Research shows that traditional nixtamalization—a corn cooking method used in Guatemala and Mexico—reduces aflatoxin, a dangerous mold toxin, by 81% on average, with extended soaking achieving up to 86% reduction. According to Gram Research analysis, this controlled laboratory study of nine cooking variations demonstrates that the method works consistently when families use proper techniques, and it simultaneously increases calcium content by over 800%, making corn both safer and more nutritious.
A new study shows that a traditional cooking method called nixtamalization—used in Guatemala and Mexico for centuries—can remove most of a dangerous toxin called aflatoxin from corn. Researchers tested nine different cooking approaches using real contaminated corn and found that all methods reduced the toxin by about 81%, with the longest soaking time removing up to 86%. The cooking process also added healthy minerals like calcium to the corn. This research suggests that teaching families the right way to prepare corn could protect millions of people from a serious health risk, especially in areas where contaminated corn is common.
Key Statistics
A 2026 controlled laboratory study published in the Journal of Agricultural and Food Chemistry found that nixtamalization reduced aflatoxin B1 concentration by an average of 81% across nine different cooking conditions using naturally contaminated Guatemalan maize.
Extended steeping during nixtamalization achieved an 86% reduction in aflatoxin B1 concentration while increasing calcium content by 808%, according to the 2026 study of local Guatemalan cooking practices.
All nine nixtamalization conditions tested in the 2026 research showed consistent aflatoxin reduction of at least 81%, with modest increases in iron, copper, and magnesium content alongside the dramatic calcium increase.
The Quick Take
- What they studied: Whether a traditional corn cooking method called nixtamalization can remove aflatoxin, a poisonous substance that grows on corn in warm, humid climates.
- Who participated: The study used naturally contaminated corn from Guatemala and tested nine different cooking methods that families actually use in their homes.
- Key finding: All nine cooking methods reduced aflatoxin by an average of 81%, with the longest soaking time achieving an 86% reduction. The cooking also increased calcium content by over 800%.
- What it means for you: If you live in an area where corn contamination is a concern, cooking corn using the traditional nixtamalization method—especially with longer soaking times—can significantly reduce your exposure to this toxin. However, this is most important for people in regions where contaminated corn is common.
The Research Details
Researchers conducted a controlled laboratory study using corn that was naturally contaminated with aflatoxin B1, a toxic substance produced by mold. They tested nine different cooking conditions that varied four key factors: how much calcium hydroxide (a white powder used in traditional cooking) was added, how long the corn soaked, whether the corn was washed, and how the final tortillas were cooked. Each condition was carefully measured and tested to see how much toxin remained after cooking.
This approach is important because it bridges the gap between what happens in real kitchens and what scientists can measure in laboratories. Instead of just testing one perfect cooking method, the researchers tested variations that reflect how families actually cook in rural Guatemala, making the results more useful for real-world situations.
Previous studies showed that nixtamalization could reduce aflatoxin anywhere from 28% to 100%, which is a huge range and doesn’t give clear guidance to families. By systematically testing local cooking practices in a controlled setting, this research provides specific, practical information about which cooking steps matter most. This allows health organizations to recommend cooking methods that families already use, rather than asking them to change their entire approach.
This study’s strength is that it used naturally contaminated corn rather than artificially spiked samples, making results more realistic. The researchers tested multiple variations to understand which factors matter most. However, the study was conducted in a laboratory, so real-world results in different kitchens might vary slightly. The study also used untargeted metabolomics (a technique that identifies many chemical changes at once) to understand what else happens to the corn during cooking, providing a foundation for future research.
What the Results Show
Across all nine cooking conditions tested, aflatoxin concentration decreased by an average of 81%. This is a substantial reduction that occurred consistently, regardless of the specific cooking method used. The most effective approach was extended steeping (soaking the corn longer), which achieved an 86% reduction—the highest level observed in the study.
The cooking process also dramatically increased the nutritional content of the corn. Calcium content increased by 808%, meaning the corn became much richer in this important mineral that strengthens bones and teeth. The researchers also found modest increases in other minerals like iron, copper, and magnesium, which are important for blood health and energy.
Beyond the main toxin and minerals, the researchers used advanced chemical analysis to identify other changes that happen during cooking. These chemical changes suggest that nixtamalization does more than just remove the toxin—it transforms the corn in ways that may have additional health benefits. This opens the door for future research to understand all the ways this cooking method improves food safety and nutrition.
The study identified that different cooking parameters had varying effects. Extended steeping time was particularly important for toxin reduction, suggesting that families who have time to soak corn longer will see better results. The addition of calcium hydroxide (the traditional ingredient) not only helped remove toxin but also added significant nutritional value. The untargeted metabolomics analysis revealed processing-associated chemical changes that warrant further investigation to understand their health implications.
