Last reviewed October 28, 2026 by the Cellovi team.
The short answer
Collagen is the main structural protein in your skin, tendons and bones. Collagen peptides are collagen broken down into small pieces, and some of those pieces reach your blood intact after you drink them. Many trials found better skin hydration and elasticity after 8 to 12 weeks of daily use, and several found more comfortable joints during exercise. The research keeps building, and we grade it Growing. One scoop of Cellovi Collagen Peptides gives you 20 g. That covers the amounts used in skin studies, up to 12 g a day, and adds 18 g of protein to your day.*
Our grade: Growing for skin hydration and elasticity and for joint comfort during activity. Frontier for hair, nails and bone, a newer area of research.
Can you absorb collagen?
Yes, partly. Most collagen is digested into amino acids, like any protein. But some short collagen peptides survive digestion. After people drank collagen hydrolysate, peptides such as Pro-Hyp (prolyl-hydroxyproline) peaked in the blood within 1 to 2 hours (Iwai et al., 2005; Iwasaki et al., 2022).
So "you can't absorb collagen" is wrong, and so is "collagen goes straight to your skin." Your body uses the amino acids and peptides as building blocks and signals, and builds its own collagen where it's needed.
Skin: what the trials show
-
A review of 19 trials with 1,125 people, mostly women aged 20 to 70, found collagen improved skin hydration and elasticity compared with placebo. The effects showed after about 90 days (de Miranda et al., 2021). A larger 2023 review pooled 26 trials with 1,721 people and also found better skin hydration (Pu et al., 2023). A 2026 review of 35 trials found better hydration and elasticity too, and a stronger skin barrier, with less water lost through the skin. Elasticity was clearest by about 12 weeks (Batool et al., 2026).* In one trial, 2.5 g a day improved skin elasticity within 8 weeks (Proksch et al., 2014).
Our reading: skin hydration and elasticity have the strongest support, and results build over 3 months or more of daily use.*
Joints and tendons
Several trials in active adults found collagen peptides eased joint discomfort during activity:
- 139 athletes with activity-related knee discomfort took 5 g a day for 12 weeks and reported less discomfort during exercise than the placebo group (Zdzieblik et al., 2017).
- 182 healthy adults with knee or hip discomfort during daily activities saw improvements after 12 weeks at 5 g a day (Schulze et al., 2024).
- College athletes taking 10 g a day for 24 weeks reported less joint discomfort when walking (Clark et al., 2008).
- 218 active adults with knee discomfort during activity took 5 g a day for 12 weeks, and their discomfort during activity fell more than with placebo (Zdzieblik et al., 2021).
Collagen works best alongside regular movement, not instead of it.*
Hair, nails and bone
Research on hair, nails and bone is growing.
On bone, the strongest trial so far followed 131 postmenopausal women for 12 months: 5 g of specific collagen peptides a day supported bone mineral density at the spine and hip compared with placebo (König et al., 2018).*
Collagen and protein
Each scoop adds 18 g of protein. Collagen is rich in glycine, proline and hydroxyproline but contains almost no tryptophan, so it is not a complete protein (Paul et al., 2019). Think of collagen as a complement to dairy, eggs, fish, meat, soy or legumes, not a replacement.
With resistance training, collagen adds up: a 2024 review of 19 trials with 768 active adults found more lean mass than training alone, mostly at 15 g a day (Bischof et al., 2024).*
How to take it
- 1 scoop a day in coffee, tea, a smoothie or water. Collagen peptides are already broken down, and a 2025 study found the key peptides were absorbed as well from coffee as from water (Virgilio et al., 2025).
- Any time of day. Consistency matters more than timing.
- Give it 12 weeks for skin, and 12 weeks or more for joints.
- Skin studies used up to 12 g a day and joint studies 5 to 10 g, many with specific branded peptides. Ours is a general bovine collagen peptide at a full 20 g, and the large reviews that pooled many peptide types still found better skin hydration and elasticity. Each scoop also adds 18 g of protein to your day.*
Who should check with a doctor first
- Anyone with a red-meat or gelatin allergy (alpha-gal): bovine collagen can trigger reactions (Mullins et al., 2012).
