, often used to treat heartburn, reduce the effectiveness of protein digestion. Too high gastric pH causes inadequately digested protein to pass into the intestines, where it rots.

Watch the video: protein - knowledge compendium

Sources:

1. Ciborowska H., Rudnicka A., Dietetics. Nutrition of a he althy and sick person, PZWL, Warsaw 2014
2. Kuchanowicz H. et al., Tables of composition and nutritional value of food, PZWL, Warsaw 2005
3. Bean A., Nutrition in sport, Zysk i S-ka, Poznań 2013