Cornbread: the evidence is about the cornmeal, and none of it is about the bread

Nobody has run a trial on cornbread, so everything here is about the cornmeal that goes into it, tested as porridge, tortillas or plain maize meal. The firmest result is about mould rather than nutrients. Lime cooking (nixtamalisation) of visibly mouldy maize cut fumonisin B1 and B2 by 95 percent and zearalenone by 89 percent. Forty healthy adults from a Soweto settlement were then randomised to eat either that maize or clean control maize, over a short exposure at a single site. That protection belongs to lime-treated maize such as masa, not to the plain cornmeal in most cornbread recipes, and two other mould toxins, deoxynivalenol and tenuazonic acid, were not reduced. The other randomised finding is about how little the body takes from maize on its own. Kenyan children aged 24 to 36 months absorbed 0.14 mg of zinc (95% CI 0.11 to 0.16) from a plain maize meal, 2.6 times less than from the same meal enriched with whole crickets. Maize was the vehicle there rather than the thing under test, and there is no adult data to match. What cornmeal contains is modest. Sifted cornmeal in the British CoFID table has 3 mg of calcium, 1.3 mg of iron and 1.0 mg of niacin per 100 g and only a trace of sodium. The salt, most of the calcium and any folic acid in a cornbread therefore come from the other ingredients and from fortification. Lime-treated masa harina is different: the six analysed USDA samples average 111.6 mg of calcium per 100 g with a range of 71.8 to 162 mg, and iron runs from 1.13 to 3.65 mg, so two cornbreads from two bags can differ twofold in minerals. Whether the finished bread counts as a whole grain or a refined one is the question that matters most and has the least evidence. A scoping review of 21 human studies found bran-rich whole grain corn products linked to better blood lipids and glucose, with no pooled estimate behind it. Refined corn products such as cornflakes and extruded snacks were linked to worse metabolic markers, in people with metabolic disorders in particular.

How much is actually in it

• In a 2019 survey of 43 corn masa flour and corn tortilla products from 28 US states, only three masa flours carried folic acid and no tortilla did, so a corn product is fortified only if its label says so. — 132 product photos from 28 US states shared in a January 2019 social media campaign (n = 43 unique products) Evidence C source
  3 of 43 products fortified with folic acid, 0 tortillas
• Enriched corn meal in the US must carry 140 mcg folic acid per 100 g since 1998, while corn masa flour may carry up to 154 mcg per 100 g only voluntarily since 2016, so whether a cornbread contributes folic acid depends on which corn flour went into it. — US fortification rules as summarised by NIH ODS Evidence E source
  140 mcg/100 g mandatory for enriched corn meals, up to 154 mcg/100 g voluntary for corn masa flour
• Lime-treated corn flour (masa harina) carries 111.6 mg calcium per 100 g in USDA Foundation data, ranging from 71.8 to 162 mg across 6 samples, and its iron ranges 1.13 to 3.65 mg, so the mineral content of a cornbread depends on the flour and the batch. — USDA Foundation Foods, 6 analysed samples of masa harina, white or yellow, dry (n = 6 samples) Evidence E source
  Calcium 111.6 mg/100 g (71.8-162.0, spread 81%), iron 1.698 mg (1.13-3.65, spread 148%), fibre 7.04 g (5.69-9.38)
• Sifted cornmeal itself has 3 mg calcium, 1.3 mg iron and 1.0 mg niacin per 100 g and only a trace of sodium in the UK CoFID table, so the salt, most of the calcium and any folic acid in a cornbread come from the other ingredients and from fortification, not from the corn. — CoFID 2021, Public Health England, record 11-011 Cornmeal, sifted (n = 1 record) Evidence E source
  Per 100 g: energy 368 kcal, protein 9.4 g, carbohydrate 73.1 g, calcium 3 mg, iron 1.30 mg, niacin 1.0 mg, sodium trace

What a real portion looks like

• In US dietary survey measures a piece of cornbread weighs 60 g from a mix and 65 g from a home recipe, and an 8-inch round pan of homemade cornbread weighs about 627 g, roughly ten pieces. — US household measures, FNDDS 2021-2023 (n = FNDDS 5,432 foods) Evidence E source
  1 piece 60 g (mix) or 65 g (home recipe), 1 cup crumbled 89 g, 8-inch pan 541 g (mix) or 627 g (home)

