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Rye is a cereal grass, Secale cereale, and it is not gluten free: NIDDK lists rye with wheat and barley as the grains that contain gluten, so it is off the menu for people with celiac disease. Rye grain is very high in fiber, about 15 grams per 100 grams in USDA data, and it tolerates harsh growing conditions and remains a major cereal in Central and Eastern Europe. This guide covers rye nutrition for the whole grain and three rye flour types, answers the question is rye gluten free with official sources, and explains ergot, the fungus that made rye history famous.
Peptide Labs does not sell rye or rye products. This article is general nutrition information, not medical advice. Our rye bread guide covers the bread itself and the research on it.
Key Takeaways
- Rye contains gluten. NIDDK, the Celiac Disease Foundation and the FDA gluten-free rule all name rye as a gluten grain.
- Per USDA, 100 grams of rye grain has 15.1 grams of fiber (54% of the Daily Value) and 112% of the Daily Value for manganese.
- Dark rye flour has about three times the fiber of light rye flour in USDA data.
- Ergot is a fungus, Claviceps purpurea, that infects rye; medieval outbreaks of ergot poisoning were called Saint Anthony's fire.
- US grain standards label rye with more than 0.30 percent ergot as a special grade, ergoty rye.
What is rye?
Rye is a cereal grain, like wheat and barley. A 2025 study in Molecules calls it one of the most important cereals of Central and Eastern Europe, valued for its resistance to environmental stress. You can find it as whole rye grain, sold as rye berries; as cracked rye and rye flakes, which look like rolled oats; and as rye flour, which goes into breads, crispbreads and crackers. Many rye breads are dense, and many mix rye flour with wheat flour.
Rye grain nutrition
The table uses the USDA FoodData Central SR Legacy entry for rye grain (FDC 168884), per 100 grams of dry grain, with Percent Daily Values from the FDA reference amounts.
| Nutrient | Rye grain, dry, per 100 g | %DV |
|---|---|---|
| Calories | 338 | |
| Carbohydrate | 75.9 g | 28% |
| Fiber | 15.1 g | 54% |
| Total sugars | 1.0 g | no DV |
| Protein | 10.3 g | 21% |
| Fat | 1.6 g | |
| Manganese | 2.58 mg | 112% |
| Copper | 0.37 mg | 41% |
| Niacin | 4.3 mg | 27% |
| Phosphorus | 332 mg | 27% |
| Magnesium | 110 mg | 26% |
| Thiamin | 0.32 mg | 26% |
| Selenium | 13.9 mcg | 25% |
| Zinc | 2.65 mg | 24% |
| Iron | 2.6 mg | 15% |
Fiber is the headline. A 2025 field study of four rye cultivars grown in five places over three seasons found dietary fiber averaging roughly 15% of the grain by weight, mostly non-starch polysaccharides, with smaller amounts of beta-glucan and lignin; growing conditions changed the numbers more than anything else. For how that compares with other foods, see our high-fiber foods list and our guide to how much fiber per day the Daily Value reflects. Rye is also a fructan source: Monash University lists rye bread and rye crispbread among grain foods particularly rich in fructans, which matters for anyone on a low FODMAP diet. Among vegetables, sunchokes are a well-known inulin source.
Rye compared with other whole grains
| Grain, dry (USDA SR Legacy, per 100 g) | Calories | Fiber | Protein |
|---|---|---|---|
| Rye grain (168884) | 338 | 15.1 g | 10.3 g |
| Barley, hulled (170283) | 354 | 17.3 g | 12.5 g |
| Wheat, hard red winter (168890) | 327 | 12.2 g | 12.6 g |
| Oats, regular and quick, dry (173904) | 379 | 10.1 g | 13.2 g |
Rye and hulled barley lead this group on fiber per 100 grams. Our barley and oats guides cover those grains, and buckwheat covers a seed that is naturally free of gluten.
Rye flour: dark, medium and light
Rye flour is sold as dark, medium or light. USDA SR Legacy has three matching entries, and the differences are large.
| Flour (USDA SR Legacy, per 100 g) | Calories | Fiber | Protein | Iron | Magnesium | Potassium |
|---|---|---|---|---|---|---|
| Rye flour, dark (168885) | 325 | 23.8 g | 15.9 g | 5.0 mg | 160 mg | 717 mg |
| Rye flour, medium (168886) | 349 | 11.8 g | 10.9 g | 2.5 mg | 63 mg | 374 mg |
| Rye flour, light (168887) | 357 | 8.0 g | 9.8 g | 0.9 mg | 32 mg | 224 mg |
| Wheat flour, whole-grain (168893) | 340 | 10.7 g | 13.2 g | 3.6 mg | 137 mg | 363 mg |
| Wheat flour, white, enriched (168894) | 364 | 2.7 g | 10.3 g | 4.6 mg | 22 mg | 107 mg |
Per USDA, dark rye flour has about three times the fiber and five times the magnesium of light rye flour. Enriched white wheat flour has more iron than light rye flour only because iron is added during enrichment. Like all flour, rye flour is a raw ingredient: FDA and CDC say not to eat or taste raw flour, dough or batter, because germs are killed only when flour is baked or cooked.
