Protein powder is one of the most popular dietary supplements in the U.S., generating $9 billion in 2023. While people use it for muscle gain, weight loss, endurance, or general health, they all complement and supplement their already healthy lifestyle choices and have certain safety and quality expectations. At Clean Label Project, rather than accepting safety as a given, we rely on data and science to reveal the truth behind what consumers are really ingesting, focusing on ensuring transparency and safety in the market.
Discover verified products tested by Clean Label Project, build smarter grocery lists, and stay informed with the latest health and food safety news.
Clean Label Project purchased and rigorously tested 165 of the top-selling protein powders, sourced from Nielsen and Amazon’s best-seller lists, and supplemented with top products from the natural and organic marketplace. It also assessed multiple panels of industrial and environmental contaminants. Collaborating with an analytical chemistry lab, Clean Label Project amassed 35,862 data points from 70 brands and 160 products to benchmark the findings.
Protein powders tested by Clean Label Project had an array of positive results for levels of arsenic, cadmium, lead, and mercury. However, 47% of products exceeded at least one federal or state regulatory set for safety, including CA Prop 65, and 21% of the samples were over 2X CA Prop 65 levels.
Heavy metals, such as arsenic, lead, mercury, and cadmium, are naturally occurring elements found in the Earth’s crust. They enter the environment through natural processes like volcanic eruptions, weathering of rocks, and soil erosion. Over time, they accumulate in air, water, and soil, where they can make their way into plants, animals, and eventually into human food sources. Though naturally occurring, the concentration of these metals can increase due to human activities such as mining, industrial processes, and agricultural practices, leading to higher exposure risks in food products.
Given the absence of federal regulations that require proactive testing to minimize the introduction into finished products, they can be unintentionally introduced into all foods and consumer products. Interestingly, certified organic products were found to have, on average, three times the lead compared to non-organic products. This was largely due to plant-based protein powders, which tend to contain higher levels of contaminants. Our studies continue to report chocolate as a high-risk ingredient.
Bisphenols, including BPA and BPS, are well-known endocrine disruptors with significant health risks. Research has shown that BPA can interfere with insulin tolerance, potentially undermining athletic training efforts for those using protein powders (Moon et al., 2015). Additionally, BPA is linked to metabolic issues, increasing the risk of type II diabetes (Le Magueresse-Battistoni et al., 2018). Fortunately, Clean Label Project’s 2023-2024 study found a significant improvement from 2018, with BPA and BPS detected in only 3 of 160 protein powder products, compared to 55% in previous tests. Plant-based protein powders were the most contaminated, containing five times more cadmium than their whey-based counterparts. Even the flavor of protein powder played a significant role in contamination levels. Chocolate protein powders, for instance, were found to have a staggering 110 times more cadmium [1] than vanilla-flavored varieties. Meanwhile, whey-based protein powders generally showed much lower contaminant levels, highlighting the variability in product safety depending on the protein source and flavoring.
| Heavy Metals (in ppb) | Dry (50 Samples) | Air & Freeze Dried (11 Samples) | Fresh/Frozen (18 Samples) |
|---|---|---|---|
| Arsenic Highest Sample | 785.7 | 362.6 | 57.0 |
| Arsenic Average | 184.6 | 148.5 | 13.9 |
| Cadmium Highest Sample | 246.1 | 247.9 | 20.6 |
| Cadmium Average | 68.5 | 69.3 | 11.3 |
| Mercury Highest Sample | 55.3 | 7.9 | 0.9 |
| Mercury Average | 3.8 | 2.4 | 0.2 |
| Lead Highest Sample | 1,576.5 | 194.4 | 16.9 |
| Lead Average | 180.1 | 53.9 | 8.5 |
| Phthalate (DEHP) (in ppb) | Dry (50 Samples) | Air & Freeze Dried (11 Samples) | Fresh/Frozen (18 Samples) |
|---|---|---|---|
| Highest Sample | 570.0 | 173.5 | 26.4 |
| DEHP Average | 53.5 | 42.7 | 4.9 |
| Acrylamide (in ppb) | Dry (50 Samples) | Air & Freeze Dried (11 Samples) | Fresh/Frozen (18 Samples) |
|---|---|---|---|
| Highest Sample | 780.0 | 103.8 | 24.7 |
| Acrylamide Average | 48.3 | 27.7 | 2.0 |
The Clean Label Project found an exceedingly high amount of arsenic, cadmium, mercury, and lead in dry, air-dried, and freeze-dried dog food. Because there are few regulations for dog food related to contaminants, Clean Label Project compared these findings to data from 3,280 food, beverage, and supplement samples tested over the past 10 years, using the averages to illustrate the elevated contaminant levels in dog food compared to human-consumable products. Over 85% of dog food owners feed their dog dry dog food.
Fresh/Frozen dog food samples we tested were lower in contaminants than our human consumables benchmark from over 3,280 products. Furthermore, on average, fresh/frozen dog food was found to have exponentially lower contaminants than dry dog food.
The difference in heavy metal levels in dry dog food vs. fresh/frozen dog food and human consumables is striking. Check the data out below!
