Glycaemic, gastrointestinal and appetite responses to breakfast porridges from ancient cereal grains: A MRI pilot study in healthy humans

Abstract

Cereal grain based porridges are commonly consumed throughout the world. Whilst some data are available for varieties that are popular in the Western world such as oats and rye, other 'ancient' grains used in the East and in Africa such as millets are thought to have beneficial health effects, such as a suppression of post prandial hunger and circulating glucose levels. These grains, a sustainable food source due to their tolerance of extreme weather and growing conditions, are commonly found throughout Asia and Africa. However, knowledge of the physiological responses to these grain varieties is very limited. This study aimed to collect initial pilot data on the physiological and gastrointestinal responses to breakfast porridges made with two millet varieties and oats and rye grains. A total of n = 15 completed the oats and rye, n = 9 the finger millet n = 12 the pearl millet meals. MRI scans were undertaken at baseline, immediately after consumption and then hourly postprandially. Blood glucose was measured at baseline, immediately after consumption and then every 15 min until t = 80 min, then every 20 min until t = 120 min, followed on each occasion by completion of VAS. Seven participants completed the entire protocol and were included in the final analysis. A subgroup analysis with the n = 10 paired comparison between the same individuals that completed the oats, rye and pearl millet was also considered. The gastric volume AUC was higher for pearl millet than oats and rye (n = 10, p<0.001). The incremental area under the curve (iAUC) for blood glucose was not significantly different between the meals although this showed a trend to be lower for pearl millet. Hunger was lower for pearl millet compared to oats and rye (n = 10, p = 0.01). There was a significant correlation between total gastric volume AUC and average appetite AUC r =-0.47, p < 0.010. Isoenergetic breakfast porridges from 'ancient' varieties of millet grains showed physiological responses that were comparable with those from common Western varieties known to have beneficial health effects. Pearl millet appeared to induce lower postprandial blood glucose response and appetite scores though the differences were not conclusive compared with the other 4 porridges and further work is needed. Improved knowledge of the effects of different cereal grains could help direct dietary advice and ultimately improve health outcomes in the general population worldwide.

Glycaemic, gastrointestinal, hormonal and appetitive responses to pearl millet or oats porridge breakfasts: a randomised, crossover trial in healthy humans

“…An alternative hypothesis could be put forward that the presence of IDF in PMP might stimulate (mechanically) the gastric wall, resulting in an increased release of mucus, which can increase the meal's gastric volume (66) . The gastric volume results are in keeping with the previous pilot study, which showed a significant difference in gastric volume between different porridges (42) . The reasons for this remain to be understood.…”

“…The sample size was calculated using fingerprick glucose pilot data from the previous study on similar porridge breakfasts (42) . Using a crossover, paired design it would be possible to detect a change of 27•4 mmol × min/l (or 33 %) in iAUC2h for blood glucose with α = 0•05 and a power of 80 % using n 26 participants.…”

“…Oats were chosen as the comparator as these are a common breakfast grain with recognised health-promoting characteristics (25,59,60) . Millet was chosen in this study as the intervention because of potential health benefits indicated by our previous work (42) . Furthermore, the potential to exploit human consumption such as millet more fully in developed countries, and the broader context of resilience with respect to growing conditions may enable it to contribute potentially to improving food security and sustainability (35) .…”

“…In a previous pilot study, a pearl millet porridge (PMP) breakfast appeared to induce lower postprandial blood glucose responses and appetite scores compared with other grains, although the differences were not conclusive (42) . The pilot study was instrumental in the subsequent development of the present study, providing a better understanding of issues related to cooking, acceptability of the meals, physical form of the products and participants' reliability in returning the food diaries.…”

Some pearl millet-based foods promote satiety or reduce glycaemic response in a crossover trial

“…Our findings differ to some degree from two recent studies conducted with pearl millet porridge by Alyami et al (43,44) in populations in the United Kingdom. Notably, we observed differences in glycaemic response but not gastric half-emptying time for pearl millet foods, whereas these previous studies did not find differences in glycaemic response but instead observed differences in gastric volume as assessed by magnetic resonance imaging (MRI).…”