White wheat bread: the yardstick for blood sugar, and what beats it

White wheat bread is a standard reference food in blood sugar research, and one result about it surprises most people. In a randomized trial in 121 adults with type 2 diabetes in Turkey, 3.5 oz (100 g) of whole wheat, wheat bran or rye bread sold there as dietary breads raised blood glucose over 2 hours no differently from 3.5 oz (100 g) of white wheat bread. That was a single-portion test, and the abstract gives no fiber content for those loaves. A darker label on the local market did not buy a gentler glucose curve in that test. What did move the numbers was the structure of the grain and what came with the bread. In 20 healthy middle-aged adults, three days of bread made from intact barley kernels instead of white wheat bread lowered the next-morning glucose response by 22 percent and insulin by 17 percent, a short trial measured on blood markers only. Eating 5.3 oz (150 g) of strawberry puree with the bread improved the 2-hour glucose profile by 36 percent in 13 to 20 healthy women per study, all of them single-meal tests.

The numbers, per 3.5 oz (100 g)

How much is actually in it

• In 58 Slovenian bread samples analyzed in the lab, white wheat breads had the least dietary fiber at 2.9 g per 3.5 oz (100 g), against 7.5 g per 3.5 oz (100 g) in wholegrain breads. — 58 bread samples commonly consumed in Slovenia (n = 58 samples) Evidence C source
  Fiber 2.9 g/100 g (white wheat) vs 7.5 g/100 g (wholegrain), means
• The single USDA reference record for white wheat bread lists 684 mg calcium, 0.51 mg thiamin and 162 mcg folate per 3.5 oz (100 g). — USDA SR Legacy food record Bread, white wheat (FDC 167532), single reference record (n = 1 record) Evidence E source
  Per 100 g: calcium 684 mg, thiamin 0.51 mg, folate 162 mcg DFE

What your body absorbs

• In stable-isotope crossover studies in healthy adults, adding 1.49 mmol of phytic acid to white wheat bread cut magnesium absorption from 32.5% to 13.0%, and adding 0.75 mmol cut it from 32.2% to 24.0%. — Two stable-isotope studies with 8-9 healthy adults per study, test meals of 200 g phytic acid-free wheat bread (n = 8-9 per study) Evidence B source
  Fractional apparent Mg absorption 32.5% to 13.0% (1.49 mmol phytic acid, P < 0.0005); 32.2% to 24.0% (0.75 mmol, P < 0.01); dose dependent

What it does to your health

• In a randomized crossover study in 20 adults with normal glucose tolerance, rye breads and pasta with 50 g carbohydrate raised blood glucose the same as white wheat bread but produced lower insulin, GIP and GLP-1 responses. — 10 men and 10 women, mean age 28, normal glucose tolerance, 50 g available carbohydrate per product (n = 20) Evidence B source
  Glucose response and gastric emptying not different; insulin, GIP and GLP-1 lower after rye breads and pasta than white wheat bread
• In randomized crossover meal studies in 13-20 healthy women, eating 5.3 oz (150 g) of strawberry puree or a mixed berry puree with white wheat bread improved the 2-hour glycemic profile by 36% and 38%, and several berries lowered the insulin response. — Healthy females, n = 13-20 per study, bread equal to 50 g available starch plus 150 g whole-berry puree, 2-h tests (n = 13-20) Evidence B source
  Glycemic profile improved 36% (strawberries) and 38% (berry mixture) with white wheat bread; insulin response reduced
• In a crossover study in 21 healthy young adults, three pasta Bolognese meals with the same carbohydrate gave 31% to 63% lower 2-hour glucose responses than white wheat bread. — Twenty-one healthy volunteers, 14 men and 7 women, mean age 24, equal available carbohydrate (n = 21) Evidence B source
  Incremental glucose 0-120 min 31%-63% lower after test meals than white wheat bread
• In a randomized crossover trial in 15 adults eating each bread for 4 weeks, plasma serotonin, taurine and glycerophosphocholine were lower after wholegrain rye bread than after white wheat bread, a lab finding with no clinical outcome measured. — 15 adults, 2 successive 4-week periods after a 4-week white wheat bread run-in (n = 15) Evidence B source
  Plasma serotonin, taurine, glycerophosphocholine lower after wholegrain rye vs white wheat period (Q < 0.05)

