Collagen: Food Sources & Daily Intake

Table of Contents

1. How to Read These Tables
2. Recommended Intakes & Upper Limits
3. Bioavailability & Absorption
4. Cooking & Storage
5. Vegetarian & Vegan Sources
6. Who Needs to Pay Attention
7. Key Research Papers
8. Connections
9. Featured Videos

How to Read These Tables

• Hydroxyproline is the collagen marker. Food databases have no “collagen” value because collagen is a protein, not a nutrient. Hydroxyproline is the workaround: it occurs almost exclusively in collagen, so the foods highest in it — gelatin, skin, bone broth and connective-tissue cuts — are exactly the foods richest in collagen.
• Grams per 100 g, not %DV. There is no U.S. Food and Drug Administration Daily Value for individual amino acids, so this table reports the absolute grams of hydroxyproline per 100 g of food and ranks foods by that. A typical serving is shown beside each food.
• The list is shorter than usual — and that is honest. Most foods carry no hydroxyproline at all, so it is only measured in some collagen-rich ones; lean muscle meat, dairy, eggs, grains and produce mostly show none. A short list here partly reflects that collagen is concentrated in skin, gelatin, bone and connective tissue, not spread evenly across the diet, and partly reflects missing data, as the next point explains.
• Gelatin, skin and broth are missing from the table. USDA FoodData Central lists dry gelatin (FDC 169599) at 85.6 g of protein, 19.0 g of glycine and 12.3 g of proline per 100 g but gives no hydroxyproline figure, and the records used here for pork skins, chicken skin, turkey and fish have none either. Bone broth is not among the foods looked up. A food with no figure cannot be ranked, so bacon’s first place comes from that gap and does not show that it holds more collagen than gelatin or skin.

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Recommended Intakes & Upper Limits

Collagen has no Daily Value: the U.S. food-label rules (21 CFR 101.9) set none for it, and the green and yellow marks in the food table above only rank each food against the richest food listed. The table below summarizes its status.

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Bioavailability & Absorption

Eaten collagen — from bone broth, gelatin or collagen peptides (collagen pre-broken into short, readily absorbed chains) — is digested down to amino acids and small peptides and absorbed well; it does not travel intact to skin or joints. In healthy volunteers who took 9.4 to 23 g of gelatin hydrolysate, hydroxyproline in peptide form peaked at 20-60 nmol/mL of plasma after 1-2 hours and fell to half of that by 4 hours; most of it was the two-unit peptide Pro-Hyp. What it provides is a concentrated supply of the exact building blocks (glycine, proline, hydroxyproline) the body uses to make its own collagen. The decisive cofactor is vitamin C: the enzymes that lock collagen's triple helix together cannot work without it, so even an abundant supply of these amino acids builds little sound collagen if vitamin C is low. Adequate total protein, vitamin C, plus copper and zinc, are what actually let the body turn dietary raw material into strong new tissue.

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Cooking & Storage

The most collagen-dense food of all is created by cooking. Simmering bones, skin, tendons and other connective tissue in water for hours dissolves their tough collagen into soft, soluble gelatin — this is precisely what bone broth is, and why broth, gelatin and slow-braised meats carry so much hydroxyproline, glycine and proline. When researchers measured it, broth made to a standard recipe held significantly less hydroxyproline, glycine and proline than a 20 g dose of collagen supplement, amounts varied widely between recipes, and the authors concluded that broth is unlikely to be a consistently reliable source of these amino acids. Slow, moist heat — braising, stewing, stock-making — is the way to release collagen from tough cuts (shank, oxtail, brisket, chuck) and from skin and bone; the long cook that breaks collagen down into gelatin is also what makes those cuts tender.

Lead in bone broth is debated. A small 2013 study found 9.5 and 7.01 µg/L of lead in chicken skin-and-cartilage broth and chicken-bone broth, against 0.89 µg/L in tap water treated the same way. A 2017 study put lead and cadmium at a few micrograms per serving and called the risk minimal; it also found calcium and magnesium under 5% of daily recommended levels per serving.

