Aflatoxins are a family of naturally occurring mycotoxins produced by Aspergillus flavus and Aspergillus parasiticus moulds that infect peanuts, maize, tree nuts, spices, and dried fruits, particularly in warm, humid growing conditions or poor storage. Aflatoxin B1 is the most potent naturally occurring carcinogen known — IARC Group 1 for liver cancer — and is responsible for a significant proportion of liver cancer cases worldwide. Despite regulatory limits, aflatoxins are among the most common mycotoxin detections in EU food monitoring programmes.
Where it's found
Peanuts and peanut butter are the most familiar source — improperly stored peanuts can develop significant Aspergillus contamination. Maize (corn) and maize-derived products: polenta, cornflour, corn-based breakfast cereals, and tortilla products. Tree nuts including pistachios, Brazil nuts, walnuts, and pecans — particularly when stored in warm, humid conditions. Dried fruits — figs, dates, raisins, and sultanas. Spices — chilli powder, paprika, turmeric, and pepper have tested positive in EU monitoring surveys. Dried herbs. Animal products — cattle consuming contaminated feed excrete aflatoxin M1 in milk (a less potent but still concerning metabolite). Coffee — green coffee beans can carry aflatoxin contamination.
Routes of exposure
Dietary ingestion of contaminated food is the primary route. Inhalation of aflatoxin-contaminated dust during handling of contaminated grain, nuts, or spices is an occupational route relevant to agricultural workers and those handling large quantities of spices at home. Aflatoxin is not eliminated by normal cooking temperatures — roasting peanuts and heating contaminated maize does not destroy the toxin, though very high temperatures for extended periods reduce levels. Aflatoxin M1 ingestion via milk from cows given contaminated feed.
Health concerns
Aflatoxin B1 is the most potent naturally occurring liver carcinogen — IARC Group 1 — causing hepatocellular carcinoma, particularly in individuals co-infected with hepatitis B virus, where the two risks multiply rather than simply add. AFB1 forms DNA adducts in liver cells causing characteristic p53 mutations. In addition to carcinogenicity, aflatoxins cause acute liver damage (aflatoxicosis) at high doses, immune suppression, and growth retardation in children in chronically exposed populations in developing countries. At the lower levels found in EU food monitoring, acute toxicity is not the concern — chronic low-level carcinogenicity and potential immune suppression are the relevant endpoints.
Evidence
IARC Group 1 carcinogenicity is based on strong evidence from human epidemiological studies (sub-Saharan Africa, Asia) and confirmed mechanistic data. The synergy with hepatitis B virus in liver cancer aetiology is well established. EU monitoring consistently detects aflatoxins in regulated food categories, with occasional exceedances. At the relatively low levels permitted in EU food (compared to high-exposure regions), the cancer risk is lower but not negligible, particularly for high-frequency consumers of peanut products and spices.
Who's most at risk
People with hepatitis B virus infection are at dramatically amplified liver cancer risk from aflatoxin exposure. Individuals with liver disease or impaired liver function are less able to detoxify aflatoxins. Children in developing countries where regulatory limits are not enforced are at highest global risk from growth impairment and acute toxicity. EU consumers face lower but non-trivial risk from chronic exposure via high-frequency consumption of affected food categories.
Regulatory status
RegulationEU Regulation (EC) 1881/2006 sets strict maximum limits for aflatoxin B1 and total aflatoxins in peanuts, tree nuts, dried fruits, spices, and cereals. Limits for direct consumption are lower than limits for products to be further processed. UK retained these limits. Monitoring by food authorities regularly finds exceedances, leading to food recalls. Aflatoxin M1 in milk is separately regulated. The Rapid Alert System for Food and Feed (RASFF) reports numerous aflatoxin notifications annually.
How to reduce your exposure
Buy peanuts and peanut butter from reputable producers with quality control systems — commercial peanut butter from major brands is extensively tested and typically has very low aflatoxin levels. Avoid home-ground nut butters from markets where storage conditions are unknown. Store nuts, dried fruits, and spices in cool, dry conditions — warm, humid storage promotes mould growth. Discard any nuts, spices, or dried fruits with visible mould or unusual odour. Vary nut consumption across different types rather than eating peanuts as the sole nut — this diversifies any aflatoxin risk across differently contaminated products.
The nutrition connection
Aflatoxins are a remarkable example of the principle that "natural" does not equal "safe" — one of the most potent carcinogens known is a natural product of a common food storage mould. For Nutriofia users building health-promoting dietary patterns that include nuts, seeds, and spices, the aflatoxin issue underscores the importance of food quality and storage conditions alongside composition. The same peanut that provides excellent protein, healthy fats, and magnesium can be a meaningful carcinogen source if poorly sourced or stored. Quality and freshness of whole foods matter as much as the food category itself.