What your body absorbs

• In Kenyan children aged 24 to 36 months a plain maize-based meal delivered only 0.14 mg of absorbed zinc (95% CI 0.11 to 0.16), 2.6 times less than the same meal enriched with whole crickets, so maize flour on its own is a poor zinc source. — Kenyan pre-school children aged 24 to 36 months, single-blinded randomised crossover, two labelled test meals one month apart, 2021 (n = 25 to 29 per meal) Evidence B source
  Absorbed zinc 0.14 mg (95% CI 0.11 to 0.16) from low-enriched maize meal vs 0.36 mg (0.30 to 0.43) with whole crickets, P < 0.001
• Breaking down phytic acid with phytase, either during preparation or at the meal, raised fractional zinc absorption from maize porridge by more than 80% in young adults, which shows how much of the zinc in maize phytate locks away. — young adults, five stable-isotope absorption studies, maize or sorghum porridge fortified with 2 mg zinc Evidence C source
  Fractional zinc absorption +80% or more with phytase, both P < 0.001, EDTA 1:1 +30% (P = 0.01)
• Five women absorbed 35% of the calcium from tortillas made of ordinary lime-cooked maize and 50% from tortillas made of low-phytate maize, so phytate, only modestly reduced by nixtamalisation, still cuts calcium absorption by 15 percentage points. — 5 healthy adult women, two 140 g tortilla test meals one month apart, dual-isotope calcium tracers (n = 5) Evidence C source
  Fractional calcium absorption 0.50 +/- 0.03 vs 0.35 +/- 0.07, P = 0.003

What cooking and storage change

• Alkaline lime cooking (nixtamalisation) of visibly mouldy maize cut fumonisin B1 and B2 by 95% and zearalenone by 89%, and 40 adults randomised to eat it had urinary mycotoxin levels no different from those eating clean maize. — 40 healthy adult volunteers from an informal settlement in Soweto, South Africa, randomised to control maize or nixtamalised mouldy maize (n = 40) Evidence B source
  Fumonisin B1 and B2 -95%, zearalenone -89% in maize, urinary FB1 and ZEN not different between groups (p > 0.05)

What it does to your health

• In 3,779 US men followed for about ten years, a Southern eating pattern built around cornbread, grits, okra and beans had a prostate cancer relative risk of 0.6 (95% CI 0.4 to 1.1), not statistically significant and not attributable to any single food. — 3,779 men in the NHANES I Epidemiologic Follow-up Study, 1982-84 to 1992, 136 incident prostate cancers (n = 3,779) Evidence C source
  RR 0.6 (95% CI 0.4-1.1), trend P = 0.08, 3rd vs 1st tertile

Safety, limits and interactions

• A systematic review of 17 epidemiological studies found only two on fumonisin, the maize mould toxin, and both linked maternal exposure to neural tube defects and hypertensive emergencies, so the evidence for pregnancy risk from contaminated maize is suggestive and thin. — pregnant women or fetuses exposed to mycotoxins, 17 epidemiological studies to December 2018 (n = 17 studies, 2 on fumonisin) Evidence C source
  Association with neural tube defects and hypertensive emergencies in pregnancy, no pooled estimate
• In the 6-year Texas Neural Tube Defect Project among Mexican American women on the Texas-Mexico border, fumonisins from maize emerged as a novel risk factor for neural tube defects alongside low folate intake. — Mexican American women living on the Texas-Mexico border, case-control study 1995-2000, 23 published analyses Evidence C source
  Fumonisins named among novel risk factors, no single estimate in abstract
• Where maize is the staple, niacin deficiency can persist: in postwar Angola 29.4% of 723 women had low urinary niacin metabolites, and the authors call niacin deficiency a public health problem there. — 723 women aged 15-49 and 690 children aged 6-59 months, multistage cluster survey, Kuito, Angola, 1999-2004 clinic data (n = 723 women, 690 children) Evidence C source
  Low niacin metabolite excretion in 29.4% of women and 6.0% of children
• US regulation caps folic acid in corn masa flour at 0.7 mg per pound, about 154 mcg per 100 g, and the addition is permitted rather than required. — 21 CFR 172.345(i), current eCFR Evidence E source
  Limit 0.7 mg folic acid per pound of corn masa flour
• FDA guidance from 2001 sets a recommended maximum of 2 ppm total fumonisins for degermed corn meal and flour and 4 ppm for whole or partially degermed corn meal, so whole-grain cornmeal is allowed twice the mould toxin of degermed cornmeal. — FDA guidance for industry on fumonisin levels in human foods, November 2001 Evidence E source
  2 ppm degermed (fat < 2.25%), 4 ppm whole or partially degermed (fat > 2.25%), 4 ppm cleaned corn for masa

