By Dr. Eugene Capitano, DC, MSc
Protein powder is marketed as a convenient way to support fitness and nutrition goals. However, testing shows that some products may contain more than protein, including essential minerals, potentially toxic elements, heavy metals, and microplastic particles (González-Weller et al., 2023; Chen et al., 2026).
The evidence does not mean that every protein powder is dangerous. It does mean that product choice, serving size, frequency of use, ingredients, and independent testing matter more than the nutrition label alone.
Protein Powder Is Not Just Protein
A 2023 study of whey protein supplements found that these products supplied a wide range of minerals, including calcium, potassium, sodium, magnesium, iron, zinc, chromium, molybdenum, nickel, and aluminum. The researchers also found that measured protein content varied widely, from 18% to 92.3%, with statistically significant differences between declared and measured protein percentages (González-Weller et al., 2023).
The same study noted that labels generally emphasize protein while providing little information about other mineral components, including elements that may have established upper intake limits (González-Weller et al., 2023).
A separate 2026 study examined 30 sports protein supplements sold in China. Every sample contained at least one of the target metals tested, including arsenic, cadmium, lead, or mercury. The researchers also detected microplastics in every sample, ranging from 2 to 19 particles per 30-gram serving, with an average of approximately 8 particles per serving (Chen et al., 2026). Microplastic counts in food are technically difficult to measure and can be inflated by airborne contamination during sample handling, so this finding is best treated as an early signal that warrants replication rather than a settled figure.
The presence of a contaminant does not automatically prove that a product will cause illness. Health risk depends on the contaminant’s concentration, how often the product is consumed, the consumer’s body weight and health status, and exposure from other foods and environmental sources.
Heavy Metals Are the Central Concern
Heavy metals can enter protein products through contaminated soil, water, air, agricultural inputs, raw ingredients, and processing or packaging materials. Plants can absorb metals from soil and water, while contaminated animal feed, drinking water, or milk may also contribute to contamination in dairy-based products (Bandara et al., 2020; Clean Label Project, n.d.).
The metals most often discussed in the reviewed files were lead, cadmium, arsenic, and mercury. Long-term exposure to these metals has been associated with serious health effects, including neurological, kidney, reproductive, and carcinogenic risks at sufficiently high exposure levels (Bandara et al., 2020).
However, the results varied considerably between products.
The figures that follow come from the Clean Label Project, an independent nonprofit that tests consumer products and also sells a certification program to brands. Its reports are market screenings, not peer-reviewed research, and its practice of measuring against California Proposition 65 thresholds rather than federal limits has drawn criticism from some scientists and industry groups. The findings are worth knowing, but they should carry less weight than the peer-reviewed studies cited elsewhere on this page.
The Clean Label Project’s 2024–25 protein powder report described testing 160 products from 70 brands, representing approximately 83% of the market. It reported that 47% of the products exceeded at least one federal or state safety threshold, and 21% exceeded twice the California Proposition 65 threshold for lead (Clean Label Project, n.d.).
The report also found higher average contamination in certain product categories. Plant-based powders showed more lead than whey-based alternatives, organic products showed higher average lead and cadmium than non-organic products, and chocolate-flavored powders showed more lead than vanilla-flavored products in that dataset (Clean Label Project, n.d.).
The report’s “Clean Sixteen” comparison also illustrated how uneven contamination can be. The five products with the highest contamination reportedly contained many times more heavy metals per serving than the 16 products identified as having non-detectable levels of lead, cadmium, mercury, and arsenic (Clean Label Project, n.d.).
These findings should not be interpreted as proof that all plant-based, organic, or chocolate products are unsafe. They show that marketing categories are not reliable substitutes for product-specific contaminant testing.
Recent Consumer Testing Raises Similar Questions
Consumer Reports tested 23 protein powders and ready-to-drink shakes in 2025. All products met or exceeded their labeled protein claims, but lead was the main contaminant of concern. Approximately 70% of the products contained more than 120% of Consumer Reports’ daily level of concern for lead, which it identified as 0.5 micrograms per day. Three products also exceeded the organization’s levels of concern for cadmium or inorganic arsenic (Consumer Reports, 2025).
