In April 2014, Esquire magazine published an interview with billionaire Jim Koch, the co-founder and chairman of the Boston Beer Company. In that interview, Koch divulged his secret for how to "drink beer all night long and never get drunk" — the secret being to swallow one teaspoon of active dry yeast per beer prior to imbibing:
"You wanna know my secret? How I can drink beer all night long and never get drunk?"
In fact, I had always wondered that. Though this was the first time I'd ever formally met Koch, I'd "met" him in the past at a few beer festivals. Those sorts of events are always kind of Bacchanalian shit shows, with people imbibing dozens of beer samples in a short period and soon stumbling around large convention halls drunk of their asses. Brewers included. But not Koch, who I'd long noticed was always lucid, always able to hold court, and hold his own with those much younger than him. This billionaire brewing raconteur was doing likewise with me at 4 PM on a Thursday afternoon despite the fact we were both now several beers deep. So what was the secret?
"Active yeast. Like you get at the grocery store."
Koch told me that for years he has swallowed your standard Fleischmann's dry yeast before he drinks, stirring the white powdery substance in with some yogurt to make it more palatable.
"One teaspoon per beer, right before you start drinking."
To understand the purported science behind this claim, however, it is first necessary to review the basics of how alcohol breaks down in the human body once it has been imbibed. According an article on hangovers in Scientific American, this process is aided by a specific alcohol-altering enzyme, ADH:
Shortly after a person starts consuming an alcoholic drink, the liver gets to work. The enzyme alcohol dehydrogenase (ADH) metabolizes the ethanol (that's the type of alcohol in alcohol) into toxic acetaldehyde. From there the liver enzyme aldehyde dehydrogenase (ALDH) metabolizes acetaldehyde into acetate, a less toxic compound that breaks down into water and carbon dioxide.
ADH is produced naturally in the human body and can be found in high concentrations in the lining of the stomach wall and in the liver. It is also — and this is where the science gets a bit confusing — added to beer in order to produce alcohol in the first place. When added to beer, it is done so via the addition of yeast.
Yeast are single-celled, microscopic fungi that have been used for millennia to create alcoholic beverages through fermentation. In beer brewing the process utilizes yeast's natural ability to produce ADH, but this ADH-mediated reaction can go in both directions: non-booze chemicals into booze, or booze into non-booze chemicals -- it depends on the specific chemistry of ADH, as discussed by pharmacologist David Kroll in a Forbes article about this claim:
In the brewing process, that's how we get alcohol from the sugars that are released from the malted barley and other grains. But it can also work in the reverse direction to metabolize the alcohol back into its precursor, acetaldehyde. Yeast also have multiple forms of the enzyme the predominate in one direction or another.
What it all boils down to is this: an enzyme exists that is capable of both converting stuff into alcohol (which is its role in brewing) and also of converting alcohol into something else (its role when found in your stomach and liver). Koch's claim rests on the assertion that eating a tablespoon of Fleischmann's bakers yeast adds enough ADH to your system, and in the right manner, to increase the rate of alcohol breakdown in the stomach, leaving less booze to enter your bloodstream.
The scientific community has, for the most part, reacted with skepticism to Koch's claims. Speaking to NPR, microbiologist Benjamin Tu argued that while yeast can degrade alcohol, they prefer sugars, making it unlikely that yeast delivered via a sugary spoonful of yogurt would be interested in breaking down the alcohol instead:
"Yeast can degrade ethanol," says [Tu]. "But they love other sugars — glucose, maltose — more. When those sugars are around, the cells turn off the genes needed for alcohol degradation."
Many beers contain some leftover sugars that don't get fermented. Yogurt has sugars, too. So if Koch is eating the yeast with yogurt, that offers the fungi something more tempting than alcohol.
Another issue raised by Tu was the amount of time the yeast would be in contact with the alcohol before being absorbed by the digestive tract -- not enough, in his view. "I think the exposure time of the alcohol to the yeast is too low," he told NPR, "Any effect of the yeast [on BAC] will be marginal."
That issue would perhaps be compounded by another one raised in both online debates and in articles: Whether or not the yeast able to remain active at all in the highly acidic environment that is the stomach. In the Forbes piece, Robert Sclafani, a professor of biochemistry at the University of Colorado Denver's School of Medicine, argued that the pH would likely reduce many of the purported ADH breakdown in the stomach: "The pH of the stomach varies from 2-4 but will be at 2 when you are eating. My guess is that the combination of pH 2 and active digestive enzymes will make it unlikely that yeast ADH can work well (its pH optimum is about 8.6)."
From a larger standpoint, only 10% of the alcohol breakdown process takes place in the stomach to begin with. That means that even if that yeast were breaking down alcohol in the stomach, Koch is only increasing the effectiveness of a minor component of a larger system that breaks booze down. The remainder of the breakdown process happens almost entirely in the liver over a longer time period.
According to George Koob,director of the National Institute on Alcohol Abuse and Alcoholism, If the yeast had any effect on intoxication at all, it would most likely be from the fact that any food residing in the stomach prolongs the amount of time alcohol will be absorbed by the digestive tract (and therefore lower the speed at which it would be entering your bloodstream). "Anything you take that occupies the stomach lining is going to impede the absorption of alcohol" he told NPR.
While the scientific community's reaction to Koch's claim was one of bemused skepticism, many in the media have used it as an opportunity to brush up on the scientific method. Aaron Goldfarb, the author of the original Esquire interview with Koch, tried it out:
So the next day I grabbed a six-pack of beer and a packet of Fleischmann's and went to work. The older I get, the more of a lightweight I surely become, but after shoveling down six teaspoons and tilting back six bottles I felt nothing more than a little buzzed. Koch told me he keeps a breathalyzer around at all times just to assure he's never too drunk. He never is. And, though I had no tangible "proof," besides the fact I was still awake, I was pretty sure I wasn't all that drunk either.
Likely the most systematic (but still quite limited) attempt was made by the writers of NPR's The Salt blog, who performed their own yeast-booze experiment with a still admittedly small dataset. By drinking beer and wine in combination with yeast/yogurt, with water, and with nothing, they found nearly no difference between yeast and and just drinking without anything else. The largest difference came from the water: "A few conclusions were clear: Yeast in yogurt doesn't slow down the absorption of alcohol very much — perhaps only a tad. But drinking a bunch of water before and between beers might have a slightly bigger effect on peak BAC than the yeast-yogurt combo."
Unfortunately, the only other data to refute or support these informal experiments come from a non-peer reviewed patent filing. That patent was submitted by a man Koch cites as both a mentor and as the source of the hot tip about yeast-based inebriation prevention: The late fermentation expert and biochemist Joseph L. Owades. These experiments were conducted in a similar way to the NPR experiment, but resulted in much more compelling results ranging from 28% to 38% reductions in BAC which he attributed to the yeast.
Kroll, in his Forbes article, took issue with the quality of these data, however:
Owades' experiments in the patent application have never been published in a peer-reviewed journal. In fact, I doubt that any journal reviewers would let the work be published as presented.
First of all, the earliest breathalyzer reading, and highest alcohol concentration, is at 10 minutes. But alcohol remaining in the mouth can make this appear artificially high. Ideally, breath should best be measured beginning at 20 minutes after the last drink. Also, we don't know how many times the analysis was repeated at each time. Finally, Owades mixed the types of alcoholic drinks, subjects, and even the yeast, used across only eight subjects.
Ultimately, however, the lack of peer reviewed data or research on this topic—for or against the claim—prevents us from making a concrete ruling on the topic at this time.