Gelatin is cooked collagen, a structural protein. It is rich in glycine (~35% of its amino acids), proline, and alanine. It has little tryptophan or cysteine.[1]

Gelatin
Protein quality "DIAAS"
Food sources Bone broth, gelatin desserts, collagen powder, oxtail, pig skin
Glycine ~35% of amino acids
Histidine Small amounts
Proline + Hydroxyproline ~21% of amino acids
Cysteine Small amounts
Tryptophan None
Methionine Small amounts, low vs muscle meat
Leucine
Lysine
Glutamic acid
Ray's verdict Generally helps
Essential balance for methionine-heavy diets; calming, liver-supportive

It balances the high methionine of muscle meat and eggs. Food structure first. Megadose pills second.

Gelatin (the cooked form of collagen) makes up about 50% of the protein in an animal, but a much smaller percentage in the more active tissues, such as brain, muscle, and liver. 35% of the amino acids in gelatin are glycine, 11% alanine, and 21% proline and hydroxyproline.

— Ray Peat[2]

The degenerative and inflammatory diseases can often be corrected by the use of gelatin-rich foods.

— Ray Peat[3]

Dosing

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Pairing gelatin with meat to balance its amino acid profile: about 5 to 10 grams alongside a large serving of meat, or around 20 grams with a half-pound steak.[4][5] As a general daily amount he called 30 grams a day "fine," while noting some people used up to 60 grams a day with good results.[6][7]

Amino acid profile

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It happens that gelatin is a protein which contains no tryptophan, and only small amounts of cysteine, methionine, and histidine. Using gelatin as a major dietary protein is an easy way to restrict the amino acids that are associated with many of the problems of aging.

— Ray Peat[8]

Restricting tryptophan or cysteine alone extended lifespan in animal work beyond many calorie-restriction trials. Gelatin shifts the amino-acid mix through food. Tryptophan and cysteine both inhibit thyroid function and mitochondrial energy.[1]

Muscle meat alone

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When only the muscle meats are eaten, the amino acid balance entering our blood stream is the same as that produced by extreme stress, when cortisol excess causes our muscles to be broken down to provide energy and material for repair.

— Ray Peat[9]

Whole-animal eating (broth, skin, cartilage with muscle) supplied glycine for balanced growth. Industrial diets that drop collagen skew toward serotonin and cortisol chemistry.[1] Collagen breakdown products promote wound healing and oppose tumor invasiveness in animal work cited there.[1]

Glycine actions

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In every type of cell, glycine apparently has the same kind of quieting, protective antistress action. The range of injuries produced by an excess of tryptophan and serotonin seems to be prevented or corrected by a generous supply of glycine. Fibrosis, free radical damage, inflammation, cell death from ATP depletion or calcium overload, mitochondrial damage, diabetes, etc., can be prevented or alleviated by glycine.

— Ray Peat[10]

Glycine is recognized as an "inhibitory" neurotransmitter, and promotes natural sleep.

— Ray Peat[11]

Glycine has wide antistress actions in that essay: fibrosis, free-radical injury, inflammation, mitochondrial calcium overload, diabetes models.[1] A randomized human stroke trial (n=200) found sublingual glycine 1 to 2 g/day safe with improved scores and lower CSF glutamate and lipid peroxidation markers.[12]

Glycine and gelatin protect against vascular leak with niacinamide, saturated fats, thyroid, and progesterone.[13] Progesterone and pregnenolone reinforce glycine-like inhibition at GABA receptors.[1]

Practical use

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Because excess tryptophan can produce muscle pain, myositis, and even muscular dystrophy, gelatin's lack of tryptophan makes it a fitting food for those problems.[14] A meta-analysis of randomized placebo-controlled trials found oral collagen lowered total WOMAC and VAS scores in osteoarthritis, with a significant drop in stiffness but not in pain or function subscores.[15]

