Collagen is one of the common proteins in human daily diet. Eating collagen does not directly increase collagen synthesis in the body, but it has a certain nutritional effect on the body. Collagen in the human body is synthesized by cells and has little to do with eating collagen.

　　Eating collagen does not directly increase collagen synthesis in the body, but it has a certain nutritional effect on the body (including skin, joints, bones, organs, muscles, etc.) (especially in experimental animals). However, there is no evidence (and the theory does not support) that its nutritional effect will exceed the protein in ordinary foods such as eggs and soybeans.

　　1. Collagen is one of the common proteins in human daily diet

　　We consume a variety of proteins through food every day, such as whey protein (from milk) , Casein (milk), ovalbumin (egg), lecithin (egg), soy protein (soy), muscle protein (meat), gluten (rice and wheat), gliadin (wheat) , Albumin (meat, liver and blood), hemoglobin (blood), elastin and collagen (animal skin, bones, tendons and other connective tissues) and various enzyme proteins (animal and plant cells).

　　The structure and characteristics of these proteins are different, some are spherical (such as globulin), some are fibrous (such as collagen); some are white (such as albumin), and some are red (such as hemoglobin); Some can be dissolved (such as albumin), some can form a jelly (such as collagen)... But their nutritional effects on the human body are very similar, that is, after digestion and absorption of the gastrointestinal tract, they are mainly used in the form of raw materials (amino acids) to build tissues and organs (such as blood, muscles, internal organs, skin, bones, etc.) and activity Substances (such as various enzymes, peptide hormones, lipoproteins, etc.) and other human proteins. Part of the raw materials (amino acids) for building human protein depends on food protein digestion and absorption, and the other part is synthesized by the body autonomously. Therefore, various proteins in food are the most important nutrients.

　　2. Collagen in the human body is synthesized by cells and has nothing to do with eating collagen

　　The types of human proteins are more complex, such as albumin (blood), globulin (blood ), hemoglobin (blood), muscle protein (muscle), collagen (bone, skin, tendons, hair, etc.), enzyme protein (various cells)... It looks like they are similar to the protein in animal food, but If you think which kind of protein you eat will supplement which kind of protein in your body ("eat what you eat"), it is too primitive and naive. This understanding is completely ignorant of the great achievements of life science in the past 100 years.

　　 Normally, every human protein, including collagen, is made by various cells. The general process is to use genetic DNA molecules as templates (drawings), use RNA as a "transcription" tool (porter), use various amino acid raw materials (bricks), and under the guidance of various enzymes (bricksmiths), "translate" into All kinds of protein molecules (buildings). Some of the proteins synthesized in the cell play a physiological role on the spot (such as hemoglobin, enzyme protein, etc.), and some are transported outside the cell to play a physiological role (such as collagen, insulin, etc.).

　　In humans (as in most animals), collagen in the body is synthesized by the cells and secreted out of the cells, and is fibrous (the molecular structure is like a spiral of three strands of twine). The amount of collagen is huge, accounting for 30% of the total protein in the body, and it is distributed in various organs and tissues, especially bones, skin, tendons, and hair. They form a fiber framework structure in the matrix between cells, which has the functions of supporting, connecting, retaining water, and protecting cells, and also affects the growth, differentiation, metabolism, and movement of cells.

　　In the complex synthesis process of collagen and other proteins, food provides only raw materials (amino acids), not the protein itself. In other words, if you eat collagen, it will not directly increase the collagen in your body. Just as you eat hemoglobin (such as animal blood), it does not directly become your hemoglobin; you eat muscle protein (such as pork), and it does not directly become your muscle protein; you eat albumin (pharmaceutical preparation). It will directly become your albumin (clinically, if you want to increase the albumin in the patient''s blood, you must use an injection method, which is not effective if taken orally). In fact, this is also the basic condition for humans to maintain the morphological stability of the species. If not, humans would have evolved into strange shapes!