What people believe that the data does not support

• Across 21 human studies, whole grain corn products high in bran were linked to better blood lipids and glucose while refined corn products were linked to worse metabolic markers, so whether cornbread counts as a healthy grain depends on the cornmeal it is made from. — 21 peer-reviewed human studies of corn flour consumption, any age, searched July 2024 (n = 21 studies) Evidence C source
  Direction only: whole grain and bran-rich corn favourable, refined corn products unfavourable, no pooled estimate

Who this works differently for

• After the FDA allowed folic acid in corn masa flour in 2016, the share of Hispanic women of reproductive age getting under 400 mcg folic acid a day stayed at 86 to 88% in NHANES 2011 to March 2020, so voluntary fortification of corn products has not yet closed the folate gap. — non-pregnant, non-lactating Hispanic women of reproductive age, NHANES 2011-2016 vs 2017-March 2020 (n = NHANES, Hispanic women 15-49) Evidence C source
  Usual folic acid intake <400 mcg/d 86.1% (95% CI 83.7-88.5) before vs 87.8% (84.8-90.7) after, p = .38

What is still unknown

• A pilot case-control study of 23 matched pairs in a US geriatric centre found that past intake of baking-powder foods including cornbread differed between people with and without Alzheimer's disease, a preliminary aluminium-additive hypothesis that the authors say needs larger studies. — 46 residents of a geriatric centre in Syracuse, New York, 23 matched pairs, diet reported by next of kin (n = 46 (23 matched pairs)) Evidence C source
  P = 0.025 for intake of pancakes, waffles, biscuits, muffins, cornbread or corn tortillas, crude OR 2.0 for high-aluminium foods

The bottom line

A piece of cornbread in US survey measures is 60 g from a mix and 65 g from a home recipe, and an 8-inch round pan of the homemade kind is about 627 g, roughly ten pieces, with no recipe specified behind those weights. Folic acid is where the label matters. Since 1998 enriched corn meal in the US must carry 140 mcg of folic acid per 100 g, while corn masa flour may carry up to 154 mcg per 100 g only voluntarily since 2016, the legal cap being 0.7 mg per pound. In a 2019 survey of 43 corn masa flour and tortilla products photographed in 28 states, three masa flours carried folic acid and no tortilla did, a convenience sample from a market that may have moved since. Among Hispanic women of reproductive age in NHANES, the share getting under 400 mcg of folic acid a day was 86.1 percent (95% CI 83.7 to 88.5) before the 2016 change and 87.8 percent (84.8 to 90.7) after it. That is a pre-post comparison with no control group, and it says voluntary fortification had not closed the gap by March 2020. Phytate in maize holds minerals back, and lime cooking only partly frees them. Five healthy women absorbed 35 percent of the calcium from tortillas made of ordinary lime-cooked maize and 50 percent from tortillas of a low-phytate maize that is not on the market, in a five-person isotope study. Adding the enzyme phytase to a zinc-fortified maize porridge, at the meal or during preparation, raised fractional zinc absorption by more than 80 percent, in an isotope study whose sample size and randomisation the abstract does not state. Neither used bread. We found no glycaemic index for cornbread, no sodium or aluminium measurement of it, and no allergy prevalence for corn eaten as cornbread. Who should be careful comes down to mould, pregnancy and places where maize is the whole diet. A systematic review of 17 epidemiological studies on mycotoxins in pregnancy found only two on fumonisin, and both linked maternal exposure to neural tube defects and to hypertensive emergencies in pregnancy, with exposure often estimated by proxy in low-income settings and no pooled estimate. The six-year Texas Neural Tube Defect Project among Mexican American women on the Texas-Mexico border, a folate-deficient population, named fumonisins among its novel risk factors without an effect size in the abstract. FDA guidance from 2001 recommends a maximum of 2 ppm total fumonisins in degermed corn meal and flour and 4 ppm in whole or partially degermed corn meal, a recommended ceiling rather than a binding limit. Whole-grain cornmeal is therefore allowed twice the toxin of degermed. In postwar Kuito, Angola, 29.4 percent of 723 women aged 15 to 49 had low urinary niacin metabolites and niacin deficiency was a public health problem, in a region where maize is the staple and poverty and diet cannot be separated. That card is about populations living on maize and says nothing about a slice of cornbread beside other food. We have no card on corn allergy in cornbread form or on any drug interaction. Two observational results should be read as questions. In 3,779 US men followed for about ten years with 136 prostate cancers, a Southern eating pattern of cornbread, grits, sweet potatoes, okra, beans and rice had a relative risk of 0.6 (95% CI 0.4 to 1.1) for the top third against the bottom. That did not reach significance, and the pattern may proxy Southern residence and sunlight. A pilot of 23 matched pairs in a Syracuse geriatric centre found that past intake of baking-powder foods including cornbread, reported by next of kin, differed between people with and without Alzheimer's disease (P = 0.025). The adjusted odds ratio was 8.6 at P = 0.19, and the authors themselves ask for larger studies. That is a hypothesis about aluminium additives and nothing more.

