Why I Don't Recommend Collagen Supplements

I don't recommend collagen supplements, and I get asked about them a lot. The evidence that they work is weaker than the marketing suggests. Reaching for a tub of powder can distract from the real reasons skin, joints or energy levels change. And emerging research raises unanswered questions about how collagen, copper deficiency and iron accumulation may interact in the pancreas, where amylin can aggregate on the collagen matrix and damage insulin-producing cells.

Collagen is everywhere now: powders, gummies, coffee creamers, "beauty" drinks. The promise is simple and appealing. Collagen keeps skin firm, we lose it as we age, so swallow some more. Here's why it isn't that simple.

Swallowed collagen doesn't go straight to your skin

Collagen is a protein, and your gut treats it like any other protein. Stomach acid and digestive enzymes break it down into amino acids and small peptide fragments before it's absorbed.

Your body then builds its own collagen from the amino acid pool, wherever it decides it's needed. There's no mechanism that delivers the collagen in your coffee to the skin on your face. Some small fragments do reach the bloodstream and may act as signals, which is the industry's main argument, but whether that makes a real difference in people is exactly what the trials are trying to show.

The evidence looks better the closer it sits to the people selling it

When you pool every trial together, collagen appears to help skin a little. When you look only at independent or high-quality trials, the benefit disappears.

That's the finding of a 2025 meta-analysis in The American Journal of Medicine (Myung and Park), which pooled 23 randomised controlled trials with 1,474 participants. Across all studies, collagen was linked to modest improvements in skin hydration, elasticity and wrinkles. But in studies without industry funding, and in the higher-quality studies, there was no effect. The authors concluded there is currently no clinical evidence to support collagen supplements for preventing or treating skin ageing.

To be fair, supplement industry groups have challenged this paper, arguing some studies were misclassified by funding source. That debate is worth knowing about. But it also illustrates the problem: most collagen research is paid for by companies that make collagen.

Joints tell a similar story. In 2011 the European Food Safety Authority assessed a collagen hydrolysate joint health claim and found cause and effect had not been established. The claim was formally refused in 2012, which is why you won't see an authorised joint health claim on a UK collagen label today.

Collagen building blocks are rarely the missing piece

Most people eating enough protein already have the raw materials for collagen. What the body also needs is the machinery to assemble it, and that depends on nutrients a collagen powder doesn't fix.

• Whole food vitamin C is needed to stabilise new collagen. Without it, collagen is weak, which is why scurvy causes bleeding gums and poor wound healing. This is not the same as isolated ascorbic acid supplements. In a 1987 controlled study, young men taking 605 mg a day of ascorbic acid had a 21% drop in ceruloplasmin's oxidase activity, the function that moves iron. A later trial found 1,000 mg a day also reduced it.
• Copper activates lysyl oxidase, the enzyme that cross-links collagen and elastin fibres so tissue has strength and elasticity.
• Enough overall protein supplies the amino acids, and ordinary foods do this well.

A useful way to explain it: collagen powder adds more bricks, but whole food vitamin C and copper are part of the mortar. If the mortar is missing, extra bricks don't build a stronger wall.

This is the key point. Without lysyl oxidase, the body can't knit collagen and elastin together, and that knitting is what gives skin its strength and elasticity. Lysyl oxidase depends on copper. So to improve skin quality, more collagen is not the answer. Making sure the body can cross-link the collagen it already makes is.

Emerging research: collagen, amylin, copper and iron

This is the part of the story most people haven't heard. It isn't proven that collagen supplements cause harm, but the research raises questions that haven't been answered yet.

Amylin is a hormone made alongside insulin by the beta cells of the pancreas. In type 2 diabetes, amylin can misfold and clump into deposits that damage those cells.