Dry dog food has
more arsenic than human consumables and
13.3x
more arsenic than fresh/frozen dog food
Dry dog food has
3.2x
more cadmium than human consumables and
6.1x
more cadmium than fresh/frozen dog food
Dry dog food has
2.7x
more mercury than human consumables and
20.7x
more mercury than fresh/frozen dog food
Dry dog food has
12.7x
more lead than human consumables and
21.2x
more lead than fresh/frozen dog food
When a test result is typically applied to a serving size, the contamination result will often change to some degree. However, when it comes to dog food, we found that the impact of serving size doesn’t demonstrate much variation in the level of heavy metal contamination. Dog food, in general, has a very large serving size compared to human food. As the following serving size results table demonstrates, there was no significant difference in the test results variances between dry and fresh/frozen.
| Heavy Metals (in ppb) | Dry (50 Samples) | Air & Freeze Dried (11 Samples) | Fresh/Frozen (18 Samples) |
|---|---|---|---|
| Arsenic Highest Sample | 442.3 | 201.2 | 40.7 |
| Arsenic Average | 93.4 | 76.4 | 7.9 |
| Cadmium Highest Sample | 153.8 | 154.9 | 12.9 |
| Cadmium Average | 42.8 | 43.3 | 7.1 |
| Mercury Highest Sample | 34.6 | 4.9 | 0.06 |
| Mercury Average | 2.4 | 1.5 | 0.1 |
| Lead Highest Sample | 985.3 | 121.5 | 10.6 |
| Lead Average | 112.6 | 33.7 | 5.3 |
When we adjusted the raw data (above) to the recommended serving size, dry dog food is still exponentially higher in heavy metals than fresh/frozen. With the recommended serving size, Dry Dog Food has the highest heavy metal result:
There are no comprehensive federal regulations specifically addressing dietary exposure to industrial and environmental chemicals in dog food, as most safety measures concentrate on physical and microbiological contaminants.
The elevated levels of heavy metals in dry, air-dried, and freeze-dried dog food can originate from multiple sources. Based on our research, we believe three key ingredients are the primary contributors:
Meat by-products consist of the parts of an animal that remain after the cuts consumed by humans are removed. This includes organs such as the livers, lungs, kidneys, and spleens, as well as bones, and other tissues. The by-products are then processed to create a meat by-product meal, which is commonly used in many dry dog foods. Heavy metals tend to concentrate in the organs and bones, which leads to higher levels of these heavy metals in dog food.
Vitamin and mineral premixes are added to many dog foods to ensure pets get the essential nutrients they need. Vitamin and minerals can naturally contain or consist of trace metals. It remains unclear whether factors like country of origin, regulatory oversight, inspection practice (announced versus unannounced), and supply-chain complexity – where ingredients change hands multiple times, making traceability more difficult – have any impact. All of these areas merit further study.
Many dog foods include seafood and plant-based carbohydrates, but these ingredients can introduce heavy metals. Seafood often contains high levels of mercury, and certain grains and root vegetables can accumulate metals like arsenic from the soil, such as
arsenic in rice.
Individually, each one of these ingredients may contribute only minimally to heavy metal levels. However, when all three are combined in a single dry dog food product, their cumulative effect can result in a substantial increase in heavy metals.
Clean Label Project partnered with the independent analytical chemistry laboratory, Ellipse Analytics, to test six panels of industrial chemicals:
The heavy metals (arsenic, cadmium, lead, and mercury), were tested by Inductively Coupled Plasma – Mass Spectroscopy (ICP-MS); Phthalates were tested by Gas Chromatography – Mass Spectroscopy (GC-MS/MS); and Bisphenols, glyphosate, and pesticides were
tested by Liquid Chromatography – Tandem Mass Spectroscopy (LC-MS/MS).
The elevated levels of heavy metals in dry, air-dried, and freeze-dried dog food can originate from multiple sources. Based on our research, we believe three key ingredients are the primary contributors:
Meat by-products consist of the parts of an animal that remain after the cuts consumed by humans are removed. This includes organs such as the livers, lungs, kidneys, and spleens, as well as bones, and other tissues. The by-products are then processed to create a meat by-product meal, which is commonly used in many dry dog foods. Heavy metals tend to concentrate in the organs and bones, which leads to higher levels of these heavy metals in dog food.
Vitamin and mineral premixes are added to many dog foods to ensure pets get the essential nutrients they need. Vitamin and minerals can naturally contain or consist of trace metals. It remains unclear whether factors like country of origin, regulatory oversight, inspection practice (announced versus unannounced), and supply-chain complexity – where ingredients change hands multiple times, making traceability more difficult – have any impact. All of these areas merit further study.
Many dog foods include seafood and plant-based carbohydrates, but these ingredients can introduce heavy metals. Seafood often contains high levels of mercury, and certain grains and root vegetables can accumulate metals like arsenic from the soil, such as
Individually, each one of these ingredients may contribute only minimally to heavy metal levels. However, when all three are combined in a single dry dog food product, their cumulative effect can result in a substantial increase in heavy metals.
Our mission is to empower consumers by delivering accurate and reliable product information based on our testing and analysis of the products they purchase. This data enables consumers to make informed choices that prioritize safety and quality in the dog food they purchase.
“The love and joy a dog brings to a family are immeasurable,” said Molly Hamilton, Executive Director of Clean Label Project®. “Every dog owner should feel confident that the food they give their pup is nutritious and free from harmful substances.”
The following companies have dog foods that are Clean Label Project Certified®:
