Protein powders: heavy metals and how to choose wisely

Protein powder is a daily staple for millions of people looking to optimize health or physical performance. Yet several recent studies reveal that a large share of these products contain concerning levels of heavy metals, pesticides, and other contaminants. Oliver Andersen, co-founder of Puri, a Danish brand also based in the United States, explains what is happening, why it happens, and how to choose better.

The heavy metals problem

In 2025, several large-scale studies analyzed the best-selling protein powders in the United States. The result: 47 percent contained lead levels above the limit set by California's Proposition 65, the strictest standard in the country. That means those products would require a warning label to be sold in that state.

Lead reaches supplements primarily through the soil. Plant-based proteins such as pea or rice protein tend to concentrate more lead and cadmium than whey or other animal-based proteins. The concentration process inherent to manufacturing amplifies the problem: if the raw material contains trace metals, the final product may contain them at levels several times higher. If you consume one or two servings a day from a contaminated brand, you could be ingesting up to twenty times the recommended lead limit.

Cadmium appears more frequently in chocolate-flavored proteins because cacao seeds are especially prone to absorbing this metal from the soil.

Concentrate versus whey protein isolate

For years, whey protein isolate was considered the purest option due to its higher protein percentage. However, the isolation process also removes beneficial bioactive compounds such as lactoferrin and other proteins with immune-modulating properties.

Whey protein concentrate retains these elements and behaves more like a whole food. Many people who believed themselves lactose intolerant report no issues with high-quality whey from grass-fed, antibiotic-free cows, suggesting the problem may have more to do with other ingredients or low-quality raw materials than with lactose itself.

Natural flavors, fillers, and label transparency

The term "natural flavors" is a regulatory catch-all that can cover a wide variety of ingredients. In Europe, natural flavors must be derived directly from natural sources. In the United States, the designation covers a much broader spectrum.

Common fillers include artificial sweeteners, thickeners, and stabilizers. Not all are harmful (guar gum, for example, is essentially prebiotic fiber), but the presence of artificial additives at high doses is a warning sign about the overall quality of the product.

Fish oil: the oxidation risk

Omega-3 fatty acids are extremely sensitive to heat, light, and moisture. An oxidized (rancid) fish oil not only loses its beneficial properties but can generate pro-inflammatory compounds. There is up to a tenfold difference in oxidation levels between a quality supplier and a poor one.

A practical test: open a capsule and chew it. A strong fishy taste is a sign of high oxidation. However, manufacturers can mask the taste with flavorings, so a laboratory oxidation test remains the most reliable method. If you live in a warm climate, retrieve deliveries quickly and store fish oil away from heat and direct light.

How to choose wisely

The Clean Label Project is a nonprofit that analyzes supplements and foods for contaminants. Its largest protein powder study covered 160 products representing 83 percent of the U.S. market by sales, tested in accredited laboratories.

Practical steps to reduce your exposure:

• Look for brands that publish third-party lab reports per batch, not just generic certifications.
• Prefer animal-based whey protein over plant-based options if reducing heavy metal exposure is a priority.
• Scan the QR code on the packaging if available to access the analysis of the specific batch you are buying.
• Avoid blends from multiple sources without batch-level data for each ingredient.
• If you consume plant-based protein, choose brands that specifically document lead and cadmium levels per batch.

The regulatory landscape: Europe versus the United States

In the United States, supplements do not require pre-market registration. In Europe, there is more control over permitted ingredients and pesticide levels in the food chain, though the approval process is slower. Neither system automatically guarantees quality, but European chemical regulations provide a layer of protection that the U.S. system does not offer equivalently.

The takeaway is clear: regulation does not replace consumer responsibility. Demanding data from brands, seeking per-batch transparency, and choosing products with verifiable third-party reports is the most direct way to protect yourself.