Quick answer

Collagen comes from animals: the skin, bone and connective tissue of cattle, pigs, chickens and fish, eaten as gelatin, bone broth or supplements. Bone broth was a weak and variable source in lab tests. Your body makes its own collagen and needs vitamin C to do it; half a cup of raw red pepper has 95 mg.^1,2,3

Key facts

Adults need 75 mg (women) or 90 mg (men) of vitamin C a day.⁴
Café bone broths held the most collagen amino acids in lab tests, and commercial broths made to a standard recipe held less than homemade ones.²
Collagen protein raises blood glycine far more than dairy protein does.⁵
Cooking and long storage reduce the vitamin C in food.³

Where collagen is found

Collagen comes from animals. The collagen in supplements and gelatin is taken from the hide and bones of cattle, the skin of pigs, the skin, scales and bones of fish, and from chicken.¹

In animals, collagen sits in skin, bone, tendon and cartilage, which is why it is extracted from hides, bones and fish skin. Type I collagen dominates skin, bone and tendon, and type II cartilage.¹

Bone broth

Bone broth made to a standard recipe held much less glycine, proline and hydroxyproline than a 20 g dose of a collagen supplement, and broths made to other recipes varied widely, so it is not a reliable source.²

The comparison was with a 20 g serving of the kind of collagen supplement used in research. Broth recipes, bones and cooking times vary, and so did the results.²

Is there plant collagen?

Vegan and vegetarian collagen made by genetically modified yeast and bacteria is becoming available, but none of the trials in a 2021 review used it, so it is untested.⁶

Every trial reviewed here used collagen from animals, mostly fish, pigs or cattle.^6,7

Foods your body needs to make collagen

Your body needs vitamin C to make collagen. Red and green peppers, oranges and other citrus fruit, kiwifruit, broccoli, strawberries and Brussels sprouts are among the best sources.^3,4

The body needs vitamin C to make collagen. Without enough of it, collagen production falls and connective tissue weakens.³

Vitamin C in selected foods³
Food	Vitamin C
Red pepper, raw, half a cup	95 mg
Orange juice, three quarters of a cup	93 mg
Orange, 1 medium	70 mg
Kiwifruit, 1 medium	64 mg
Green pepper, raw, half a cup	60 mg
Broccoli, cooked, half a cup	51 mg
Strawberries, half a cup	49 mg
Brussels sprouts, cooked, half a cup	48 mg

Glycine and proline

Collagen is rich in glycine: 20 g of collagen protein raised blood glycine to about 2.6 times the peak seen after the same amount of dairy protein, while dairy gave the higher leucine peak.⁵

Glycine and proline are not among the nine essential amino acids, so the body can also make them itself.⁸

Do collagen foods work like supplements?

No trial reviewed here tested collagen-rich foods for skin or joints. The trials gave measured amounts of supplements, mostly 2.5 to 10 g a day for skin.⁷

Allergies

Fish is one of the nine major food allergens, so fish collagen and fish gelatin are out for people with a fish allergy. Some people with alpha-gal syndrome, an allergy to red meat usually caused by tick bites, also react to gelatin.^9,10

Questions people ask

Does cooking destroy vitamin C?

It reduces it. Vitamin C dissolves in water and is destroyed by heat, so steaming or microwaving keeps more than boiling, and many of the best sources are eaten raw.³

Is gelatin a good source of collagen?

Gelatin is collagen in a non-hydrolyzed form, and studies have used it as a collagen source: 15 g of gelatin with vitamin C was the dose in one exercise study.^5,11

See what we make

Every product shows its whole label and what its lab report covers. The store opens soon.

See the Full Measure line Collagen Peptides Collagen Peptides

Sources

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.