{"url":"https://whatshealthyandwhy.com/mycotoxins/molds-in-food-and-health-risks","path":"/mycotoxins/molds-in-food-and-health-risks","alternates":{"json":"https://whatshealthyandwhy.com/api/articles/mycotoxins/molds-in-food-and-health-risks.json","markdown":"https://whatshealthyandwhy.com/mycotoxins/molds-in-food-and-health-risks.md"},"topic":{"slug":"mycotoxins","name":"Mycotoxins","url":"https://whatshealthyandwhy.com/mycotoxins"},"slug":"molds-in-food-and-health-risks","order":1,"title":"Molds in food and health risks","question":"Do mold toxins in nuts, grains and coffee harm your health?","answer":"Aflatoxin probably raises liver cancer risk, especially with hepatitis B, but evidence of harm from other mold toxins at typical intakes is limited.","description":"How invisible mold toxins in grains, nuts, coffee, and dried foods accumulate in the body — and practical ways to reduce your exposure","confidence":4,"confidenceNote":"Systematic reviews firmly link aflatoxin to liver cancer, mainly in high-exposure regions; ochratoxin and fumonisin evidence is suggestive and limited.","evidenceSummary":{"rctCount":0,"metaAnalysisCount":2,"totalParticipants":"439+","replicated":true,"newestStudyYear":2024},"category":{"categoryTitle":"What's Harming You","categorySlug":"harming-you","subcategoryName":"Hidden Dangers in Food","subcategorySlug":"food-dangers","url":"https://whatshealthyandwhy.com/explore/harming-you/food-dangers"},"actions":["Store nuts, grains and dried fruit in cool, dry, sealed containers; buy smaller amounts and use them promptly [5].","Throw out moldy nuts, corn or soft fruit entirely; toxins can spread through porous food before mold is visible [5].","Vary your grains (rice, quinoa, millet, buckwheat) and, if you drink a lot of coffee, choose washed (wet-processed) coffee [2]."],"cautions":["Cooking does not destroy mycotoxins, so heat will not make moldy food safe [3].","If you have hepatitis B, aflatoxin exposure matters more: the two multiply liver cancer risk rather than simply adding [1].","Organic labeling does not guarantee lower mycotoxin levels; storage matters more than how food was grown."],"simpleText":"Mycotoxins are invisible, tasteless poisons produced by molds that colonize grains, nuts, dried fruits, and coffee — often before you ever open the package. Unlike the mold you can see and cut away from bread, mycotoxins spread through food before visible mold appears and survive heat, so cooking does not make contaminated food safe [3]. Aflatoxin B1, found primarily in peanuts, corn, and tree nuts, is classified as a Group 1 human carcinogen — the strongest possible classification — and is the most potent naturally occurring carcinogen known. Ochratoxin A is a widespread kidney toxin found in coffee, cereals, wine, and dried fruits [2]. Simple habits — choosing fresh over old, storing food correctly, diversifying your diet — can meaningfully reduce your lifetime exposure.","mediumText":"What mycotoxins are and why they matter\n\nFungi produce mycotoxins as secondary metabolites — chemical byproducts that likely evolved as defenses against competing microorganisms. Over 400 distinct mycotoxins have been identified, but a handful account for nearly all the human health concern:\n\nAflatoxins (AF) are produced mainly by Aspergillus flavus and Aspergillus parasiticus, molds that thrive in warm, humid conditions. Aflatoxin B1 (AFB1) is the most common and most toxic. It binds to DNA after metabolic activation in the liver, forming adducts that drive mutations in tumor suppressor genes, especially TP53 [1]. It is classified as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC). The primary foods at risk are peanuts, corn (maize), tree nuts (pistachios, Brazil nuts, walnuts), and some spices. Climate projections suggest warmer conditions will expand the geographic zones where aflatoxin contamination is likely.\n\nOchratoxin A (OTA) is produced by Aspergillus and Penicillium species and is a nephrotoxin — meaning its main target organ is the kidney. Long-term exposure is associated with kidney damage and is classified as IARC Group 2B (possible human carcinogen). OTA is found across a wide range of common foods: roasted coffee, cereals (especially oats, barley, and wheat), dried vine fruits (raisins, currants), wine, grape juice, cocoa, and dried herbs and spices [2].