Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Oats can be thought of as uniquely nutritious, and one route they improve human health is by providing prebiotics that increase the growth of beneficial gut microbiota. Of course, there are oats and then there are oats, ranging from steel-cut oats, to, even better, intact oat groats (their form before being cut), all the way down to highly processed cereals such as Honey Nut Cheerios.

Rolling crushes the grain, which may disrupt cell walls and damage starch granules, making them more available for digestion––which is bad, since we want the starch to make it all the way down to our colon to feed our good gut bacteria. Grinding into oat flour to make breakfast cereals is even worse. If you compare the blood sugar and insulin responses, you can see significantly lower spikes with the more intact steel-cut oats.

Okay, but what about ochratoxin? Oats are the leading source of dietary exposure of this mold contaminant, but they aren’t the only source. There’s a worldwide contamination of food crops with mycotoxins, with some experts throwing around estimates as high as 25 percent of the world’s crops. That statistic is attributed to the Food and Agriculture Organization of the United Nations. But it turns out that statistic is bogus. It’s not 25 percent. Instead, it may be more like 60 to 80 percent. The high occurrence is likely explained by a combination of the improved sensitivity of testing methods, as well as the impact of climate change.

Spices have been found to have some of the highest concentrations of mycotoxins, but because they are ingested in such small quantities, they’re not considered to be a significant source. We can certainly do our part to minimize risk, though. It is also the consumers’ responsibility to keep spices dry after opening sealed containers or packages.

What about dried herbs? Mycotoxins in plant-based dietary supplements: the highest mycotoxin concentrations were found in milk thistle-based supplements. It turns out that wet and humid weather is needed during milk thistle harvest, which evidently is why they end up being so moldy. Considering the fact that milk thistle preparations are mainly used by people who suffer from a liver disease, such high intake of compounds toxic to the liver may present some concern.

Wine sourced from the United States also appears to have particularly high levels. In fact, the single highest level found to date around the world is in an American wine, but there’s contamination in wine in general. In fact, some suggest that’s why we see such consistent levels in people’s blood—perhaps because lots of people are regular wine drinkers.

Ochratoxin is said to be a kidney toxin with immunosuppressive, birth defect-causing, and carcinogenic properties. So, what about ochratoxin decontamination—removing the toxin—in wine? Now ideally, we’d try to prevent the contamination in the first place, but since this isn’t always practical, there is increased focus on finding effective methods of detoxification of mycotoxins already present in foods.

And that’s where yeast comes in as a promising solution, because the mycotoxins bind to the yeast cell wall. The thought is that you could strain out the yeast, but another approach would be to eat something like nutritional yeast to prevent the absorption.

It works in chickens. Give yeast along with aflatoxin (another mycotoxin), and you diminish the severity of the resulting disease. But using something like nutritional yeast as a binder depends on the stability of the yeast-mycotoxin bond throughout the digestive tract. We know yeasts can remove ochratoxin in foods, but we didn’t have a clue if it would work in the gut until 2016. Yeast was found to bind up to 44 percent of the ochratoxin, but in actuality, it was probably closer to only about a third, since some of the bindings weren’t stable.

So, if you’re trying to stay under the maximum daily intake, and you drink a single glass of wine, even if your bar snack is popcorn seasoned with nutritional yeast, you’d still probably exceed the tolerable intake. But what does that mean? How bad is this stuff? We’ll find out next.

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