Collagen has eleven randomised trials that enrolled only women, and almost none of them is about skin. Four measured bone after menopause, four measured muscle or body composition, two measured tendons in athletes and one measured appetite. The bone and muscle results that look positive mostly come from one manufacturer's peptides; the head-to-heads with whey protein did not favour collagen; and no trial has enrolled pregnant or breastfeeding women.
Women asking what collagen does for them mostly find answers about skin. This page answers from the female-only trials on muscle, bone and tendon — what was measured, in whom, at what amount, and who supplied the collagen. Skin and hair have their own literature, linked below.
The census
PubMed was searched on 27 October 2026 for randomised controlled trials of collagen peptides or collagen hydrolysate with women, female, premenopausal or postmenopausal in the title. It returned 17 records. Six were set aside: two are not collagen-supplement trials, one enrolled men and women, one is a single-athlete case study, one is a companion paper of a trial already counted, and one tested undenatured type II collagen, a different ingredient. Eleven remain:
| Endpoint | Trials | Women | Collagen given |
|---|---|---|---|
| Bone density or bone markers | 4 | 39–131 per trial, postmenopausal | 5–10 g/day, 6–12 months |
| Muscle, fat-free mass, body composition | 4 | 22–77 per trial | 15–60 g/day, 6 days to 12 weeks |
| Tendon | 2 | 11 and 22 athletes | 30 g per session, 8–10 weeks |
| Appetite | 1 | small crossover | single servings |
The title restriction means trials that enrolled women without saying so in the title are missed; the same method on the male side is on collagen for men, which found thirteen records. Skin trials, which usually enrol women, rarely say so in their titles and are a separate subject.
Muscle and strength
The one positive training trial. Jendricke and colleagues (2019, Freiburg) gave 77 premenopausal women 15 g a day of collagen peptides or a placebo while they trained three days a week for 12 weeks. Fat-free mass, measured by bioimpedance, rose in both groups and more on collagen; body fat fell more; hand-grip strength rose more; leg strength rose in both, more clearly on collagen. The peptide was BODYBALANCE, made by GELITA. The paper's acknowledgments say the research "was in part funded by GELITA GmbH", while its formal funding statement reads "This research received no external funding" — both lines are in the published full text.
The whey comparisons. Three women-only trials set collagen against whey protein at matched protein:
- Oikawa 2020 (McMaster, 22 healthy women aged about 69): 30 g of whey or collagen twice a day for 6 days with unilateral resistance exercise. Whey raised muscle protein synthesis, acutely and over the period; collagen did not.
- Giglio 2019 (Brazil, 37 overweight women): about 25 g of protein a day from whey or collagen for 8 weeks. Whey reduced android (abdominal) fat; BMI rose slightly on collagen.
- Hays 2009 (Arkansas, older women): whey against a collagen hydrolysate fortified with amino acids, on nitrogen balance and body composition.
The reason is the amino-acid profile: collagen is low in leucine, which triggers muscle protein synthesis — in the Giglio trial the collagen group took about 0.1 g of leucine a day against 2.6 g on whey. The full head-to-head picture, including the male trials, is on collagen vs whey protein and collagen peptides for muscle growth.
Bone after menopause
The four bone trials all enrolled postmenopausal women with low bone density. The two that scanned bone and found a benefit — König 2018 (131 women, spine T-score +0.10 vs −0.03 on placebo over 12 months) and Lampropoulou-Adamidou 2022 (51 women, with calcium and vitamin D) — both used 5 g a day of the same branded peptide, with support from its maker or distributor. A trial of 10 g a day of a generic hydrolysate for 24 weeks found no effect on bone markers, and a calcium-collagen chelate trial found less whole-body loss. None counted fractures. The trial-by-trial detail, the four-year follow-up and the funding table are on collagen for bones.
Tendons in female athletes
Two small trials from the same Liverpool group gave 30 g of hydrolysed collagen with 500 mg vitamin C before each training session:
- Lee 2024 — 11 professional footballers, 10 weeks of pre-season training: patellar-tendon stiffness rose 15.4% on collagen against 4.6% on placebo.
