Flour tortilla: what enriched wheat flour carries, and one overdosed batch

A flour tortilla is mostly refined wheat flour, so nearly all the science on this page is about that flour. The strongest finding comes from a Cochrane review of 5 randomized trials with 2315 people aged 2 and over. Flour fortified with iron may cut the risk of anemia by 27% (risk ratio 0.73, 95% CI 0.55 to 0.97) over 3 to 24 months, and the reviewers rate that evidence as low certainty. None of those trials tested tortillas as such. In the United States, enriched flours and grain products must carry 140 mcg of added folic acid per 3.5 oz (100 g), according to the NIH Office of Dietary Supplements, though not every tortilla is made from enriched flour. Across 14 observational studies covering more than 33 million births, mandatory folic acid fortification of flour and grains was associated with 44% fewer neural tube defects (RR 0.56), mostly from before and after comparisons.

The numbers, per 3.5 oz (100 g)

As people eat it, per 3.5 oz (100 g)

How much is actually in it

• According to the NIH Office of Dietary Supplements, US enriched flours and grain products must contain 140 mcg of added folic acid per 3.5 oz (100 g). — US food supply Evidence E source
  140 mcg folic acid per 3.5 oz (100 g) enriched grain product

What a real portion looks like

• Among 801 women in Northern Mexico, flour tortillas were one of the main dietary sources of fiber, alongside corn tortillas, onions and beans. — 801 women residing in Northern Mexico, 2007-2009 (n = 801) Evidence C source
  Median fiber intake 33.14 g/day; flour tortillas among top sources

What your body absorbs

• In a randomized study in adults with overweight, replacing 30% of the refined flour in tortillas with soy flour lowered blood glucose at 90 to 120 minutes after eating. — Adults with overweight or obesity (N = 17; 10 completed the tortilla matrix), single test meals (n = 17) Evidence B source
  Lower plasma glucose at 90-120 min for 30% soy tortillas (p = 0.0009); insulin unchanged
• Short studies reviewed systematically found that low-phytate white bread raised serum iron about twice as much as high-phytate whole wheat bread within 2 hours (59 vs 30 ug Fe/100 mL). — Healthy or iron-deficient participants in 8 human intervention studies (n = 8 studies) Evidence C source
  Serum iron rise 59 vs 30 ug Fe/100 mL at 2 h

What cooking and storage change

• According to the NIH Office of Dietary Supplements, baked bread has 20% to 30% less thiamin than its raw ingredients. — Baked grain products Evidence E source
  Thiamin loss 20-30% on baking

What it does to your health

• A Cochrane review of randomized trials found that iron-fortified wheat flour may cut the risk of anemia in populations by 27%. — General populations aged 2 years and above, 5 trials, 2315 participants, 3 to 24 months (n = 2315) Evidence A source
  Anemia RR 0.73 (95% CI 0.55 to 0.97); low-certainty evidence
• Observational data from 17 cohorts with over 875,000 people did not link refined grain intake to cardiovascular disease (HR 1.08). — Prospective cohort studies, more than 875,000 participants (n = 875000) Evidence C source
  CVD HR 1.08 (95% CI 0.99-1.18); stroke HR 1.06
• Observational data show no clear link between refined grains and high blood pressure (RR 0.97 per 90 g a day). — Nine prospective cohort studies (n = 4 cohorts) Evidence C source
  Refined grain RR 0.97 (0.93-1.02) per 90 g/d (4 cohorts); high vs low RR 0.94 (0.88-1.01), 5 cohorts

Safety, limits and interactions

• In a 2023 Finnish school outbreak, eating flour tortillas with excess calcium propionate (over 24,000 mg/kg against a 2,000 mg/kg limit) was linked to 3.3 times higher odds of illness. — Students and staff of 17 schools in a Finnish municipality, 721 cases (n = 721 cases) Evidence C source
  AOR 3.3 (95% CI 1.4-7.4) for tortillas
• Tortilla samples from that outbreak contained more than 24,000 mg/kg of calcium propionate, over 10 times the EU maximum of 2,000 mg/kg. — Tortilla samples from the implicated production period (n = 3 samples) Evidence C source
  >24,000 mg/kg versus 2,000 mg/kg limit

Who this works differently for

• Observational studies link mandatory folic acid fortification of flour and grains with 44% fewer neural tube defects. — Births in 14 observational studies, over 33 million participants (n = 33000000) Evidence C source
  NTD RR 0.56; North America RR 0.46