- Anyone with a history of kidney stones or kidney disease: large amounts of collagen raise urinary oxalate (Knight et al., 2006).
- Anyone pregnant or breastfeeding, where there are no studies.
Collagen peptides are generally well tolerated; trials reported no meaningful side effects. They are made from bovine hide, so they are not vegetarian, vegan or halal-certified.
Where it fits in your day
Cellovi Grass-Fed Collagen Peptides is one ingredient, unflavored, $2.79 a scoop, with a 28-day supply option. Stir it into a Ceremonial Matcha latte, or add it to your morning coffee.*
Common questions
Can your body absorb collagen?
Yes, partly. Most is digested into amino acids, but some short collagen peptides reach the blood intact within 1 to 2 hours. Your body uses them as building blocks and signals.
How long does collagen take to work for skin?
Many trials found better skin hydration and elasticity after 8 to 12 weeks of daily use, and one large review saw the effects after about 90 days. Give it 12 weeks.*
Can I put collagen in hot coffee?
Yes. A 2025 study found the key peptides were absorbed as well from coffee as from water.
Is collagen a complete protein?
No. It has almost no tryptophan, so treat it as a complement to dairy, eggs, fish, meat, soy or legumes, not a replacement. Each scoop adds 18 g of protein.
Sources
- Iwai K et al. Identification of food-derived collagen peptides in human blood after oral ingestion of gelatin hydrolysates. Journal of Agricultural and Food Chemistry, 2005.
- Iwasaki Y et al. 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.
- Pu SY et al. Effects of oral collagen for skin anti-aging: a systematic review and meta-analysis. Nutrients, 2023.
- de Miranda RB, Weimer P, Rossi RC. Effects of hydrolyzed collagen supplementation on skin aging: a systematic review and meta-analysis. International Journal of Dermatology, 2021.
- Batool A et al. Oral collagen peptides and skin rejuvenation: a systematic review and an updated meta-analysis of randomized controlled trials. Journal of Cosmetic Dermatology, 2026.
- Proksch E et al. Oral supplementation of specific collagen peptides has beneficial effects on human skin physiology: a double-blind, placebo-controlled study. Skin Pharmacology and Physiology, 2014.
- Zdzieblik D et al. Improvement of activity-related knee joint discomfort following supplementation of specific collagen peptides. Applied Physiology, Nutrition, and Metabolism, 2017.
- Schulze C et al. Impact of specific bioactive collagen peptides on joint discomforts in the lower extremity during daily activities: a randomized controlled trial. International Journal of Environmental Research and Public Health, 2024.
- Clark KL et al. 24-week study on the use of collagen hydrolysate as a dietary supplement in athletes with activity-related joint pain. Current Medical Research and Opinion, 2008.
- Paul C, Leser S, Oesser S. Significant amounts of functional collagen peptides can be incorporated in the diet while maintaining indispensable amino acid balance. Nutrients, 2019.
- Virgilio N et al. Unravelling the bioavailability of amino acids and bioactive peptides from collagen hydrolysate in coffee in healthy volunteers. Food Research International, 2025.
- Mullins RJ et al. Relationship between red meat allergy and sensitization to gelatin and galactose-α-1,3-galactose. Journal of Allergy and Clinical Immunology, 2012.
- Knight J et al. Hydroxyproline ingestion and urinary oxalate and glycolate excretion. Kidney International, 2006.
- Zdzieblik et al. Randomized, placebo-controlled trial of specific collagen peptides and activity-related knee discomfort in active adults. Nutrients, 2021.
- König et al. Randomized, placebo-controlled trial of specific collagen peptides and bone density in postmenopausal women. Nutrients, 2018.
- Bischof et al. Systematic review and meta-analysis of collagen peptides with exercise training in healthy adults, 19 trials. Sports Medicine, 2024.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
