Fiber Content in One Slice of Bread
A single slice of bread typically contains 1.5-1.7 grams of dietary fiber for white bread and 2.8-3.6 grams for wholegrain bread, based on standard serving sizes.
Fiber Content by Bread Type
The fiber content varies substantially depending on the type of bread:
White/Refined Grain Bread
- White wheat bread: approximately 1.5 g per slice (based on 3.0-3.4 g per 100g) 1
- Most commonly consumed type, particularly among adolescents 2
- Contains approximately 4% fiber by dry weight in white flour 3, 4
Wholegrain Bread
- Wholegrain bread: approximately 2.8-3.6 g per slice (based on 5.6-7.2 g per 100g) 1
- Provides 10-15% fiber by dry weight 4
- Mean fiber content of 7.5 g per 100g in analyzed samples 2
Specialty Breads
Clinical Context
Most commercially available sliced breads are "low" in fiber, with 64% of breads sold in Quebec containing less than 2 g per two-slice serving 5. This is concerning because:
- Two slices of typical white bread provide only 3-3.4 g of fiber 5
- This represents merely 10-11% of the recommended daily intake of 30 g/day
- White bread remains the dominant choice despite lower fiber content 2, 3
Practical Implications
Substituting white bread with wholegrain bread significantly increases fiber intake:
- Replacing 30% of white bread consumption increases daily fiber by 1.4 g/day 2
- Replacing 50% increases daily fiber by 2.0 g/day 2
- Each extra 5 g/day of fiber reduces systolic BP by 2.8 mm Hg and diastolic BP by 2.1 mm Hg 6
Fiber Targets for Health
According to EU regulations, bread can be labeled as 1:
- "Source of fiber": ≥3 g per 100g (approximately 1.5 g per slice)
- "High fiber": ≥6 g per 100g (approximately 3 g per slice)
Key Takeaway
For patients needing to increase fiber intake, recommend wholegrain bread over white bread, as it provides approximately double the fiber per slice (2.8-3.6 g vs 1.5 g). This simple substitution can meaningfully contribute to the recommended daily fiber intake of 28-38 g/day for adults 6.