Do peanut butters have aflatoxins? The surprising truth behind the pantry staple

January 9, 2026 •

3 min read

Did you know that aflatoxin-producing fungi can grow on agricultural crops like peanuts? This natural occurrence raises the critical question: do peanut butters have aflatoxins, and if so, how safe are they for consumption?

Quick Summary

Commercial peanut butter brands in regulated markets contain minimal aflatoxins due to rigorous testing and effective processing methods like sorting, roasting, and blanching. The primary risk exists with unregulated products or poor storage.

Key Points

Aflatoxins in Peanuts: Aflatoxins are a mycotoxin produced by fungi (Aspergillus species) that can contaminate peanuts, especially in hot, humid conditions.
Low Risk in Regulated Products: Commercial peanut butter in countries like the US is rigorously tested and processed to keep aflatoxin levels well below government-set safety limits.
Processing Reduces Aflatoxins: Manufacturing steps, including sorting, cleaning, blanching, and roasting, are highly effective at significantly reducing aflatoxin contamination.
Be Cautious with Unregulated Sources: A higher risk of aflatoxin exposure is associated with unregulated products from informal markets or poor home storage conditions.
Liver Cancer Link: Chronic exposure to high levels of aflatoxins is a known risk factor for liver cancer, underscoring the importance of food safety standards.
Consumer Vigilance: Always buy from trusted brands, store properly in a cool, dry place, and visually inspect for signs of spoilage.

What are Aflatoxins and Why Do They Affect Peanuts?

Aflatoxins are naturally occurring mycotoxins, which are toxic secondary metabolites produced by certain fungi, primarily Aspergillus flavus and Aspergillus parasiticus. These fungi thrive in hot, humid conditions and can contaminate crops in the field, during harvest, and throughout storage. Peanuts are particularly susceptible to this contamination due to how and where they are grown. Aflatoxins, especially the potent B1 type, are known carcinogens and can cause serious health issues, particularly affecting the liver. However, the risk for consumers in countries with strong food safety regulations is low due to robust quality control.

The Commercial Peanut Butter Production Process

In regulated markets like the US and Canada, peanut butter manufacturers implement strict measures to minimize aflatoxin contamination. The journey from peanut field to jar involves multiple checkpoints to ensure safety:

Sourcing and Inspection: Reputable companies source their peanuts from regions and suppliers with effective farming and storage practices. The raw peanuts are then inspected and often tested for aflatoxin levels before processing even begins. The US Department of Agriculture (USDA) and Food and Drug Administration (FDA) collaborate to enforce rigorous standards.
Sorting and Cleaning: Upon arrival at the processing plant, peanuts undergo a series of sorting procedures. This can include mechanical sorting, which removes discolored, shriveled, or damaged nuts, as well as visual inspection. This step is crucial because mold growth is most common on compromised nuts.
Blanching and Roasting: Peanuts are blanched to remove their skins, a process that can significantly reduce aflatoxin concentrations. High-temperature roasting further denatures the heat-stable aflatoxins. One study noted that roasting at 160°C reduced total aflatoxin by 51%, while even higher temperatures can achieve greater reductions.
Final Product Testing: Even after all these steps, the finished peanut butter may be tested again to ensure it falls below regulatory limits. The FDA sets a maximum limit of 20 parts per billion (ppb) for aflatoxin in human food.

How Consumers Can Minimize Aflatoxin Exposure

While commercial peanut butter is safe, consumers can take extra precautions, especially with less-regulated products like those from informal markets or homemade batches.

Simple Tips to Stay Safe:

Choose Reputable Brands: Buy from major, well-known brands that you can trust to follow strict quality control procedures.
Store Properly: Keep peanuts and peanut butter in a cool, dry place to prevent mold growth. Freezing can further prolong freshness and inhibit mold.
Inspect Before Eating: Always check peanuts for any signs of mold, discoloration, or shriveling. Discard any nuts that appear damaged or off.
Consider Making Your Own: If you prefer homemade peanut butter, start with high-quality, fresh, and visibly undamaged peanuts from a trusted supplier. You can even consider fermenting the peanuts to further reduce mycotoxin levels.
Use Natural Antioxidants: Some studies suggest that consuming foods rich in antioxidants like carrots and celery may help mitigate the effects of aflatoxins.

Comparison of Aflatoxin Risk in Peanut Butter


Feature	Commercial Regulated Peanut Butter	Unregulated/Homemade Peanut Butter
Source of Peanuts	Controlled, high-quality sourcing from reputable suppliers.	Variable sourcing, often using lower-grade peanuts.
Aflatoxin Testing	Rigorous testing at multiple stages, including raw and finished products.	Little to no testing. Safety is unverified and potentially high risk.
Processing	Sorting, cleaning, blanching, and high-heat roasting significantly reduce aflatoxin.	Potentially inconsistent or improper processing that may not effectively reduce contaminants.
Regulatory Oversight	FDA and USDA oversight ensures strict compliance with safety limits.	No government oversight, relying on the producer's unverified safety standards.
Shelf Life	Extended shelf life due to stabilizers and preservatives that inhibit microbial growth.	Shorter shelf life and higher susceptibility to spoilage without stabilizers.
Risk Level	Very low risk of high-level contamination due to controls.	High risk, especially in developing countries or with poor storage.

Conclusion

Yes, peanut butters can contain aflatoxins because they are derived from peanuts, a crop susceptible to the mold that produces these toxins. However, the risk to consumers of commercial peanut butter in countries with robust food safety regulations is extremely low. Regulatory bodies like the FDA set and enforce strict limits, and the multi-step manufacturing process is specifically designed to identify and remove contaminated peanuts. The primary danger lies with unregulated or improperly stored products, often found in developing countries or made under substandard conditions. By choosing reputable brands and practicing proper storage, consumers can enjoy peanut butter with confidence that the risks associated with aflatoxins have been effectively mitigated.

For more information on aflatoxins and other food safety issues, you can visit the National Cancer Institute's Aflatoxin page.

Frequently Asked Questions

No, not all peanut butter is contaminated. While the potential for contamination exists with raw peanuts, commercial manufacturers use stringent processes like sorting, blanching, and high-heat roasting to significantly reduce aflatoxin levels to safe limits set by regulatory bodies.

In countries with strict food safety regulations, it is extremely rare to get aflatoxin poisoning from commercial peanut butter. The risk is primarily associated with consuming highly contaminated products, which are usually from unregulated sources in developing regions.

Yes, roasting is an effective method for reducing aflatoxin levels in peanuts. Studies show that high-heat roasting can reduce contamination by 50% or more, depending on the temperature and duration.

The safety of peanut butter, whether natural, organic, or conventional, depends on the supplier's quality control rather than the label. The most important factor is purchasing from a reputable brand that tests its products and adheres to food safety standards.

The U.S. Food and Drug Administration (FDA) has set an 'actionable limit' of 20 parts per billion (ppb) for total aflatoxins in human foods, including peanut products. Commercial brands generally follow even stricter internal limits.

To prevent mold growth, store your peanut butter in a cool, dry place. For natural peanut butter, the separation of oil is normal; simply stir it back in. Refrigeration can help prolong its freshness and inhibit any potential microbial growth.

Aflatoxins are odorless, tasteless, and colorless, so you cannot detect them by sight or smell. However, you should always discard any peanut butter or nuts that show visible mold, discoloration, or a bitter taste, as this can indicate fungal growth.