Study on Rye Porridge, Inulin, and Wheat Gluten

Research Overview

A 2017 study aimed to determine if the addition of inulin and wheat gluten, a plant protein, could enhance the appetite-suppressing effects of rye porridge. The researchers also examined how fiber breakdown influences appetite and the levels of insulin and glucagon-like peptide-1 (GLP-1).

Key Findings

The study concluded that neither inulin nor wheat gluten significantly improved the appetite-suppressing capabilities of rye porridge. However, increased rye intake resulted in greater fiber breakdown and a reduction in meal-induced blood sugar spikes after a subsequent meal, without impacting insulin and GLP-1 levels. While the breakdown of fiber into short-chain fatty acids, hydrogen, and methane is known to enhance feelings of satiety, the specific contributions of these components remain unclear. Additionally, the mechanisms by which proteins reduce appetite are not fully understood, although the secretion of GLP-1—which slows stomach emptying and boosts insulin levels—may play a role.

Implications for Obesity Strategies

Understanding how fiber and protein-rich foods affect appetite can lead to improved strategies for addressing the increasing rates of obesity.

Study Details

Participants and Methodology

Conducted in Sweden and published in the British Journal of Nutrition, the study involved 21 healthy adults aged 18-60, who entered between March and August 2013. To minimize hormonal fluctuations affecting appetite, the female participants were either post-menopausal or regularly used hormonal contraceptives.

During clinical visits, participants consumed one of six breakfasts in random order after fasting for 12 hours and avoiding alcohol, strenuous activity, and fiber-rich foods. The breakfasts included various rye porridge preparations and whole bread for comparison.

Appetite Assessment

Participants rated their appetite—specifically hunger, fullness, and desire to eat—on a scale from 0 to 100 at 30-minute intervals, starting 30 minutes before breakfast. Breath samples were analyzed for hydrogen and methane levels after each rating, and blood samples were collected throughout the visit.

Results on Appetite and Satiety

No differences in appetite were noted before breakfast. However, participants reported approximately 16% lower hunger levels throughout the day after consuming RP55 compared to other breakfasts, except RPHG. Before lunch, hunger was about 20% lower with RP55 and RPHI compared to whole bread. Fullness ratings were significantly higher on average before dinner and lunch with RP55.

The desire to eat before lunch was 25% lower with RPHI compared to RP40 and 22% lower than with whole bread. Hydrogen levels were three times higher after consuming RP55 compared to whole bread, while RPHI and RPIG showed even greater increases in hydrogen levels.

Blood Sugar and Hormonal Levels

Blood sugar levels were higher with RP55 compared to RPHI or RP40 two hours post-breakfast. Notably, RP55 was associated with 7% higher blood sugar levels than other porridges, excluding RPIG. Meal-induced increases in blood sugar were reduced with RPHI and RP55 more than with whole bread, leading to an average blood sugar reduction of 6% with RP55. No significant differences in insulin and GLP-1 levels were observed across breakfast meals.

Conclusion

The study found that inulin and gluten did not enhance appetite suppression from rye porridge. Increased whole grain rye intake, however, correlated with greater fiber breakdown and lower blood sugar spikes after a second meal, without affecting insulin and GLP-1 levels. The larger portion size of RP55 likely contributed to the decreased appetite observed in the study. Further research is necessary to clarify the relationships between fiber breakdown, post-meal blood sugar, and appetite regulation mechanisms.

Author Information

Written By: Raishard Haynes, MBS