Jared Hirschfield, Cathryn Bigham, National Center for Health Research
Protein powders have become increasingly popular in recent years among a wide range of people — from professional athletes to those too busy to grab a full meal. They assume that supplementing their diet with sports nutrition powders is a safe and easy way to add muscle faster and recover more quickly. Many of these products are advertised as “natural” or “organic” and promise immediate and dramatic results.
But are these supplements actually safe? In addition to protein, these powders often contain potentially harmful chemicals, and some are even contaminated with toxins and metals. How could that be? Under the Dietary Supplement Health and Education Act, no dietary supplements, including protein powders, are regulated by the FDA to make sure they are safe or effective.[1] There is also no requirement that supplements be tested to make sure they contain what the labels say they contain. Research has shown that many dietary supplements sold in major drug store chains, natural food stores, and respected online outlets do not contain what they are supposed to or contain ingredients not listed on the label.[2]
What’s in Your Protein Powder?
When comparing and purchasing sports nutrition powders, consumers should pay close attention to the list of ingredients. Additives, such as caffeine, creatine, and sweeteners, are sometimes in these powders but are not mentioned in advertisements. When consumers are unaware of these additives, they can be especially harmful. For example, consuming several cups of coffee or tea throughout the day in addition to a protein powder that contains caffeine could have unpleasant side effects, including tremors, migraines, and insomnia.[3] Creatine, a popular sports supplement, increases the amount of water in your muscle cells, leading to significant weight gain and putting you at a higher risk for dehydration, stomach pain, and muscle cramping.[4][5] Creatine can be particularly dangerous for people with kidney or liver disease and has not been studied for safety in children or adolescents under the age of 18.[6] In addition, the American Heart Association recommends a daily added sugar limit of 25 to 36 grams, but some protein powders have as much as 23 grams of added sugar per scoop.[7,8] Others contain artificial sweeteners like sucralose or aspartame, which can be harmful in large quantities. For these reasons, consumers need to know exactly what is in their daily protein shakes and how it may affect their health.
Toxins and Contaminants
Unfortunately, looking through the list of ingredients sometimes isn’t enough. The Clean Label Project conducts Protein Powder Category Reports. Their report from 2024-25 tested 70 of the best-selling protein powder brands for pesticides, heavy metals, bisphenol A (BPA), and other unsafe contaminants.[9] California Proposition 65 lists limits to chemicals that can be harmful to health. The Clean Label report showed 47% of the protein powders exceeded at least one California Proposition limit for heavy metals. 21% of the samples were more than twice as high as the maximum Proposition levels of safety.[9] These heavy metals can cause permanent health concerns, including kidney and brain damage.[9,10] Surprisingly, “organic” products contained about twice as much cadmium and three times as much lead as their non-organic counterparts. [9]
In 2018 The Clean Label Project detected BPA in about half of the examined powders.[11] BPA is a product that disrupts the endocrine system and causes many health issues. Fortunately, in their 2023-2024 protein powder study, they found that only 3 of 160 protein powders contain either BPS or BPA. This is an important improvement, but they did not study all the powders that may be on the market today. They also fail to list the three powders that do contain BPA.[9]
Many Americans consume these powders as part of a healthy, exercise-filled lifestyle, not realizing that the contaminants have the potential to cause serious and potentially irreversible damage to their bodies. The Clean Label Project lists the top 16 powders that did not detect lead, cadmium, mercury, or arsenic. Most of them are whey proteins.
What Should You Do Instead?
Many Americans think that more protein is better. The recommended daily allowance (RDA) is 0.8 grams of protein per kilogram of body weight.[12] According to this guideline, someone who weighs 140 pounds should consume roughly 50 grams of protein per day, the equivalent of 6 ounces of lean meat, 5 ounces of nuts, or 20 ounces of tofu. Contrary to common belief, consuming much more than recommended amounts of protein can actually have harmful effects on your bones, kidneys, and liver.[13]
Aside from rare cases, no one needs protein supplements to reach their fitness goals. A diet rich in whole foods like legumes, nuts, and soy products provides plenty of protein to build muscle. By maintaining a well-balanced, nutritious diet, you can live healthily while avoiding the hidden ingredients and contaminants of sports nutrition powders.
The Bottom Line
Protein powders often contain hidden ingredients and dangerous contaminants. If you are going to use a protein supplement, remember that these are largely unregulated products. If you experience any unusual side effects, stop using the product immediately and consult with your physician.
[1] “Dietary Supplement Health and Education Act of 1994.” National Institutes of Health: Office of Dietary Supplements (U.S. Department of Health and Human Services). https://ods.od.nih.gov/About/DSHEA_Wording.aspx
[2] Shmerling, R. H. S. “What’s in your supplements?“ Harvard Health. 15 February 2019. https://www.health.harvard.edu/blog/whats-in-your-supplements-2019021515946
[3] “Caffeine: How much is too much?” Mayo Clinic. 19 March 2022. http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/caffeine/art-20045678?pg=1
[4] Powers, M.E. et al. “Creatine Supplementation Increases Total Body Water Without Altering Fluid Distribution.” Journal of Athletic Training, 38(1). 2003. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC155510/
[5] “Creatine.” Mayo Clinic. 13 December 2023. https://www.mayoclinic.org/drugs-supplements-creatine/art-20347591
[6] “Creatine Information | Mount Sinai—New York.” (n.d.). Mount Sinai Health System. Retrieved February 21, 2025, from https://www.mountsinai.org/health-library/supplement/creatine
[7] “Added Sugars.” American Heart Association. 02 August 2024. http://www.heart.org/en/healthy-living/healthy-eating/eat-smart/sugar/added-sugars
[8] “The hidden dangers of protein powders.” Harvard Health Publishing. 15 August 2022. https://www.health.harvard.edu/staying-healthy/the-hidden-dangers-of-protein-powders
[9] “CLP Insights: 2024-25 Protein Powder Category Report.” Clean Label Project. https://cleanlabelproject.org/wp-content/uploads/securepdfs/CleanLabelProject_ProteinStudyWhitepaper_010625.pdf
[10] “Heavy Metal Poisoning.” National Organization for Rare Disorders. 24 October 2024. https://rarediseases.org/rare-diseases/heavy-metal-poisoning/
[11] “2018 Protein Powder Study.” Clean Label Project. https://www.cleanlabelproject.org/protein-powder/
[12] Pendick, Daniel. “How much protein do you need every day?” Harvard Health Publishing. 22 June 2023. https://www.health.harvard.edu/blog/how-much-protein-do-you-need-every-day-201506188096
[13] Delimaris, Ioannis. “Adverse Effects Associated with Protein Intake above the Recommended Dietary Allowance for Adults.” ISRN Nutrition. 18 July 2013. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4045293/#B1