Does Nutritional Yeast Trigger Crohn’s Disease?

Does Nutritional Yeast Trigger Crohn’s Disease?
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Is the exaggerated reaction of many Crohn’s disease patients to baker’s, brewer’s, and nutritional yeast just a consequence of their inflamed leaky gut, or might the yeast be a contributing cause?

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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.

“Baker’s yeast in Crohn’s disease—Can it kill you?” Well, that’s an inflammatory title (no pun intended). Crohn’s disease is an inflammatory bowel disease. Might baker’s yeast, which is the same yeast as brewer’s yeast, which is the same yeast as nutritional yeast, play a role in Crohn’s disease?

It all started with this study published in 1988, showing that people with Crohn’s disease tend to have more antibodies to yeast than people without Crohn’s disease. Antibodies are like homing devices our immune system makes to attack foreign invaders. That’s one part of our immune system; another is cell-mediated immunity, where our white blood cells attack invaders directly. And, the same hypersensitive reaction to yeast was found in the white blood cells of Crohn’s disease patients, as well.

If you draw blood from healthy people, even bakers who are around yeast all the time, and you expose their peripheral blood leukocytes, their immune system white blood cells, to yeast, nothing happens. They just kind of ignore it, because it’s typically harmless. But, do the same thing with Crohn’s disease patients, and their white blood cells go crazy.

Now, when I say typically harmless, if you have cancer, or AIDS, or are immunocompromised, you could potentially get infected from like, home-brewed beer, or probiotic yeast supplements, but they don’t think the yeast is actually infecting Crohn’s patients. People with Crohn’s may just be hypersensitive to exposure to the inactive, dead yeast in typical food products, which may help explain why, when you rest their bowels, when you make Crohn’s patients fast, they get better.

In fact, that’s why we add yeast extracts and proteins to vaccines, as an adjuvant, an irritant like aluminum, to make the vaccines work better, by heightening the immune response. But, might that be raising the risk of autoimmune disease, boosting our immune response a little too much, especially in people who may be genetically susceptible, like with Crohn’s?

And, the greater the anti-yeast response, the more severe the disease, in both children and maybe adults too. So, maybe we should try a yeast-free diet for Crohn’s patients, and see if they get better. But, wait a second. Just because anti-yeast antibodies are associated with Crohn’s disease doesn’t mean the reaction to yeast is causing the Crohn’s disease. Maybe the Crohn’s disease is causing the reaction to yeast. What? Think about it. Crohn’s causes an inflamed, leaky gut; so, maybe the Crohn’s came first, allowing yeast particles to leak into the bloodstream, resulting in the anti-yeast reaction. So, instead of the yeast reaction triggering the Crohn’s, maybe the Crohn’s just triggers the yeast reaction. “Whether the…antibodies are actually triggering [inflammatory bowel disease] or are only…consequence[s] of gut inflammation…remains elusive.”

So, how could we test it? Well, if anti-yeast antibodies are just a consequence of food particles leaking through the gut, Crohn’s patients should have antibodies to all sorts of common foods. But, no. Higher anti-yeast antibodies in Crohn’s disease compared to controls, but no greater reaction in Crohn’s patients to milk, wheat, or egg proteins, which would presumably all leak through, too.

Or, you can look at it the other way; instead of other foods, what about other inflammatory bowel disorders—ulcerative colitis or acute gastroenteritis? There, you could get inflamed and leaky, too, yet no increased yeast reaction. So, there does appear to be something unique about the yeast-Crohn’s relationship. But, maybe inflamed Crohn’s intestines just uniquely and selectively allow yeast through? If you cut out the Crohn’s, can you stop the yeast reaction?

Crohn’s gets so bad that most patients have to go under the knife, and get sections of their intestines removed. So, when the inflamed segments are removed, does the yeast reaction go away? No; no change post-op. So, a change in Crohn’s activity does not lead to a change in the yeast reaction. But, we still have to prove that the yeast reaction comes first.

Thankfully, the Israeli military “systematically [draws blood] from [their] recruits,” follows their health for years; so, you can go back and check the blood of newly-diagnosed Crohn’s victims. And indeed, those who went on to have Crohn’s were years earlier disproportionately reacting to yeast. So, it’s not like yeast reactions were low until Crohn’s hit, and then they shot up; yeast reactivity crept up year after year, before the diagnosis. Now look, it’s possible that there was some subclinical gut leakiness in the years preceding diagnosis that led to the yeast reaction, but there doesn’t appear to be any association between yeast reactivity and gut leakiness.

So: “Do high [blood] levels of [anti-yeast] antibodies result from a leakiness of the gut barrier in Crohn’s disease?” No; that does not appear to be the case. So, if Crohn’s isn’t leading to the yeast reaction, does that mean that the yeast reaction is leading to the Crohn’s?

Any time you have two things that appear to be associated—in this case reacting to yeast and Crohn’s disease—they both can appear tied together because X causes Y, or because Y causes X. Well, in this case it appears that Y does not cause X. But, does that mean that X causes Y? Well, there’s another option. Maybe there’s a third factor that causes both of them independently. Maybe the only reason yeast reactivity and Crohn’s disease appear to go together is that there’s a third factor causing them both—like, for instance, candida, which I’ll cover, next.

Please consider volunteering to help out on the site.

Icons created by Gay Soon Lay, parkjisun, Milky, and Anna Hatzisavas from The Noun Project.

Image credit: Kristina DeMuth. Image has been modified.

Motion graphics by Avocado Video

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.