Sources

1. cbrd-v1-07 · product availability survey
   People from 28 states shared photos of 132 products, including 43 unique corn masa flour or corn tortilla products. Of those, only three corn masa flour products included folic acid...None of the corn tortilla products were fortified.
   Birth Defects Res, 2019 · checked 2026-09-23
2. cbrd-v1-13 · NIH ODS 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)...In April 2016, FDA approved the voluntary addition of up to 154 mcg folic acid/100 g to corn masa flour [15].
   NIH Office of Dietary Supplements, Folate fact sheet for health professionals · checked 2026-09-23
3. cbrd-v1-17 · reference dataset
   FDC Corn flour, masa harina, white or yellow, dry: Calcium, Ca 111.6 mg, range 71.8-162.0, n=6 · Iron, Fe 1.698 mg, range 1.13-3.65, n=6 · Fiber, total dietary 7.038 g, range 5.69-9.38, n=6
   USDA FoodData Central Foundation Foods, release 2026-04-30 · checked 2026-09-23
4. cbrd-v1-18 · reference dataset
   CoFID 11-011 Cornmeal, sifted: Energy 368 kcal · Protein 9.4 g · Carbohydrate 73.1 g · Calcium 3 mg · Iron 1.30 mg · Niacin 1.0 mg · Sodium Tr
   CoFID 2021, Public Health England, Open Government Licence v3.0 · checked 2026-09-23
5. cbrd-v1-16 · reference dataset
   FNDDS 2707810 Cornbread, prepared from mix: 1 piece 60 g · 1 surface inch 9 g · 1 cup, crumbled 89 g · 1 square cornbread (8 inch pan) 541 g · FNDDS 2707811 Cornbread, made from home recipe: 1 piece 65 g · 1 round cornbread (8 inch pan) 627 g
   USDA FNDDS 2021-2023 · checked 2026-09-23
6. cbrd-v1-01 · randomised crossover trial
   We found that AZ from meals with whole crickets (geometric mean: 0.36 mg; 95%CI: 0.30, 0.43) was 2.6 times higher than from low-enriched maize meals (0.14 mg; 0.11, 0.16; P < 0.001), while it was not different from low-chitin cricket flour meals.
   Nat Commun, 2025 · checked 2026-09-23
7. cbrd-v1-02 · clinical trial, double isotopic tracer ratio
   Adding phytase to the maize porridge immediately before consumption or using phytase for dephytinization during meal preparation both increased FAZ by >80% (both P < 0.001).
   J Nutr, 2014 · checked 2026-09-23
8. cbrd-v1-03 · clinical trial, dual-isotope
   Bioavailability of calcium is, however, compromised by phytate, which is present in large quantities in maize kernels and is only modestly reduced by nixtamalization...Mean fractional absorption of calcium from tortillas prepared from the low-phytate maize (0.50 +/- 0.03) was significantly (P = 0.003) greater than that from tortillas prepared from the control maize (0.35 +/- 0.07).
   Am J Clin Nutr, 2005 · checked 2026-09-23
9. cbrd-v1-04 · randomised controlled trial
   Forty adult healthy volunteers from an informal settlement in Kliptown, Soweto (South Africa), were randomly assigned to consume control maize or visibly moldy maize subjected to nixtamalization...while reducing fumonisin B1 (FB1), fumonisin B2, and zearalenone (ZEN) by 95%, 95%, and 89%, respectively.
   Toxins (Basel), 2025 · checked 2026-09-23
10. cbrd-v1-11 · prospective cohort study
