Can Mold Cause Liver Damage? The Science Explained

Certain molds produce toxic compounds called mycotoxins that can absolutely damage the liver, ranging from mild enzyme elevations to acute liver failure and, over years of chronic exposure, liver cancer. The best-studied culprit is aflatoxin B1, a mycotoxin made by Aspergillus flavus and related fungi, classified by the World Health Organization as a Group 1 carcinogen. But aflatoxin is not the only mold-derived threat to the liver. Several other mycotoxins, including ochratoxin A and deoxynivalenol, also show liver-damaging effects, and the ways they cause harm extend beyond simple poisoning into disrupted metabolism and compromised gut barriers.

How Aflatoxin B1 Attacks the Liver

Aflatoxin B1 does not walk into liver cells and start destroying things on its own. It actually needs to be converted into a more dangerous form first, and the liver itself does the converting. Two enzyme families in liver cells handle this activation step. Once aflatoxin B1 arrives in the liver, these enzymes oxidize it into several products. Most of those products are harmless breakdown forms, but one of them is a highly reactive molecule that binds directly to DNA and proteins inside liver cells.¹ That reactive intermediate is the real troublemaker. It damages DNA strands, triggers cell death, and, when the exposure is repeated over time, sets the stage for cancer.

The liver has its own defense system against this reactive form. An enzyme called glutathione S-transferase can neutralize the dangerous intermediate before it reaches DNA. But this defense has limits. When aflatoxin exposure is high or prolonged, or when a person’s nutritional status is poor, the protective system gets overwhelmed. The balance between activation and detoxification largely determines how much damage a given dose of aflatoxin will do.²

Acute Poisoning vs. Chronic Exposure

Mold-related liver damage operates on two very different timescales, and the consequences look nothing alike.

At the acute end, swallowing a large dose of aflatoxin B1 in a short period can cause what researchers call acute aflatoxicosis. This manifests as sudden, severe liver failure. Patients develop jaundice, confusion from hepatic encephalopathy, and rapidly deteriorating organ function. In documented outbreaks, the clinical picture has included fulminant hepatic failure alongside muscle breakdown and multi-organ collapse.³ In severe cases, it kills.⁴ Outbreaks have been reported in parts of sub-Saharan Africa and South Asia, typically linked to contaminated grain stores.

Chronic exposure is subtler and far more widespread. Eating low levels of aflatoxin-contaminated food over months and years does not cause the dramatic organ failure of acute poisoning. Instead, it quietly promotes DNA mutations in liver cells, drives chronic inflammation, and gradually pushes the liver toward cancer. This long-term risk is the primary public health concern in regions where aflatoxin contamination of staple foods like maize, groundnuts, and rice is common.

The Cancer Connection

The link between aflatoxin and liver cancer, specifically hepatocellular carcinoma, is one of the most thoroughly documented connections between a food contaminant and a specific cancer. Aflatoxin B1 is known to cause a characteristic mutation in a gene called TP53, which normally functions as a tumor suppressor. In liver cancers associated with aflatoxin exposure, this specific mutation shows up at strikingly high rates. One study of aflatoxin-associated liver cancers found the TP53 mutation in about 82% of cases, with a particular “hotspot” mutation that serves almost as a molecular fingerprint of aflatoxin damage.⁵ That frequency is much higher than what is seen in liver cancers from the general population, making this mutation a useful marker for distinguishing aflatoxin-driven cancers from those caused by other factors.

The discovery of aflatoxins themselves happened almost by accident. In the early 1960s, roughly 100,000 turkey poults died in England from an unknown disease, which was eventually traced to Brazilian groundnut meal contaminated with Aspergillus flavus. Since then, at least 20 distinct aflatoxins have been identified, though B1, B2, G1, and G2 are the ones that matter most for human health.

Why Hepatitis B Makes Everything Worse

One of the more alarming findings in aflatoxin research is that people who carry the hepatitis B virus and are also exposed to aflatoxin face a cancer risk that is far greater than what either factor alone would predict. This is not just an additive effect where the two risks stack on top of each other. Cohort studies from China and Taiwan, using biomarkers that accurately reflect dietary aflatoxin exposure, have shown a multiplicative interaction between hepatitis B and aflatoxin B1 in causing liver cancer.⁶

This synergy matters enormously in global public health because the geographic overlap between chronic hepatitis B and high aflatoxin exposure is significant. Parts of sub-Saharan Africa and East Asia carry high burdens of both. Hepatitis B vaccination programs and improved food storage practices may each reduce liver cancer rates, but addressing both together has outsized protective effects precisely because the two risks amplify each other.