The bottom line

On the heart, refined flour looks neutral in observational data. A meta-analysis of 17 cohort studies with more than 875,000 people found refined grain intake was not associated with cardiovascular disease (HR 1.08, 95% CI 0.99 to 1.18, from 9 of those cohorts). For high blood pressure, each extra 3.2 oz (90 g) of refined grains a day carried a risk ratio of 0.97 (95% CI 0.93 to 1.02) across 4 cohorts. Both are associations open to confounding, and refined grains were studied as a group. One small randomized study tested a changed tortilla, with 30% of the refined flour swapped for soy flour. In adults with overweight or obesity, only 10 of whom completed the tortilla test meals, blood glucose was lower 90 to 120 minutes after eating (p = 0.0009). That was a single meal of a product made for the study. Baking costs some thiamin. The NIH Office of Dietary Supplements says bread has 20% to 30% less than its raw ingredients, a bread figure we apply to tortillas only by analogy. Short absorption tests found low-phytate white bread raised serum iron about twice as much as high-phytate whole wheat bread within 2 hours (59 against 30 ug per 3.4 fl oz (100 mL)), yet the review behind that number called the overall results inconclusive. Among 801 women in northern Mexico, flour tortillas were one of the main sources of fiber, alongside corn tortillas, raw onions and beans. The safety finding here is a single incident. Three samples from tortillas made during a limited production period held more than 24,000 mg/kg of the preservative calcium propionate, over ten times the EU maximum of 2,000 mg/kg. Among students and staff of 17 schools in one Finnish municipality, with 721 cases, eating those tortillas was associated with 3.3 times higher odds of illness (95% CI 1.4 to 7.4). That was an overdosed batch and says nothing about tortillas made within the limit. The folic acid figures above describe fortification of the flour supply and births across whole populations. No card on this page says how much one tortilla adds toward folate needs in pregnancy. We have no card on wheat allergy, celiac disease or medicines for this page, so it cannot answer those questions.

Compared with other foods

Sources

1. ftl-daily-r7-09 · Agency fact sheet
   In January 1998, the U.S. Food and Drug Administration (FDA) began requiring manufacturers to add 140 mcg folic acid/100 g to enriched breads, cereals, flours, corn meals, pastas, rice, and other grain products [13] to reduce the risk of neural tube defects (NTDs).
   NIH Office of Dietary Supplements, Folate fact sheet for health professionals · checked 2026-09-29
2. ftl-daily-r7-11 · Cross-sectional
   The main dietary sources of fiber in this population were corn tortillas, raw onions, flour tortillas, and beans.
   Environ Sci Pollut Res Int, 2021 · checked 2026-09-29
3. ftl-daily-r7-02 · RCT
   Results: Compared with the control condition, substituting 30% of refined flour with soy flour significantly reduced the area under the concentration-time curve for postprandial glucose for breads (p = 0.03) and arepas (p = 0.04), and reduced plasma glucose concentrations at 90-120 min for tortillas (p = 0.0009).
   Nutrients, 2026 · checked 2026-09-29
4. ftl-daily-r7-03 · Systematic review
   Results were inconclusive as acute postprandial studies increased non-haem iron bioavailability (especially in low-phytate breads); for example, low-phytate white bread produced a greater 2 h increase in serum iron than high-phytate wholemeal bread (59 vs. 30 μg Fe/100 mL), while exogenous phytase increased iron absorption by 50% for ferrous sulfate and 61% for iron bis-glycine chelate.
   Front Nutr, 2026 · checked 2026-09-29
5. ftl-daily-r7-10 · Agency fact sheet
   For example, bread has 20%–30% less thiamin than its raw ingredients, and pasteurization reduces thiamin content (which is very small to begin with) in milk by up to 20% [3].
   NIH Office of Dietary Supplements, Thiamin fact sheet for health professionals · checked 2026-09-29
6. ftl-daily-r7-01 · Cochrane review
   Iron-fortified wheat flour with or without other micronutrients added versus wheat flour (no added iron) with the same other micronutrients added may reduce by 27% the risk of anaemia in populations (risk ratio (RR) 0.73, 95% confidence interval (CI) 0.55 to 0.97; 5 studies, 2315 participants; low-certainty evidence).
   Cochrane Database Syst Rev, 2021 · checked 2026-09-29
7. ftl-daily-r7-06 · Meta-analysis of cohort studies
   Meta-analyses of hazard ratios (HR) and 95% confidence intervals (CI) obtained from 17 prospective cohort studies (>875,000 participants) indicated that refined grain intake was not associated with risk of CVD (HR = 1.08, 95% CI, 0.99-1.18, I2 = 70%; 9 cohorts), stroke (HR = 1.06, 95% CI 0.92-1.23, I2 = 70%; 9 cohorts), or heart failure (HR = 0.95, 95% CI 0.77-1.16, I2 = 10%; 5 cohorts).
   Trends Cardiovasc Med, 2024 · checked 2026-09-29
8. ftl-daily-r7-07 · Meta-analysis of cohort studies
   The summary RR (95% CI) for high vs. low refined grain intake was 0.94 (0.88-1.01, I2 = 7.9%, pheterogeneity=0.36, n = 5) and per 90 g/d was 0.97 (0.93-1.02, I2 = 0%, pheterogeneity=0.42, n = 4).
   Sci Rep, 2025 · checked 2026-09-29
9. ftl-daily-r7-04 · Outbreak cohort study
   In a questionnaire-based retrospective cohort study, consumption of flour tortillas and vegetable filling served at lunch were statistically associated with illness (adjusted odds ratio (aOR) = 3.3; 95% confidence interval (CI): 1.4-7.4 for the tortillas and aOR = 1.5; 95% CI: 1.1-2.1 for the filling).
   Euro Surveill, 2026 · checked 2026-09-29
10. ftl-daily-r7-05 · Outbreak investigation
    In three samples from tortillas produced during a limited production period, high concentrations of calcium propionate (E 282) were measured (> 24,000 mg/kg), exceeding the regulatory maximum limit of 2,000 mg/kg.
    Euro Surveill, 2026 · checked 2026-09-29
11. ftl-daily-r7-08 · Meta-analysis of observational studies
    The pooled analysis revealed that mandatory folic acid fortification was associated with a 44% reduction in the risk of NTDs (RR = 0.56).
    BMC Nutr, 2026 · checked 2026-09-29