Opti-Biologics

“Presenting Scientific Research for Optimization of Everyday Life"

Journal Review #6: Probiotics for Gut Health


August 28, 2022

An Inside Look at the Benefits of Probiotic Supplementation for both Gut & Systemic Health

Nutrients for the Gut Microbiota and Their Effects on Overall Health
Background - There is increasing evidence that the gut microbiota has a direct impact on cognition and brain health. A Poorly balanced gut microbiota has been associated with many neuropsychiatric disorders, including but not limited to Parkinson’s, Alzheimer’s, depression, and general anxiety. There are many ways in which bacteria, viruses, and fungi in the gut influence brain health, and they will be discussed in this post. First, a general understanding of the gut microbiota is required. 
The gut microbiota is the collection of microorganisms in the gut. These microorganisms are bacteria, fungi, and viruses. Bacterial colonies are the most important players in the gut microbiota. This is due to certain bacteria’s ability to use fuel and create waste products. These waste products can end up in our bloodstream, thus affecting our entire cardiovascular system and brain. A bacteria is referred to as a healthy/good bacteria if its byproduct or waste product is beneficial to the host; that is, the waste product is anti-inflammatory. A bacteria is considered unhealthy/bad if its byproduct is harmful to the host, or proinflammatory. More recent studies have found that the number of good bacteria is not as relevant to metabolic health as the ratio of healthy and bad bacteria. 
There are many practices that promote healthy gut microbiota, including but not limited to regular physical exercise, a well-balanced diet, vegetable intake, and probiotic supplementation. These practices rely on altering the ratio of good: to bad bacteria, thus promoting an increase in beneficial byproducts that promote health. Just as a good diet and exercise promote healthy gut microbiota, a poor diet and a sedentary lifestyle promote unhealthy gut microbiota. This unhealthy gut microbiota leads to the release of proinflammatory byproducts that alter the metabolism and brain chemistry of the individual, thus trapping them in an unhealthy loop. This unhealthy loop is comprised of inflammatory cascades and altered hormone excretion, thus making it extremely overwhelming for the individual to escape the loop without professional guidance. 
This cycle of dysregulated gut health is also seen in a variety of disorders such as obesity and type 2 diabetes mellitus. Advice such as a sustained caloric deficit and regular exercise is not strongly adhered to in these subjects, likely due to this dysregulation of hormones. The good news is that there are other ways to further improve gut microbiota health. These practices are far less exhausting and can improve the likelihood of adhering to a diet and exercise regiment. Probiotics are foods that contain microbes, and consumption of these foods can greatly alter the gut microbiota. Thus, simply eating yogurt fortified with certain bacterial species and vitamins can improve gut microbiota health. 
Today’s market is flooded with overpriced capsule probiotics, even simple market places such as Trader Joe’s have shelves full of them. To an untrained or even trained eye, making a choice on which to use can be extremely overwhelming. Besides, these capsules are not like nootropics in the sense that, upon administration, an immediate sense of well-being is achieved. These probiotics take time to work and improve, so an immediate feeling of well-being is not going to be present. However, over-time eating foods with probiotics and vitamins have just as much of an impact as a general probiotic. In this journal review, two studies analyze the effects of either yogurt or probiotic supplements on obese subjects or dialysis patients.
Journal #1: Yogurt Consumption - The first journal article aims to determine the effect of yogurt consumption on a variety of metabolic or endocrine parameters. To observe the effects of yogurt, 118 obese subjects completed the study and were previously randomly assigned to four groups: (1) Regular yogurt (2) Probiotic yogurt (3) Vitamin-D Yogurt (4) Probiotic + Vitamin-D yogurt. All subjects were also put on a low-calorie diet and advised to increase physical activity. At the end of the study, no significant differences in physical activity or caloric consumption were found between groups. Several measurements were taken, including insulin, GLP-1 levels, and ghrelin levels.  
  • Ghrelin - Hormone that promotes the feeling of hunger. It binds to receptors in the hypothalamus.
  • GLP-1 - Glucagon-like peptide 1 is a hormone produced by the gut that promotes the feeling of satiety via slowing gastric emptying.
  • Insulin - Hormone produced by beta cells of the pancreas in response to glucose and, to a lesser extent, fat. acts to insert GLUT proteins into tissues and promotes anabolic pathways such as mTOR. It primarily acts to lower blood glucose levels. 
The subjects' levels were all measured at baseline, or 0 weeks, and then again at the end of the study, 10 weeks. During a 10-week calorically restricted diet and the dietary addition of probiotic yogurt or vitamin-D yogurt, GLP-1 levels significantly increased from baseline. Interestingly, in the probiotic + vitamin-D yogurt group, GLP-1 levels did not reach significance, possibly due to interacting effects between the microbes and vitamin-D. In the probiotic yogurt and vitamin-D yogurt groups, ghrelin did not significantly increase. 
Overall, the consumption of probiotic yogurt or vitamin-D yogurt seems to promote the increase of GLP-1 while not impacting the level of ghrelin. This is important because while on a calorically restricted diet, ghrelin usually increases, which makes the subject hungry. The more ghrelin, the more likely the subject will not adhere to a diet plan, thus rendering the diet ineffective at losing excess fat. Therefore, keeping GLP-1 high, promoting satiety, and keeping ghrelin low or at baseline, is optimal for adherence to a low-calorie diet. 
Journal #2: Probiotic Supplementation - The second study focuses on probiotic supplementation for dialysis patients. The mean age of the patients was 68 years old, and 18 subjects completed the study. The patients were supplemented with a probiotic supplement and, after 3 months of the administration, species abundance was significantly different than compared to baseline. After 3 months of supplementation, short-chain fatty acids also significantly increased. The short-chain fatty acids are byproducts of bacterial energy use and can circulate in the bloodstream. These include butyric acid, acetic acid, and valeric acid. Despite the significant increase in these short-chain fatty acids, which are usually anti-inflammatory, C-reactive protein did not significantly change from baseline. 
  • C-reactive protein - Marker in the blood commonly used to detect systemic inflammation and/or kidney issues.
However, serum calprotectin significantly decreased compared to baseline after 3 months of consistent probiotic supplementation. Calprotectin is another marker of acute inflammation, therefore, the decrease observed in this study shows a positive impact of probiotic supplementation on inflammation. Other inflammatory markers such as interleukin-6 and tumor necrosis alpha were also significantly decreased. These molecules are signaling molecules sent out by immune cells that initiate the inflammatory cascade. Therefore, a decrease in the molecules would lead to less inflammation. The immune system is extremely complex, with each cell type consisting of multiple subtypes. To simply state that probiotic supplementation for 3 months significantly increased Treg immune cells and decreased inflammatory monocyte count. 
  • TReg - Specialized T cell population that acts to suppress the other immune cells thus acting as an anti-inflammatory cell. 
The probiotics used in the study consisted of B. bifidum BGN4 and B. longum BORI, which have both been extremely promising in other areas of research, such as mental health. While other strains of bacteria have been shown to be beneficial, these strains have years of data supporting them. Other strains and probiotic combinations will be highlighted in later blog posts, but for those individuals looking to start a probiotic regiment, these strains are a perfect place to begin. 
 