Aflatoxin Is Not the Only Mold Toxin That Harms the Liver

Aflatoxin B1 gets the most attention because it is the most potent and best studied, but other mycotoxins produced by different mold species also damage the liver through distinct mechanisms.

Ochratoxin A (OTA), produced primarily by Aspergillus and Penicillium species, is historically associated with kidney damage but is increasingly recognized as a liver toxin too.⁷ Animal studies have shown that OTA exposure leads to increased markers of liver and kidney damage in a dose-dependent manner, driven by oxidative stress and mitochondrial damage in liver cells.⁸ OTA is found in a range of foods including wine, coffee, dried fruits, and cereals, which means low-level exposure is surprisingly common even in developed countries with good food-safety infrastructure.

Deoxynivalenol (DON), a mycotoxin produced by Fusarium molds in grains, is another one with emerging liver implications. Mouse studies have demonstrated that acute DON exposure triggers fat accumulation in the liver, resembling the early stages of non-alcoholic fatty liver disease. The mechanism appears to involve the mobilization of fats from other tissues into the liver, overwhelming the organ’s ability to process them.⁹ While the human evidence for DON-induced fatty liver is still limited, these animal findings suggest that the relationship between mold toxins and liver health extends well beyond the acute poisoning and cancer endpoints that dominate the aflatoxin literature.

The Gut-Liver Pipeline

One of the more interesting developments in mycotoxin research has been the growing understanding that these toxins damage the liver partly through the gut. The liver receives most of its blood supply from the portal vein, which drains directly from the intestines. This means that anything getting through the gut wall reaches the liver first. Under normal conditions, the intestinal lining acts as a selective barrier, keeping most harmful substances out of the bloodstream. Mycotoxins like aflatoxins and fumonisins have been shown to disrupt the tight junctions between intestinal cells, making the gut wall leakier and allowing toxins and bacteria to cross into the blood flowing toward the liver.¹⁰

Research in mice has confirmed that aflatoxin B1 exposure decreases the production of key proteins that hold intestinal cells together, increases gut permeability, and boosts levels of bacterial endotoxins in the bloodstream. Those endotoxins activate inflammatory signaling in the liver, compounding the direct toxic effects of the aflatoxin itself.¹¹ Beyond barrier damage, aflatoxin B1 also shifts the composition of gut bacteria and disrupts their normal metabolic activity, promoting chronic inflammation through what scientists describe as the gut-liver axis.¹²

This gut-mediated pathway is significant because it means mycotoxin-related liver injury is not solely about the toxin reaching the liver directly. The secondary wave of bacterial products leaking through a damaged gut wall adds an inflammatory burden on top of the direct chemical insult, potentially explaining why chronic low-level exposure causes disproportionate harm over time.

Metabolic Disruption Beyond Cell Damage

Liver damage from mycotoxins does not stop at inflammation and DNA mutations. Several mold toxins also interfere with how the liver processes fats and sugars, creating metabolic problems that might not be immediately obvious. Ochratoxin A exposure in mice altered liver levels of cholesterol, triglycerides, and glucose, and appeared to inhibit the normal burning of fatty acids. These metabolic changes were linked to disrupted gut barrier function and shifts in intestinal bacteria, reinforcing the idea that the gut-liver connection is central to how mycotoxins cause metabolic harm.¹³

This metabolic angle matters because it suggests that mycotoxin exposure could contribute to conditions like fatty liver disease without ever causing the dramatic symptoms of acute poisoning. A person chronically exposed to low levels of multiple mycotoxins could develop metabolic liver dysfunction that looks clinically similar to diet-related fatty liver. In regions where food contamination is common and where diagnostic resources are limited, these cases could easily be attributed to other causes.

Occupational Risks Most People Don’t Consider

When people think about mold and liver damage, they usually picture contaminated food. But inhalation is another exposure route that catches certain workers off guard. A study of flour mill workers and bakers found that their levels of the liver enzymes AST and ALT were significantly elevated compared to unexposed controls, consistent with ongoing liver stress.¹⁴ The connection was airborne Aspergillus spores and the aflatoxin B1 they produce, which workers breathe in during grain handling. Similarly, workers at municipal solid waste management centers have shown abnormal liver and kidney function profiles tied to aflatoxin B1 exposure, with measurable changes in their blood antioxidant levels suggesting that oxidative stress was a driving factor.¹⁵

These occupational findings highlight an underappreciated risk. Home environments with visible mold growth expose residents to far lower concentrations than an industrial flour mill, but the principle applies on a spectrum. Persistent airborne mold exposure is not just a respiratory issue; it has systemic implications that reach the liver through both inhalation and the eventual swallowing of spore-laden mucus cleared from the airways.