Sources: bone broth, oxtail and shank, unsweetened gelatin desserts, hydrolyzed collagen powder (similar amino acids, no gel). Gelatin before bed for sleep appears in the same article.[1] Pavlov's beef-broth recommendations for digestive disorders appear in the historical notes there.[1]

Vitamin C-enriched gelatin before intermittent exercise raised collagen synthesis more than exercise alone in a double-blind trial (15 g gelatin with 48 mg vitamin C one hour before activity; 5 g also beat placebo).[16] Pantothenic acid (0.2 g/day) with ascorbic acid (1.0 g/day) alone for 21 days showed no measurable effect on wound healing in an earlier trial.[17]

Beef foot broth
From ReciPeatsBeef foot broth

Gelatin-rich and low-fiber, a practical starting point for gut-friendly broth.

BPC-157

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BPC-157 (Body Protection Compound 157) is a synthetic peptide derived from a protein found in gastric juice. It is used off-label for gut lining repair and injury healing, including tendon and wound recovery.

Community reports describe combining BPC-157 with L-glutamine and zinc carnosine to increase gut integrity in cases of persistent digestive inflammation.[18]

No comment from Ray Peat naming BPC-157 specifically has been found in the corpus. He was skeptical of the peptide-supplement category generally: "Currently popular peptides have produced amazing results for the people who sell it. I think most of them are either useless or dangerous."[19]

Despite widespread off-label self-injection, the evidence base is entirely preclinical: a 2026 review of BPC-157's cytoprotective effects on hemorrhage, thrombosis, and wound healing was built entirely on rodent and in vitro data, with the authors explicitly stating that "reliance on preclinical models necessitates further clinical validation." No completed human clinical trial establishing a safe or effective dose has been published as of this review.[20] People self-administering it are, in effect, running an uncontrolled n=1 trial on themselves with a compound whose human dosing has never been formally established.

This page is a stub.

Bone broth

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Bone broth is long-simmered bones, joints, and connective tissue. Heat turns collagen into gelatin. The liquid carries glycine-rich protein, minerals, and flavor. Homemade stock from joints and skin is closer to traditional gelatinous broth than a commercial carton of "broth" cut with seed oils and flavorings.

Broth as daily gelatin

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Broth is the practical daily form of gelatin. Muscle meat alone supplies a stress-like amino acid mix. Broth, skin, and oxtail supply the glycine-rich half of the animal. Together they balance methionine and tryptophan load. See Gelatin, Glycine, Collagen.

Dilute broth is not a complete meal. Use it as a base under meat, potato, carrot, and salt, or as a warm drink with adequate protein elsewhere. Very thin "broth" that never gels when chilled is mostly mineral water with aroma; cook long enough and with enough connective tissue that it sets.

Preparation

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Simmer joints, feet, necks, or oxtail with a splash of acid (vinegar) if you like, skim, salt, and chill. Fat can be kept or removed by preference. Use within a few days or freeze. Powdered collagen is a backup when stock is unavailable; it lacks the full mineral and matrix context of real bones but matches the amino acid goal.

Broth does not replace thyroid or food energy. It is the structural-protein side of an animal-food diet. See Gelatin for the full amino acid argument.

A small controlled study found chicken bone broth carried markedly higher lead levels than the water used to make it, 7.01-9.5 µg/L versus 0.89 µg/L for tap water treated the same way, since bones sequester lead that can leach out during long simmering.[21]

Gut inflammation

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In a mouse model of chemically induced colitis (TNBS-induced, mimicking ulcerative colitis), bone broth given after the colon injury cut inflammatory cytokine expression well below the untreated colitis group: interleukin-1β dropped by roughly 61%, IL-6 by roughly 95%, and TNF-α by roughly 69%, though none returned fully to the levels of healthy controls. Treated animals also kept more intact colon epithelium and crypt structure than untreated colitis animals.[22] This is animal-model evidence without a human trial. Gelatin has a broader anti-inflammatory, gut-supportive reputation.

Recipes

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Beef foot broth
From ReciPeatsBeef foot broth

Gelatin-rich stock from connective tissue.

