Collagen
Collagen is the protein that holds skin, bone, tendons and cartilage together, about a third of all the protein in the body. The body builds it from amino acids with the help of vitamin C; collagen in food and supplements is digested into amino acids first.
1 / 3 of the protein in the body is collagen
Every third amino acid in a collagen chain is glycine
Daily need · none set; the body makes its own
- Main type Type I skin, bone, tendons
- Built with Vitamin C without it, fibers stay weak
- Tryptophan None so it is not a complete protein
- Evidence for skin Modest small, mostly industry-funded trials
Sources: biochemistry and nutrition textbooks, systematic reviews of randomized trials. Not medical advice.
Where Collagen Comes From in Food
Only animal foods contain collagen, and mostly the tough parts that modern diets often skip. The Caltide food library does not measure it, so there is no ranking here.
Foods With Collagen
- Gelatincooked collagen, the base of jellies, gummies and aspics
- Bone broth and stocklong simmering pulls collagen out of bones and joints as gelatin; the amount varies a lot
- Skin and connective tissuechicken and fish skin, pork rind, and slow-cooked cuts such as shank and oxtail
Foods That Help You Make Collagen
- Any protein foodmeat, fish, eggs, dairy, soy and beans supply the amino acids collagen is built from
- Fruit and vegetables rich in vitamin Csuch as citrus, peppers, kiwi and strawberries
What Is Collagen?
A collagen molecule is three protein chains wound around each other like a rope. The winding only works because every third amino acid is glycine, the smallest one, which fits in the middle of the twist. Much of the rest is proline and hydroxyproline, an amino acid found almost nowhere else in the body.
To turn proline into hydroxyproline, the enzymes that build collagen need vitamin C. Without it, the chains cannot lock together firmly. That is the cause of scurvy: gums bleed, skin bruises easily and old wounds reopen, because the body keeps replacing collagen and can no longer make it strong.
There are 28 known types. Type I makes up most of the collagen in skin, bone, tendons and ligaments; type II is the main one in cartilage; type III sits alongside type I in skin, blood vessels and organs.
What Happens to Collagen You Eat
Collagen in food or a supplement is digested like any other protein, into single amino acids and short fragments of two or three. Some fragments, such as prolyl-hydroxyproline, reach the blood intact, and researchers are studying whether they signal skin and cartilage cells to make more collagen. What is clear is that eaten collagen is not carried to the skin and placed there whole.
Collagen vs. Whey Protein
Ten grams of collagen powder and ten grams of whey both count as ten grams of protein on the label. They are not the same protein. Collagen has no tryptophan at all and little leucine, while whey has every essential amino acid in good amounts. For building muscle or meeting your protein needs, collagen grams count for much less than their label suggests.
What Collagen Supplement Trials Show
Supplements are a common second source of collagen, usually as hydrolyzed collagen (collagen peptides) from cattle, pigs, fish or chicken. Reviews of randomized trials find small improvements in skin hydration and elasticity after several weeks. Most trials were small, many were paid for by the companies selling the product, and trials not funded by industry found smaller effects or none.
For joints, a few small trials in osteoarthritis and in athletes with activity-related joint pain report modest relief. For bone, hair and nails, the evidence is thinner still. None of this shows collagen works better than eating enough protein and vitamin C.
Common Collagen Mistakes
Thinking the type on the label decides where it goes. Type I or type II on a tub of peptides does not steer the amino acids to skin or joints once they are digested.
Counting it as full protein. It lacks tryptophan, so it cannot be your only protein source.
Buying vegan collagen. Collagen in food and supplements comes from animals. A product sold as vegan collagen usually supplies building blocks such as amino acids and vitamin C, not collagen.
Collagen Supplements
Three forms are sold, differing in how far the collagen has been broken down.
Collagen Supplement Forms
- Collagen peptides (hydrolyzed collagen)broken into short chains, dissolves in hot or cold drinks; the form in most powders and most skin trials
- Gelatinpartly broken down, sets into a gel; the same building blocks, less convenient to mix
- Undenatured type II collagenintact collagen from chicken cartilage, taken in small doses and studied for joints, with limited evidence
Collagen Safety
- Allergiesmarine collagen comes from fish, and some products from eggshell membrane; check the source if you have a food allergy
- Side effectsusually mild, such as a feeling of fullness or an upset stomach
Caltide does not total collagen yet. Sources: textbooks and reviews of randomized trials. Not medical advice.
Related Nutrients
Collagen Sources and References
The figures and claims on this page are checked against these sources.
Questions About Collagen
The main structural protein in the body, about a third of all its protein. It forms the fibers that give skin, bone, tendons, ligaments and cartilage their strength.
No. Digestion breaks collagen into amino acids and small fragments of two or three amino acids, which enter the blood. The body then builds its own collagen where it needs it, from whatever amino acids are available.
The evidence is modest. Reviews of randomized trials report small gains in skin hydration and elasticity, but most trials were small, short and paid for by supplement makers, and trials without industry funding found smaller effects or none.
Possibly a little. A few small trials in people with osteoarthritis and in athletes with joint pain found modest relief, but the studies are too few and too varied to be sure.
No. Collagen contains no tryptophan, one of the nine essential amino acids, and little of several others. Its grams count as protein on a label, but it cannot replace protein from meat, dairy, eggs, soy or beans.
Not in the usual sense. The collagen in food and supplements comes from animals. Most products sold as vegan collagen contain no collagen; they are blends of amino acids, vitamin C and other nutrients the body uses to make its own.
Both are collagen that has been broken down, gelatin partly and peptides further. Gelatin dissolves in hot water and sets into a gel as it cools; collagen peptides (hydrolyzed collagen) dissolve without gelling, which is why powders use them.
The enzymes that lock collagen fibers into shape need vitamin C. Without it the body makes weak collagen, which is why scurvy causes bleeding gums, easy bruising and wounds that heal slowly.
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