• Collagen and amylin. A 2025 study in the Journal of the American Chemical Society (Hazari et al.) found that fibrillar collagen speeds up amylin clumping, and that collagen loaded with amylin caused beta cell death and reduced insulin secretion. Collagen I also increases in the pancreas as diabetes progresses.
• Copper and amylin. Several lab studies show copper binds amylin and slows its aggregation. A 2013 study found the copper–amylin complex protected pancreatic cells from amylin toxicity. Not every study agrees: one found copper increased toxicity under some conditions.
• Deficiency may strip the shield. If severe copper deficiency removes this protective binding, amylin would lose a stabiliser and be more prone to aggregate on the pancreatic collagen matrix, the process the 2025 study linked to beta cell death. This connection hasn't yet been tested directly. [1, 2]
• Iron and amylin. Higher body iron stores and iron overload have been linked to higher type 2 diabetes risk. In the lab, iron binds human amylin at the same site copper uses, changes how it aggregates, and the iron–amylin complex generates reactive oxygen species. Iron trapped inside cells is the kind most likely to drive this oxidative stress, and beta cells have relatively weak antioxidant defences.
• Copper deficiency and trapped iron. Copper is needed for ceruloplasmin, which moves iron out of tissues. In a 2011 case series, two of four patients with acquired copper deficiency had iron overload in the liver, and the other two had cirrhosis or advanced fibrosis. Copper-deficient animals build up iron in liver cells. When ceruloplasmin is missing entirely, as in the genetic condition aceruloplasminaemia, iron accumulates in the pancreas, retina and brain, and diabetes is a common feature.
• Copper deficiency and blood sugar. Copper-deficient rats show impaired glucose tolerance, and this has also been reported in volunteers deliberately depleted of copper.

Put together, these findings suggest a possible chain. Low copper removes a protection against amylin clumping and allows iron to build up, while collagen in the pancreas gives amylin a surface to aggregate on. What hasn't been studied is whether swallowing collagen supplements adds to this. Oral collagen is digested before it's absorbed, so it may not. But until someone looks, I don't think it's wise to add collagen on top of an unrecognised copper problem.

One finding seems to point the other way: studies tend to show people with diabetes have higher copper in their blood. But blood copper is a poor guide to copper status. Only a small fraction of the body's copper circulates in the blood; most is held in tissues such as the liver, brain, muscle and bone. Around 95% of blood copper is carried by ceruloplasmin, an acute-phase protein that rises with inflammation, infection, pregnancy and oestrogen, including HRT and the contraceptive pill. Zinc supplements and some medications also affect it, and immune cells use copper to kill pathogens. Type 2 diabetes involves chronic low-grade inflammation, so high blood copper may reflect inflammation rather than plenty of copper in the tissues. The question is always why copper is high, not just that it is.

My real worry: supplements can hide a problem worth finding

The biggest risk isn't the collagen itself. It's self-treating a symptom and missing its cause. Copper deficiency is a good example. It's usually described as uncommon, but I'd argue it's more common than we're led to believe.

• Many diets fall short. More than a quarter of adults in North America take in less copper than the estimated average requirement. Leslie Klevay, who has researched copper for decades, argues that food tables overestimate copper intake by an average of 77%.
• Blood tests can hide it. Ceruloplasmin rises with inflammation, pregnancy, the contraceptive pill and some medications, which can mask a deficiency and give falsely reassuring results.
• Connective tissue. The link is written into medical history. What is now called occipital horn syndrome was originally classified as Ehlers-Danlos syndrome type IX. It's a copper transport disorder that lowers lysyl oxidase activity, causing loose skin, hernias and hypermobile joints. Whether milder copper shortfalls contribute to the far more common hypermobility and connective tissue problems hasn't been properly studied.
• Heart disease. Klevay's copper deficiency theory of ischaemic heart disease, first proposed over 40 years ago, points to more than 80 similarities between copper- deficient animals and people with heart disease. It remains a hypothesis, but one that has never been properly ruled out.

Copper is absorbed mainly in the stomach and upper small intestine. A review of 55 published cases of copper deficiency myelopathy (Jaiser and Winston, 2010) found the most common causes were:

• Previous upper GI surgery, including gastric bypass, in almost half of cases. Symptoms often appeared years, even decades, after the operation.
• Too much zinc, from zinc supplements or zinc-containing denture creams. Zinc blocks copper absorption in the gut.
• Malabsorption, such as coeliac disease.

Copper deficiency can cause anaemia and low white cell counts. Because copper- dependent proteins help move iron around the body, the anaemia can look like iron deficiency and fail to improve with iron tablets. It can also cause numbness, tingling and unsteady walking that closely mimic B12 deficiency. Blood counts often normalise with treatment, but nerve damage may only partly recover, so early recognition matters.

If someone has had stomach surgery, takes zinc, or has anaemia that isn't responding to treatment, the answer is a conversation with their GP and the right blood tests, not another supplement.