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Vegetarian & Vegan Sources

Plants contain no collagen at all — collagen is exclusively an animal tissue, so there is no plant-based gelatin, bone broth or collagen peptide. That does not mean a plant-based eater cannot have healthy collagen, because the body builds its own collagen rather than depending on eating it. The raw materials — the amino acids glycine and proline — come from ordinary plant protein (beans, lentils, soy foods, peanuts, seeds and whole grains), and the body assembles collagen from them as long as total protein is adequate and, critically, vitamin C intake is good, since vitamin C is the limiting cofactor for collagen synthesis. Copper and zinc help too. So what a plant-based diet supplies for skin, joints and connective tissue is varied protein plus vitamin-C-rich produce — not a collagen food, which plants cannot supply.

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Who Needs to Pay Attention

You cannot become “collagen deficient” from diet the way you can run short of a vitamin — the body continuously makes its own. What declines is collagen production: it falls with age (driving thinner skin, wrinkles, weaker joints and slower healing) and is impaired by low protein, smoking, high sugar intake and especially low vitamin C — severe vitamin C deficiency (scurvy) is essentially a collapse of collagen synthesis, causing fragile skin, bleeding gums and poor wound healing. People with high connective-tissue demand — recovering from surgery, wounds or burns, athletes loading tendons and joints, and older adults — benefit most from concentrated collagen sources (bone broth, gelatin or collagen peptides). In every case the biology is the same: the body needs the building blocks and the vitamin C, since collagen-rich food without vitamin C cannot be turned into strong new tissue.

A 2025 meta-analysis of 23 randomized trials (1,474 people) found that collagen supplements improved skin hydration, elasticity and wrinkles overall, but trials without pharmaceutical-company funding and high-quality trials showed no significant effect, and its authors concluded there is currently no clinical evidence to support their use to prevent or treat skin aging. An earlier meta-analysis of 26 trials (1,721 people) reported better skin hydration and elasticity and called for larger trials. In a small crossover trial of 8 healthy men, 15 g of vitamin C-enriched gelatin taken 1 hour before 6 minutes of rope-skipping doubled a blood marker of collagen making (the amino-terminal propeptide of collagen I).

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Key Research Papers

1. Linus Pauling Institute — vitamin C and collagen synthesis
2. PubMed: oral collagen peptides, skin and joint outcomes
3. Peterkofsky B (1991). Ascorbate requirement for hydroxylation and secretion of procollagen: relationship to inhibition of collagen synthesis in scurvy. American Journal of Clinical Nutrition;54(6 Suppl):1135S-1140S. — PubMed PMID: 1720597
4. Iwai K, Hasegawa T, Taguchi Y, Morimatsu F, Sato K, Nakamura Y, Higashi A, Kido Y, Nakabo Y, Ohtsuki K (2005). Identification of food-derived collagen peptides in human blood after oral ingestion of gelatin hydrolysates. Journal of Agricultural and Food Chemistry;53(16):6531-6536. — PubMed PMID: 16076145
5. Alcock RD, Shaw GC, Burke LM (2019). Bone Broth Unlikely to Provide Reliable Concentrations of Collagen Precursors Compared With Supplemental Sources of Collagen Used in Collagen Research. International Journal of Sport Nutrition and Exercise Metabolism;29(3):265-272. — PubMed PMID: 29893587
6. Monro JA, Leon R, Puri BK (2013). The risk of lead contamination in bone broth diets. Medical Hypotheses;80(4):389-390. — PubMed PMID: 23375414
7. Hsu DJ, Lee CW, Tsai WC, Chien YC (2017). Essential and toxic metals in animal bone broths. Food & Nutrition Research;61(1):1347478. — PubMed PMID: 28804437
8. Myung SK, Park Y (2025). Effects of Collagen Supplements on Skin Aging: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. American Journal of Medicine;138(9):1264-1277. — PubMed PMID: 40324552
9. Pu SY, Huang YL, Pu CM, Kang YN, Hoang KD, Chen KH, Chen C (2023). Effects of Oral Collagen for Skin Anti-Aging: A Systematic Review and Meta-Analysis. Nutrients;15(9):2080. — PubMed PMID: 37432180
10. Shaw G, Lee-Barthel A, Ross ML, Wang B, Baar K (2017). Vitamin C-enriched gelatin supplementation before intermittent activity augments collagen synthesis. American Journal of Clinical Nutrition;105(1):136-143. — PubMed PMID: 27852613

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Connections

• All Amino Acids
• Vitamin C, Collagen & Why Sailors Fell Apart — interactive animation
• Collagen (Main Page)
• Collagen Benefits
• Collagen History
• Proline
• Glycine
• Bone Broth
• Vitamin C

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