Pregnancy, Infancy, and Early-Life Vulnerability

Young children and developing fetuses are disproportionately vulnerable to aflatoxin’s effects. A narrative review found that aflatoxin exposure during pregnancy can lead to reduced fetal growth, low birth weight, impaired bone growth, and developmental effects including reduced brain size. It can also contribute to neonatal jaundice, which is itself a sign of liver stress, and may disrupt hormone synthesis.¹⁶ The link between aflatoxin exposure, endemic liver disease, and malnutrition in certain regions further complicates the picture, as poor nutrition reduces the body’s capacity to detoxify aflatoxin.¹⁷

In practical terms, this means that communities relying on staple grains prone to fungal contamination, particularly in tropical climates with poor storage infrastructure, face compounding risks. A malnourished pregnant woman eating contaminated grain passes aflatoxin to a developing fetus whose liver detoxification systems are not yet mature. The combination of immature enzymes, nutritional deficiency, and toxin exposure creates a vulnerability that no single factor would produce alone.

Protective Compounds Being Studied

Given that eliminating mycotoxin exposure entirely is impractical in many parts of the world, researchers have been investigating compounds that could blunt the liver damage. Antioxidant nutrients, including vitamins, carotenoids, chlorophyll derivatives, and selenium, show promise in protecting against mycotoxin-induced cellular damage. Their benefit appears to stem from neutralizing reactive oxygen species that mycotoxins generate, thereby shielding liver cell membranes from destruction.¹⁸

More specific findings have come from animal research. Lactoferrin, a protein found in milk, reduced oxidative stress and inflammatory signaling in the livers of mice exposed to deoxynivalenol.¹⁹ Resveratrol, a compound found in grapes and berries, alleviated liver injury caused by T-2 toxin (another mycotoxin produced by Fusarium molds) by supporting the liver’s own antioxidant defense pathways.²⁰ These are animal findings, and translating them into human dietary recommendations requires caution. But they point toward a consistent theme: the liver’s antioxidant defenses are a key bottleneck in mycotoxin tolerance, and bolstering those defenses could offer meaningful protection.

Why Species Differ So Dramatically in Sensitivity

One factor that complicates risk assessment is the enormous variation in aflatoxin sensitivity across species. The same dose of aflatoxin B1 that devastates a turkey’s liver barely affects a mouse. These differences are driven by how efficiently each species’ liver converts aflatoxin into its dangerous reactive form versus how quickly it can neutralize that form. The ratio between activation and detoxification enzyme activity largely determines species-specific vulnerability, and levels of aflatoxin-DNA adducts formed in different species track closely with their cancer susceptibility.²¹

Humans fall somewhere in the middle of this sensitivity range. We activate aflatoxin B1 efficiently enough that it poses real risk, but our glutathione-based detoxification is more capable than that of highly susceptible species like turkeys or certain fish. This middle-ground status is part of why aflatoxin research took so long to produce clear human cancer risk estimates. Laboratory animals that are extremely sensitive overestimate human risk; those that are resistant underestimate it. Epidemiological data from human populations, particularly the biomarker-based cohort studies from Asia, ultimately provided the strongest evidence for human carcinogenicity.

Food Safety and What Actually Reduces Exposure

Regulatory agencies around the world set maximum allowable levels of aflatoxins and other mycotoxins in food, with guidance from organizations like the FAO and WHO shaping standards. Detection methods have become increasingly sophisticated, allowing food safety laboratories to measure mycotoxin contamination at very low concentrations.²² In countries with strong regulatory enforcement, commercial food products are routinely tested and batches exceeding limits are pulled.

For individuals, the practical steps are straightforward but worth knowing. Proper storage of grains, nuts, and dried foods keeps moisture below levels that allow mold growth. Visibly moldy foods, particularly grains and legumes, should be discarded rather than trimmed and eaten, since mycotoxins can penetrate beyond the visible mold. Cooking destroys some mycotoxins, but aflatoxins are heat-stable enough that normal cooking temperatures do not eliminate them. Diversifying dietary staples helps too, since reliance on a single grain crop magnifies the risk from any contamination event affecting that crop. These measures are most critical in tropical and subtropical regions where hot, humid conditions favor mold growth and where food storage infrastructure may be limited, but they apply anywhere mold contamination of food is possible.