\n\nDeoxynivalenol (DON), also called vomitoxin, is a Fusarium toxin found predominantly in wheat, barley, oats, rye, and corn. It inhibits protein synthesis and triggers immune and inflammatory responses at low doses. It is the mycotoxin most frequently detected in staple grain foods globally.\n\nFumonisins are another class of Fusarium toxins found primarily in corn. They interfere with sphingolipid metabolism and are classified as Group 2B possible carcinogens [6].\n\nZearalenone (ZEN) is an estrogenic mycotoxin from Fusarium species that can disrupt reproductive hormones at relatively low exposure levels.\n\nWhich foods carry the highest risk\n\nNot all foods carry equal mycotoxin risk. The highest-concern categories:\n\nPeanuts and peanut butter — Aflatoxin contamination is common in peanuts worldwide. Peanut butter is regulated in most countries, but natural and artisan products without rigorous testing carry more variable risk. Studies suggest that commercial peanut butters from large manufacturers have more consistent quality control than natural-grind varieties.\n\nCorn and corn-based products — Corn is highly susceptible to both aflatoxins (in warm climates) and fumonisins and DON (Fusarium species in temperate climates). Masa, polenta, tortillas, corn cereals, and popcorn all carry this exposure. Organic certification does not guarantee lower mycotoxin content — organic corn can be contaminated just as conventional corn can, since mycotoxins are a biological rather than a pesticide issue.\n\nCoffee — Ochratoxin A is consistently detected in roasted coffee beans worldwide. A 2024 systematic review of global data found OTA present in all categories of coffee products, with levels varying significantly by origin, processing method, and roasting temperature [2]. Wet-processed (washed) coffee generally has lower OTA than dry-processed (natural) coffee because fermentation and washing remove the surface molds responsible for OTA production before drying. Darker roasts tend to reduce OTA more than lighter roasts due to extended heat exposure.\n\nDried fruits — Raisins, dried figs, dates, apricots, and other dried fruits can carry ochratoxin A. The drying process creates favorable conditions for mold growth if humidity is not carefully controlled.\n\nTree nuts — Pistachios, Brazil nuts, and walnuts are particularly vulnerable to aflatoxin contamination. Cracked or split shells allow mold access during storage.\n\nWheat and other grains — DON and zearalenone are common in wheat, oats, and barley grown in temperate, humid regions, including much of Europe and the US.\n\nPractical ways to reduce exposure\n\nStorage matters more than purchase. Once you bring food home, proper storage is the most important variable you control. Mycotoxin-producing molds thrive in warm, humid conditions. Store grains, nuts, and dried fruits in cool, dry locations — ideally in sealed containers that minimize humidity exposure. Refrigerating peanut butter after opening slows mold growth if any contamination is present.\n\nBuy in smaller quantities and use promptly. Time in storage increases the probability of mold growth. Buying nuts, dried fruits, and whole grains in smaller amounts and using them within a reasonable time reduces cumulative exposure compared to purchasing in bulk and storing for months.\n\nDiscard visibly moldy food entirely. Unlike many other food concerns, visible mold on a food that has been sitting for a while is a signal that mycotoxins may already be present throughout the product, not just at the mold site. The common practice of cutting away mold and eating the rest is riskier with foods like corn, soft fruits, and nuts than with firm foods, because mycotoxins diffuse through porous food matrices before mold is visible [5].\n\nChoose wet-processed coffee. If coffee is a significant part of your daily routine, choosing washed (wet-processed) single-origin coffees reduces ochratoxin A exposure compared to natural-process coffees, based on the processing chemistry involved [2].