Folks, we have really good, really unsurprising news. According to Dan Buettner, a National Geographic reporter, longevity expert, and founder of the Blue Zones, bread is a staple food for the majority of the longest-living people on the planet.

In a recent Instagram post, Buettner shared that in the Blue Zone regions of Ikaria, Greece, and Sardinia, Italy, most consume bread on a daily basis. But not just any loaf, mind you—according to him, many rely primarily rely on sourdough bread. To learn why, keep reading—key health benefits of sourdough bread, why it’s part of a longevity-boosting diet, how to make it from scratch, and how to shop for the right one at the store ahead. Plus, Buettner reveals his all-time favorite store-bought bread that he eats regularly.

Longevity-boosting benefits of sourdough bread

According to Buettner, what distinguishes sourdough bread from other styles—and what gives it its longevity-boosting benefits—is the natural probiotics (aka good gut bacteria) it contains due to fermentation. “Thanks to the process of fermentation required for making starter, sourdough bread tends to have more prebiotic properties and also may enhance nutrient absorption compared to other forms of bread, especially those made without whole grains,” registered dietitian Kelly Jones, MS, RD previously shared with Well+Good. Indeed, research has shown that foods rich in prebiotics and probiotics can have significant benefits on gut health, immunity, and longevity.

“Thanks to the process of fermentation required for making starter, sourdough bread tends to have more prebiotic properties and also may enhance nutrient absorption compared to other forms of bread, especially those made without whole grains.”—Kelly Jones, MS, RD

What’s more, Buettner notes that the process of fermentation involved in making sourdough bread makes it more easily digestible than other non-fermented types. “Sourdough bread is typically leavened with lactobacillus, a bacteria that metabolize most of the gluten and lowers the glycemic load, rather than just yeast,” Buettner says. That said, Buettner points out that not all types of sourdough have these benefits—especially not many store-bought types. In fact, he notes that most of the kinds you’ll find in the grocery store have additives and likely don’t provide the same benefits as fermented sourdough consumed in longevity hotspots around the world. “The problem is that store-bought sourdough bread is often highly processed with flavorings that make it taste sour,” he says.

So, where to find the best type of sourdough, according to a longevity expert? Your local bakery. “It takes one to two days for the dough to rise before it’s ready to bake. It often doesn’t happen in the grocery store,” Buettner says. Conversely, a local bakery specializing in sourdough bread will likely have exactly what you’re looking for: pillowy soft but crusty-on-the-outside sourdough bread. (Say no more.)

A local bakery specializing in sourdough bread will likely have exactly what you’re looking for: pillowy soft but crusty-on-the-outside sourdough bread.

However, in the case that you can’t make it to a bakery, Buettner says there’s another type of store-bought bread that has similar benefits: Food For Life’s Cinnamon Raisin Ezekiel 4:9 Flourless Sprouted Grain Bread. “I eat Ezekiel bread all the time because the top ingredients are sprouted wheat, millet, and barley. It also has a much lower glycemic index, and you have to keep it in the freezer,” Buettner says.

Of course, if you’re feeling extra ambitious, you can always try making it from scratch with the Blue Zone’s three-ingredient Ikarian-style sourdough bread recipe below.

Okay, and it only feels right that we address the elephant in the room: What happens if you ate moldy bread by accident? Although one of the benefits of sourdough bread is that it’s less likely to mold over quickly, thanks to the way it’s made (ahem, hi, fermentation), you can never be too prepared. The good news? Even if you do accidentally nosh on a piece of blue-green bread, you’ll more than likely come out unscathed. Have no fear!

Ikarian-style sourdough bread recipe

Yields 6 servings

Ingredients1 (6/25 oz) package dry live-culture yeast-free sourdough starter for wheat flour (like Desem)6-8 cups bread flour (or equal parts semolina flour and bread flour)3 Tbsp canola or vegetable oilWater

1. Make the starter based on the instructions given in or on the packet. In general, you’ll mix a small amount of non-chlorinated water (such as bottled spring water) with the starter, then feed it small amounts of flour over the course of several days until it’s bubbling with a distinctly fermented aroma.

2. Place two cups of prepared starter in a large bowl and stir in two cups of lukewarm non-chlorinated water.

3. Stir in four cups of bread flour until a soft dough forms, adding more flour in one-cup increments until the dough can be gathered into a coherent, not sticky, ball. (Place the excess starter in a separate bowl and continue to feed with non-chlorinated water and small amounts of flour every few days as directed by the package to preserve for another baking.)

4. Lightly flour a clean, dry work surface. Set the ball of dough on it and knead until elastic and very smooth, about 20 minutes, adding more flour in one-tablespoon increments if the dough seems sticky.

5. Gather back into a ball, place in a large bowl, cover with a clean kitchen towel, and set aside in a warm, draft-free place until doubled in bulk, between six and 12 hours. (Do not stint on the time.)

6. Plunge your clean fist into the dough to deflate it. Turn out onto a dry, clean, lightly floured work surface and knead lightly for one minute. Shape into a free-form round or oval loaf about 10 inches in diameter or at the oval’s longest point.

7. Lightly grease a large-lipped baking sheet and transfer the loaf to it. Cover with a clean kitchen towel and set aside in a warm, draft-free place until doubled in bulk, four to eight hours. Meanwhile, position the rack in the center of the oven and heat the oven to 350°F.

8. Bake until browned and hollow sounding when tapped, about one hour.

9. Transfer to a wire baking rack and cool for at least 10 minutes or up to two hours before slicing to serve.

Tip: For easier preparation, knead the dough in the bowl of a stand mixer with the dough hook at low speed in step two. (Also, a second rising yields an exceptionally sour bread. However, you can skip this step. If so, knead the bread as directed in step three, skip the first rising and all of step four, then form the dough into the desired shape, letting it rise one time only as directed in step five.)