How Sourdough Bread Is Helping People Eat Gluten Again

There's some magic behind the fermentation process.
Katy Severson

If you’re sensitive to gluten, sourdough bread could be your new best friend.

Gluten is the most misunderstood substance of the new millennium, so demonized that even coffee, yogurt and body wash are labeled “gluten-free” as a selling point.

But we’ve been eating grains for some 100,000 years, so what accounts for the sudden, massive increase in gluten intolerance?

Marketing accounts for most of it: Eighty-six percent of Americans who think they’re gluten-intolerant aren’t. But it also has to do with the way we’re baking bread.

The invention of quick-rise commercial yeast has replaced the way we’ve baked bread since the beginning. But now, the rising popularity of sourdough bread is teaching us something: It’s easier to digest.

Sourdough has been a kind friend to our guts through the ages.

Before commercial yeast, or “baker’s yeast,” was popularized in the 1960s, we made bread with a sourdough starter. It’s a mix of fermented grain and water that collects the wild yeast that lives all around us in the air, on our bodies, and in the flour itself.

The complex, symbiotic ecosystem of a sourdough starter works to leaven, flavor and build the structure of the dough. The slow fermentation process invites a magical combination of wild yeast, bacteria and enzymes, and lactobacillus (the same bacteria in yogurt) releases lactic acid to create the sour flavor that sourdough is known for. The enzymes unlock minerals in the wheat otherwise unavailable to us. The yeast, which feeds on complex starches, releases CO2 as a byproduct. And gluten, demonized as it may be, traps that CO2 and creates the rise and texture of the loaf.

Of course, our ancestors knew this, to some degree. The magic of bread-baking was understood long before we learned the science of it.

As author Michael Pollan points out in Cooked, bread-baking was a miraculous invention of its time: It turned a previously indigestible grass into a nutritious, satisfying food. But the fermentation, it turns out, was key.

So what exactly is this miracle of science that makes sourdough easier to digest?

At her workshops in Marshall, North Carolina, Tara Jensen puts a ball of bread dough under running water. Once the starches dissolve and rinse off, what remains is pure gluten: a sticky, gluey mass of protein that has the texture of a balloon. Holding that tough glob of gluten, it’s obvious why it might be hard to digest.

But sourdough ― the only bread she bakes ― has a trick for helping us digest gluten. It utilizes natural fermentation, a process that attracts wild yeast and bacteria that, with time, digest complex starches in the dough to produce a byproduct that makes the dough rise. The longer the dough ferments, the more the gluten is broken down for us.

This happens through a process called hydrolysis, in which enzymes break down large, indigestible proteins into smaller amino acids.

Other studies point to phytic acid ― an acid found in wheat flour ― is also broken down during sourdough fermentation.

The research surrounding non-celiac gluten sensitivity is complicated. We still don’t know exactly what causes non-celiac sensitivities to foods containing gluten.

Several recent studies point to fructan, a compound found in bread, as well as in other things like bananas and garlic. Many gluten-sensitive people have found digestive relief from avoiding fructan-containing foods (also called FODMAPS). Sourdough bread does not contain fructan once it goes through fermentation. Other studies point to phytic acid ― an acid found in wheat flour ― which breaks down during sourdough fermentation.

In each of these studies, components hypothesized to be toxic to gluten-sensitive people are rendered digestible during sourdough fermentation. As a result, many people are finding that they can eat gluten again.

When it comes to celiac disease, though, the studies aren’t not enough to draw a broad conclusion. Those diagnosed with celiac are cautioned against eating any foods containing gluten, including sourdough, before consulting their doctor.

But the research is intriguing. Those with minor digestive issues or non-celiac gluten sensitivities will almost certainly find relief with properly made sourdough.

Proper refers to bread that’s leavened with a sourdough starter and left to ferment before baking. Many breads at the grocery store labeled “sourdough” have a sour flavor added, but are leavened with commercial yeast, foregoing fermentation. If unsure, ask your bakery if the bread is leavened naturally.

We messed with a good thing, but we’re coming around again.

Thankfully, sourdough bread is becoming easier to find. Part of the sourdough revolution is returning to these ancient practices and working against innovations (like quick-rise yeast) that we never needed in the first place.

And as a result, we might be making friends with gluten again.

boerescul via Getty Images

Here’s how to make a sourdough starter at home:

Take equal parts bread flour and lukewarm water (4 ounces of each is a good place to start) in a jar and cover with cheesecloth. Let it sit for three to four days in a warm place in your kitchen, stirring daily.

By Day 4, you should see early signs of fermentation, such as tiny bubbles on the surface. If you don’t see any signs of fermentation, try to move to a warmer place and wait a couple more days.

Now you begin “refreshing,” or “feeding” it. To do this, weigh out 1 ounce of your starter and add 4 ounces of flour and 4 ounces of water. Stir well. Let sit overnight and then feed again the next day around the same time, weighing out 1 ounce of the refreshed starter, and adding 4 ounces flour and 4 ounces water.

Continue to refresh it around the same time every day. You will notice that it becomes more active: This can take from one week to three weeks, depending on environmental factors. A house in the woods will likely attract more wild yeast and bacteria, and an apartment in New York City might take more time.

Look for signs like large, “dish-soap-like bubbles.” This generally means it’s ready for baking. You can also perform the “float test.” Take a small amount of your starter and test if it floats in a bowl of water. If it floats, it’s ready to bake bread.

If you can retrieve a small sourdough starter from someone else, this process will be much shorter. You’ll just need to refresh, or “feed” the starter for three days to five days until it passes the float test.

If your starter begins to collapse in your jar or develops a strongly acidic smell, it might be past its peak. But don’t worry, you can always bring it back! Start refreshing again every day until it passes the float test. This should take anywhere between three days to seven days, depending on how dormant your starter is.

You can store your starter in the refrigerator (without feeding it) for months. Just make sure you allow a few days for refreshment before baking.

CORRECTION: A previous version of this story misstated the findings and implications of an Italian study and linked to the incorrect study. That study has been removed, and replaced with additional information and studies about non-celiac gluten sensitivities and how they might arise.

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