Heavy metals in Protein powder

This page draws on evidence from FDA, together with 7 peer-reviewed studies and 2 other cited sources. The complete citation list is at the bottom of the page.

Overview

This provisional ingredient page records source-specific measurements for protein powder. Its population contamination profile has not been synthesized. The direct answer uses the FDA table on this page and the market screens it cites. Those figures are not a synthesized population range. See Ingredients for the ingredient inventory.

Heavy metal contamination profile

The profile fields remain pending until an evidence synthesis supports a population estimate. Source observations are listed separately below. The FDA Total Diet Study table later on this page is unchanged.

Reported measurements

Bandara and colleagues report micrograms per serving, not per kilogram. Consumer Reports set, Table 1: whey protein (n=11) total arsenic 0.40 to 1.80, cadmium not detected to 1.30, lead not detected to 1.63, and mercury not detected to 0.37. Weight gainer (n=4): total arsenic 3.73 to 5.63, cadmium not detected to 1.87, lead not detected to 4.50, and mercury not detected to 0.23. Clean Label Project set (n=133), Table 3 medians: total arsenic 0.55, cadmium 1.44, lead 0.08, and mercury 0.61. The same table prints 95th percentiles of 2.17, 6.84, 0.21, and 2.26, and maxima of 3.42, 13.18, 0.97, and 5.31. The note states arsenic is total arsenic. The authors cite USP 2012 elemental-impurity permitted daily exposures of arsenic 15, cadmium 5, lead 10, and mercury 15 µg/day, and a CDC blood-lead guidance of 5 µg/dL. Those figures are the authors’ comparators. A human health risk assessment of heavy metal ingestion among consumers of protein powder supplements

Clean Label Project’s 2024-25 report, 160 products, prints the share of products above the California Proposition 65 lead reference used in the report: all products 47 percent, and 21 percent above twice that reference. Plant-based powders 77 percent. Whey powders 28 percent. Collagen powders 26 percent. Organic powders 79 percent, with 41 percent above twice the reference. Chocolate-flavored powders 65 percent, with 29 percent above twice the reference. The note also states that certified-organic products averaged three times the lead and twice the cadmium of non-organic products, plant-based powders averaged three times the lead and five times the cadmium of whey-based powders, and chocolate-flavored powders averaged four times the lead and 110 times the cadmium of vanilla-flavored powders. The report does not print per-product concentrations. CLP Insights: 2024-25 Protein Powder Category Report (Protein Study 2.0)

The Canadian Food Inspection Agency 2018-19 survey, protein powders (n=195), ppm, means from quantifiable results only. Arsenic: 84 percent positive, mean 0.028, range below the limit of detection to 0.214. Cadmium: 82 percent positive, mean 0.060, range below the limit of detection to 0.219. Lead: 71 percent positive, mean 0.035, range below the limit of detection to 0.237. Mercury: 50 percent positive, mean 0.003, range below the limit of detection to 0.022. The note states that one brown rice protein powder reached 0.022 ppm mercury, the survey maximum. The arsenic column is the table’s arsenic column. The note’s later routing line calls the survey arsenic total arsenic. Toxic Metals in Selected Foods – April 1, 2018 to March 31, 2019: Food chemistry – Targeted surveys – Final report Rice protein results from that survey and from later retail and government tables are on Rice protein. Pea protein results are on Pea protein.

The cited market screens do not identify or rank retail brands here. Clean Label Project’s 2024-25 report screened 160 products from 70 top-selling US brands, approximately 83 percent of the US protein supplement market, at Ellipse Analytics. It reported that 47 percent exceeded the California Proposition 65 lead reference used in the report and 21 percent exceeded twice that reference. Plant-based powders were at 77 percent, certified-organic powders at 79 percent (41 percent over twice the reference), and chocolate-flavored powders at 65 percent (29 percent over twice the reference), while whey-based powders were at 28 percent and collagen-based powders at 26 percent. Sub-cohort sample sizes were not disclosed. Certified-organic products averaged twice the cadmium of non-organic products, plant-based powders averaged five times the cadmium of whey-based powders, and chocolate-flavored powders averaged 110 times the cadmium of vanilla-flavored powders (1).

