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Quinoa's natural coating could cause a distressing gastrointestinal reaction and outweigh all its nutritional benefits.

By Jen Karetnick
March 01, 2021
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Recently, my daughter, who is gluten-intolerant and largely vegan, produced a delicious minestrone for dinner. She replaced the pasta with quinoa and added chickpeas along with the classic kidney beans to the recipe, making it even heartier. It was so tasty, we both consumed two bowls.

Later that evening, I became violently ill, the way I do when I inadvertently eat eggs, to which I am allergic. But I hadn't eaten eggs. Meanwhile, my daughter also felt unwell, but to a slightly lesser extent. What caused our similar reactions that differed in intensity?

Simply put: It was the quinoa. She didn't know that you should always rinse or soak it beforehand.

Classified botanically as a pseudocereal that's related to both amaranth and spinach, quinoa comes from the Andean regions of Peru and Bolivia. Its use is ancient: It first fed cattle as long as 7,000 years ago before humans also started to consume it about 4,000 years ago. Technically, it is not a grain but a seed.

Therein lies the problem. As seeds, quinoa is naturally susceptible to being eaten in the wild, which would reduce its ability to reproduce. So the plant creates at least 40 natural phyto-compounds called saponins that taste "soapy" or bitter upon consumption, prompting predators—birds, insects, and animals—to leave it alone.

quinoa in a spoon on a dark background
Credit: A. Martin UW Photography / Getty Images

According to Monica Auslander Moreno, MS, RD, "People can [also] be intolerant to the outer coating of the seeds. They're quite hard to digest because of the saponins." In fact, she says, consider it this way: When you say something is for the birds, you're calling it unpalatable. "Quinoa," she notes quite literally, "is not even for the birds."

Rinsing it beforehand does remove at least some of these saponins. Unfortunately, this knowledge became lost in the translation when quinoa began to be promoted as an ancient "superfood," amazing for everyone, in the mid-2000s. South American farmers and cooks, working with their native crop, retain and pass down this important information. North Americans at the mercy of marketers cashing in on a trend? Not so much.

Quinoa isn't the only plant to produce saponins. Many plants have them. We mainly consume them from legumes, especially kidney beans, chickpeas, and lentils, as well as oats, spinach, onion, garlic, asparagus, beets, tea, and yams. But because saponins vary in chemical structure, some are beneficial; for instance, the ones in oats and spinach actually help with digestion rather than actively working against it. Other plants' saponins might not affect you either way because they don't occur in the part that you eat.

But when it comes to quinoa, nearly all saponins exist in the outer part of the seed itself. A study published in the March 2020 edition of Molecules not only identifies the bitter and astringent properties of these 40-plus saponins, but it also investigates the best methods for removing them in both laboratory and commercial settings, from triple-washing and leaching to heat treatment, extrusion, roasting, and mechanical abrasion.

Leaching and roasting your quinoa at home is obviously a little labor-intensive. But knowing that such studies occur precisely because quinoa is problematic should induce you to at least read labels more carefully with an extra discerning eye. Indeed, just because a label says "pre-rinsed" doesn't mean you should skip washing it, especially if you're cooking quinoa for a group of people, any of whom could have a different level of experience with saponins. You might get away with not washing it for yourself if you've been building up a tolerance. But what if your kids are eating it for the first time? You have no idea how they'll react, given every person's anatomical differences.

Consider, too, what pre-rinsed actually means: Not a whole lot. How carefully has it been washed? Once? Twice? By hand, which is largely the way quinoa is traditionally gathered, or with commercial sprayers? Usually, this kind of information isn't available, even if you look for it. So find out for yourself by watching the water as it runs over the seeds. If it "soaps up," it still has saponins left on the coating. Rinse (or soak) until you see no more bubbles.

In fact, Moreno says you should always rinse any grain—buckwheat, millet, amaranth, sorghum, farro, or rice—no matter what. You don't know what happens to any commercial product on its way to packaging. She also recommends sampling different grains, pseudocereals, or seeds instead of utilizing one type all the time. Moreno says to try eating a little at a time first instead of a large portion, especially if you've never tried it before.

That advice goes double for quinoa. For one thing, if you have any sensitive gastrointestinal issue, the saponins or the outer layer of the quinoa seeds could worsen your symptoms. Both my husband and daughter have inflammatory bowel disease (ulcerative colitis and Crohn's, respectively), and quinoa has never been easy for them to digest. Often, it's been downright painful. Now they know why.

If you have a history of food allergies, you could have a lengthy, multi-symptom reaction to saponins. This is what my problem turned out to be. And because we included kidney beans and chickpeas in the soup, I received a triple dose.

While I'm steering clear of eating it for the near future, Moreno isn't anti-quinoa, and you shouldn't be, either. "It came to be promoted so rapidly because it's so high in fiber and high in protein. It's very nutrient-dense, rather affordable, and easy to cook," she says. "If you love it, enjoy it." Just proceed with caution, and a good rinse of water.

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