- Nulty and Erskine 2025 — 22 international master field-hockey players aged about 37, 8 weeks of eccentric training: tendon cross-sectional area rose in both groups, more on collagen; muscle size and force rose equally in both.
Six and ten women per collagen group are small numbers, and the effect is on the tendon, not the muscle. The joint and tendon trials in mixed and male groups are on collagen for joints.
Pregnancy and breastfeeding
Not studied. A PubMed search on 27 October 2026 for randomised trials of collagen peptides in pregnancy, lactation or breastfeeding returned three records, none of which enrolled pregnant or breastfeeding women. ClinicalTrials.gov returned 24 records for collagen peptides and pregnancy, none testing a collagen supplement in pregnancy. No trial means no evidence either way: it does not show harm and it does not show safety. Anyone pregnant or breastfeeding should take the question to their midwife, obstetrician or doctor.
Skin and hair
Most collagen trials in women measure skin — elasticity, hydration, wrinkles — and those are a different question from the muscle, bone and tendon axis this site covers. Peptide Glow Journal's collagen peptides for hair and skin counts that literature.
The amounts the trials used
Reported as what the trials gave, with dates, never as a recommendation:
| Trial (year) | Women | Amount | Duration |
|---|---|---|---|
| König (2018) | Postmenopausal, low BMD | 5 g/day | 12 months |
| Lampropoulou-Adamidou (2022) | Postmenopausal, osteopenia | 5 g/day + calcium, vitamin D | 12 months |
| Cúneo (2010) | Postmenopausal, osteopenia | 10 g/day | 24 weeks |
| Jendricke (2019) | Premenopausal, training | 15 g/day | 12 weeks |
| Lee (2024), Nulty (2025) | Athletes | 30 g per session + 500 mg vitamin C | 8–10 weeks |
| Oikawa (2020) | Older women | 30 g twice daily | 6 days |
The range across all collagen trials is on how much collagen per day; types and sources are on types of collagen.
What is not established
- Fractures — no collagen trial has counted them.
- Pregnancy and breastfeeding — no trial.
- Generic collagen — the positive bone and muscle trials used branded peptides from one maker; generic powders are largely untested on these endpoints.
- Collagen against creatine in women — no head-to-head. Creatine's female trials, including one that measured bone over a year, are on the female creatine trials and creatine and menopause.
Sources and dates
- PubMed search via NCBI E-utilities, 2026-10-27:
(collagen peptide*[tiab] OR collagen hydrolys*[tiab] OR hydrolyzed collagen[tiab] OR hydrolysed collagen[tiab]) AND (women[ti] OR female[ti] OR postmenopausal[ti] OR premenopausal[ti]) AND randomized controlled trial[pt]— 17 records; pregnancy/lactation/breastfeeding search — 3 records, none relevant. ClinicalTrials.gov API v2, "collagen peptides AND pregnancy", 24 records, 2026-10-27. - Jendricke P et al. (2019), Nutrients 11(4):892, PMID 31010031, full text PMC6521629 (product, acknowledgments and funding statement, read 2026-10-27).
- Oikawa SY et al. (2020), Am J Clin Nutr 111(3):708–18, PMID 31919527.
- Giglio BM et al. (2019), Nutrients 11(9):2051, PMID 31480676; Hays NP et al. (2009), J Am Diet Assoc 109(6):1082–7, PMID 19465192; Duarte GMF et al. (2022), Br J Nutr 128(2):345–51, PMID 34407895.
- Lee J et al. (2024/2025), Exp Physiol 110(11):1551–60, PMID 39207908; Nulty CD, Erskine RM (2025), Int J Sport Nutr Exerc Metab 35(6):510–19, PMID 40992424.
- König D et al. (2018), PMID 29337906; Lampropoulou-Adamidou K et al. (2022), PMID 34980546; Elam ML et al. (2015), PMID 25314004; Cúneo F et al. (2010), PMID 19892499 — detail on collagen for bones.