    a Southern pattern characterized by such foods as cornbread, grits, sweet potatoes, okra, beans, and rice...higher intake of the Southern pattern showed a reduction in risk (3rd versus 1st tertile relative risk, 0.6; 95% confidence interval, 0.4-1.1; trend P = 0.08) that approached statistical significance.
    Cancer Epidemiol Biomarkers Prev, 2004 · checked 2026-09-23
11. cbrd-v1-08 · systematic review of epidemiological studies
    Only two studies assessed effects of maternal exposure to Fusarium mycotoxins (e.g., fumonisin) on adverse pregnancy outcomes. These studies found that maternal fumonisin exposure may be associated with hypertensive emergencies in pregnancy and with neural tube defects.
    Mycotoxin Res, 2020 · checked 2026-09-23
12. cbrd-v1-09 · case-control study review
    Studies in this folic acid deficit-population also revealed several novel risk factors, namely, diarrhea, stress, fumonisins, and the combination of nitrosatable drug exposure with high nitrate/nitrite intake.
    Birth Defects Res A Clin Mol Teratol, 2012 · checked 2026-09-23
13. cbrd-v1-10 · prevalence survey
    Excretion of niacin metabolites was low in 29.4% of the women and 6.0% of the children...The identification of niacin deficiency as a public health problem should refocus attention on this nutritional deficiency in Angola and other areas of Africa where maize is the staple.
    Am J Clin Nutr, 2007 · checked 2026-09-23
14. cbrd-v1-14 · regulation, 21 CFR
    (i) Folic acid may be added to corn masa flour at a level not to exceed 0.7 milligrams of folic acid per pound of corn masa flour.
    21 CFR 172.345 Folic acid (folacin), eCFR · checked 2026-09-23
15. cbrd-v1-15 · FDA guidance for industry
    The recommended maximum levels for fumonisins in human foods and in animal feeds that FDA considers achievable with the use of good agricultural and good manufacturing practices are presented below...Degermed dry milled corn products (e.g., flaking grits, corn grits, corn meal, corn flour with fat content of < 2.25%, dry weight basis)...2 parts per million (ppm)
    FDA, Guidance for Industry: Fumonisin Levels in Human Foods and Animal Feeds, 2001 · checked 2026-09-23
16. cbrd-v1-05 · scoping review
    Findings indicated that whole grain corn products, particularly those high in fiber-rich corn bran, were associated with favorable effects on blood lipid and glycemic profiles. Conversely, refined corn products, such as cornflakes and extruded snacks, were linked to less favorable metabolic outcomes, particularly in individuals with metabolic disorders.
    J Nutr, 2025 · checked 2026-09-23
17. cbrd-v1-06 · cross-sectional survey (NHANES)
    The proportion of Hispanic WRA with folic acid usual intakes <400 μg/d did not change (2011-2016: 86.1% [95% Confidence Interval, CI: 83.7-88.5]; 2017-March 2020: 87.8% [95% CI: 84.8-90.7]; p = .38)
    Birth Defects Res, 2024 · checked 2026-09-23
18. cbrd-v1-12 · matched case-control pilot
    Intake of pancakes, waffles, biscuits, muffins, cornbread and/or corn tortillas differed significantly (P=0.025) between cases and controls...Larger studies are warranted to corroborate or refute these preliminary findings.
    Age Ageing, 1999 · checked 2026-09-23