Rice, corn, quinoa, millet, sorghum, teff, buckwheat, and amaranth are all naturally free of gluten. These grains (and pseudo-grains) do not contain the specific proteins found in wheat, barley, and rye that trigger celiac disease and gluten sensitivity. But “naturally gluten-free” doesn’t always mean safe straight off the shelf, so the details matter.
Why These Grains Are Safe
Gluten is a term for the storage proteins in wheat, barley, and rye. These proteins cause an immune reaction in people with celiac disease and can trigger symptoms in people with non-celiac gluten sensitivity. Other grains contain their own storage proteins, but those proteins have a different structure and do not provoke the same immune response. Corn, for instance, contains a protein called zein, and rice has its own storage protein as well. Neither causes the intestinal damage associated with celiac disease.
The Complete List of Gluten-Free Grains
These are the grains and grain-like foods widely recognized as naturally gluten-free:
- Rice (white, brown, and wild rice)
- Corn (including cornmeal, grits, and polenta)
- Quinoa
- Millet
- Sorghum
- Teff
- Buckwheat (despite the name, not related to wheat)
- Amaranth
- Flax
- Tapioca (from cassava root)
- Arrowroot
Quinoa, buckwheat, and amaranth are technically pseudo-cereals, meaning they come from broadleaf plants rather than grasses. Nutritionally and culinarily they function like grains, and they’re grouped together in gluten-free diets.
What About Oats?
Oats occupy a gray zone. They don’t contain wheat, barley, or rye proteins, but they do contain a related protein called avenin. Most people with celiac disease tolerate oats without issues, but a meaningful subset does not. In one study published in PLOS Medicine, researchers found avenin-reactive immune responses in 5 out of 9 celiac patients tested, suggesting the reaction is more common than previously assumed.
On top of the avenin question, conventional oats are almost always contaminated with wheat or barley from shared fields and milling equipment. If you eat oats, look for products specifically labeled “gluten-free oats,” which come from dedicated growing and processing lines. Even then, if you have celiac disease, it’s worth paying attention to how your body responds.
Cross-Contamination Is the Real Risk
A bag of plain millet or buckwheat sounds safe, but many naturally gluten-free grains are processed in the same facilities as wheat. Shared milling equipment is the biggest culprit. Stone burr mills, commonly used for grinding grain into flour, are porous and can harbor gluten residue even after thorough cleaning. This means a bag of buckwheat flour ground on the same stones as wheat flour may contain enough gluten to cause a reaction.
For people with celiac disease, this isn’t a theoretical concern. Even small amounts of gluten cause intestinal damage whether you feel symptoms or not. Buying grains and flours that carry a gluten-free certification is the most reliable way to avoid this problem. If you mill your own flour at home, use a dedicated mill that has never processed wheat, barley, or rye.
How to Read Labels
In the United States, any food labeled “gluten-free” must contain less than 20 parts per million (ppm) of gluten. That’s the threshold set by the FDA, equivalent to 20 milligrams of gluten per kilogram of food. Products that are inherently gluten-free, like plain rice, can also carry this label as long as any unavoidable contamination stays below 20 ppm.
Third-party certifications go further. The Gluten-Free Certification Organization (GFCO), whose seal appears on many products, requires 10 ppm or less, which is half the FDA threshold. If a tested product lot exceeds that limit, GFCO requires a recall. For grains specifically, GFCO also tests for physical contamination, requiring fewer than 0.25 gluten-containing grain kernels per kilogram. When you’re choosing between two bags of quinoa and one carries the GFCO seal, that’s a meaningful difference in testing rigor.
How Gluten-Free Grains Cook and Taste
One reason people stick with rice and corn is familiarity, but the lesser-known options have distinctive qualities worth exploring.
Millet cooks up fluffy with a mild flavor, making it a versatile side dish that takes on whatever seasoning you add. Sorghum has a chewy texture and nutty taste, and it works well as a substitute for couscous in salads and bowls. Teff grains are tiny, so they cook into a porridge-like consistency. Teff has a naturally sweet flavor and is traditionally ground into flour for Ethiopian injera bread, but cooked whole it makes a good hot cereal.
Quinoa and amaranth both cook quickly (about 15 to 20 minutes) and have a slightly earthy, nutty taste. Buckwheat groats, sometimes sold as kasha, have a more robust flavor and hold their shape well in pilafs and grain bowls. For baking, rice flour and tapioca starch are the most common gluten-free bases, though sorghum and teff flours add more nutritional depth.
Nutritional Strengths Worth Knowing
Gluten-free grains aren’t nutritionally interchangeable. Quinoa and amaranth are complete proteins, meaning they contain all nine essential amino acids, which is unusual for plant foods. Teff is notably high in iron and calcium. Millet provides a good source of B vitamins and magnesium.
Sorghum stands out for its antioxidant content. It’s rich in plant compounds that have demonstrated anti-inflammatory and antioxidant effects in lab studies. Dark-colored varieties, particularly black and red sorghum, contain a class of pigments that are relatively rare in the food supply and have shown potential for reducing oxidative stress. While these findings come from lab and animal research rather than large human trials, sorghum is one of the more nutrient-dense options on the gluten-free list.
A common concern with gluten-free diets is that they can end up low in fiber, since many processed gluten-free products rely on refined starches. Cooking with whole gluten-free grains like sorghum, millet, teff, and quinoa solves that problem. These grains deliver fiber, protein, and micronutrients that refined gluten-free bread and pasta typically lack.