Collagen Peptides: What They Are, Benefits and How Much to Take

At a Glance

• What they are Collagen peptides (also called hydrolyzed collagen) are collagen broken into small pieces so they dissolve easily and are digested quickly.
• Skin Pooled trials found better hydration, elasticity and wrinkles, but high-quality and independently funded trials found no clear effect²³.
• Joints and bones 5 g a day reduced knee pain during sport in athletes and improved bone density in postmenopausal women in single trials⁴⁵.
• How much Trials used 2.5 to 15 g a day for 8 weeks to 12 months¹⁰.
• Top pick NAKED Collagen – the #1 pick in our guide to the best collagen powder: one ingredient, bovine collagen peptides, with the NSF Contents Certified mark.

The Short Answer: Collagen peptides are a convenient protein supplement with modest, mixed evidence. Industry-funded trials often report better skin, less joint pain during exercise and stronger bones, but the best skin studies without industry funding found no effect³. Most positive trials tested specific branded peptides at 2.5 to 15 g a day¹⁴⁵.

On this page

1. What Are Collagen Peptides?
2. How Your Body Absorbs Them
3. Collagen Peptides Benefits: What the Evidence Shows
4. How Much Collagen Peptides Should You Take?
5. Is Collagen a Complete Protein?
6. How to Choose Collagen Peptides
7. Side Effects and Safety
8. Final Verdict
9. Frequently Asked Questions

Collagen peptides are also an incomplete protein: they lack tryptophan, so they shouldn’t be your main protein source¹⁰. If you want to try them, a plain, single-ingredient powder is the simplest choice. For products, see our guide to the best collagen powder.

What Are Collagen Peptides?

Collagen is the main structural protein in skin, tendons, cartilage and bone. Collagen peptides are made by breaking collagen from cowhide, fish skin or pig skin into short chains with enzymes. The terms collagen peptides, hydrolyzed collagen and collagen hydrolysate mean the same thing.

• Collagen peptides: Dissolve in hot or cold liquids and don’t gel.
• Gelatin: Partly broken-down collagen that gels when cooled.
• Undenatured type II collagen (UC-II): Used in tiny doses (about 40 mg) for joints and works differently. See our collagen for joints guide.

How Your Body Absorbs Them

After you swallow collagen, short peptides such as prolyl-hydroxyproline (Pro-Hyp) reach the blood¹¹. In a study of 9 people, gelatin raised blood Pro-Hyp, peaking about 2 hours after eating it. A low-molecular-weight hydrolysate raised these peptides further, while a regular hydrolysate performed similarly to gelatin for one of the peptides measured¹¹. The authors concluded gelatin could be as useful as a regular hydrolysate¹¹. Hydrolysis also makes collagen easier to mix into drinks.

Collagen Peptides Benefits: What the Evidence Shows

Benefit	Key study	Result	Evidence
Skin wrinkles and hydration	19 trials, 1,125 people2	Better hydration, elasticity and wrinkles	Mixed
Skin (by funding and quality)	23 trials, 1,474 people3	No effect in independent or high-quality trials	Mixed
Knee pain during sport	139 athletes, 5 g a day, 12 weeks4	Less pain during activity; no difference at rest	Limited
Bone density	131 postmenopausal women, 5 g a day, 12 months5	Higher spine and hip bone density	Limited
Muscle with strength training	53 older men, 15 g a day, 12 weeks6	More lean mass and strength vs placebo	Limited
Achilles tendon pain	20 patients with exercise9	Faster improvement in a pilot study	Very limited

Skin

A 2021 review of 19 trials in 1,125 people, mostly women, found hydrolyzed collagen improved skin hydration, elasticity and wrinkles compared with placebo². A 2025 review of 23 trials reached a different conclusion after splitting the trials: studies funded by companies showed benefits, but studies without company funding and high-quality studies showed no significant effect³. The authors concluded there’s currently no clinical evidence to support collagen for skin aging³.

Joints

In 139 athletes with knee pain during sport, 5 g of collagen peptides a day for 12 weeks reduced pain during activity more than placebo, though pain at rest didn’t differ⁴. In a later trial in 180 young, physically active adults, 5 g a day for 12 weeks also reduced knee pain during activity⁸. For other joint supplements, see our collagen for joints guide.

Bones

In 131 postmenopausal women with low bone density, 5 g of specific collagen peptides a day for 12 months increased bone density at the spine and hip compared with placebo⁵. This was one trial with one branded product.

Muscle

In 53 older men with low muscle mass, 15 g of collagen peptides after resistance training for 12 weeks increased lean mass by 4.2 kg vs 2.9 kg with placebo⁶. A published letter questioned how large these changes were⁷, and the placebo was silica rather than another protein⁶.

Tendons

In a pilot study of 20 people with Achilles tendon pain doing calf exercises, adding collagen peptides sped up improvement⁹. The study was small and had no group without exercise.