Is rye gluten free?
No. NIDDK states that gluten is a protein found naturally in wheat, barley and rye, and its celiac diet page lists rye and triticale among the grains to leave out. The Celiac Disease Foundation describes gluten as the name for proteins found in wheat, rye, barley and triticale. Under the FDA gluten-free rule (21 CFR 101.91), a gluten-containing grain is wheat, rye, barley or a crossbred hybrid of them, such as triticale, and a food labeled gluten-free must keep any unavoidable gluten below 20 parts per million.
In rye, the gluten proteins are called secalins (the rye prolamins) plus glutelins. A 2025 Food Chemistry paper notes that almost all gluten tests are calibrated to wheat and that no rye-specific reference material existed, which is why researchers are building one for rye traces in gluten-free foods. Two practical points follow:
- Allergen labels will not flag rye. Wheat is one of the nine major food allergens under US law; rye is not, so a Contains statement may not mention it. Read the ingredient list.
- Testing comes first. NIDDK says doctors don’t recommend starting a gluten-free diet before celiac testing, because it can change test results. A doctor or registered dietitian can guide the diet after diagnosis.
Ergot: the fungus in rye history
Ergot is a disease caused by the fungus Claviceps purpurea, which colonizes the flowers of grasses, including cereal crops, and forms typical black kernels on the plant. A 2021 history in Clinics in Dermatology explains that eating infected rye containing ergot alkaloids, usually in contaminated bread, caused poisoning known as ergotism. In the Middle Ages, regions where rye was a staple recorded many outbreaks, called Saint Anthony’s fire or holy fire, with neurologic disorders and gangrene; the nature of ergot was not understood until the 18th century.
Modern grain handling watches for it. Under the official United States Standards for Rye (7 CFR 810.1205), rye that contains more than 0.30 percent of ergot is graded as a special grade called ergoty rye. The same 2021 review notes that ergot alkaloids still pose a risk to human and animal safety if they appear in food, which is why grain inspection grades track it.
How to cook with rye
Plain kitchen guidance, not a health claim:
- Rye berries: rinse and simmer in plenty of water until tender but chewy, then drain; they work in grain salads and soups much like wheat berries.
- Rye flakes: cook like rolled oats for porridge, or add to granola and muffins.
- Rye flour: blend with wheat flour for lighter breads, or on its own for dense loaves and crispbreads; dark rye flour absorbs more water than light.
- Storage: keep rye flour airtight in a cool, dry place and use it by the date on the package.
Frequently Asked Questions
Is rye gluten free?
No. NIDDK, the Celiac Disease Foundation and the FDA gluten-free rule all list rye as a gluten grain.
Can people with celiac disease have rye?
Rye is among the grains NIDDK lists for people with celiac disease to leave out. Ask your doctor or a registered dietitian about your own diet.
Is rye the same as wheat?
No. Rye is Secale cereale and wheat is Triticum. Both contain gluten, but only wheat is a major food allergen under US labeling law.
What is the difference between dark and light rye flour?
Per USDA, dark rye flour has about three times the fiber, more protein and five times the magnesium of light rye flour.
What is ergot?
A fungus, Claviceps purpurea, that infects rye and other grasses and produces ergot alkaloids. US grain standards set a special grade for rye with more than 0.30 percent ergot.
Is rye healthy?
Per USDA, rye grain is high in fiber and manganese and low in fat. For research on rye foods, see our rye bread guide.
Questions about a label? Contact us or read our Buyer’s Guide. Food comes first; follow the label and ask a healthcare provider before starting a supplement, especially if you take medicines, are pregnant or have a food allergy. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Last reviewed October 2026.
Related guides: Sunchokes: USDA Nutrition, Inulin, Gas and the Jerusalem Artichoke Name, Rye Bread: USDA Nutrition per Slice, Research and How It Compares, Barley: USDA Nutrition, Pearl vs Hulled, Beta-Glucan and Gluten.