All broth recipes All bone broth recipes

Collagen

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Collagen is the main structural protein of connective tissue: skin, tendons, cartilage, bone matrix. When cooked (denatured), collagen becomes Gelatin. Ray Peat favors collagen and gelatin to offset the methionine- and tryptophan-heavy profile of muscle meat, supporting Liver function and calmer metabolism.[23]

Food forms

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  • Collagen: native protein in raw connective tissue (tough when unhydrolyzed)
  • Gelatin: heat-denatured collagen; gels when cooled
  • Collagen hydrolysate: enzymatically broken peptides; same amino acid profile, no gel

All are glycine-rich relative to steak or chicken breast.

A 30 g drink of hydrolyzed collagen and a free amino-acid mix matched to it raised blood glycine about equally in a randomized trial in young adults.[24]

When we eat animal proteins in the traditional ways (for example, eating fish head soup, as well as the muscles, or "head-cheese" as well as pork chops, and chicken-foot soup as well as drumsticks), we assimilate a large amount of glycine and gelatin.

— Ray Peat[25]

Modern diets under-consume connective-tissue proteins relative to muscle meat, skewing amino acids toward thyroid-suppressing tryptophan and cysteine.[26]

Aging and elasticity

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A glycine-analogue hypothesis for glyphosate proposes substitution into collagen and related matrix proteins that would disrupt folding and elasticity; proteomics in cultured mammalian cells did not detect that substitution under the conditions tested. See Glyphosate.[27][28]

In rat tail tendon work, excess Estrogen reduces collagen elasticity; Progesterone is protective. That is experimental biology, not dietary collagen as hormone replacement. [29]

A 2025 trial isolated the three amino acids that make up collagen's repeating unit, glycine, proline, and hydroxyproline, in a 3:1:1 ratio (5000 mg glycine, 1700 mg proline, 1700 mg hydroxyproline daily in the human arm). In C. elegans the blend increased lifespan 6-27% across five trials, more than whole collagen did. In 20-month-old mice it preserved grip strength and lowered visceral fat over 6 months. In a 3-month human trial, skin texture rose from 59.9% to 65.1% and cheek hydration rose from 35.9 AU to 48.3 AU; the wrinkle-reduction trend did not reach significance. Over 6 months, epigenetic age fell by an average of 1.4 years, with a maximum reduction of 12.1 years in women and 8.9 years in men.[30]

Joint pain in athletes

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In a 24-week randomized, placebo-controlled trial of 147 collegiate athletes with activity-related joint pain, 10 g/day of collagen hydrolysate significantly reduced joint pain at rest and during walking, standing, and running/direction changes compared to placebo, most clearly in the subgroup with knee pain; benefits took up to 24 weeks to become apparent.[31]

Food sources

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Bone broth, oxtail, pig skin, gelatin powder, collagen supplements. See Gelatin and Glycine.

