Corn Masa & Corn Tortillas: Nutrients, What Research Shows and Safety

Corn masa is the dough, or the dry flour, made from corn that has been soaked and cooked in limewater (calcium hydroxide), a process called nixtamalization. It is the base of corn tortillas, tamales and many other foods in the Americas. The grain is dried corn (Zea mays, grass family Poaceae). This page covers the masa flour and what is known about corn tortillas made from it. It keeps the food apart from corn chips, sweet corn and supplements. For plain popped corn see popcorn.

Read this first

• The lime step matters for niacin. MedlinePlus says corn is a poor source of tryptophan and its niacin is tightly bound, so people who eat a lot of untreated corn can develop pellagra (niacin deficiency); soaking corn in limewater releases the niacin, and pellagra is rare in Central America where tortillas are made this way. [5]
• Check the label for wheat and for "enriched." Masa flour can be enriched with iron and B vitamins and, in some products, folic acid. USDA lists 256 mcg of folate (DFE) per 100 g in enriched masa and 29 mcg in unenriched masa. [1] [2]
• Mold toxins are the main storage concern for corn. WHO says maize is among the cereals frequently affected by aflatoxins, and it links fumonisins, made by a mold that grows on maize, to esophageal cancer in people. [6]
• Evidence in one line: the niacin point is well established; for chronic disease, we found only a narrative review that calls for better studies. [3]
• Allergy: for trouble breathing or swelling of the face, lips or throat after eating, call 911 (or your local emergency number). [12]

What is in it (USDA values)

The values below are for white masa flour, unenriched (USDA FoodData Central item 169696, SR Legacy). [1] The serving column is the USDA household portion of 1 cup of the dry flour, 114 g. [1] This is dry flour, not a cooked tortilla: our USDA file has no values for prepared tortillas, tamales or fresh masa dough, so we show none.

% Daily Value uses the FDA 2016 Daily Values; values vary with the corn variety, how much of the bran and germ is kept, and how the flour is made. The serving figures are the 100 g values multiplied by 1.14.

Enriched masa flour (USDA item 169694) has the same fiber, protein and minerals but more of the added nutrients. Per 100 g: iron 8.5 mg, thiamin 1.475 mg, riboflavin 0.805 mg, niacin 9.93 mg and folate 256 mcg DFE. [2] In one cup (114 g) that is 54% of the Daily Value for iron, 140% for thiamin, 71% for riboflavin, 71% for niacin and 73% for folate. The FDA rule for enriched corn meals lists the added amounts per pound: thiamin, riboflavin, niacin, folic acid and iron. [7]

The calcium in the table comes mostly from the lime. A 2026 study of home nixtamalization of maize from Guatemala found calcium rose sharply, with smaller rises in iron, copper and magnesium. [4]

What research says

Eaten as food vs taken as a supplement. All of the evidence above is about corn foods. We did not find a trial that used a masa extract or supplement.

How much is a normal serving

The only USDA household portion in our file is 1 cup of dry masa flour (114 g, about 414 kcal), which makes a lot of tortillas, so treat it as a measuring unit, not a portion. [1] The 2025-2030 Dietary Guidelines for Americans set a goal of 2 to 4 servings of whole grains a day. [10] The page we read did not say how many tortillas make a serving, and we did not find a rule saying whether tortillas count as whole grain, which depends on how much of the bran and germ stay in the flour. This is information, not a prescription.

Safety, allergy and medicines

• Gluten and celiac disease: NIDDK says gluten is found in wheat, barley and rye, and that it can reach processed foods through ingredients and cross-contact. [11] Corn is not on that list, but we did not read a source on what is in every tortilla product, so read the ingredient list for wheat and the label for "gluten-free." A "gluten-free" label means fewer than 20 parts per million (FDA rule, as NIDDK describes it). [11]
• Allergy: the MedlinePlus list of the most common food allergens (milk, egg, shellfish, fish, peanuts, sesame, soy, tree nuts and wheat) does not name corn. [12] Tortillas and tamales may contain other allergens such as wheat, milk or soy; read the label. For signs of anaphylaxis (trouble breathing, throat swelling), call 911 and use prescribed epinephrine. [12]
• Mold toxins: WHO links aflatoxins to liver damage and liver cancer and fumonisins in maize to esophageal cancer in people. It advises discarding grain that looks moldy, discolored or shriveled. [6] Nixtamalization lowered aflatoxin in the 2026 study, but a lab result does not make moldy grain safe. [4] [6]
• Pregnancy and folic acid: CDC says the U.S. Public Health Service recommends 400 mcg of folic acid daily for women who could become pregnant. [13] Most corn tortillas in the store survey were not fortified, so a tortilla label should not be assumed to supply folic acid. [8] Ask your clinician about folic acid.
• Kidney disease: masa flour has 231 mg of phosphorus and 262 mg of potassium per 100 g. [1] NIDDK advises people with kidney disease to limit added phosphorus and follow their kidney team's potassium advice. [14] Ask the kidney team about portions.
• Raw dough and flour: FDA says never to eat or taste raw flour, dough or batter, because flour is a raw product that can carry germs such as E. coli and Salmonella. [15] That advice is about flour in general; we did not find masa-specific guidance, so cook masa dough fully.
• High-heat cooking: FDA says acrylamide forms in frying, roasting and baking at high temperature. It names potato products, coffee and grain foods such as breakfast cereal, cookies and toast, and does not name tortillas or tortilla chips. [16]
• Medicines and diabetes: we did not find a medicine interaction for masa in the sources we read. Dry masa flour has 76.6 g of carbohydrate per 100 g. [1] People who count carbohydrate should use the label of the exact product.

Choosing, storing and food safety

• Buy flour and tortillas as fresh as you can and store them dry; WHO says to avoid keeping grain for long periods. [6]
• Throw away flour or grain that smells musty or looks moldy, discolored or shriveled. [6]
• Check the label for "enriched," folic acid, wheat and the ingredient lime (calcium hydroxide, "cal"). [2] [7] [8]
• Keep raw masa and flour away from ready-to-eat foods, wash hands and surfaces after handling, and cook dough fully. [15]

Related pages

• Hominy and grits
• Popcorn
• Sweet corn
• Gluten, celiac disease and gluten sensitivity basics
• Fortified foods
• Foods in pregnancy: what official bodies advise