The highest results were concentrated in several plant-based products. One product contained 7.7 micrograms of lead per serving, while another contained 6.3 micrograms per serving. Consumer Reports cautioned against consuming those products (Consumer Reports, 2025).
The organization also noted an important limitation: its results were based on multiple samples and lots purchased during a specific period. Contaminant levels may change between lots and may not reflect the current contents of every product carrying the same name (Consumer Reports, 2025).
Does This Mean Protein Powder Is Unsafe?
The answer is more nuanced than a simple yes or no. A 2020 human health risk assessment used data from previous Consumer Reports and Clean Label Project testing. It concluded that the modeled exposure from the products assessed did not create an increased non-carcinogenic risk and that protein powder contributed only a fraction of average daily exposure to arsenic, cadmium, lead, and mercury, even under a three-serving-per-day scenario (Bandara et al., 2020).
At the same time, the study found that risk was driven mainly by arsenic and cadmium in particular products. It also emphasized that risk assessment should consider total exposure from the diet and environment rather than treating the mere detection of a hazardous substance as proof of harm (Bandara et al., 2020).
A 2024 study of 25 protein supplements found cadmium concentrations ranging from 0.01 to 0.78 milligrams per kilogram. The researchers reported that estimated weekly cadmium intake exceeded the tolerable weekly intake set by the European Food Safety Authority. However, their broader screening metrics did not indicate appreciable non-carcinogenic or carcinogenic risk under the conditions modeled (Irshad et al., 2024).
Another study of 47 whey protein supplements estimated that consuming 30, 60, or 100 grams per day for 25 years produced a hazard index below one. The researchers estimated that the index would exceed one at approximately 115 grams per day under their specific assumptions (Bethencourt-Barbuzano et al., 2023).
The newer 2026 study produced a more cautionary result under heavier-use scenarios. Its modeled hazard index was 0.45 at 30 grams per day and 0.90 at 90 grams per day. In a probabilistic simulation, the 95th-percentile hazard index reached 1.28 under high-use conditions (Chen et al., 2026).
Taken together, the studies support caution rather than panic. Most users are unlikely to experience immediate harm from occasional use, but repeated consumption of highly contaminated products can add avoidable exposure.
How Consumers Can Reduce Exposure
1. Do Not Assume That “Natural” Means Contaminant-Free
Organic and plant-based labels describe how ingredients are produced or what type of protein is used. They do not guarantee low levels of lead, cadmium, arsenic, or other contaminants. In the Clean Label Project data, organic and plant-based products showed higher contamination averages than some alternatives (Clean Label Project, n.d.).
2. Look for Credible Third-Party Testing
Independent certification and batch testing can provide information that is not included in a standard nutrition label. Consumer Reports noted that some companies claimed independent testing or NSF certification, which includes limits for lead, inorganic arsenic, and cadmium (Consumer Reports, 2025).
A certification logo is not the same as a guarantee of zero contamination. Consumers should check what the certification covers and whether the manufacturer provides current batch-specific testing results.
3. Limit Unnecessary Servings
More protein powder means more exposure to everything else in the product. Avoid automatically increasing from one scoop to several scoops per day, especially when the powder is being used as a meal replacement.
Consumer Reports advised limiting exposure by reducing servings and avoiding products with the highest contaminant results (Consumer Reports, 2025).
4. Treat Proposition 65 Warnings as Information
A Proposition 65 warning does not mean that a product will cause immediate poisoning. It does indicate that the product may expose consumers to a chemical listed under California’s warning law. It should prompt consumers to investigate the product, serving frequency, and available testing information.
5. Be More Cautious During Pregnancy, Childhood, and Medical Treatment
Consumer Reports specifically recommended greater caution for children and people who are pregnant or may become pregnant. Anyone with kidney disease, a history of heavy-metal exposure, or a medically restricted diet should discuss regular supplement use with a healthcare professional (Consumer Reports, 2025).
