Bread flour: what enrichment adds and what that does

The strongest evidence about this flour concerns what gets added to it. A Cochrane review of randomized trials found that wheat flour fortified with iron may cut the risk of anemia by 27% (RR 0.73, 95% CI 0.55 to 0.97, 5 studies, 2315 people). The evidence is low certainty, from low and middle income settings using 40 to 80 mg iron per kg of flour. In the United States, flour labeled enriched must carry per pound 2.9 mg thiamin, 1.8 mg riboflavin, 24 mg niacin, 0.7 mg folic acid and 20 mg iron. Unenriched bread flour also exists. Six US samples of enriched unbleached bread flour measured 14.3 g protein per 3.5 oz (100 g) (range 13.3 to 15.2), with 5.55 mg iron and 145 ug folate. UK strong white flour is listed at 11.3 g protein and 16 ug folate per 3.5 oz (100 g). The UK flour in that dataset carried no folic acid, and the wheat and the enrichment rules differ between the two countries.

The numbers, per 3.5 oz (100 g)

How much is actually in it

• US enriched white bread flour measured 14.3 g protein per 3.5 oz (100 g), with six samples between 13.3 and 15.2 g. — six samples of enriched unbleached white bread flour analyzed for USDA Foundation Foods (n = 6) Evidence E source
  Protein 14.3 g (13.3-15.2); iron 5.55 mg (4.87-5.83); folate 145 ug (121-160); thiamin 0.953 mg (0.823-1.09); selenium 33.3 ug (2.6-80.6) per 3.5 oz (100 g)
• UK strong white bread flour is listed at 11.3 g protein and 16 ug folate per 3.5 oz (100 g), far below the US enriched figures. — UK composition data for strong white wheat bread flour (CoFID 11-887) Evidence E source
  Energy 353 calories, protein 11.3 g, fiber 3.3 g (AOAC), iron 1.92 mg, calcium 134 mg, thiamin 0.30 mg, folate 16 ug per 3.5 oz (100 g)

What your body absorbs

• In an RCT of 45 adults, rolls with folic acid raised red cell folate by 0.37 umol/L over 16 weeks, as much as the reduced L-5-MTHF form. — healthy men and women aged 18-45, n = 45, 16 weeks (n = 45) Evidence B source
  Erythrocyte folate +0.37 (0.17, 0.57) umol/L with folic acid rolls and +0.48 (0.27, 0.71) with L-5-MTHF rolls vs placebo; no difference between forms
• Women eating one folic acid fortified wheat roll a day raised red cell folate by 20% and serum folate by 30% in 90 days. — 14 healthy women on the lower dose roll, 12 weeks (n = 29) Evidence B source
  Erythrocyte folate +20% (p < 0.05), serum folate +30% (p < 0.001) after 90 days on about 166 ug folic acid a day

What cooking and storage change

• Laboratory analysis found baking lost 20 to 25% of the folic acid added to wheat roll dough, with roll size changing retention. — fortified wheat breakfast rolls analyzed by HPLC Evidence D source
  20-25% loss of added folic acid in baking; no significant loss during 90 days frozen storage

What it does to your health

• A Cochrane review of 10 trials found iron-fortified wheat flour may cut the risk of anemia by 27%, on low-certainty evidence. — 10 randomized trials, 3319 people aged two years and over in seven countries, 3 to 24 months (n = 3319) Evidence A source
  Anemia RR 0.73 (95% CI 0.55-0.97; 5 studies, 2315 participants); iron deficiency RR 0.46 (0.20-1.04), very low certainty
• Across 30 pre and post studies, mandatory grain folic acid fortification raised serum folate by 15.0 nmol/L. — populations in countries with mandatory grain fortification, 30 articles (n = 30 articles) Evidence C source
  Serum/plasma folate +15.0 nmol/L (95% CI 9.4-20.5); red cell folate +329.4 nmol/L (243.9-414.9); folate deficiency prevalence ratio 0.08 (0.03-0.23)

What people believe that the data does not support

• In the US, flour labeled enriched must carry set amounts of thiamin, riboflavin, niacin, folic acid and iron per pound. — flour sold as enriched flour in the United States Evidence E source
  Per pound: thiamin 2.9 mg, riboflavin 1.8 mg, niacin 24 mg, folic acid 0.7 mg, iron 20 mg; calcium optional up to 960 mg

Who this works differently for

• In one non-randomized study, wheat flour with folic acid was linked to 68% fewer neural tube defects in births. — women of reproductive age and pregnant women, 8037 births, one non-randomized trial (n = 8037) Evidence C source
  Total neural tube defects RR 0.32 (95% CI 0.21-0.48), low certainty
• An Australian autopsy study found Wernicke-Korsakoff syndrome less common than before thiamine enrichment of bread flour began. — brains from 2212 sequential autopsies in New South Wales, 1996-1997 (n = 2212) Evidence C source
  25 cases, prevalence 1.1%, lower than before thiamine enrichment of bread flour