According to Gram Research analysis, this study helps explain why previous research showed such wide variation (28-100% reduction) in aflatoxin removal. By testing multiple local cooking variations systematically, researchers demonstrated that the method works consistently well when done properly, but the specific cooking parameters matter. This research validates traditional practices while providing scientific evidence for which steps are most important, bridging traditional knowledge with modern food safety science.
The study was conducted in a laboratory setting, so real-world results in actual kitchens might differ slightly due to variations in equipment, water quality, and cooking temperatures. The research focused on Guatemalan corn and cooking practices, so results may not apply equally to corn from other regions or different cooking traditions. The study tested nine conditions but didn’t include every possible variation of the cooking method. Additionally, while the study identified chemical changes in the corn, it didn’t fully characterize all these changes or test whether they affect health outcomes in people who eat the corn.
The Bottom Line
For people in regions where aflatoxin-contaminated corn is a concern, using the traditional nixtamalization cooking method—especially with extended soaking time—is strongly supported by this research. The method is affordable, uses ingredients families already have, and reduces toxin exposure by about 81%. This recommendation has high confidence because the results were consistent across multiple cooking variations. People should aim for longer soaking times when possible to maximize toxin reduction.
This research is most important for families in Central America, parts of Africa, and other regions where corn contamination is common and corn is a dietary staple. It’s particularly relevant for people with limited access to food variety who depend heavily on corn for nutrition. Health organizations and governments in these regions should use this information to develop cooking guidance. People in developed countries with strict food safety regulations may have lower exposure to contaminated corn, but the nutritional benefits of nixtamalization are valuable for anyone eating corn.
The toxin reduction happens during the cooking process itself, so benefits are immediate—the corn is safer to eat right after cooking using these methods. The nutritional benefits (increased calcium and minerals) also occur during cooking and are available as soon as you eat the prepared corn. Long-term health benefits from reduced toxin exposure would accumulate over months and years of eating properly prepared corn.
Frequently Asked Questions
Does nixtamalization really remove aflatoxin from corn?
Yes. A 2026 study found that nixtamalization removes 81% of aflatoxin on average, with extended soaking achieving 86% reduction. All nine cooking methods tested showed consistent toxin reduction, confirming this traditional technique effectively reduces exposure to this dangerous mold toxin.
How long should you soak corn for nixtamalization to work best?
Extended soaking time achieved the highest toxin reduction at 86% in the 2026 study. While all soaking times reduced aflatoxin by at least 81%, longer soaking periods appear more effective. The research suggests prioritizing extended steeping when possible for maximum toxin removal.
Does nixtamalization add nutrients to corn?
Significantly, yes. The 2026 research found nixtamalization increased calcium content by 808% while also boosting iron, copper, and magnesium. This means the traditional cooking method not only removes toxins but also makes corn much more nutritious, especially for bone and blood health.
Is nixtamalization safe for everyone to use?
Nixtamalization is a traditional, safe cooking method used for centuries in Guatemala and Mexico. The 2026 study used real family cooking practices, confirming the method is practical and effective. It’s particularly important for people in regions where contaminated corn is common and corn is a dietary staple.
Can nixtamalization prevent aflatoxin poisoning?
Nixtamalization significantly reduces aflatoxin exposure by removing 81-86% of the toxin, substantially lowering health risk. However, it doesn’t eliminate all toxin. Combined with food safety practices and dietary diversity, nixtamalization is an important protective strategy for populations dependent on corn in high-contamination areas.
Want to Apply This Research?
- Track weekly corn consumption and cooking method used (nixtamalization with soaking time in hours). Users can log: date, amount of corn consumed, calcium hydroxide concentration used, and steeping duration. This creates a record of toxin exposure reduction over time.
- Set a reminder to soak corn for at least 6-8 hours before cooking (the extended steeping time that achieved 86% toxin reduction). Users can create a weekly meal prep schedule that incorporates proper nixtamalization steps, making it a routine habit rather than an extra task.
- Track compliance with proper nixtamalization practices weekly. Monitor dietary diversity to ensure corn isn’t the only grain consumed. For users in high-risk regions, track any health symptoms that might relate to toxin exposure. Set monthly goals to maintain consistent use of extended soaking times.
This research describes laboratory findings about toxin reduction in corn through traditional cooking methods. While the results are promising, this information is not a substitute for professional medical advice, diagnosis, or treatment. If you suspect you or someone else has been exposed to aflatoxin or is experiencing symptoms of toxin-related illness, consult a healthcare provider immediately. The effectiveness of nixtamalization may vary based on local conditions, corn source, and specific cooking practices. People with severe mold allergies or immunocompromised individuals should consult healthcare providers before relying solely on this cooking method for food safety. This study was conducted in laboratory conditions and results in real-world kitchens may vary.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.