Fumonisin B2 (FB2) is a toxic mycotoxin produced by Fusarium molds, frequently contaminating corn and corn-based foods worldwide.
Like its close relative fumonisin B1, FB2 is classified as a possible human carcinogen and is linked to health risks such as birth defects, cancer, and serious animal diseases.
Fumonisin B2 (FB2) is a harmful mycotoxin made by certain molds, especially Fusarium fungi, which commonly infect corn. FB2 is chemically similar to another toxin called fumonisin B1 (FB1).
FB2 can be harmful, as can FB1: both FB1 and FB2 are classified by the World Health Organization as Group 2B carcinogens, meaning they are "possibly cancer-causing" to humans (Okolo et al., 2025).
Fumonisins are commonly found in food and feed with other mycotoxins.
FB2 gets into food when corn or corn-based products become moldy. Mold can grow on crops while they are still in the field, especially when the weather is very dry, followed by wet conditions.
It can also develop during storage if the grain is kept in warm or damp places. Pre- and post-harvest practices critically affect fumonisin contamination.
FB2 is commonly found in cornmeal, corn flour, tortillas, breakfast cereals, corn-based snacks, and even in animal feeds.
Animals that eat moldy feed may also suffer health problems.
Fumonisins are harmful because they interfere with how cells make important fats called sphingolipids. These fats are needed for healthy cell membranes and cell signals.
Fumonisins block an enzyme called ceramide synthase, which leads to an unhealthy buildup of certain fats and the loss of others. This can damage organs and cause disease.
FB2 and other fumonisins can cause serious diseases in animals. From contaminated feed, horses can develop brain damage (equine leukoencephalomalacia), and pigs can develop lung disease (porcine pulmonary edema).
In people, studies suggest that fumonisins might increase the risk of birth defects and cancer.
One study in Texas and Mexico found that women who ate more fumonisin-contaminated corn were more likely to have babies with neural tube defects (NTDs).
Other studies have found higher rates of esophageal cancer in parts of the world where people eat a lot of contaminated corn, such as South Africa and China.
While fumonisin poisoning in people is rare, these risks make controlling fumonisin levels in food is important.
FB2 is not something doctors usually test for in patients. Food safety agencies and researchers mainly do testing.
Governments and food companies regularly test corn and animal feeds for fumonisins to meet safety standards.
The U.S. FDA recommends that corn products for people contain less than 2–4 parts per million (ppm) of total fumonisins.
Animal feeds also have restrictions, especially for horses and pigs.
Scientists sometimes measure fumonisin levels in blood or urine to check if people have been exposed. This helps them study whether fumonisins are linked to health problems like cancer or birth defects.
Fumonisin B2 levels can be tested in food, and in biological samples from humans and animals.
Food and Feed: Maize, corn-based foods, animal feeds (primary matrices for regulatory and veterinary testing).
Biological Samples (Humans and Animals):
Various testing methods can be utilized for fumonisin B2 levels.
Enzyme-linked immunosorbent Assay (ELISA) is widely used to detect FB2 in food, feed, and biological samples such as urine or serum. It is a quick and cost-effective screening tool, making it practical for research and food safety settings.
However, clinicians should be aware that ELISA can overestimate FB2 levels due to cross-reactivity with related compounds, and its diagnostic accuracy in clinical medicine is limited.
Lateral Flow Immunoassays (LFA) provide rapid, semi-quantitative results and are well-suited for field-based testing of feed, grain, or other corn-based food products.
These test strips are simple to use and useful in agricultural or food inspection contexts but have limited application in clinical settings due to their lower sensitivity and inability to process complex biological matrices.
High-performance liquid Chromatography with Fluorescence Detection (HPLC-FLD) is commonly used to confirm FB2 presence in food, feed, and biological fluids.
Because FB2 lacks strong UV absorbance, a derivatization step is required before analysis. This method is more accurate than ELISA and is typically used to validate initial screening results.
Liquid Chromatography–Tandem Mass Spectrometry (LC-MS/MS) is the gold standard for accurately quantifying FB2 and related fumonisins (FB1, FB3), including their hydrolyzed or masked forms. It offers high sensitivity and specificity and is suitable for clinical samples (urine, blood) and food/feed testing.
High-Resolution Mass Spectrometry (HRMS) is primarily used in research settings. It allows for the detection of both free and masked fumonisins in complex matrices such as animal or human tissues, providing advanced capabilities for investigating fumonisin exposure and metabolism in experimental or postmortem studies.
The FDA has set the following limits for the presence of fumonisins in human and animal food:
Fumonisin B2 in food may have the following significance:
The food or feed is unsafe if FB2 is found at high levels. To protect health, it may be recalled or removed from the market.
If the amount is low and under the legal limit, the food is considered safe, but it is still better to limit exposure when possible.
Finding FB2 in blood or urine means the person has recently eaten contaminated food. Based on these measurements, scientists can estimate how much fumonisin was consumed.
Researchers sometimes check the balance of certain fats in the blood (called the Sa/So ratio) to see if fumonisins have started affecting the body.
Doctors do not usually test for fumonisins in routine medical care, but they should know the risks when working in areas where corn is a major part of the diet.
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