In case you haven’t noticed, collagen supplements are everywhere, with promises of younger looking skin, a very strong drawcard! I have often wondered whether these claims are backed by science, so I decided it was time to take a closer look. What I found was intriguing - here’s what I discovered.
Let’s start at the beginning. Collagen is a protein, and found in our skin, bones, blood vessels, and connective tissues throughout our body. It is continually being turned over, with an estimated half-life of between 2-5 months (4). As we age, collagen levels decline throughout our bodies because the fibroblasts that manufacture collagen produce less with time (1). In addition, collagen is often damaged by external factors like exposure to UV light, smoking, and ingestion of sugars and other foods that cause glycation (read more here). Like all proteins, collagen is made up of long chains of amino acids, but collagen contains particularly high levels of the amino acid glycine (around 33%), as well as proline (around 10%) and hydroxyproline (around 13.5%). This unusual amino acid composition is interesting - we’ll come back to it later.
What are collagen supplements made from?
Collagen supplements are extracted from animal tissues - predominantly the skin, bones and scales of cattle, pigs, fish, squid and jellyfish. It is chemically denatured to create gelatin, which may be further broken down by hydrolysation into free amino acids and small chains of amino acids known as peptides. Hydrolysed collagen is soluble in water and therefore more commonly used than gelatin in supplements.
What effects do collagen supplements have on skin?
This is where it gets both interesting and confusing. There have been a number of studies looking at the effects of collagen on the skin. However because of variability in study design and the composition of the supplements used in the studies, it can be difficult to know what to make of them. This is where a systematic review is helpful.
A systematic review (2) of 19 studies showed that overall, hydrolysed collagen supplements resulted in improvements in skin wrinkles, elasticity and hydration. However, each of the studies used different collagen preparations - collagen was given alongside additional substances including vitamins, minerals, antioxidants, hyaluronic acid, chondroitin sulphate and/or coenzyme Q10. So it is possible that these other substances worked with or enhanced the effects of the collagen. What’s more, although improvement in the appearance of the skin was evident, it was not demonstrated that levels of collagen in the skin had increased. For example, the reviewers pointed out that a reduction in wrinkles and increased elasticity could be due to improved hydration, and not necessarily due to more collagen being produced in the skin.
So yes, taking collagen supplements does seem to improve the appearance of the skin, but the studies so far have been complicated because most have tested collagen together other substances. What’s more, we don’t know for sure whether collagen supplements result in more collagen being produced in the skin. Overall, however, the results are promising.
How could collagen supplements be working?
We mentioned earlier that collagen has an unusual amino acid composition. Collagen is unusually rich in the amino acid glycine, as well as proline and hydroproline. Glycine is an amino acid that is not abundant in animal protein (4). Although humans can synthesise glycine, it was recently shown that our ability to do so is more limited than first thought (3, 4). Therefore, it’s possible that most diets are deficient in key amino acids needed to support the synthesis of new collagen. If so, collagen supplements that are, by nature, rich in glycine and proline could be providing these key amino acids, overcoming the rate-limiting step for collagen production.
There is also some evidence that collagen-derived peptides could directly stimulate collagen synthesis, although this has not been demonstrated in clinical trials (5).
I’m vegetarian or vegan - what are my options?
As you probably already know, you can’t get collagen from plants. All the same, there are vegan supplements on the market with ‘collagen’ in the title. I’ve checked out a few and they seem to contain either (i) collagen-supporting nutrients like zinc, vitamin C or pro-vitamin A, but with no added protein or amino acids, or (ii) plant derived proteins claiming to deliver a similar amino acid profile to collagen, together with collagen-supporting nutrients. To my knowledge, there have not been any proper studies looking at whether any of the vegan supplements improve skin health.
If, like me, you prefer plant-based foods, and you like the hypothesis that collagen is boosted by supplementing glycine and proline, you can boost your intake of these amino acids by eating more soy-based products, asparagus, black beans, cabbage, cashews, chia seeds, kidney beans, mushrooms, peanuts, pistachios, pumpkin seeds, seaweed, and sunflower seeds (6).
Interestingly, a study looking at the effect of diet on the blood levels of different amino acids showed that vegans had the highest blood levels of glycine, followed by fish-eaters and vegetarians, whereas meat-eaters had the lowest concentrations (7). This could reflect the fact that meat and dairy products contain relatively low levels of glycine.
What’s your final word?
The evidence that collagen supplements help improve the appearance of skin is clear. However, we still don’t know exactly what the collagen supplements are doing - in particular, we don’t know for sure that new collagen is being laid down in the skin. What’s more, some of the benefits of collagen supplements could be from ingredients other than collagen - the vitamins, minerals and other bioactives that were added to the collagen in the studies.
At the same time, recent science suggests that we might be deficient in two key amino acids (glycine and proline) needed for collagen synthesis, and collagen supplements are naturally rich in these amino acids. So overall, there’s a strong case that collagen supplements could work by boosting our production of collagen.
Will I be taking collagen? No - I prefer to stick to a plant-based diet. And a comforting thought: if it’s true that collagen supplements work by supplying the amino acids that are possibly lacking in a standard meat-based diet, my plant-based diet could well be providing all the nutrients I need already.
(1) Varani, J. et al. ‘Decreased collagen production in chronologically aged skin.’ (2006) Am. J. Pathol. 168:1861-1868
(2) de Miranda, R.B. et al. ‘Effects of hydrolysed collagen on skin ageing: a systematic review and meta-analysis. (2021) Int. J. Dermatol. 60:1449-1461
(3) Melendez-Havia, E. et al. ‘A weak link in metabolism: the metabolic capacity for glycine biosynthesis does not satisfy the need for collagen synthesis.’ (2009) J. Biosci. 34:853-72
(4) Holwerda, A. M. and van Loon, J.C. ‘The impact of collagen protein ingestion on musculoskeletal connective tissue remodelling: a narrative review.’ (2022) Nutrition Reviews 80:1497-1514
(5) The effect of a 12-week dietary intake of food supplements containing collagen and MSM on dermis density and other parameters: A double-blind, placebo-controlled, randomised four-way study comparing the efficacy of three test products.’ (2023) Journal of Functional Foods. 100
(7) Schmidt, J.A. et al. ‘Plasma concentrations and intakes of amino acids in male meta-eaters, fish-eaters, vegetarians and vegans: a cross-sectional analysis in the EPIC-Oxford cohort. Eur. J. Clin. Nutr. (2016) 70:306-312.