The Downsides of Collagen Supplements

Collagen has taken the supplement world by storm. The global market grew 25% in 2019, and double-digit growth is expected in 2020, according to Gelita, the leading manufacturer of collagen products worldwide.

Some clinical studies show that collagen supplements can work, improving skin, joint and bone health. I won’t discuss effectiveness here. What I want to discuss is if there are any downsides to your health in taking these products. You’ll find almost nothing on the internet cautioning about the health risks of collagen.

Are collagen supplements bad for you?

There are 4 areas of concern:

  1. Tryptophan depletion leading to low serotonin, and consequently poor mood
  2. High histamine in histamine-sensitive individuals
  3. Contaminants and impurities
  4. Additives

1. Tryptophan depletion

Collagen is an incomplete protein; it is missing tryptophan. The issue is not only that collagen is devoid of this essential amino acid; but also that it causes active depletion of the tryptophan that you have.

In fact, scientific experiments designed to study the effects of low tryptophan feed subjects collagen to induce tryptophan depletion.

When ingesting an incomplete protein like collagen, your body uses up more tryptophan to make protein, to “catch up” to the other amino acids. In addition, the other amino acids out-compete tryptophan to cross the blood-brain barrier, further reducing the brain’s available amount.

What is wrong with low tryptophan?

Poor mood

Your body requires tryptophan to make serotonin, a neurotransmitter and hormone. Serotonin has a major impact on your mood. It is calming and helps you contend with stress. Low serotonin is associated with:

  • Anxiety, irritability, low self-esteem, depression
  • Eating disorders, OCD, PTSD
  • Poor sleep quality; insomnia

One of serotonin’s primary roles is to be calming. Low serotonin can mean greater anxiety, stress, or depression. It can also make depression may be more likely to occur in people who have experienced depressive episodes in the past.

For anxiety and depression, doctors will often prescribe an SSRI (like Prozac or Zoloft), which stands for selective serotonin reuptake inhibitor. SSRIs increase levels of serotonin to improve mood.

Low serotonin is also connected with other psychological conditions including eating disorders, OCD and PTSD.

Poor sleep

Serotonin is key to the creation of melatonin in your body. Melatonin is a hormone that regulates your sleep/wake cycle. Low melatonin leads to poor sleep and can even trigger insomnia.

Experts disagree

Some experts say that the tryptophan-depleting effects of collagen only occur if collagen is a person’s primary source of protein. See this video by nutrition blogger Chris Masterjohn, PhD. Chris says that if the body has sufficient access to complete protein, then this cascade need not occur. Note that Chris’ blog is sponsored by Ancestral Supplements, a maker of collagen products. Setting aside his potential bias, it can’t hurt to ensure that the collagen in your coffee is not a substitute for breakfast. Get plenty of non-collagen-derived protein every day.

Also, the effects are temporary. Tryptophan-depletion studies show that once the collagen is stopped, tryptophan levels return to normal.

To be clear, no study has proven that collagen supplements cause the above disorders. Serotonin’s actions in the body are complex and not completely understood. All we do know is that most collagen supplements, in the absence of complete protein, can deplete tryptophan.

On the other hand, there is evidence that collagen supplementation can trigger a cascade of events that lead to anxiety and sleeplessness; see the references below, and read more here at food-mood expert Trudy Scott’s website:

More studies are needed to understand these issues. If you are taking collagen supplements and find yourself experiencing symptoms like those mentioned above, you may want to stop the collagen for two-to-three months (to give your body time to adjust) to see how you feel.

Note: any mental illness should also be treated by a physician; do not delay in seeking professional help, even if you believe collagen may be part of the problem.

2. Collagen and histamine

A completely different concern with collagen is that it is high in histamine. Histidine is an amino acid in collagen that converts to histamine. Histamine overload can cause allergy-like symptoms, even if you are not allergic to it (see my article on histamine sensitivity here).  

In addition, many people take collagen in the hopes of healing a leaky gut. Unfortunately, because the gut contains a high concentration of mast cells, which release histamine, collagen supplements can lead to gut irritation in some people.

3. Contaminants and impurities

Collagen supplements are made from skin and bones (and sometimes hooves and horns) of cows and pigs. It may also be made from chicken cartilage, bones and feet; the scales of fish; and eggshells. In other words, all the leftover parts. Some might say that this honors the animal and is less wasteful. But one has to pause and wonder if this material is wholesome and consumable for human beings.

Acids and other chemicals like bleach are used to extract the collagen from these animal byproducts. The resulting matter is then dried and ground into a fine powder. It is a highly processed, let’s-face-it-gross, chemical affair. Even if you have a picture of a happy cow on your collagen supplement package, be assured it was not a petty process to create the product.

The concern here, however, is not the aesthetics of the process, but its healthfulness. Non-organic animals sourced for collagen may be fed poor quality food, antibiotics, or hormones that make their way into collagen supplements. Bovine collagen could be contaminated with pesticides, heavy metals or infections like bovine spongiform encephalitis (BSE) or other pathogens.