A reanalysis of two earlier third-party sets without brand names used a Consumer Reports dataset from 2010 (15 products) and a Clean Label Project dataset from 2018 (133 products). The latter had medians of 0.55 µg total arsenic, 1.44 µg cadmium, 0.08 µg lead, and 0.61 µg total mercury per serving. Whey-protein total arsenic was 0.40 to 1.80 µg per serving (n=11), and weight-gainer total arsenic was 3.73 to 5.63 µg per serving (n=4) (2).

FDA Total Diet Study food 510, three protein-powder composites, measured lead at 5.7 to 7.9 µg/kg and cadmium at 8.1 to 22 µg/kg. Total mercury was not detected in any composite (reporting limit 1 µg/kg) (3). The Canadian Food Inspection Agency 2018-19 survey of 195 protein powders, with means calculated from quantifiable results only, reported mean lead of 0.035 ppm (mg/kg) and mean cadmium of 0.060 ppm (mg/kg). Lead was detected in 71 percent of protein powders, and one brown rice protein powder had 0.022 ppm total mercury, the survey maximum (4).

Protein powder metals and gut studies that did not use a powder serving

Protein powders on this page are reported as arsenic, cadmium, lead, and mercury in a serving or in a survey lot. The gut records below are urinary arsenic, larval zebrafish water, rat cadmium chloride, tooth and maternal blood lead, and a review of methylmercury metabolism. A powder brand should not convert a biomarker or a review into a per-serving microbiome claim.

Hoen et al. 2018 related urinary total arsenic at 6 weeks to stool microbiota in 204 infants in the New Hampshire Birth Cohort Study. Urinary total arsenic had median 0.4 µg/L and mean 0.63 µg/L. Feeding-stratified means were 0.5 µg/L in exclusively breastfed infants, 0.9 µg/L in mixed-fed infants, and 1.2 µg/L in formula-only infants. Overall composition was marginally associated with natural-log urinary arsenic after adjustment for feeding and urine specific gravity (pseudo-F 1.85, p = 0.05). The clearest association was in formula-fed males (n = 33, pseudo-F 2.30, p = 0.008). Formula-fed females (n = 23) did not show that association. The direction is an early-life arsenic biomarker toward infant gut microbiota. Urinary arsenic is not a concentration in this ingredient.

Dahan et al. 2018, per WikiBiome source summary, DOI 10.3389/fmicb.2018.01323, exposed larval zebrafish to 10, 50, and 100 ppb arsenic in water for 20 days. Arsenic exposure explained 54.7 percent of the variance in overall bacterial composition. The class 1 integron relative copy number at the highest concentration was 9 times the control value. The note does not state whether the dissolved arsenic was inorganic or total, and it does not give the number of larvae. The direction is arsenic in water toward the larval microbiome. The model is not a human gut, and the summary does not support an arsenic concentration in food.

Liu et al. 2023, per WikiBiome source summary, DOI 10.3389/fvets.2023.1219729, exposed Sprague-Dawley rats to cadmium chloride for 30 days. The note states lower intestinal ZO-1, higher TNF-alpha and IL-6 in intestine and blood, and Muribaculaceae in blood that was absent in the unexposed group. The note does not print the dose or the number of rats. The direction is cadmium toward gut and blood microbiota and barrier markers.

Sitarik et al. 2020 measured tooth lead and stool microbiota at 1 month and 6 months in 146 maternal-child pairs in the Detroit-area WHEALS cohort. In utero tooth lead was associated with fungal community composition at 1 month. Lead was not associated with overall bacterial community structure. Taxon-level bacterial shifts were higher Collinsella at 1 month, higher Bilophila at 6 months, and lower Bacteroides. The direction is lead exposure toward microbiota composition. Tooth lead is a biomarker, not a concentration in this ingredient.

Eggers et al. 2023, per WikiBiome source summary, DOI 10.3389/fmicb.2023.1193919, followed 123 children in the Mexico City PROGRESS cohort. Maternal blood lead means were 33.6 µg/L in the second trimester and 34.9 µg/L in the third. Stool metagenomes at ages 9 to 11 showed lower Bacteroides caccae with lead exposure. Weighted quantile sum regression gave a negative overall mixture effect (beta = -0.17) in both trimesters. The direction is prenatal lead toward the childhood gut microbiota. The summary does not support a lead concentration in food.