See also

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References

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  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Ray Peat, "Gelatin, stress, longevity," raypeat.com.
  2. ↑ Gelatin, stress, longevity, Ray Peat newsletter
  3. ↑ Gelatin, stress, longevity, Ray Peat newsletter
  4. ↑ Ray Peat, "Gelatin, stress, longevity," raypeat.com.
  5. ↑ Ray Peat, "Tryptophan, serotonin, and aging," raypeat.com.
  6. ↑ One Radio Network: Milk.
  7. ↑ One Radio Network: Vitamin D, Thyroid, Evolving Consciously.
  8. ↑ Gelatin, stress, longevity, Ray Peat newsletter
  9. ↑ Gelatin, stress, longevity, Ray Peat newsletter
  10. ↑ Gelatin, stress, longevity
  11. ↑ Gelatin, stress, longevity, Ray Peat newsletter
  12. ↑ Neuroprotective effects of glycine for therapy of acute ischaemic stroke
  13. ↑ Ray Peat, "Leakiness, aging, and cancer," raypeat.com.
  14. ↑ Ray Peat, "Gelatin, stress, longevity," raypeat.com.
  15. ↑ García-Coronado JM, Martínez-Olvera L, Elizondo-Omaña RE, et al. "Effect of collagen supplementation on osteoarthritis symptoms: a meta-analysis of randomized placebo-controlled trials," Int Orthop. 2019;43(3):531-538. doi:10.1007/s00264-018-4211-5. PMID 30368550. WOMAC WMD -8.00, 95% CI -13.04 to -2.95.
  16. ↑ Shaw G, et al. "Vitamin C-enriched gelatin supplementation before intermittent activity augments collagen synthesis," Am J Clin Nutr. 2017. PMID 27852613.
  17. ↑ Vaxman F, et al. "Effect of pantothenic acid and ascorbic acid supplementation on human skin wound healing process. A double-blind, prospective and randomized trial," Eur Surg Res. 1995;27(3):158-66. PMID 7781653.
  18. ↑ Danny Roddy, Bioenergetic Helpline transcript.
  19. ↑ Ray Peat, Ray Peat Forum Q&A, "Peptide Supplements Critique."
  20. ↑ Sikiric P, Barisic I, Udovicic M, et al. "Cytoprotection as a Unifying Strategy for Hemorrhage and Thrombosis: The Role of BPC 157 and Related Therapeutics,"Pharmaceuticals (Basel). 2026;19(3):463. doi:10.3390/ph19030463.
  21. ↑ Monro JA, Leon R, Puri BK, "The risk of lead contamination in bone broth diets," Med Hypotheses. 2013;80(4):389-90. PMID 23375414.
  22. ↑ "Analysis of the Anti-Inflammatory Capacity of Bone Broth in a Murine Model of Ulcerative Colitis," Medicina (Kaunas). 2021;57(11):1138. doi:10.3390/medicina57111138. PMC8618064.
  23. ↑ "Gelatin, stress, longevity," Ray Peat article
  24. ↑ Aussieker T, Kaiser J, Hendriks FK, Janssen TAH, Senden JM, van Kranenburg JMX, Goessens JPB, Zorenc A, Kornips E, Brinkhuizen T, Baar K, Snijders T, Holwerda AM, van Loon LJC. "The Effects of Ingesting a Single Bolus of Hydrolyzed Collagen versus Free Amino Acids on Muscle Connective Protein Synthesis Rates," Med Sci Sports Exerc. 2025;57(11):2394-2408. doi:10.1249/MSS.0000000000003788. PMID 40523226.
  25. ↑ "Gelatin, stress, longevity," Ray Peat article
  26. ↑ "Gelatin, stress, longevity," Ray Peat article
  27. ↑ Samsel A, Seneff S. "analogue of glycine," J Biol Phys Chem. 2016;16:9-46.
  28. ↑ Antoniou MN, et al. "Exosomes derived from mesenchymal stem cells reverse EMT via TGF-β1/Smad pathway and promote repair of damaged endometrium," BMC Res Notes. 2019;12:494. doi:10.1186/s13104-019-4534-3. PMID 31358049.
  29. ↑ Lee CA, Lee-Barthel A, Marquino L, Sandoval N, Marcotte GR, Baar K, "Estrogen inhibits lysyl oxidase and decreases mechanical function in engineered ligaments," Journal of Applied Physiology. 2015;118(10):1250-7. doi:10.1152/japplphysiol.00823.2014. PMID 25979936.
  30. ↑ Dakhovnik A, Mantovani M, Knufinke M, et al. "A collagen amino acid composition supplementation reduces biological age in humans and increases health and lifespan in vivo," npj Aging. 2025;11:91. doi:10.1038/s41514-025-00280-7.
  31. ↑ Clark KL, Sebastianelli W, Flechsenhar KR, et al. "24-Week study on the use of collagen hydrolysate as a dietary supplement in athletes with activity-related joint pain," Curr Med Res Opin. 2008;24(5):1485-96. PMID 18416885.