Does Krill Oil Contain Heavy Metals? A Deep Dive into Purity

January 7, 2026 •

3 min read

A 2021 study showed that krill, despite their place low on the food chain, can accumulate heavy metals. This raises questions about product safety: does krill oil contain heavy metals, and what measures ensure quality?

Quick Summary

This article examines factors impacting krill oil purity, including source and processing. It explains the potential for heavy metal contamination and highlights the importance of third-party testing and certifications.

Key Points

Low on the Food Chain: Krill's position minimizes but does not eliminate the risk of heavy metal bioaccumulation, a common misconception.
Sourcing Matters: The origin of the krill is critical; sourcing from pristine Antarctic waters significantly reduces contamination risk.
Third-Party Testing: Reputable manufacturers use third-party testing and certifications (like IFOS) to verify purity and potency.
Look for Certifications: Consumers should check for certifications like MSC and IFOS to ensure products are sustainably sourced and tested for contaminants.
Purity Depends on Quality Control: The cleanliness of a krill oil product is ultimately a result of the manufacturer's quality control, not just the source animal.
Astaxanthin is a Natural Advantage: Krill oil contains natural astaxanthin, a potent antioxidant that helps protect the oil from oxidation and rancidity.

Concerns over heavy metal contamination, especially mercury, in marine supplements are common. Krill oil, from shrimp-like crustaceans in Antarctic waters, is often promoted as a safer alternative to fish oil. Krill's diet of phytoplankton avoids the bioaccumulation of toxins. However, no part of the marine ecosystem is entirely isolated from contamination. Studies on krill oil supplements have revealed varying results concerning heavy metal levels. Some research found mercury, lead, and cadmium levels below limits. Yet, other studies found that some krill oil samples exceeded tolerable limits for lead and sometimes arsenic. These findings demonstrate that contamination risk depends on sourcing and manufacturing standards.

The Myth of Absolute Purity

While krill minimizes biomagnification risk, industrial pollutants mean no part of the ecosystem is free from contamination.

Why Contamination Can Occur

Environmental Factors: Pollutants can travel globally.
Harvesting and Processing: Improper techniques can introduce contaminants. For instance, if the krill's shell is not removed immediately after harvesting, fluoride can migrate into the oil.
Adulteration: Some low-quality krill oil products may be blended with cheaper, less pure oils, including fish oil, without proper labeling.

The Role of Testing and Certifications

Consumers should rely on a manufacturer's commitment to transparency and testing. Reputable brands go beyond relying on the krill's natural purity and implement strict quality control measures to guarantee a safe final product. Third-party certification is key.

How to Verify Purity

Check for Certifications: Look for seals from third-party organizations such as the Marine Stewardship Council (MSC) for sustainable harvesting and the International Fish Oil Standards (IFOS) program. The IFOS program tests supplements for contaminants, including heavy metals like mercury, and verifies potency.
Demand Traceability: Quality companies provide information on their sourcing and supply chain. Traceability ensures that the product can be tracked, guaranteeing its authenticity and quality.
Look for Transparency: Good manufacturers will readily make their third-party test results available to consumers. These reports, often called Certificates of Analysis, provide detailed information on the heavy metal content and other purity metrics.

Krill Oil vs. Fish Oil: A Purity Comparison

While the risk of heavy metal contamination is higher with fish oil, quality depends on the manufacturer's practices, regardless of the source. The following table compares general purity characteristics:


Feature	Krill Oil	Fish Oil
Trophic Level	Low on the food chain, minimal bioaccumulation risk from diet.	Can be high on the food chain (e.g., tuna, swordfish), higher risk of bioaccumulation.
Purity Potential	Inherently purer raw material due to low trophic level.	Higher potential for contamination in raw material, requiring extensive purification.
Processing Needs	Less extensive processing required to remove contaminants.	More extensive and harsher processing often necessary to filter out toxins.
Natural Preservative	Contains astaxanthin, a powerful antioxidant that helps maintain freshness.	Lacks natural antioxidants, making it more prone to oxidation and potential rancidity if not handled well.

The Power of Astaxanthin

Krill oil contains astaxanthin, a potent antioxidant. Astaxanthin offers its own health benefits and protects the omega-3 fatty acids from oxidation. This inherent stability contributes to the overall purity and quality.

Conclusion: Making an Informed Choice

Does krill oil contain heavy metals? While it is a lower-risk source than many fish oils, it is not immune to contamination. Supplement purity depends on quality sourcing, processing, and third-party testing. To ensure a safe product, look for transparent brands with certifications like IFOS or MSC. Making an informed choice helps leverage the health benefits of krill oil.

For more detailed information on krill oil research and its potential benefits for skin health, you can consult studies like this one on the National Institutes of Health website.

Frequently Asked Questions

Generally, yes. Krill are lower on the food chain than most fish used for fish oil, meaning they accumulate fewer heavy metals. However, the ultimate safety and purity depend on the manufacturing and testing of the final supplement, not just the source.

Yes, contamination can occur. Although krill are low on the food chain, environmental pollutants are widespread in oceans. The manufacturing process itself, or improper handling, could also introduce contaminants.

The best way is to choose a brand that is transparent about its sourcing and provides third-party testing results. Look for certifications from reputable organizations like IFOS, which verify purity and potency.

No, not all brands adhere to the same quality control standards. It is crucial to choose a reputable brand that voluntarily submits its products for independent, third-party testing and makes those results public.

Based on research, potential contaminants include mercury, lead, cadmium, and arsenic. Reputable testing procedures screen for these specific heavy metals.

Krill are lower on the food chain and don't consume other fish. Mercury bioaccumulates and biomagnifies as it moves up the food chain, so krill naturally have lower initial levels of mercury than larger predatory fish.

Certifications, such as those from IFOS or MSC, indicate that an independent organization has tested the product and verified its purity, potency, and that it meets environmental standards for sourcing.