Safety, limits and interactions

• Bakery bread sampled in Zagreb, including white wheat bread, averaged 2.30 g salt per 3.5 oz (100 g), almost twice the 1.4% limit set by Croatian regulation, and salt varied widely between bakeries. — Three bread types from 25 small and 5 national industrial bakeries in Zagreb, Croatia (n = 30 bakeries) Evidence C source
  Mean salt 2.30 ± 0.22 g/100 g vs 1.4 g/100 g national threshold

What people believe that the data does not support

• In a randomized trial in 121 adults with type 2 diabetes, 3.5 oz (100 g) of whole wheat, wheat bran or rye bread, sold in Turkey as dietary breads, raised blood glucose over 2 hours no differently from 3.5 oz (100 g) of white wheat bread. — 121 patients with type 2 diabetes in Turkey, 100 g bread eaten within 10 min, 2-hour test (n = 121) Evidence B source
  No significant difference in glycemic (p = 0.093) or insulinemic (p = 0.297) effect between four breads
• US rules require bread sold as enriched to carry, per pound, 1.8 mg thiamin, 1.1 mg riboflavin, 15 mg niacin, 0.43 mg folic acid and 12.5 mg iron, so its B vitamins and iron are largely added, not native to white flour. — Enriched bread, rolls and buns sold in the United States Evidence E source
  Per pound: thiamin 1.8 mg, riboflavin 1.1 mg, niacin 15 mg, folic acid 0.43 mg, iron 12.5 mg; optional calcium to 600 mg

Who this works differently for

• In the same Slovenian survey modeling, replacing 30% or 50% of white wheat bread with wholegrain bread would raise mean fiber intake by 1.4 or 2.0 g a day, and adolescents ate white wheat bread most often. — Nationally representative SI.Menu dietary survey, Slovenia, focus on adolescents Evidence C source
  +1.4 g/day fiber (30% swap), +2.0 g/day (50% swap), modeled
• In a crossover trial in 20 middle-aged adults, 3 days of barley kernel bread instead of white wheat bread lowered next-morning blood glucose response by 22% and insulin response by 17%, and improved an insulin sensitivity index by 25%. — 20 healthy middle-aged subjects, 3 consecutive days per bread, test at standardized breakfast on day 4 (n = 20) Evidence B source
  B-glucose response -22%, s-insulin response -17%, ISI(composite) +25%, fasting GLP-1 +56% vs white wheat bread
• In a crossover trial in 9 men aged 65-70, white wheat bread, rolled oats and oat porridge gave equally high glucose and insulin responses, while boiled intact oat and wheat kernels gave low responses. — Nine healthy male volunteers aged 65-70 years (n = 9) Evidence B source
  No difference in glycemic and insulinemic indices between rolled oats, oat porridge and white wheat bread; kernel porridges low
• In a crossover trial in 12 healthy Chinese men, drinking dairy or soy milk 30 minutes before white wheat bread lowered blood glucose and insulin after the meal more than drinking the milk with the bread. — Twelve healthy Chinese male participants, five test occasions, 3.5-hour sampling (n = 12) Evidence B source
  Preload lowered postprandial glycemia and insulinemia vs co-ingestion; co-ingestion lowered glucose and GI vs bread with water
• In a 3-day crossover trial in 33 adults aged 50-70, barley kernel bread lowered breakfast blood glucose responses compared with white wheat bread, whatever the baseline gut Prevotella to Bacteroides ratio. — 33 healthy adults aged 50-70, BMI < 28, grouped by fecal Prevotella/Bacteroides ratio (n = 33) Evidence B source
  Lower blood glucose response after barley kernel bread vs white wheat bread (P < 0.01), independent of microbiota group

