A team from New Zealand investigated the fecal bulking efficacy of 28 representative Australasian breakfast cereals.
A rat model was developed for this purpose, which gave similar responses as humans to cereal fibers.
Fecal bulking efficacy was measured as increases in fully hydrated fecal weight/100 g diet.
This was based upon precise measurements of food intake, fecal dry matter output, and fecal water-holding capacity (g water held without stress/g fecal dry matter).
The effects of cereals were compared to a baseline diet containing 50% sucrose.
When compared, increments in hydrated fecal weight due to 50% breakfast cereal ranged from slightly negative (Cornflakes, -2 g/100 g diet) to about 80 g/100 g diet (San Bran).
Most breakfast cereals increased hydrated fecal weight by between 10 and 20 g/100 g diet from a baseline of 21 g/100 g diet.
| Most cereal servings contributed < 10% of daily reference fecal bulk value.
| Asia Pacific Journal of Clinical Nutrition |
However, 4 products containing high levels of wheat bran had an exceptionally large impact on hydrated fecal weight (increase > 20 g/100 g diet).
The changes resulted more from relative changes in dry matter output than in fecal water retention/gram.
For most breakfast cereals, fecal bulking was far less than that for wheat bran.
Data from human clinical trials and dietary fiber recommendations were used to define a theoretical daily reference value for fecal bulk.
The researchers found that most breakfast cereals contributed, per serving, less than 10% of this value.
John A. Monro, of the Food Industry Science Centre, New Zealand Institute for Crop and Food Research, Palmerston North, commented, "Some high bran breakfast cereals may contribute substantially to, and many are reasonable sources of, fecal bulk.
"However, for most of them, 1 or 2 servings at breakfast cannot be relied on to effectively redress shortfalls in fecal bulk elsewhere in the diet."