Also, chemical residue from processing could taint the final product. Supplements labeled grass-fed, pasture-raised, pesticide-free, free-range, or organic require our trust that these animals were treated as stated far back in the production chain, from factory farms to supplement manufacturers.

A recent whitepaper (March 2018) from the Clean Label Project calls for greater safety oversight of collagen supplements. One of its findings is that just 10% of the top-selling collagen supplements sold on amazon are labeled as organic.

The study tested 134 protein powder products from 54 brands and found:

  • 64% of the collagen products tested had measurable levels of arsenic
  • 17% of the collagen products tested had measurable levels of cadmium
  • 34% of the products tested positive for mercury but only at trace levels
  • 37% of the products tested had measurable levels of lead

What is so troubling about collagen supplements is that the manufacturers tout the benefits without disclosing any of these potential downsides. The way these products are made, and the potential health downsides, may be at odds with health-minded consumers’ values and goals.

Note: these products are likely not in violation of FDA safety rules. The FDA allows a certain level of contaminants that it considers safe. Whether they are correct in doing so is controversial. At a minimum, consumers deserve to be better informed, and I hope this article does its part to help.

4. Additives

Read the labels. Many collagen products add other nutrients, flavorings, or thickeners to their formulas. Make sure you want these additional ingredients, and that you are not overloading on any nutrient. For example, if your collagen powder contains added vitamin C, you may want to avoid taking any other vitamin C products. If you are watching your sugar, look out for added sweeteners.

Here are some examples of added ingredients in top-selling collage powder brands on Amazon as of this writing. Check out the biotin levels in the aptly-named Zeal brand:

Supplement Additive Examples:

Brand Additives to Collagen Base Formula
Vital Proteins Original Collagen Peptides• Vitamin C, 100mg (90% DV)
• Sodium, 110mg (5% DV)
• Hyaluronic Acid, 80mg
Nature’s Bounty Collagen Beauty Blend• Organic dried cane syrup
• Stevia
Physician’s Choice Collagen PeptidesDigestive Enzyme Blend (Proteases, Amylase, Cellulase, Lactase, Lipase, L. acidophilus)
Neocell Collagen Protein Peptides – Mandarin Orange• Vitamin C, 60mg (67%)
• Hyaluronic Acid, 30mg
• Amla fruit extract, 5mg
• Stevia
• Natural flavors
Zeal Multi Collagen• Vitamin C, 50mg (60%)
• Hyaluronic Acid, 50mg
• Biotin, 5,000mcg (16,670%)
Ancient Nutrition Multi Collagen – Chocolate• Organic cocoa
• Natural chocolate flavorings
• Stevia
• Xanthan gum
• Guar gum
Obvi Super Collagen Protein• Biotin, 100mcg (33%)
• Vitamin C, 90mg (100%)
• Vitamin E, 35mg (233%)
• Calcium, 47mg (4%)
• Iron, 3mg (18%)
• Magnesium, 23mg (5%)
• Natural and artificial flavors
• Salt
• Sucralose
• Silicon Dioxide
• Acesulfame Potassium

As you can see, you may be getting a lot more than just collagen in your supplement powder, including artificial ingredients. These ingredients aren’t necessarily harmful; just make sure you know what you are getting.

What should you do?

So does this mean you should ban collagen supplements from your life? Maybe. There are other ways to nurture your collagen production:

  • Get plenty of vitamin C, necessary to collagen production
  • Make sure you are meeting your daily requirements of copper and iron (do not exceed daily values); they also support collage production
  • Get adequate protein. Vegans can get a complete protein from eating a variety of plant-based foods including beans, lentils, whole grains, nuts, seeds and vegetables
  • Eat the rainbow. A wide variety of different-colored fruits and vegetables will supply your body with the antioxidants it needs to create collagen, and a range of phytonutrients to help protect your collagen
  • Avoid the sun, which can break down collagen (but you need some sunshine daily to create vitamin D)
  • Avoid refined carbs and sugar; they can cause inflammation, which can in turn break down collagen
  • Don’t smoke; smoking breaks down collagen

If you want to take collagen supplements

Here are some guidelines:

  • Choose a brand labeled organic, grass-fed and pasture-raised.
  • Find a brand that adds tryptophan to the product. They aren’t many, but here are two:
    • Giant Complete collagen. Currently sold out or unavailable on amazon and the Giant website
    • Progressive, a Canadian brand that used to be available on amazon but is no longer. It does not ship to the U.S.
  • Choose a brand that provides the amino acid breakdown on the label.
  • When using tryptophan-fortified collagen, make sure that the added tryptophan is in the right ratio to the other amino acids. According to the Institute of Medicine’s Food and Nutrition Board, tryptophan should be 0.7% of the total amino acids in a complete protein.
  • Alternatively, you can take a tryptophan supplement at the same time as your collagen supplement. Again, make sure you are taking it in the right ratio to the other amino acids in that supplement. You will have to do some math. Make sure you choose a high-quality brand of tryptophan. Consider choosing one approved by
  • Make sure that collagen isn’t your only source of protein.
  • Do not take more than one dose of collagen a day. If you expect to be eating a lot of high-histamine foods on a given day, you may want to forgo your collagen that day (unless you know you do not have a histamine sensitivity). More collagen is not better. According to Gelita, benefits accrue from taking small amounts regularly.
  • Consider choosing a brand with a positive review from, which provides independent, unbiased analyses of brand name products.