The bottom line

Per 100 g, white wheat bread is the low-fiber loaf. Lab analysis of 58 breads commonly eaten in Slovenia found 2.9 g of fiber per 3.5 oz (100 g) in white wheat bread against 7.5 g in wholegrain bread, as means from one country with no spread given. Adolescents there ate white wheat bread most often. Swapping 30 or 50 percent of it for wholegrain bread would add 1.4 or 2.0 g of fiber a day, and that is a model on survey data, with no health outcome measured. Much of what the US label shows is added. Federal rules require bread sold as enriched to carry, in each pound, 1.8 mg thiamin, 1.1 mg riboflavin, 15 mg niacin, 0.43 mg folic acid and 12.5 mg iron. The single USDA reference record lists 684 mg calcium, 0.51 mg thiamin and 162 micrograms of folate per 3.5 oz (100 g). That is one record with no spread across samples, and it may not describe the loaf on your shelf. Whole grain brings phytic acid, and that has a cost for one mineral. In two stable-isotope studies with 8 to 9 healthy adults each, phytic acid added to white wheat bread at 1.49 mmol cut magnesium absorption from 32.5 to 13.0 percent, and a 0.75 mmol dose cut it from 32.2 to 24.0 percent. Those were one-off test meals with the compound added to white bread, so they do not compare real whole wheat and white loaves. Other glucose results are narrower than they sound. In 20 young adults with normal glucose tolerance, two rye breads and pasta raised blood glucose the same as white wheat bread and produced lower insulin, GIP and GLP-1 responses, with no sizes in the abstract. Rolled oats and oat porridge matched white wheat bread in 9 men aged 65 to 70, while boiled intact oat and wheat kernels gave low responses. Three pasta Bolognese meals gave 31 to 63 percent lower 2-hour glucose than white wheat bread in 21 young adults, which compares a mixed dish with plain bread. In 12 healthy Chinese men, dairy or soy milk drunk 30 minutes before the bread lowered glucose and insulin more than the same milk drunk with it, and the abstract gives no size. Barley kernel bread lowered breakfast glucose after three days in 33 adults aged 50 to 70, whatever their gut bacteria profile. After four weeks on wholegrain rye bread, 15 adults had lower plasma serotonin, taurine and glycerophosphocholine than after four weeks on white wheat bread, a lab finding with no clinical outcome. Salt is the one safety fact on this page. Bakery bread sampled from 30 bakeries in Zagreb averaged 2.30 g of salt per 3.5 oz (100 g), almost twice the 1.4 percent Croatian limit, and that mean covers all bread types together and one city. We hold no card on wheat allergy, celiac disease, pregnancy or medicines for this bread, so this page cannot speak to them.