　　In clinical practice, in order to directly supplement Proteins, whether they are extremely large in molecular weight (such as albumin, immunoglobulin, antibody, etc.) or relatively small in molecular weight (often called peptides, such as insulin, oxytocin, growth hormone, cell growth factor, etc.) It should be directly injected into the blood through injection, and cannot be taken orally through the gastrointestinal tract, otherwise it will be digested and decomposed into amino acids equivalent to ordinary food.

　　3. What is the nutritional effect of eating collagen

　　As mentioned earlier, the nutritional effects of various proteins in food are very similar, mainly after digestion (decomposition) It is used to synthesize human protein after absorption, and collagen is no exception. So what is the nutritional value of collagen compared to other proteins?

　　The classic method for measuring the nutritional value of a certain protein is this: special feed for laboratory animals, providing only this protein (no more Other proteins), look at how animals (especially young animals, which have a strong demand for protein) grow and develop. Under the premise of the same intake, if the experimental animal that only eats a certain protein (A) grows better than only another protein (B), then it is considered that A has a higher nutritional value than B.

　　Evaluated according to this method, whey protein (milk) and ovalbumin (eggs) have the highest nutritional value, muscle protein (meat) is also very good, and soy protein (soybean) is also good. Collagen is very bad. The growth and development of experimental animals that only eat collagen is very bad. This is because, compared with those proteins with high nutritional value, the molecular structure of collagen is seriously lacking in tryptophan (the content is almost 0). Tryptophan is a very important amino acid that the human body (and most animals) cannot synthesize on its own and must be provided by food. Once it is absent from the diet, serious obstacles will occur in the synthesis of various proteins in the body. Because it contains almost no important tryptophan, collagen is often said to be "no nutritional value" or "very low nutritional value."

　　However, animal experiments are not equivalent to human life. This kind of "only eat a certain protein" animal experiment is not completely in line with the reality of human life. In our daily diet, we always ingest a variety of proteins. In general, even one food will provide many kinds of protein. When ingesting mixed protein, collagen has certain nutritional value. After digestion (decomposition) and absorption, although there is no tryptophan, it can provide more than ten other amino acids, which can be used for protein synthesis in the body. As for tryptophan, it can be provided by other foods or proteins. Therefore, in the case of an ordinary diet (mixing various proteins), intake of collagen has a nutritional effect and can provide raw materials for protein synthesis in the body like other proteins.

　　4. Why there are experimental studies (papers) showing that eating collagen is effective

　　As mentioned above, in the case of ordinary diet (mixing various proteins), intake of collagen has Nutritional effect. This is often vigorously promoted by those who admire collagen, and it also provides a theoretical basis for the following phenomena: experimental animals that eat ordinary feed (mixed protein), after adding collagen, the protein nutritional status of the body has improved, including skin, bones, Joints, hairs and other parts that experimenters are willing to pay attention to. Especially for those animals with insufficient protein in the feed, the improvement (representing the effect of adding collagen) is more obvious.

　　Similar animal experiments are often used to "prove" that eating collagen is effective. To some extent, this kind of proof is not unreasonable. However, don''t forget that animal experiments are not equivalent to human life. Animal experiments In order to "prove" that collagen is effective, in addition to adding collagen to the feed of a part of the experimental animals, the feed of the other part of the experimental animals (as a control) is either low in total protein or completely free of collagen. This is obviously not in line with human daily diet, so it is not convincing.

　　To prove that oral collagen is effective (improving skin, bone and joint conditions), the most convincing animal experiment should be this: First, the animal feed of the experimental group is well-balanced (rich in various Protein), then add collagen; the animal feed of the control group is also rich in various proteins (balanced diet), and then add as much egg protein (or whey protein and other high-quality proteins). If the skin, bones or joints of the experimental group are indeed better than the control group, it proves that oral collagen has the irreplaceable effect of ordinary food (eggs, milk, etc.). Second, when adding collagen to animals in the experimental group, different dosages should be designed. For example, some animals add 0.2g/kg body weight (this value is only for illustration), and others add 0.4g/kg body weight. If the latter (adding more collagen) is better than the former (adding less collagen) to improve skin, bones and joints, it proves that oral collagen has a "dose effect" and is really effective.

