Updated 6 Aug 2025, Dr Matthew Jarvie-Thomas BM BCh MA (Hons) (Oxon)

1. What is the evidence for collagen supplements?

There are >25 randomised controlled trials (RCTs) for oral collagen supplements. When researchers combine the results of these trials (a meta-analysis), a clear picture emerges:

Two large meta-analyses for oral collagen included over 3000 participants. Participants took 2.5-10g of hydrolysed collagen over 2-4 months. In aggregate, these studies demonstrated:

• Skin elasticity improved 4-12%
• Wrinkle depth was reduced by 8-16%
• Skin hydration improved 8-15%
• Results were visible within 2-3 months
• Collagen supplements were extremely well-tolerated with minimal side effects. The most commonly reported was mild and transient bloating. No serious adverse events were reported.

The quality of this evidence, and the magnitude of the effects seen, put collagen supplements amongst the best-evidenced options for skin support at home. The weight of evidence far surpasses many of the more expensive, time consuming, and risk-laden alternative options that consumers are presented with.

2. Why 10 grams per day?
Most modern studies settle on 10g of hydrolysed collagen a day. Collagen supplements are extremely well tolerated at higher doses, but the recommended dose has to be weighed against potential risk of side effects and cost.

3. Why Hydrolysed?

Hydrolysed collagen has been "pre-digested" or broken down into peptides and amino acids. This dramatically improves absorption and bioavailability. Hydrolysed collagen is the version tested and supported by RCTs.

4. Marine vs Bovine vs Vegan Collagen

There isn't enough evidence to claim either marine or bovine collagen is significantly better than the other. Marine collagen contains a slightly higher concentration of type1 collagen, the most abundant type in the skin. Some small studies have suggested absorption of marine collagen is faster than bovine, but more work is needed here too.

"Vegan collagen" formulas are synthesised amino acids and not widely supported by high quality clinical trials. They are classified as novel food groups in many jurisdictions including the EU.

5. Why Vitamin C?

Vitamin C is an essential co-factor for collagen synthesis and stabilisation. Some studies have demonstrated a greater magnitude of improvement from taking collagen + vitamin C over taking just collagen alone. The literature we have suggests an ideal dose of >100mg per day.

6. What About Hyaluronic Acid?

Hyaluronic acid (HA) is strongly hydrophilic - it can hold 1,000 times its weight in water. In a 12-week study, oral supplementation with low-molecular-weight HA lifted skin hydration by 28%. The effects of oral collagen and HA are synergistic and complementary on paper, but further research is needed before we can claim the combination is a significant upgrade vs collagen alone.

6. B-Vitamins

Many B vitamins are also cofactors for collagen synthesis. In a state of deficiency of these vitamins, collagen synthesis is significantly impaired . Many collagen complexes include them as an insurance policy against these deficiencies.

References

1. 
   Effects of collagen supplements on skin aging: A systematic review and meta-analysis of randomized controlled trials. Am J Med. 2025;S0002-9343(25)00283-9. doi:10.1016/j.amjmed.2025.04.034 (PubMed)
   
2. 
   Effects of oral collagen for skin anti-aging: A systematic review and meta-analysis. Nutrients. 2023;15(9):2080. doi:10.3390/nu15092080 (PubMed)
   
3. 
   The efficacy and safety of CollaSel Pro® hydrolysed collagen peptide supplementation without addons in improving skin health in adult females: A double-blind, randomized, placebo-controlled clinical study using biophysical and skin imaging techniques. J Clin Med. 2024;13(18):5370. doi:10.3390/jcm13185370 (PMC)
   
4. 
   The effects of dietary supplementation with collagen and vitamin C and their combination with hyaluronic acid on skin density, texture and other parameters: A randomised, double-blind, placebo-controlled trial. Nutrients. 2024;16(12):1908. doi:10.3390/nu16121908 (PubMed)
   
5. 
   Oral supplementation with a new hyaluronic acid matrix ingredient improves skin brightness, hydration, smoothness and roughness: Results from a randomized, double-blinded, placebo-controlled study. Dermatol Ther (Heidelb). 2025;15(8):2099-2116. doi:10.1007/s13555-025-01447-6 (PubMed)
   
6. 
   Oral administration of hyaluronic acid to improve skin conditions via a randomized double-blind clinical test. Skin Res Technol. 2023;29(6):e13412. doi:10.1111/srt.13412 (PMC)
   
7. 
   Effect of intake of selected nutrients on skin firmness and elasticity in women. Front Nutr. 2024;11:1483678. doi:10.3389/fnut.2024.1483678 (PubMed)
   
8. 
   Oral nicotinamide reduces transepidermal water loss: A randomized controlled trial. Br J Dermatol. 2016;175(6):1363-1365. doi:10.1111/bjd.14648 (PubMed)
   

Regulatory Note:
This page summarises published scientific research. It does not claim that any specific product will prevent, treat or cure disease. Food supplements should sit alongside, not replace, a varied diet and healthy lifestyle.

(Prepared for educational purposes; last reviewed 6 Aug 2025.)