\n\nDiversify your grain intake. Eating a variety of grains — quinoa, rice, millet, buckwheat, amaranth — rather than depending heavily on wheat and corn reduces your exposure to any single mycotoxin family.\n\nHeat does not help. Unlike bacteria, mycotoxins are heat-stable chemical compounds. Normal cooking temperatures do not destroy them. The mitigation strategies are pre-consumption: storage, purchasing habits, and variety selection.\n\nSee our cadmium in food page and arsenic in rice page for related coverage of other invisible food contaminants.","deepText":"Evidence Review\n\nAflatoxin B1 as a liver carcinogen (Hamid et al., 2013)\n\nHamid and colleagues reviewed the global distribution and mechanistic evidence for aflatoxin B1 as a cause of hepatocellular carcinoma (HCC), focusing on sub-Saharan Africa and Southeast Asia where both aflatoxin exposure and liver cancer rates are high [1]. The review summarized the molecular pathway to carcinogenesis: after ingestion, AFB1 is metabolized in the liver to AFB1-8,9-epoxide, a reactive intermediate that forms bulky DNA adducts. These adducts cause characteristic G-to-T transversions in codon 249 of the TP53 tumor suppressor gene — a mutation signature so specific to AFB1 that it has been used as a molecular epidemiology marker in human studies. When hepatitis B virus (HBV) infection coexists with high AFB1 exposure, the two act synergistically — the combined relative risk of HCC is not merely additive but multiplicative.\n\nIARC classified AFB1 as Group 1 (carcinogenic to humans) based on sufficient evidence from both animal studies and human epidemiology. Population-attributable fraction estimates suggest AFB1 contributes to 4.6–28.2% of all HCC cases globally, with the highest burden in Africa and Southeast Asia where regulatory limits are weakly enforced and staple diets are corn- and groundnut-heavy. In North American and European populations where food safety monitoring is robust and peanut products are rigorously tested, individual exposure from any single contaminated product is far less likely, but cumulative exposure across multiple products over years remains the primary concern.\n\nOchratoxin A in coffee: global exposure data (Massahi et al., 2024)\n\nThis 2024 systematic review by Massahi et al. synthesized worldwide data on ochratoxin A across all coffee product categories including green coffee, roasted beans, ground coffee, instant coffee, and espresso [2]. Key findings:\n\n- OTA was detected in virtually all coffee categories worldwide, though at concentrations that varied enormously by origin, processing, and form\n- Wet-processed (washed) green coffees showed consistently lower OTA levels than natural-processed coffees — a finding attributed to the fermentation and washing steps that remove the Aspergillus spores on the outer bean layers before drying\n- Roasting significantly reduces OTA compared to green coffee, with darker roasts achieving greater reduction (estimated 40–80% OTA reduction depending on bean type and roast profile)\n- Instant coffee showed among the lowest OTA levels per serving due to dilution during manufacturing and high-temperature processing steps\n- Human health risk assessment found that for average consumers in most countries, estimated daily intake remained below the tolerable daily intake (TDI) established by EFSA (17 ng/kg body weight/day). However, heavy coffee drinkers — more than 4 cups daily — approached meaningful percentages of the TDI from coffee alone, not counting contribution from cereals, wine, and dried fruits\n\nThe authors noted significant heterogeneity across studies due to differing sampling methods, detection limits, and geographic origins, and recommended further biomonitoring studies to better characterize aggregate exposure.