　　If you can see animal experiments that meet the above conditions, then life sciences’ original understanding of collagen (including the most basic biochemistry and cell biology textbooks) should be revised. Human tests must satisfy the above conditions to be convincing. However, the existing human studies only give collagen to some people, and then check whether the skin texture or joint function has improved. There is no strict control (using proteins such as eggs, milk or meat as controls), even if the test results find There is an improvement, and it may not necessarily prove that collagen is effective. For the reason analysis, see the next section.

　　5. Why some people take oral collagen to show the effect

　　oral collagen health care has been popular for many years, and many people eat collagen. Some people have little effect after eating, the reasons are relatively easy to explain, such as the quality of the selected products is not enough, the dosage is not enough, not suitable for themselves, or there are other interference factors. But some people do show the effect after eating collagen, such as the skin texture is more delicate, etc., is this not enough to show that collagen is effective?

　　Someone eats collagen to have an effect, and slowly After the conclusion that collagen is effective, after carefully analyzing the three possible causes, it is not too late to draw a conclusion. The first possibility is the placebo effect, which is a widespread objective phenomenon. Theoretically, the placebo effect caused by oral collagen cannot be attributed to collagen, but as long as you are willing (only look at the effect and do not care about the theory), of course, collagen can be considered effective.

　　 The second possibility is that all kind people are not willing to accept it, but it is common in the health care industry. That is to secretly add (or unconsciously introduce) other ingredients in collagen products, such as estrogen (the effect is very obvious), vitamins (slightly effective) and so on. This kind of claim to sell A, but in fact, B is quietly working, it is no wonder that in health products. For example, the sale of L-carnitine actually works with sibutramine (weight-loss drug); the sale of pure Chinese medicine hypoglycemic health products actually works with metformin (hypoglycemic drugs); the sale of ganoderma lucidum fairy grass What works is to add Jingjing (sleep medicine); what is sold is grape seed extract that actually works on hormones. The incident shows that health products along this route can often show very "good" effects and are popular with some consumers.

　　 The third possibility is something I don’t want to believe, but it does exist. That is, oral collagen has played a practical role through a theoretical approach that is currently unclear. If its effects include increased collagen synthesis in human parts such as skin and bones, then we may have to update our existing life science knowledge. Because this means that for the first time, it is possible to directly increase the synthesis of the same protein in the body by eating (orally) a certain protein, but it has no or little effect on other proteins in the body.

　　6. What dietary sources of collagen

　　 has said so much, it’s time to go back to the basic question of what dietary sources of collagen are. Collagen only exists in human and animal bodies, and all plants do not contain collagen, so any health product that claims to be "plant collagen" is a naked deception.

　　⑴Animal skin (pig skin jelly, fish skin jelly, fish skin, chicken skin, skinned dog meat), tendons (pig tendons, beef tendons, hoof, etc.), cartilage (bone meat) as daily food Connected, brittle bones, etc.) are rich in collagen. Pork, beef and mutton and poultry meat have lower collagen content, while fish meat has slightly higher collagen content.

　　⑵Some “exotic” foods contain a lot of collagen (with collagen as the main component), such as sea cucumber, shark fin, bird''s nest, flower gum, fish glue, bear paw, donkey-hide gelatin, etc. This often makes many people face a dilemma of choice. I believe that the special effects of these rare ingredients must support collagen. Denying the special role of collagen also negates these rare ingredients.

　　⑶ Collagen as a food additive. It has been used to extract food-grade "gelatin" from animal skins, bones, tendons, and add it as food additives in yogurt, ham, milk drinks and other foods; or provide industrial-grade gelatin (the famous "leather shoe extract") for Non-edible industrial products. The main ingredient of gelatin is collagen, or collagen and gelatin are "all the way", and they are similar. There is no difference between the two, but the extraction method and solubility are slightly different. So now even milk has added collagen (pictured)? Adding gelatin (gelatin) milk suddenly wakes up: collagen is not a vest-wearing gelatin!

　　⑷Collagen as a health supplement protein. Some are oral liquids, some are powders; some are called collagen, some are called "collagen peptides", and some are called "hydrolyzed collagen", which are similar.