The Gut Hormone Axis
The gut microbiome plays an important role in regulating blood sugar and hunger levels!
A healthy gut microbiome can improve insulin signaling, blood sugar levels and leptin sensitivity (Pascale et al., 2019). (Ochoa et al., 2014)
Leptin is an important satiety hormone (i.e. keeps us feeling full after a meal). An imbalance in the gut microbiome has been linked to leptin resistance (the inability of cells to recognize leptin resulting in increased hunger), and in animal models the probiotic Lactobacillus rhamnosus GG (LGG) improves leptin sensitivity.
This is likely due to the role of dysbiosis (an imbalance in gut bugs) and increased intestinal permeability ("leaky gut") in brain inflammation. Research suggests that these factors increase permeability of the blood brain barrier and activate an inflammatory immune response from glial cells (immune cells in the brain). Leptin is produced by fat cells and stimulates the hypothalamus (brain region) to reduce hunger levels. The neuroinflammation induced by gut dysbiosis and increased intestinal permeability may be a key trigger in the inability of the hypothalamus to appropriately respond to high levels of leptin (known as leptin resistance) (Han et al., 2021).
Leptin can also suppress sweet taste receptors, reducing the reward we get from consuming sugar laden foods. Leptin resistance increases this sense of reward felt from consuming sweet foods reinforcing sweet cravings.
Supporting the gut microbiome, increasing levels of short chain fatty acids and repairing the gut barrier may play a role in improving leptin sensitivity!
Studies also suggest that the gut microbiome influences ghrelin levels which is a hunger stimulating hormone. One clinical trial showed that supplementing prebiotics reduced ghrelin levels, post prandial (post-meal) blood glucose levels and insulin levels (mirroring reduced blood glucose levels) versus the control group. Both control and intervention groups made zero changes to their dietary and lifestyle habits. Intervention group participants however noted a reduction in appetite (Parnell & Reimer, 2009).
In conclusion, the gut microbiome plays an essential role in metabolic health. Prebiotics, probiotics and dietary changes can be utilised as a tool to support healthy blood sugar, insulin and hunger hormone levels to improve overall metabolic health!
Han, H., Yi, B., Zhong, R., Wang, M., Zhang, S., Ma, J., Yin, Y., Yin, J., Chen, L., & Zhang, H. (2021). From gut microbiota to host appetite: gut microbiota-derived metabolites as key regulators. Microbiome 2021 9:1, 9(1), 1–16. https://doi.org/10.1186/S40168-021-01093-Y
Ochoa, M., Lallès, J. P., Malbert, C. H., & Val-Laillet, D. (2014). Dietary sugars: their detection by the gut–brain axis and their peripheral and central effects in health and diseases. In European Journal of Nutrition (Vol. 54, Issue 1). Dr. Dietrich Steinkopff Verlag GmbH and Co. KG. https://doi.org/10.1007/s00394-014-0776-y
Parnell, J. A., & Reimer, R. A. (2009). Weight loss during oligofructose supplementation is associated with decreased ghrelin and increased peptide YY in overweight and obese adults. The American Journal of Clinical Nutrition, 89(6), 1751. https://doi.org/10.3945/AJCN.2009.27465