\n\nSystematic review of mycotoxin exposure and human cancer risk (Claeys et al., 2020)\n\nThis comprehensive systematic review by Claeys et al. searched epidemiological databases for studies directly linking dietary mycotoxin exposure to human cancer incidence, mortality, or biomarkers [3]. Of the studies meeting inclusion criteria:\n\n- The strongest and most consistent evidence concerned aflatoxins and hepatocellular carcinoma — the association is considered established at the epidemiological level, especially in populations with high hepatitis B prevalence where the synergistic interaction amplifies risk substantially\n- For ochratoxin A, the evidence is suggestive but limited — most human data rely on cross-sectional biomarker studies rather than prospective cohorts, making causal inference difficult\n- Fumonisins and esophageal cancer showed an association in studies from high-exposure regions (parts of southern Africa and China where corn is a dietary staple and processing is minimal), though confounding by other factors makes definitive attribution challenging\n- The authors identified a major evidence gap: most prospective cohort studies with long-term cancer follow-up have not routinely measured dietary mycotoxin exposure, meaning the epidemiological database is thinner than for other dietary carcinogens like aflatoxin in high-incidence settings\n\nThe review concluded that reducing aflatoxin exposure remains the highest-priority public health intervention among the mycotoxins, particularly in low- and middle-income countries, and that food safety programs targeting maximum limits in grain staples have measurable population-level impact.\n\nHuman biomonitoring in a real-world exposure scenario (Kyei et al., 2022)\n\nKyei and colleagues conducted urinary biomonitoring in 439 pregnant women in rural Bangladesh, measuring biomarkers of 35 mycotoxins simultaneously to characterize co-exposure patterns [4]. This is methodologically important because most laboratory and regulatory studies examine single mycotoxins in isolation, while real human exposure involves simultaneous contamination of the diet across multiple compounds. …","deepTruncated":true,"references":[{"id":"1","title":"Aflatoxin B1-induced hepatocellular carcinoma in developing countries: Geographical distribution, mechanism of action and prevention","authors":"Hamid AS, Tesfamariam IG, Zhang Y, Zhang ZG","year":2013,"journal":"Oncology Letters","pmid":"23599745","url":"https://pubmed.ncbi.nlm.nih.gov/23599745/"},{"id":"2","title":"A worldwide systematic review of ochratoxin A in various coffee products - human exposure and health risk assessment","authors":"Massahi T, Kiani A, Moradi M, Soleimani H, Omer AK, Habibollahi MH, Mansouri B, Sharafi K","year":2024,"journal":"Food Additives and Contaminants: Part A","pmid":"39259858","url":"https://pubmed.ncbi.nlm.nih.gov/39259858/"},{"id":"3","title":"Mycotoxin exposure and human cancer risk: A systematic review of epidemiological studies","authors":"Claeys L, Romano C, De Ruyck K, Wilson H, Fervers B, Korenjak M, Zavadil J, Gunter MJ, De Saeger S, De Boevre M, Huybrechts I","year":2020,"journal":"Comprehensive Reviews in Food Science and Food Safety","pmid":"33337079","url":"https://pubmed.ncbi.nlm.nih.gov/33337079/"},{"id":"4","title":"Assessment of multiple mycotoxin exposure and its association with food consumption: a human biomonitoring study in a pregnant cohort in rural Bangladesh","authors":"Kyei NNA, Cramer B, Humpf HU, Degen GH, Ali N, Gabrysch S","year":2022,"journal":"Archives of Toxicology","pmid":"35441239","url":"https://pubmed.ncbi.nlm.nih.gov/35441239/"},{"id":"5","title":"Strategies to reduce mycotoxin levels in maize during storage: a review","authors":"Chulze SN","year":2010,"journal":"Food Additives and Contaminants: Part A","pmid":"20349375","url":"https://pubmed.ncbi.nlm.nih.gov/20349375/"},{"id":"6","title":"Individual and combined effects of subclinical doses of deoxynivalenol and fumonisins in piglets","authors":"Grenier B, Loureiro-Bracarense AP, Lucioli J, Pacheco GD, Cossalter AM, Moll WD, Schatzmayr G, Oswald IP","year":2011,"journal":"Molecular Nutrition and Food Research","pmid":"21259430","url":"https://pubmed.ncbi.nlm.nih.gov/21259430/"}],"wordCount":2285,"source":{"path":"src/content/topics/mycotoxins/molds-in-food-and-health-risks.md"},"citeAs":"“Do mold toxins in nuts, grains and coffee harm your health?.” What's Healthy and Why. https://whatshealthyandwhy.com/mycotoxins/molds-in-food-and-health-risks","notice":"General information backed by peer-reviewed research, not medical advice."}