Meet The Author


Hello everyone, 

My name is Joshua Giblin. I am a post-bachelor researcher/research technician at USC. My interests range from nutrition to nanomedicine and also practical science to improve everyday life. Through this blog, I aim to communicate practical scientific research and present it to curious individuals so that an educated decision can be made. Thank you for reading the blog and showing your support.

 

Editors

A special thanks to the people involved behind the scenes. Without them, these informative and influential posts would not be what they are.
Anna Richardson - Undergraduate
Molly Giblin - High School Student 
Literature cited
  1. Choi, E., Yang, J., Ji, G.-E., Park, M. S., Seong, Y., Oh, S. W., Kim, M. G., Cho, W. Y., & Jo, S. K. (2022). The effect of probiotic supplementation on systemic inflammation in dialysis patients. Kidney Research and Clinical Practice, 41(1), 89–101. https://doi.org/10.23876/j.krcp.21.014

  2. Daniel, N., Nachbar, R. T., Tran, T. T. T., Ouellette, A., Varin, T. V., Cotillard, A., Quinquis, L., Gagné, A., St-Pierre, P., Trottier, J., Marcotte, B., Poirel, M., Saccareau, M., Dubois, M.-J., Joubert, P., Barbier, O., Koutnikova, H., & Marette, A. (2022). Gut microbiota and fermentation-derived branched chain hydroxy acids mediate health benefits of yogurt consumption in obese mice. Nature Communications, 13(1), 1343. https://doi.org/10.1038/s41467-022-29005-0

  3. Hajipoor, S., Hekmatdoost, A., Pasdar, Y., Mohammadi, R., Alipour, M., Rezaie, M., Nachvak, S. M., Balthazar, C. F., Sobhiyeh, M. R., Mortazavian, A. M., & Cruz, A. G. (n.d.). Consumption of probiotic yogurt and vitamin D-fortified yogurt increases fasting level of GLP-1 in obese adults undergoing low-calorie diet: A double-blind randomized controlled trial. Food Science & Nutrition, n/a(n/a). https://doi.org/10.1002/fsn3.2816


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