Rye kernel breakfast increases satiety in the afternoon - an effect of food structure

Abstract

Background: The structure of whole grain cereals is maintained to varying degrees during processing and preparation of foods. Food structure can influence metabolism, including perceived hunger and satiety. A diet that enhances satiety per calorie may help to prevent excessive calorie intake. The objective of this work was to compare subjective appetite ratings after consumption of intact and milled rye kernels.

Methods: Two studies were performed using a randomized, cross-over design. Ratings for appetite (hunger, satiety and desire to eat) were registered during an 8-h period after consumption of whole and milled rye kernels prepared as breads (study 1, n = 24) and porridges (study 2, n = 20). Sifted wheat bread was used as reference in both study parts and the products were eaten in iso-caloric portions with standardized additional breakfast foods. Breads and porridges were analyzed to determine whether structure (whole vs. milled kernels) effected dietary fibre content and composition after preparation of the products. Statistical evaluation of the appetite ratings after intake of the different breakfasts was done by paired t-tests for morning and afternoon ratings separately, with subjects as random effect and type of breakfast and time points as fixed effects.

Results: All rye breakfasts resulted in higher satiety ratings in the morning and afternoon compared with the iso-caloric reference breakfast with sifted wheat bread. Rye bread with milled or whole kernels affected appetite equally, so no effect of structure was observed. In contrast, after consumption of the rye kernel breakfast, satiety was increased and hunger suppressed in the afternoon compared with the milled rye kernel porridge breakfast. This effect could be related to structural differences alone, because the products were equal in nutritional content including dietary fibre content and composition.

Conclusions: The study demonstrates that small changes in diet composition such as cereal grain structure have the potential to effect feelings of hunger and satiety.

Trial registration: This trial was registered at clinicaltrials.gov as NCT01042418.

Figures

Figure 1

Molecular weight distributions of extractable arabinoxylan (solid line) and β-glucan (dashed line) in the rye products. Vertical lines denote weight-average molecular weights.

Figure 2

Relative molecular weight distribution of fructan. DP = degree of polymerization.

Figure 3

Appetite ratings (n = 24) during 8 h after consumption of breakfast meals including wheat reference bread (-■-), bread with milled rye kernels (--△--) and bread with whole rye kernels (--□--).

Figure 4

Appetite ratings (n = 24) for the morning and afternoon time intervals after intake of breakfast meals including wheat reference bread (black); bread with milled rye kernels (white) and bread with whole rye kernels (checked). Different letters within time interval and appetite rating indicate significant difference (p < 0.05).

Figure 5

Appetite ratings (n = 20) during 8 h after consumption of breakfast meals including wheat reference bread (-■-), porridge of milled rye kernels (--△--) and porridge of whole rye kernels (--□--).

Figure 6

Appetite ratings (n = 20) for the morning and afternoon time intervals after consumption of breakfast meals including wheat reference bread (black); porridge of milled rye kernels (white) and porridge of whole rye kernels (checked). Different letters within time interval and appetite rating indicates significant difference (p < 0.05).