The glycaemic index (GI) of carbohydrate foods is a useful tool for predicting postprandial glucose and insulin responses (1). Results from human studies suggest an inverse relationship between GI of ingested food and postprandial appetite responses (2). However, evidence on the effects of GI on subjective and objective satiety responses is inconclusive (3). Therefore, the aim of this study was to assess the impact of GI on postprandial appetite response in humans.
We conducted a randomised controlled crossover trial on 13 adults presenting with normoglycaemia, normal BMI and mean age of 28.7 ± 6.6 years. Participants were randomly allocated to consume a high GI meal (HGI) consisting of mashed potatoes, and low GI (LGI) meal of canned whole chickpeas, each providing 50 g total available carbohydrates, after an overnight fast. Postprandial subjective satiety and appetite responses were captured using visual analogue scale (VAS) in 3 domains: hunger, fullness, and prospective food intake. Plasma ghrelin values were also measured by immunoassay (intra-assay variations < 15%), in venous blood samples collected over 3 hours following breakfast intake. Postprandial total area under the curves (AUCs) were calculated by the trapezoidal method, and data were analysed using t-test with statistical significance set at p < 0.05. Data are presented as mean ± SD.
There were great variations observed in individual responses after intake of both interventions in all outcomes illustrated above. Postprandial hunger responses were significantly lower after ingestion of LGI meal (91.2 ± 37.1 mm × h) in comparison to HGI meal (113.5 ± 26 mm × h) (p = 0.035); and postprandial fullness responses were significantly higher as demonstrated by AUC values over the 3 hour period following breakfast intake (107.3 ± 37.1 mm × h) and (80.2 ± 24.7 mm × h) (p = 0.012) respectively. However, there was no significant difference in prospective food intake following different GI meals (104.6 ± 41.9 mm × h) and (126.2 ± 26.3 mm × h), respectively. In addition, there were no differences observed in postprandial ghrelin response (p > 0.05).
The results suggest that a low meal GI positively affects postprandial satiety response. However, the impact on appetite hormone ghrelin is unclear possibly due to high individual variances in hormonal responses.

Influence of glycaemic index on subjective appetite responses in healthy adults

The gastrointestinal tract is amongst the most densely populated ecosystems on earth, home to an abundant and diverse collection of microbial species, not just bacteria but also Archaea, viruses, fungi etc. Significant interest in this area has been sparked in recent years by an appreciation of the importance of the gut microbiota in the health of the host, and this has led to the microbiome of humans and animals being investigated in depth. Studies have drawn links between host nutrition, the gut microbiota and metabolic and immune functions, which in consequence affect physiology.



The first investigations of the structure of the microbiota were culture-based, however the introduction of sequencing technologies such as Sanger sequencing and subsequent development of 454 sequencing and metagenomics approaches have become the mainstay of microbiota studies. The creation of reference databases and analysis software has provided invaluable tools for assigning taxonomy to generated data. Great progress in characterising the structure of the microbiome recently has paved the way for ongoing and future studies on the functional interactions between the microbiota and the host. Studies on the function of the microbiota are critical in understanding the role of the microbiota in human homeostasis and disease pathogenesis.



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