Special thanks to Trudy Scott for calling attention to the issue of low tryptophan caused by collagen supplements:

Interested in taking MSM for collagen support or to help with your arthritis? Learn about it here and whether you should take it.

Did you know you can order your own blood tests in most states to check your nutrient levels? Learn how here.

Looking for health info you can trust? Here are my favorite Health and Wellness blogs of 2021: the winners of my Wellie awards.


  2. Oesser, S., Adam, M., Babel, W., & Seifert, J. (1999). Oral administration of (14)C labeled gelatin hydrolysate leads to an accumulation of radioactivity in cartilage of mice (C57/BL). The Journal of nutrition129(10), 1891–1895.
  3. Liang, J., Pei, X., Zhang, Z., Wang, N., Wang, J., & Li, Y. (2010). The protective effects of long-term oral administration of marine collagen hydrolysate from chum salmon on collagen matrix homeostasis in the chronological aged skin of Sprague-Dawley male rats. Journal of food science75(8), H230–H238.
  4. Effects of Acute Tryptophan Depletion on Brain Serotonin Function and Concentrations of Dopamine and Norepinephrine in C57BL/6J and BALB/cJ Mice. Biskup CS, Sánchez CL, Arrant A, Van Swearingen AED, Kuhn C, et al. (2012) Effects of Acute Tryptophan Depletion on Brain Serotonin Function and Concentrations of Dopamine and Norepinephrine in C57BL/6J and BALB/cJ Mice. PLOS ONE 7(5): e35916.
  5. Klaassen, T., Klumperbeek, J., Deutz, N. E., van Praag, H. M., & Griez, E. (1998). Effects of tryptophan depletion on anxiety and on panic provoked by carbon dioxide challenge. Psychiatry research77(3), 167–174.
  6. Cowen, P. J., & Browning, M. (2015). What has serotonin to do with depression?. World psychiatry : official journal of the World Psychiatric Association (WPA)14(2), 158–160.
  7. Baumgarten, H. G., & Grozdanovic, Z. (1998). Role of serotonin in obsessive-compulsive disorder. The British journal of psychiatry. Supplement, (35), 13–20.
  8. Murrough, J. W., Czermak, C., Henry, S., Nabulsi, N., Gallezot, J. D., Gueorguieva, R., Planeta-Wilson, B., Krystal, J. H., Neumaier, J. F., Huang, Y., Ding, Y. S., Carson, R. E., & Neumeister, A. (2011). The effect of early trauma exposure on serotonin type 1B receptor expression revealed by reduced selective radioligand binding. Archives of general psychiatry68(9), 892–900.
  9. Leibowitz, S.F. The Role of Serotonin in Eating Disorders. Drugs 39, 33–48 (1990).
  10. Hajak, G., Huether, G., Blanke, J., Blömer, M., Freyer, C., Poeggeler, B., Reimer, A., Rodenbeck, A., Schulz-Varszegi, M., & Rüther, E. (1991). The influence of intravenous L-tryptophan on plasma melatonin and sleep in men. Pharmacopsychiatry24(1), 17–20.
  11. Ramsay, D. B., Stephen, S., Borum, M., Voltaggio, L., & Doman, D. B. (2010). Mast cells in gastrointestinal disease. Gastroenterology & hepatology6(12), 772–777.
  13. “Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids”. Food and Nutrition Board of Institute of Medicine, National Academies Press. 2005. p. 691.
  15. Jorgensen, L. N., Kallehave, F., Christensen, E., Siana, J. E., & Gottrup, F. (1998). Less collagen production in smokers. Surgery123(4), 450–455.
  16. DePhillipo, N. N., Aman, Z. S., Kennedy, M. I., Begley, J. P., Moatshe, G., & LaPrade, R. F. (2018). Efficacy of Vitamin C Supplementation on Collagen Synthesis and Oxidative Stress After Musculoskeletal Injuries: A Systematic Review. Orthopaedic journal of sports medicine6(10), 2325967118804544.
  17. O’Dell B. L. (1981). Roles for iron and copper in connective tissue biosynthesis. Philosophical transactions of the Royal Society of London. Series B, Biological sciences294(1071), 91–104.
  18. Katta, R., & Desai, S. P. (2014). Diet and dermatology: the role of dietary intervention in skin disease. The Journal of clinical and aesthetic dermatology7(7), 46–51.

Vicki Spellman

Vicki Spellman is a certified Holistic Nutritionist (AFPA) and Senior VP at a large healthcare communications firm.

Recent Posts