“Baker’s yeast in Crohn’s disease—Can it kill you?” Well, that’s an inflammatory title (no pun intended). Crohn’s disease is an inflammatory bowel disease. Might baker’s yeast, which is the same yeast as brewer’s yeast, which is the same yeast as nutritional yeast, play a role in Crohn’s disease?

It all started with this study published in 1988, showing that people with Crohn’s disease tend to have more antibodies to yeast than people without Crohn’s disease. Antibodies are like homing devices our immune system makes to attack foreign invaders. That’s one part of our immune system; another is cell-mediated immunity, where our white blood cells attack invaders directly. And, the same hypersensitive reaction to yeast was found in the white blood cells of Crohn’s disease patients, as well.

If you draw blood from healthy people, even bakers who are around yeast all the time, and you expose their peripheral blood leukocytes, their immune system white blood cells, to yeast, nothing happens. They just kind of ignore it, because it’s typically harmless. But, do the same thing with Crohn’s disease patients, and their white blood cells go crazy.

Now, when I say typically harmless, if you have cancer, or AIDS, or are immunocompromised, you could potentially get infected from like, home-brewed beer, or probiotic yeast supplements, but they don’t think the yeast is actually infecting Crohn’s patients. People with Crohn’s may just be hypersensitive to exposure to the inactive, dead yeast in typical food products, which may help explain why, when you rest their bowels, when you make Crohn’s patients fast, they get better.

In fact, that’s why we add yeast extracts and proteins to vaccines, as an adjuvant, an irritant like aluminum, to make the vaccines work better, by heightening the immune response. But, might that be raising the risk of autoimmune disease, boosting our immune response a little too much, especially in people who may be genetically susceptible, like with Crohn’s?

And, the greater the anti-yeast response, the more severe the disease, in both children and maybe adults too. So, maybe we should try a yeast-free diet for Crohn’s patients, and see if they get better. But, wait a second. Just because anti-yeast antibodies are associated with Crohn’s disease doesn’t mean the reaction to yeast is causing the Crohn’s disease. Maybe the Crohn’s disease is causing the reaction to yeast. What? Think about it. Crohn’s causes an inflamed, leaky gut; so, maybe the Crohn’s came first, allowing yeast particles to leak into the bloodstream, resulting in the anti-yeast reaction. So, instead of the yeast reaction triggering the Crohn’s, maybe the Crohn’s just triggers the yeast reaction. “Whether the…antibodies are actually triggering [inflammatory bowel disease] or are only…consequence[s] of gut inflammation…remains elusive.”

So, how could we test it? Well, if anti-yeast antibodies are just a consequence of food particles leaking through the gut, Crohn’s patients should have antibodies to all sorts of common foods. But, no. Higher anti-yeast antibodies in Crohn’s disease compared to controls, but no greater reaction in Crohn’s patients to milk, wheat, or egg proteins, which would presumably all leak through, too.

Or, you can look at it the other way; instead of other foods, what about other inflammatory bowel disorders—ulcerative colitis or acute gastroenteritis? There, you could get inflamed and leaky, too, yet no increased yeast reaction. So, there does appear to be something unique about the yeast-Crohn’s relationship. But, maybe inflamed Crohn’s intestines just uniquely and selectively allow yeast through? If you cut out the Crohn’s, can you stop the yeast reaction?

Crohn’s gets so bad that most patients have to go under the knife, and get sections of their intestines removed. So, when the inflamed segments are removed, does the yeast reaction go away? No; no change post-op. So, a change in Crohn’s activity does not lead to a change in the yeast reaction. But, we still have to prove that the yeast reaction comes first.

Thankfully, the Israeli military “systematically [draws blood] from [their] recruits,” follows their health for years; so, you can go back and check the blood of newly-diagnosed Crohn’s victims. And indeed, those who went on to have Crohn’s were years earlier disproportionately reacting to yeast. So, it’s not like yeast reactions were low until Crohn’s hit, and then they shot up; yeast reactivity crept up year after year, before the diagnosis. Now look, it’s possible that there was some subclinical gut leakiness in the years preceding diagnosis that led to the yeast reaction, but there doesn’t appear to be any association between yeast reactivity and gut leakiness.

So: “Do high [blood] levels of [anti-yeast] antibodies result from a leakiness of the gut barrier in Crohn’s disease?” No; that does not appear to be the case. So, if Crohn’s isn’t leading to the yeast reaction, does that mean that the yeast reaction is leading to the Crohn’s?

Any time you have two things that appear to be associated—in this case reacting to yeast and Crohn’s disease—they both can appear tied together because X causes Y, or because Y causes X. Well, in this case it appears that Y does not cause X. But, does that mean that X causes Y? Well, there’s another option. Maybe there’s a third factor that causes both of them independently. Maybe the only reason yeast reactivity and Crohn’s disease appear to go together is that there’s a third factor causing them both—like, for instance, candida, which I’ll cover, next.

Please consider volunteering to help out on the site.

Icons created by Gay Soon Lay, parkjisun, Milky, and Anna Hatzisavas from The Noun Project.

Image credit: Kristina DeMuth. Image has been modified.

Motion graphics by Avocado Video

Doctor's Note

This is something I warned people about not long ago on social media. It takes some time from when I first research a topic until the video is produced and uploaded to the site, so for breaking or important news, I rely on our Facebook, Twitter, Instagram, and YouTube channels to let everyone know as quickly as I can. Please consider following along and joining in on the conversation.

Warned about? So is yeast really a potential problem? Yes, and not just for Crohn’s. This is the first of a four-part video series. See also:

And for more videos about Crohn’s, visit the topic page.

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