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fermented beer

One of my favorite things about social media is how it encourages people to toss off simple questions they’d never take the time to type out and stick in an envelope or email.

Just the other day, one came over the electronic transom from a fellow named Jeff. His question: Are wild-fermented beers good for you because of their probiotic effects?

Oh, wow. That’s a perfect example of the kind of simple question it could take a lifetime to untangle.

It’s like one of those queries kids floor you with: Mommy, when was the first day of everything?

After a moment of baffled silence, you reply: Great question, my child; let’s schedule a trip to the planetarium, and we can spend a week on this one.

Is beer really as complicated as the cosmos? Kind of, yes.

[callout]Is beer really as complicated as the cosmos? Kind of, yes.[/callout]

Let’s start by unpacking the question. First off: What are wild-fermented beers, anyway?

For millennia, much of what we ate was made digestible with the help of wild yeasts — the teeny-tiny, natural microorganisms that live on every plant leaf and float on every breeze.

Yeasts eat stuff, carbohydrates mainly. And as they eat, they excrete alcohol and carbon dioxide.

Some wild yeasts cleverly excrete other things, too. Somewhere along their evolutionary path, they must have figured: “Having no legs is really slowing us down. We could get places faster if we could get fruit flies to carry us.” And thus, these yeasts started excreting beautiful, fruity scents, like apricot and apple.

If you’ve ever eaten bread with a wonderful apple fragrance (but no apple ingredients), this explains it: An enterprising microorganism was trying to hitchhike on a passing fruit fly when some humans intercepted it and press-ganged it into making their daily bread.

When you bake bread, yeasts eat the carbs in the flour and excrete carbon dioxide, which creates all the lovely holes that make the inside of a baguette so airy. They excrete some alcohol, too, but it all gets cooked off during baking.

Unlike bakers, beer brewers generally want to retain that alcohol. But they employ an otherwise similar yeast-reliant process, creating a soup of malted (sprouted) barley and water, and then letting wild yeasts do their thing, eating and excreting to their hearts’ content.

Perhaps by now you are thinking: Neat! I want to raise some of these wild little yeast fellows myself!

No problem: Take some organic grapes and stems, and submerge them in a flour-and-water slurry. Soon you’ll see bubbling. That’s the action of yeast at work.

Strain out the grapes and stems, and you’ve got a colony of wild yeast. You can keep them as pets, or use them as a starter for beer or sourdough bread.

You can do the same thing with grated organic potatoes or apples, simply submerging the grated substance in a flour slurry and letting nature take its yeasty course.

Interestingly, if you do this experiment in Maine with Maine ingredients, you’ll get different sourdough than if you did it in Arizona with Arizona ingredients. Wild yeast is both absolutely universal and utterly local.

Another way to get yeast is to culture the air — that is, just leave some carbs lying around and the yeast will fly in on the wind. Sometimes you’ll get great flavors, sometimes weird ones.

[callout]This is how beer was made for centuries: Just leave your malted-barley soup out and see what happens. [/callout]

This is how beer was made for centuries: Just leave your malted-barley soup out and see what happens. Sometimes great things. Sometimes, not so great.

In the 1800s, people decided to eliminate the not-so-great things, and strains of commercial yeast were developed. Brewers and bakers selected the wild yeasts they liked best and grew them in tanks. The yeasts would dry out and go dormant if you took away their water, then reanimate if you added water again. And voilà! Commercial yeast was born.

Fermentation soon cleaved into two camps. One was the wild-fermented beers, sourdough breads, and old-fashioned wines made from yeast captured from the air. The other was the products made from packets of refined yeast.

What was lost when we started industrially raising yeast? All the nice weirdness. We lost the funky tangerine flavors, the lovely banana notes, the element that’s redolent of Maine or so very Arizona — the complex wild stuff that makes food taste a little more special.

Wild yeasts are still appreciated by many brewers and bakers. There’s even a backlash against commercial yeast, which includes the natural-wine movement, in which vintners add nothing, letting the natural yeast on the grapes and in the air do the work.

There’s also a wild-yeast movement in beer brewing, though beer makers are less uptight than winemakers (surprise!). They add “things” in search of interesting flavors, such as old batches of beer or even commercial cultures of wild-yeast strains.

One way of “adding nothing” while still getting yeast from last year’s batch is to use an old barrel where the good yeast once was. (Remember how the yeast can dry out and go dormant, then reanimate?)

In any event, the “wild” part of “wild-fermented” is currently experiencing an explosion of popularity, as new generations become fascinated by all those wild possibilities. As of this writing, there are more than 1,500 American wild ales cataloged at

So, is there any reason to think the wild yeasts in beer, wine, or bread are especially beneficial to our health?

Nobody knows for sure. In his book The Blue Zones: 9 Lessons for Living Longer From the People Who’ve Lived the Longest, Dan Buettner  writes about the people on the Greek island of Ikaria, where many live into their 90s, free of dementia and other chronic diseases. He identifies a number of characteristics he thinks might be key to longevity, including plenty of local wild-fermented wine and sourdough bread. So, maybe.

Here’s another maybe: Brewer’s yeast (right out of the tank) has been recommended for centuries as a folk-medicine cure. More recently, it’s been recommended for its high levels of B vitamins, including thiamine, niacin, riboflavin, and folic acid, as well as the minerals chromium, selenium, zinc, and copper.

Which leads us back to Jeff’s original question: Are the wild yeasts in beer good for you? And how much active probiotic material is actually present in the beer we drink?

Truth is, we don’t know. We’re used to seeing yogurt containers hailing the number of “live active cultures” they contain. But no one counts these in beer. So no one knows exactly how many probiotics make it from the brew tank to the bottle to your stomach.

We do know that some yeasts are making that journey, because you can see it in the glass, as a haze, or left behind in the bottle, as a film or sludge. Look for that yeast in a beer that is unpasteurized or in an ale that is “bottle conditioned.”

Even if wild yeasts have positive probiotic effects, it would be hard to separate this effect out from beer’s other potential positive effects.

A 2012 review of studies published in the journal Nutrients concluded that beer is healthy in moderation: A beer or two a day appears to be beneficial for your heart, largely because of all the polyphenols contributed by hops, elements that are antioxidant, anticarcinogenic, anti-inflammatory, and antiviral. Those studies were of ordinary beer, so it stands to reason that the wild-fermented kind might be that much better.

Of course, too much beer is anything but good for your well-being. For one thing, alcohols, sugars, and other refined carbs can encourage an overgrowth of troublesome yeasts (like Candida albicans) that can do more harm than good. And, obviously, alcohol is addictive.

[callout]My best guess is that all beer has a bad health effect if you drink it all by yourself while sobbing into the glass. And all beer can have good health effects if you enjoy it, happily and in moderation, with someone you love.[/callout]

So what’s the answer already? Good, or not good? I have no idea.

My best guess is that all beer has a bad health effect if you drink it all by yourself while sobbing into the glass. And all beer can have good health effects if you enjoy it, happily and in moderation, with someone you love.

So that’s my answer. I hope you enjoyed this trip to the planetarium, in which we achieved much of the answer, but in no way all of it.

Perhaps the more important question is this: If wild-fermented beer is of uncertain probiotic value but reliably delivers wild-crafted satisfaction, and can be enjoyed in healthy, happy moderation, can we all just raise a glass to that?

Illustration by: Tom Kaczynsk

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