Other reasons I'm cautious

• Light regulation. In the UK, collagen products are sold as food supplements. They don't need to prove they work before going on sale, and quality and dose vary between brands.
• Cost. A daily collagen habit can cost more over a year than a good diet change that actually delivers protein, healthy fats, whole food vitamin C and minerals.
• Not suitable for everyone. Collagen is usually made from cow, pig or fish skin and bones, which matters for vegetarians, vegans, some faiths and people with fish allergies. Vegan or algae "collagen" products usually contain no collagen at all. They're boosters, often containing zinc and ascorbic acid, the two things I've suggested avoiding.

What I recommend instead

Put the money and attention into the things with solid evidence behind them.

1. Don't smoke. Smoking damages collagen and slows wound healing.
2. Eat enough protein from a mix of foods: fish, eggs, dairy and meat.
3. Get whole food vitamin C from whole fruit and vegetables every day, rather than ascorbic acid supplements.
4. Include copper-containing foods such as nuts, seeds, wholegrains, shellfish and beef liver.
5. Keep blood sugar in check if you have diabetes. High glucose stiffens and damages existing collagen over time.
6. Do not take zinc supplements. Zinc blocks copper absorption, and you can get enough zinc from your diet. I don't recommend multivitamins or cold remedies either, as many contain hidden zinc.
7. See your GP about unexplained symptoms, especially tiredness, anaemia, tingling, balance problems, or easy bruising, and mention any stomach surgery or supplements you take.

If you take collagen, that's your choice. I just want you to know what the evidence does and doesn't show, and not to let a supplement replace the basics or a proper check-up.

Disclaimer and sources

This blog is for information, not medical advice. It reflects my reading of the research, and it isn't a substitute for advice tailored to you. If you're worried about your health or thinking about starting or stopping a supplement, talk to a clinician who knows your history.

• Myung SK, Park Y. Effects of collagen supplements on skin aging: a systematic review and meta-analysis of randomized controlled trials. The American Journal of Medicine, 2025.
• Industry responses to the Myung meta-analysis, NutraIngredients, August 2025.
• Commission Regulation (EU) No 379/2012, refusing the collagen hydrolysate joint health claim (EFSA Journal 2011;9(7):2291).
• Hazari MA et al. Faster amylin aggregation on fibrillar collagen I hastens diabetic progression through β-cell death and loss of function. Journal of the American Chemical Society, 2025.
• Lee EC et al. Copper(II)–human amylin complex protects pancreatic cells from amylin toxicity. Physical Chemistry Chemical Physics, 2013.
• Mukherjee S, Dey SG. Heme bound amylin: spectroscopic characterization, reactivity, and relevance to type 2 diabetes. Inorganic Chemistry, 2013.
• Hepatic iron overload or cirrhosis may occur in acquired copper deficiency and is likely mediated by hypoceruloplasminemia. Journal of Clinical Gastroenterology, 2011.
• Hassel CA et al. Impaired glucose tolerance in copper-deficient rats. Journal of Nutrition, 1983.
• Qiu Q et al. Copper in diabetes mellitus: a meta-analysis and systematic review of plasma and serum studies. Biological Trace Element Research, 2017.
• Jaiser SR, Winston GP. Copper deficiency myelopathy. Journal of Neurology, 2010.
• Neurological complications due to copper deficiency in Wilson disease treatment. Neurological Sciences, 2023.
• Ceruloplasmin. StatPearls, NCBI Bookshelf.
• Study of ethinyl oestradiol and norethisterone on plasma copper and zinc in post- menopausal women. Hormone and Metabolic Research, 1985.
• Copper deficiency. Canadian Medical Association Journal, 2025.
• Klevay LM. Copper nutriture and ischemic heart disease: a brief review. Medical Research Archives, 2022.
• Defining the clinical, molecular and ultrastructural characteristics in occipital horn syndrome. Genes, 2019.
• Jacob RA et al. Effect of varying ascorbic acid intakes on copper absorption and ceruloplasmin levels of young men. Journal of Nutrition, 1987.
• Tofighi M et al. The effect of ascorbic acid on serum level of copper, zinc, ceruloplasmin enzyme activity and iron parameters in men.
• Collins JF, Prohaska JR, Knutson MD. Metabolic crossroads of iron and copper. Nutrition Reviews, 2010.
• Alghrably M et al. Interaction of amylin species with transition metals and membranes. Journal of Inorganic Biochemistry, 2019.