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This article claims that eating active yeast powder before drinking will mitigate the effects of alcohol, by breaking down the alcohol before it enters your blood stream.

You see, what Owades knew was that active dry yeast has an enzyme in it called alcohol dehydrogenases (ADH). Roughly put, ADH is able to break alcohol molecules down into their constituent parts of carbon, hydrogen, and oxygen. Which is the same thing that happens when your body metabolizes alcohol in its liver. Owades realized if you also have that enzyme in your stomach when the alcohol first hits it, the ADH will begin breaking it down before it gets into your bloodstream and, thus, your brain.

Is there any truth to this?

Are there any risks from eating raw yeast? There is a rather nasty (but rare) condition called Auto-brewery syndrome which could have the opposite effect if the yeast got into your intestines intact.

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I guess the weekend experiment is set then :) –  Forkrul Assail Apr 25 at 13:14
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Yeast doesn't break down alcohol anyway... it excretes it, when "breaking down" sugars. The proposed mechanism sounds pretty far-fetched to me, just on the surface. –  Flimzy Apr 25 at 14:35
    
ADH2 in saccharomyces, an isoform of the more familiar ADH1, is more active converting ethanol to acetaldehye. However, I am also extremely skeptical that it could function in the pH range present in the stomach. It is more likely the fact that a person is taking time to eat yogurt and drinking water to flush it down and thus keeping themselves hydrated that may mitigate the intoxication. –  Scott Apr 25 at 20:08
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Snopes quotes answers from here. –  Oddthinking Apr 26 at 17:14
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2 Answers 2

up vote 28 down vote accepted

No, it is highly implausible that eating yeast will stop you from getting drunk.

Inside the stomach the pH is around 1-2, the activity of enzymes is typically strongly dependent on the pH. Outside of their optimal pH range enzymes generally work much slower or not at all.

Yeast ADH has a pH optimum in the neutral to alkaline range, at low pH values it is not active at all. The following two papers looked at the effect of pH on ADH and both observed that ADH was unstable at low pH values

From "The Role of Zinc in Alcohol Dehydrogenase: V. THE EFFECT OF METAL-BINDING AGENTS ON THE STRUCTURE OF THE YEAST ALCOHOL DEHYDROGENASE MOLECULE":

At acid pH, both activity and zinc of the enzyme are lost also (18, 19), but the effect of H+ ions on the structure of the enzyme differs markedly from that here described for chelating agents. Yeast alcohol dehydrogenase, 3.3 x 1O-5 M, when dialyzed for 24 hours in 0.1 M sodium acetate, pH 4.0, 0°, becomes polydispersed and precipitates on increasing the temperature by only 4°. Apparently, H+ ions critically affect sensitive groups of this enzyme in addition to those involved in activity and zinc binding.

From "Effect of pH on the Liver Alcohol Dehydrogenase Reaction":

We are unable to study the rate of hydride transfer at more acidic pH values because our enzyme preparation undergoes rapid loss of activity below pH 5.9

So the proposed mechanism of the higher alcohol tolerance is highly implausible. There could be an effect of eating yeast separate from ADH, or yeast could have isoforms that also work at lower pH. But as the only evidence in favor seems to be anecdotal I would doubt that eating yeast as a significant effect.

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The pH of the stomach is oftentimes temporarily above 7, eg during a bout of beer drinking. It takes about 45 minutes for your stomach to drop in pH after eating/drinking. Hence, I would argue there is a short, but plausible window for ADH to be active. Additionally, the ADH may be active in the small intestine rather than the stomach, per se. loomisinstitute.com/articles/… –  Streblo Apr 25 at 15:58
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@Streblo The stomach pH is more complicated, but I haven't seen a source that says that it can go up to 7, 5 was the highest I've seen. Your linked source contains a few rather dubious statements, and the whole site seems rather focused on promoting food enzymes. –  Fabian Apr 25 at 17:07
    