How Much Collagen Peptides Should You Take?

Trials used 2.5 to 15 g a day¹⁰:

• Skin: 2.5 g a day for 8 weeks in a branded trial¹.
• Joints and bones: 5 g a day for 12 weeks to 12 months⁴⁵.
• Muscle with training: 15 g a day after workouts⁶.

Most plain collagen powders give 10 to 20 g per serving. Effects took weeks to months to appear in trials, so give it at least 8 to 12 weeks.

Is Collagen a Complete Protein?

No. Collagen lacks the essential amino acid tryptophan, so it’s an incomplete protein¹⁰. A 2019 analysis estimated collagen could make up as much as 36% of daily protein while still meeting essential amino acid needs, well above the 2.5 to 15 g used in trials¹⁰. Don’t count collagen as a replacement for protein foods.

How to Choose Collagen Peptides

• Pick a single ingredient: Plain bovine or marine collagen peptides with nothing added.
• Look for third-party testing: A mark such as NSF helps confirm what’s in the tub.
• Check the dose per scoop: Aim for at least 2.5 to 10 g, in line with the trials.
• Don’t overpay for claims: “Grass-fed” describes how cattle were raised, not how much collagen you get.
• Branded peptides: Many trials used specific branded peptides, so results may not apply to every product¹⁴⁵.

For marine vs bovine, see our guide to the best marine collagen.

Our Top Collagen Peptides Pick

NAKED Collagen

1 ingredientNSF Contents Certified9.5 g per serving

The #1 pick in our guide to the best collagen powder. It lists only bovine collagen peptides and carries the NSF Contents Certified mark. Most positive trials used specific branded peptides, so results may not carry over exactly to any one product.

Check price on Amazon → See all 7 picks

Side Effects and Safety

In the Achilles pilot study, no side effects were reported⁹, but large long-term safety studies are limited. Fish collagen isn’t suitable for people with fish allergies, and most collagen comes from animals, so it isn’t vegetarian.

Final Verdict

Collagen peptides are an easy-to-mix protein with some positive trials for skin, joints and bones, but the evidence is modest, often industry-funded, and independent skin trials show no clear benefit³⁴⁵. They can’t replace complete protein in your diet¹⁰.

If you want to try them, consider NAKED Collagen, a single-ingredient bovine collagen powder with the NSF Contents Certified mark. Compare all picks in our guide to the best collagen powder, or see our picks for women and men.

Important: This guide is for general information and isn’t medical advice. Talk to your doctor before using collagen if you have a food allergy or take prescription medicine.

Frequently Asked Questions

Sources & History11 sources · updated November 13, 2026

References

1. Oral Intake of Specific Bioactive Collagen Peptides Reduces Skin Wrinkles and Increases Dermal Matrix Synthesis — Skin Pharmacology and Physiology, 2014
2. Effects of Hydrolyzed Collagen Supplementation on Skin Aging: A Systematic Review and Meta-Analysis — International Journal of Dermatology, 2021
3. Effects of Collagen Supplements on Skin Aging: A Systematic Review and Meta-Analysis of Randomized Controlled Trials — American Journal of Medicine, 2025
4. Improvement of Activity-Related Knee Joint Discomfort Following Supplementation of Specific Collagen Peptides — Applied Physiology, Nutrition, and Metabolism, 2017
5. Specific Collagen Peptides Improve Bone Mineral Density and Bone Markers in Postmenopausal Women: A Randomized Controlled Study — Nutrients, 2018
6. Collagen Peptide Supplementation in Combination With Resistance Training Improves Body Composition and Increases Muscle Strength in Elderly Sarcopenic Men: A Randomised Controlled Trial — British Journal of Nutrition, 2015
7. Exceptional Body Composition Changes Attributed to Collagen Peptide Supplementation and Resistance Training in Older Sarcopenic Men — British Journal of Nutrition, 2016
8. The Influence of Specific Bioactive Collagen Peptides on Knee Joint Discomfort in Young Physically Active Adults: A Randomized Controlled Trial — Nutrients, 2021
9. Oral Supplementation of Specific Collagen Peptides Combined With Calf-Strengthening Exercises Enhances Function and Reduces Pain in Achilles Tendinopathy Patients — Nutrients, 2019
10. Significant Amounts of Functional Collagen Peptides Can Be Incorporated in the Diet While Maintaining Indispensable Amino Acid Balance — Nutrients, 2019
11. Comparison of Gelatin and Low-Molecular Weight Gelatin Hydrolysate Ingestion on Hydroxyproline (Hyp), Pro-Hyp and Hyp-Gly Concentrations in Human Blood — Food Chemistry, 2022

Update history

• November 13, 2026New guide covering what collagen peptides are, how they’re absorbed, benefits for skin, joints, bones, muscle and tendons, how much to take, protein quality and how to choose, based on 2021 and 2025 skin meta-analyses, branded trials and a 2019 protein analysis.