Giambo et al. 2021, per WikiBiome source summary, DOI 10.3892/wasj.2021.90, screened 600 articles and included 97. For mercury, the note states that methylation and demethylation are a core process in methylmercury metabolism and that microbiota changes have been linked to neurodevelopmental effects in rat offspring. The note does not assign a new sample size to that mercury summary. The direction summarized is microbiota toward methylmercury metabolism, and exposure toward microbiota in the offspring studies. The review does not test this ingredient.

Study table

What remains uncertain

No study cited here fed protein powder or separated whey, plant, and collagen lots. Dahan and colleagues used larval zebrafish and did not name the arsenic species. Liu and colleagues do not print the cadmium dose. Giambo and colleagues review other papers. They do not print a mercury fraction, and the powder notes that report mercury do not all speciate methylmercury.

FDA TDS FY2018–FY2020 source observations

FDA measured the prepared foods named below. Each row describes that food and preparation, not every form of this ingredient. Values are µg/kg (ppb) on the FDA sample basis. ND means not detected; it is not a measured zero. Reporting limits can vary between composites. FY2018-FY2020 TDS Elements Analytical Results

References

Works cited in this page’s text, in first-appearance order. See Sources for this page’s source inventory. Each title links to a source record with bibliographic details, reported findings, and document provenance.

1. FY2018-FY2020 TDS Elements Analytical ResultsU.S. Food and Drug Administration · FDA Total Diet Study · 2022 · www.fda.govDataset
2. A human health risk assessment of heavy metal ingestion among consumers of protein powder supplementsBandara SB, Towle KM, and Monnot AD · Toxicology Reports · 2020 · doi.org/10.1016/j.toxrep.2020.08.001Peer-reviewed
3. CLP Insights: 2024-25 Protein Powder Category Report (Protein Study 2.0)Clean Label Project · 2025 · cleanlabelproject.orgIndustry
4. Toxic Metals in Selected Foods – April 1, 2018 to March 31, 2019: Food chemistry – Targeted surveys – Final reportCanadian Food Inspection Agency · 2020 · inspection.canada.caGovernment
5. Sex-specific associations of infants’ gut microbiome with arsenic exposureAnne G. Hoen, Juliette C. Madan, Zhigang Li, Modupe Coker, Sara N. Lundgren, Hilary G. Morrison, et al. · Scientific Reports · 2018 · doi.org/10.1038/s41598-018-30581-9Peer-reviewed
6. Exposure to arsenic alters the microbiome of larval zebrafishDahan D, Jude BA, Lamendella R, Keesing F, and Perron GG · Frontiers in Microbiology · 2018 · doi.org/10.3389/fmicb.2018.01323Peer-reviewed
7. Environmental cadmium exposure alters the internal microbiota and metabolome of Sprague-Dawley ratsLiu S, Deng X, Li Z, Zhou W, Wang G, Zhan J, et al. · Frontiers in Veterinary Science · 2023 · doi.org/10.3389/fvets.2023.1219729Peer-reviewed
8. Fetal and early postnatal lead exposure measured in teeth associates with infant gut microbiotaSitarik AR, Arora M, Austin C, Bielak LF, Eggers S, Johnson CC, et al. · Environment International · 2020 · doi.org/10.1016/j.envint.2020.106062Peer-reviewed
9. Prenatal lead exposure is negatively associated with the gut microbiome in childhoodEggers S, Midya V, Bixby M, Gennings C, Torres-Olascoaga LA, Walker RW, et al. · Frontiers in Microbiology · 2023 · doi.org/10.3389/fmicb.2023.1193919Peer-reviewed
10. Influence of toxic metal exposure on the gut microbiotaGiambo F, Italia S, Teodoro M, Briguglio G, Furnari N, Catanoso R, et al. · World Academy of Sciences Journal · 2021 · doi.org/10.3892/wasj.2021.90Peer-reviewed

Sources

Source records associated with this topic. Inclusion does not establish that every finding applies to this product or ingredient. References above identify works cited in the text.

Update history

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