Sources

1. wwbr-r7-02 · food composition analysis
   A substantial variation in dietary fibre content was observed across bread types, with wholegrain breads providing the highest levels (mean: 7.5 g/100 g) and white wheat breads the lowest (2.9 g/100 g).
   Nutrients, 2025 · checked 2026-09-28
2. wwbr-r7-15 · dataset
   Bread, white wheat (FDC 167532): Calcium, Ca 684 mg; Thiamin 0.51 mg; Folate 162 µg per 100 g
   USDA FoodData Central, SR Legacy 2018, FDC 167532 Bread, white wheat · checked 2026-09-28
3. wwbr-r7-01 · RCT (crossover, isotope)
   The addition of phytic acid lowered fractional apparent magnesium absorption from 32.5 +/- 6.9% (no added phytic acid) to 13.0 +/- 6.9% (1.49 mmol added phytic acid; P < 0.0005) and from 32.2 +/- 12.0% (no added phytic acid) to 24.0 +/- 12.9% (0.75 mmol added phytic acid; P < 0.01).
   Am J Clin Nutr, 2004 · checked 2026-09-28
4. wwbr-r7-08 · RCT (crossover)
   Glucose responses and the rate of gastric emptying after consumption of the 2 rye breads and pasta did not differ from those after consumption of white wheat bread. However, insulin, GIP, and GLP-1 responses, except for GLP-1 responses to the rye bread containing oat beta-glucan concentrate, were lower after the consumption of rye breads and pasta than after consumption of white wheat bread.
   Am J Clin Nutr, 2002 · checked 2026-09-28
5. wwbr-r7-09 · RCT (crossover)
   Strawberries, bilberries, lingonberries, and chokeberries consumed with WB and the berry mixture consumed with WB or RB significantly reduced the postprandial insulin response. Only strawberries (36%) and the berry mixture (with WB, 38%; with RB, 19%) significantly improved the glycemic profile of the breads.
   J Nutr, 2013 · checked 2026-09-28
6. wwbr-r7-11 · RCT (crossover)
   Incremental glucose responses (0–120 min) were significantly lower (31%–63%) following all the test meals than after the WWB meal (Table 3).
   Nutrients, 2016 · checked 2026-09-28
7. wwbr-r7-13 · RCT (crossover)
   Plasma concentrations of serotonin, taurine, and glycerophosphocholine were significantly lower after the WGR than WW period (Q < 0.05).
   Am J Clin Nutr, 2019 · checked 2026-09-28
8. wwbr-r7-04 · cross-sectional survey
   Samples of white wheat bread, dark wheat bread, and other types of bread were collected, and the salt content was determined with the Mohr method. Salt content varied widely between bakeries, with an average content of 2.30±0.22 g per 100 g of bread, which is almost twice the threshold content (1.4 %) defined by the Croatian National Regulation on Cereals and Cereal Products.
   Arh Hig Rada Toksikol, 2019 · checked 2026-09-28
9. wwbr-r7-05 · RCT
   No significant difference was found in either glycemic or insulinemic effects between four types of breads when compared to each other (p=0.093 for glycemic effect and p=0.297 for insulinemic effect). CONCLUSION: Three different bread types consumed as an alternative to white bread in Turkey, increase blood glucose levels of diabetic patients similar to white bread.
   Diabetes Res Clin Pract, 2008 · checked 2026-09-28
10. wwbr-r7-14 · regulation
    Each such food contains in each pound 1.8 milligrams of thiamin, 1.1 milligrams of riboflavin, 15 milligrams of niacin, 0.43 milligrams of folic acid, and 12.5 milligrams of iron.
    21 CFR 136.115, Enriched bread, rolls, and buns (FDA) · checked 2026-09-28
11. wwbr-r7-03 · modeling study
    In adolescents, white wheat bread was most often consumed, contributing disproportionately to total bread intake and limiting dietary fibre intake. We modelled two substitution scenarios, replacing 30% and 50% of white wheat bread with wholegrain bread, which resulted in mean dietary fibre increases of 1.4 g/day and 2.0 g/day, respectively.
    Nutrients, 2025 · checked 2026-09-28
12. wwbr-r7-06 · RCT (crossover)
    3 d of intervention with BB increased gut hormones in plasma (p) the next morning at fasting (p-glucagon-like peptide-1; 56%) and postprandially (p-glucagon-like peptide-2; 13% and p-peptide YY; 18%). Breath H₂ excretion and fasting serum (s) SCFA concentrations were increased (363 and 18%, respectively), and b-glucose (22%) and s-insulin responses (17%) were decreased after BB intervention. Insulin sensitivity index (ISI(composite)) was also improved (25%) after BB.
    Br J Nutr, 2015 · checked 2026-09-28
13. wwbr-r7-07 · RCT (crossover)
    SUBJECTS: Nine healthy male volunteers between 65 and 70 years of age participated in the study. RESULTS: The rolled oats and oat porridge elicited high metabolic responses. No differences in the glycaemic and insulinaemic indices (IIs) were seen between these products and white wheat bread. In contrast, the kernel porridges produced low glucose and insulin responses.
    Eur J Clin Nutr, 1995 · checked 2026-09-28
14. wwbr-r7-10 · RCT (crossover)
    Co-ingestion of dairy milk or soy milk with bread lowered postprandial blood glucose response and glycemic index. Co-ingesting soy milk with bread increased insulin response and insulinemic index significantly compared to co-ingestion of dairy milk and preload treatments. Preloads (30 min prior to bread) significantly lowered postprandial glycemia and insulinemia compared to co-ingestion.
    Eur J Nutr, 2017 · checked 2026-09-28
15. wwbr-r7-12 · RCT (crossover)
    A 3-day randomized crossover intervention with BKB and white wheat bread (control) was performed. Cardiometabolic test variables were analyzed the next day following a standardized breakfast. RESULTS: The BKB intervention lowered the blood glucose responses to the breakfast independently of Prevotella/Bacteroides ratios (P < 0.01).
    Eur J Nutr, 2019 · checked 2026-09-28