The bottom line

Folic acid baked into bread does reach the blood. In a 16-week randomized trial of 45 healthy adults aged 18 to 45, wheat rolls with folic acid raised red cell folate by 0.37 umol/L over placebo (95% CI 0.17 to 0.57). Rolls with a microencapsulated reduced form, L-5-MTHF, did about the same. A smaller trial in women found red cell folate up 20% and serum folate up 30% after 90 days of fortified rolls, though it compared two doses with no unfortified group. In one laboratory test of one roll recipe, baking lost 20 to 25% of the added folic acid, and 90 days in the freezer lost no significant amount. Across 30 before and after studies, mandatory grain fortification raised serum folate by 15.0 nmol/L (95% CI 9.4 to 20.5), with maize flour and rice counted alongside wheat and heterogeneity above 73%. For pregnancy, the evidence concerns fortification across whole populations rather than any one person's diet. One non-randomized study of 8037 births linked wheat flour fortified with folic acid and other micronutrients to 68% fewer neural tube defects (RR 0.32, 95% CI 0.21 to 0.48), on low-certainty evidence, and no randomized trial reported this outcome. An Australian study of 2212 autopsies from 1996 and 1997 found Wernicke-Korsakoff brain damage in 1.1%, lower than before thiamine was added to bread flour, in a comparison with earlier studies that had no control group. We hold no card on safety limits, allergy or drug interactions for bread flour itself, so this page has no caution section.

Sources

1. brfl-r6-01 · USDA Foundation Foods, dataset
   Flour, bread, white, enriched, unbleached (FDC 790146): Protein 14.3 g, range 13.3-15.2; Iron, Fe 5.55 mg, range 4.87-5.83, samples 6; Folate, total 145.0 ug, range 121.0-160.0; Thiamin 0.953 mg, range 0.823-1.09; Selenium, Se 33.3 ug, range 2.6-80.6
   USDA FoodData Central, Foundation Foods, release 2026-04-30, FDC 790146 · checked 2026-09-29
2. brfl-r6-02 · CoFID 2021, dataset
   CoFID 11-887 Flour, wheat, bread/strong, white: Energy 353 kcal, Protein 11.3 g, AOAC fibre 3.3 g, Iron 1.92 mg, Calcium 134 mg, Thiamin 0.30 mg, Folate 16 ug
   CoFID 2021 (Public Health England), code 11-887 · checked 2026-09-29
3. brfl-r6-05 · RCT
   At 16 wk, the mean (95% CI) erythrocyte folate was 0.48 (0.27, 0.71) and 0.37 (0.17, 0.57) μmol/L higher in the L-5-MTHF (P < 0.001) and folic acid wheat roll (P = 0.001) groups, respectively, than in the placebo group.
   J Nutr, 2013 · checked 2026-09-29
4. brfl-r6-06 · RCT
   After 90 days of intervention, an increase of 20 % (p < 0.05) was observed. At day 0, mean serum folate concentrations were 16.9 +/- 4.3 nmol/L. The mean serum folate concentrations increased by 30 % (p < 0.001) after 90 days.
   Eur J Nutr, 2002 · checked 2026-09-29
5. brfl-r6-07 · laboratory analysis
   The baking procedure resulted in 20-25 % loss of fortified folic acid in the rolls used in the present study. The size of the rolls affected the retention of folic acid during baking.
   Eur J Nutr, 2002 · checked 2026-09-29
6. brfl-r6-04 · Cochrane meta-analysis of RCTs
   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. brfl-r6-09 · meta-analysis of observational studies
   For serum/plasma folate concentrations, the MDM across all studies was 15.0 nmol/L (95% CI: 9.4, 20.5).
   J Nutr, 2026 · checked 2026-09-29
8. brfl-r6-03 · federal regulation
   It contains in each pound 2.9 milligrams of thiamin, 1.8 milligrams of riboflavin, 24 milligrams of niacin, 0.7 milligrams of folic acid, and 20 milligrams of iron.
   21 CFR 137.165, Enriched flour (eCFR, current) · checked 2026-09-29
9. brfl-r6-08 · non-randomized trial
   In one non-RCT, wheat flour fortified with folic acid and other micronutrients was associated with significantly lower occurrence of total neural tube defects, spina bifida, and encephalocoele, but not anencephaly, compared to unfortified flour (total neural tube defects risk ratio (RR) 0.32, 95% confidence interval (CI) 0.21 to 0.48; 1 study, 8037 births; low-certainty evidence).
   Cochrane Database Syst Rev, 2019 · checked 2026-09-29
10. brfl-r6-10 · prevalence study
    There has been a significant reduction in the prevalence of WKS in Australia since the introduction of thiamine enrichment of bread flour.
    Med J Aust, 1998 · checked 2026-09-29