Vomitoxin
The summer of 1972 was an unusually rainy season in the Corn Belt – the “I” states: Indiana, Iowa, Illinois – and many of the corn fields were infected by the fungus Fusarium graminearum, which in its anamorph lifecycle goes by the name Gibberella zeae (a much cooler name, if you ask me), and also infects wheat and barley (1). These things happen, and the corn was fed to the pigs anyways. But a funny thing happened on the way to the slaughterhouse, the pigs either vomited, or stopped eating, and lost weight. And no one likes an anorexic pig (2).
So in comes the U.S. Department of Agriculture to the rescue. From samples of infected corn they ground, extracted, separated and identified the culprit. They named it vomitoxin, because it caused pigs to, you know, vomit. Seriously. And if the pigs had diarrhea instead, they would have named it shitoxin. OK, I made that one up.
If you grow tomatoes, Fusarium may sound familiar, as Fusarium oxysporum is responsible for the fungal disease “fusarium wilt,” which is a vascular disease and causes leaves to yellow and die. Gardeners, like me, don’t like fusarium wilt.So just what is shitoxin…I mean vomitoxin? Vomitoxin, also known by the lame name deoxynivalenol, belongs to a family of mycotoxins (fungus derived toxins) called trichothecenes. The trichothecenes share the tricyclic backbone exemplified by vomitoxin on the left. Many of these mycotoxins are produced by the fungal genus Fusarium.
Of the trichothecenes, and there’s nearly 200 of them, vomitoxin is relatively tame. It’s cousin though, T-2, is responsible for tens of thousands of deaths and has even been used as a biological weapon. So while you aren’t likely to die from vomitoxin exposure, it does constitute a serious economic and health liability.
Because of its hazards to livestock and humans, most countries have set thresholds for allowable vomitoxin concentrations in grain products. The U.S Food and Drug Administration has set a limit of 1 part per million (ppm, or 1000 ug vomitoxin/kg grain), while many other countries in Europe and Asia have set a limit of 0.5 ppm. In the U.S. economic losses due to vomitoxin exceed over 1 billion annually because of inferior quality of the grain and crop, feed, and livestock losses (3).
There’s really no getting around vomitoxin. Our grains and grain products, such as breads, crackers and cereals, have it. And unfortunately the trichothecene mycotoxins are stable to baking processes. In making bread, for example, vomitoxin concentration is only decreased 7% (4). The question to ask is how much are we exposed to and what is the impact to human health. Fortunately, this is a well-studied area, and has made what I thought was going to be a short, silly posting into something a bit more in depth than I wanted. Such is life.
A three-year study was conducted in the Jiangsu province of China to determine the vomitoxin prevalence and concentration in wheat crops (5). From 180 samples, 75% of them contained detectable levels of vomitoxin, ranging from 14 to 41,000 ug/kg, with an average of 488 ug/kg, or 0.488 ppm. These result are fairly typical, I just used a result from China because it seems that nearly everything in the U.S. is made in China.
So let’s travel from China to France, and explore how much vomitoxin is in the foods we eat. In a total diet study, 577 foods from mainland France, meant to be representative of the population’s diet, were analyzed for mycotoxins, including vomitoxin (6). Foods highest in vomitoxin were ones that you might expect, breads, pasta, and pastries, with concentrations of 132, 56, and 73 ug/kg, respectively. When applied to typical diets, the average French adult is exposed to 0.40 ug per kilogram of body weight per day (ug/kg bw/day), while a child is exposed to 0.55 ug/kg bw/day. The health-based guidance value for exposure is set at 1 ug/kg bw/day. These were just averages, and when looking at the 95th percentile of 0.75 and 1.0 ug/kg bw/day, for adults and children, there are many that meet or exceed the recommended exposure to vomitoxin.
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If your intolerance problem isn’t celiac disease, it might instead be sensitivity to vomitoxin. In that case, you may need to exclude not only wheat, but also other grain products that are susceptible to Fusarium oxysporum, such as corn (maize).