I wonder if it would work in people on acid-suppressing drugs like PPIs? –  Melissa Apr 25 at 18:48
    
The author also mentions he mixes the yeast in yogurt, but as yogurt is mildly acidic, I don't know how much effect that will have. –  Dan Esparza Apr 25 at 19:05
    
The ADH is not unlikely to be exposed to the stomach pH in yeast, so this only matters to the extent that yeast's structural integrity is compromised. Since yeast generally tolerate acidity quite well (easily down to a pH of 4 for some yeasts) there is a reasonable chance that the yeast could thrive in the upper ranges of stomach pH. An example of this can be found here where a man had a persistent infection in his stomach that was actually fermenting to produce alcohol. –  Salain Apr 25 at 21:42
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It seems decidedly skepticism-worthy based on the previous answers. I do not know the science, but I did find a link to a patent filing for the Prequel product filed by Joseph Owades, who also appears to be a legitimate scientific source as an industrial biochemist and Ph.D. Quotes are included in comments below.

http://patents.justia.com/patent/6284244

Mediating the effects of alcohol consumption by orally administering active dry yeast

Patent number: 6284244

Abstract: Mediating the effects of alcohol consumption by orally administering an active dry yeast containing alcohol dehydrogenase to a person prior to or simultaneously with consumption of an alcohol-containing beverage to oxidize a portion of the alcohol while it is still in the stomach of the person is described.

Issued: September 4, 2001

Inventor: Joseph L. Owades

Considering he obtained the patent and cites an 8-person sample research study showing it has an effect, it seems plausible. Whether it's exactly alcohol dehydrogenase directly and in the stomach specifically is inconclusive from the patent. Other alcohol dehydrogenases are found in the stomach however:

"At the high ethanol concentrations in stomach after drinking, sigma-ADH is probably the ADH form with the largest contribution to human gastric ethanol metabolism."

Purification and characterization of a new alcohol dehydrogenase from human stomach.

Authors: A Moreno and X Parés

Journal of Biological Chemistry, 1991

http://www.jbc.org/content/266/2/1128.full.pdf+html

Joseph Owades also seems to be an interesting guy. His post-mortem in the Washington Post:

http://www.washingtonpost.com/wp-dyn/content/article/2005/12/20/AR2005122001540.html

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"It has been found that ingesting active dry bakers yeast (the yeast most readily available commercially) or brewers, vintners or distillers yeast, just before, or during, the drinking of an alcoholic beverage, oxidizes a portion of the alcohol while still in the stomach, which results in a lower peak blood alcohol level, and also a lesser area under the curve of a plot of blood alcohol level vs. time." –  Flex Organ Apr 26 at 4:02
    
"The action of the alcohol dehydrogenase on the alcohol is only in the stomach, so the alcohol dehydrogenase source must be ingested while the alcoholic beverage is still in the stomach. It will have no effect once the alcohol has left the stomach and entered the bloodstream, because the enzyme is destroyed by the acidity and proteolytic action in the stomach." –  Flex Organ Apr 26 at 4:04
    
Also, in response to an above mention that the Saccharomyces cerevisiae infection was found in a stomach and thus survived under stomach pH levels, this is the case study of the most recent 61-year old in the NPR article. file.scirp.org/Html/1-2100535_33912.htm The infection was found in stool cultures and the small intestine. They were not necessarily surviving in the stomach for long. –  Flex Organ Apr 26 at 4:09
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You do not need to demonstrate that a treatment works to get a patent; there are plenty of patents for non-existent effects, so that's not definitive evidence. If you can find the 8-person study, we may have some evidence. –  Oddthinking Apr 26 at 6:16
    
The pH of the stomach is only relevant to the survival of the yeast cell. If the yeast cell can survive the stomach environment, the enzyme activity would be occurring inside the yeast cell membrane and thus not be exposed to the environments pH. Alcohol would be transported across the yeast cell membrane and acted upon in the yeast cytosol –  MikeM Apr 26 at 7:58
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