6. Remember That Protein Powder Is Optional for Many People
Protein supplements can be useful for some athletes, older adults, or people who struggle to meet their nutritional needs. However, nutrition experts cited by Consumer Reports argued that many people already obtain enough protein from ordinary foods (Consumer Reports, 2025).
The Bottom Line
Your protein powder may be carrying more than protein, but the headline should not be that every product is toxic. The stronger conclusion is that protein powders vary widely, and some have contained measurable levels of heavy metals or other contaminants.
A responsible choice means looking beyond protein grams. Consider the ingredient source, serving size, frequency of use, independent testing, warning labels, and the reliability of the manufacturer’s quality controls.
The best protein powder is not necessarily the one with the most aggressive health claims. It is the one that provides useful nutrition while offering credible evidence about what else is in the scoop.
Contaminants are one half of the label question. The other half — what the word “clean” actually tells you about sweeteners, emulsifiers, and flavour systems — is examined in The Clean Protein Myth: What Is Really Hiding in Your Protein Powder? on our Science Blog.
TLC PureOrigin™ does not rely on supplier claims alone. Every batch of raw ingredients is independently third-party tested before production, and every finished blend is tested again after final blending for heavy metals and microbiological contaminants.
Every bag of TLC PureOrigin™ protein carries a QR code linked directly to batch-specific testing records. Scan the QR code on your bag to access the testing records for your specific production batch.
Scan. Verify. Trust.
Author Information
Dr. Eugene Capitano earned an MSc in Psychology & Neuroscience of Mental Health from King’s College London. He holds the ACSM Exercise is Medicine® (EIM) Credential and is an ACSM Certified Personal Trainer® (ACSM-CPT®). His research interests include the gut–brain axis, functional nutrition, metabolic health, and translational microbiome science.
Medical and Nutritional Disclaimer
This information is provided for educational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. Individuals must consult a qualified healthcare provider or registered dietitian before making significant changes to their diet or exercise regimen.
References
Bandara, S. B., Towle, K. M., & Monnot, A. D. (2020). A human health risk assessment of heavy metal ingestion among consumers of protein powder supplements. Toxicology Reports, 7, 1255–1262. https://doi.org/10.1016/j.toxrep.2020.08.001
Bethencourt-Barbuzano, E., González-Weller, D., Paz-Montelongo, S., Gutiérrez-Fernández, Á. J., Hardisson, A., Carrascosa, C., Cámara, M., & Rubio-Armendáriz, C. (2023). Whey protein dietary supplements: Metal exposure assessment and risk characterization. Nutrients, 15(16), 3543. https://doi.org/10.3390/nu15163543
Chen, M., Dong, R., & Lai, W. (2026). Heavy metal and microplastic exposure from sports protein supplements: Integrated health risk modeling and scenario analysis. Environmental Research, 295, 123988. https://doi.org/10.1016/j.envres.2026.123988 (PMID 41655677)
Clean Label Project. (n.d.). CLP insights: 2024–25 protein powder category report. [Independent nonprofit testing report; not peer-reviewed.]
https://cleanlabelproject.org/wp-content/uploads/CleanLabelProject_ProteinStudyWhitepaper_010625.pdf
Consumer Reports. (2025, October 14). Protein powders and shakes contain high levels of lead. https://www.consumerreports.org/lead/protein-powders-and-shakes-contain-high-levels-of-lead-a4206364640/
González-Weller, D., Paz-Montelongo, S., Bethencourt-Barbuzano, E., Niebla-Canelo, D., Alejandro-Vega, S., Gutiérrez, Á. J., Hardisson, A., Carrascosa, C., & Rubio, C. (2023). Proteins and minerals in whey protein supplements. Foods, 12(11), 2238. https://doi.org/10.3390/foods12112238
Irshad, M., Ahmed, M., Ramzan, M., Fatima, M., Aftab, F., Sanaullah, M., Qamar, S., Iftikhar, Z., Wani, T. A., & Zargar, S. (2024). Appraisal of potentially toxic metals contamination in protein supplements for muscle growth: A chemometric approach and associated human health risks. Journal of Trace Elements in Medicine and Biology, 85, 127481. https://doi.org/10.1016/j.jtemb.2024.127481