Connie: Good evening, dear friends. It’s great to have you here with us on this beautiful Saturday evening. Thanks for joining us. Today, we invited Professor Hofstadter to our program. Thank you for being here, Dr. Hofstadter.
Dr. Hofstadter: Thanks for inviting me. I’m excited to be here.
Connie: As is known to all, we all live in a sea of microorganisms. A few microorganisms are pathogenic, and most are harmless or even necessary, as the growth and development of many plants and animals depend on symbiotic microorganisms in these close cooperative partnerships. As a chronic metabolic disease, obesity affects people’s health in many ways, and can also lead to the development of many other metabolic diseases. Due to the many changes in people’s life and eating habits, more and more people with obesity problems are in the present age. Probiotics were expected to have some effects on human health, so does it help in the prevention or treatment of obesity as well? So, today we are going to discuss probiotics and their relationships with obesity. Where would you like to begin, Dr. Hofstadter?
Dr. Hofstadter: I want to start off by introducing that Metabolism of dietary components is the best way to maintain homeostasis. Upon metabolic disbalance, complications like obesity, diabetes mellitus type 2, atherosclerosis, cardiovascular disorders, hypertension may develop. The prevalence of these disorders is exponentially increasing, and was estimated to reach 333 million by 2025. Among other things, obesity is a disorder that happens when the body accumulates excess fat. Influences such as hormonal, neural, hereditary, and environmental are also involved in the development of obesity in addition to an unhealthy lifestyle. To manage high body weight, a healthy diet and physical exercise are always recommended.
Connie: Definitely, many diseases in modern society are related to obesity. But what is the standard of obesity? After all, we can’t just judge a person whether he or she is obese just from his or her appearance.
Dr. Hofstadter: Right. There is certainly a criterion for obesity. Body mass index is defined as the weight in kilograms divided by the height in meters squared. This is an index that is commonly used to classify overweight and obesity in adults due to its low cost and simplicity. The World Health Organization has defined overweight as having a body mass index between 25.0 and 29.9, and obesity as having a body mass index greater or equal than 30.0.
Connie: We now know that regular metabolism is particularly important to avoid obesity. But what does this have to do with gut microbe?
Dr. Hofstadter: Well. Gut microbiota composition has been closely associated with various metabolic disorders. Various researches have proved that changes in gut microbiota can directly lead to differences in body weight index and body mass index. The diversity and abundance of few microbes can promote energy harvesting and metabolic pathways that lead to obesity. Consequently, modulation of intestinal microbiota may be a possible target for good health. In this regard, probiotics or the beneficial gut bacteria, have been found to encourage the abundance of intestinal microbiota, boost intestinal capacity and reinstate the microbiota changes that occurred during obesity.
Connie: Wow, I will need to take better care of my microbiota then. And we know that the bacteria in the intestines of healthy people exist in a certain proportion and maintain dynamic balance. Beneficial bacteria such as Bifidobacterium and Lactobacillus account for more than 99%, while harmful bacteria such as Salmonella and Staphylococcus, and conditionally pathogenic bacteria including Escherichia coli and Enterococcus account for less than 1%. In other words, beneficial bacteria have an absolute advantage, and harmful bacteria are in a state of being suppressed so that we can well protect our intestines and maintain our health. And that was in general the case for the healthy population. I was wondering what is the situation of gut microbe in people with obesity issues?
Dr. Hofstadter: Yeah, that’s a good question. The situation is definitely different here. Obese people have higher levels of toxins in the intestines than normal people. Often these toxic substances can cause chronic inflammation, lead to excessive secretion of insulin. Now you have problems like not easily alleviated hunger and unconscious food intake. And at the same time, the intestinal flora imbalance will further increase, and you see, now you have a vicious circle, so obesity becomes inevitable.
Connie: Traditionally, there are certain metabolic enzymes, including pancreatic lipases and pancreatic phospholipase A2, that are responsible for digestion and dietary fat absorption. IN other words, these enzymes might be targeted for obesity control. It’s great to learn that probiotics might be a potential obesity treatment. My next question is, what is the mechanism of gut microbe affecting obesity?
Dr. Hofstadter: To put it simply, although there are several unknown facts, a general agreement is that gut microbiota is associated with obesity through dietary sugar fermentation, lipid metabolism, and metabolic pathways leading to food intake control and energy balance regulation. In addition, probiotics might enhance intestinal microbiota dysbiosis caused by high-calorie diets by improving the useful bacteria and dipping the pro-inflammatory bacteria.
Connie: I see. So it’s for sure that probiotics can be a treatment for obesity?
Dr. Hofstadter: Many studies are looking into it. Recently, various co-researcher conducted a systematic review of obesity management through probiotics supplementation utilizing diverse databases like PubMed, Cochrane, Excerpt Medica Database, Web of Science, and Scopus. The probiotic supplementation decreased weight increase or fat accretion in 72 animal studies in 61 trials utilizing specific strains of Lactobacillus and Bifidobacterium. In addition, three out of 15 clinical trials showed positive results as well.
Connie: that’s exciting. So any studies looking at the mechanism of probiotics affecting obesity at the molecular level?
Dr. Hofstadter: There is a study on overweight and obese individuals suggesting that consumption of probiotic yogurt including L. acidophilus, L. casei, B. lactis, and S. thermophilus along with a low-calorie diet can significantly increase the expression of genes such as toll-like receptor-2 and fork-head box protein P3, thus adding to the initiation of inflammatory responses and antigen-specific adaptive immunity. In addition, the L. reuteri strain has also been reported to enhance indicators of obesity and proinflammatory factors, altering the gene expression of insulin and lipid metabolism in white adipose tissues as well. A soy fermented beverage with probiotic Enterococcus faecium and Bifidobacterium longum also reduced adipocytes and increased interleukin 6 and interleukin 10 levels in the mice model.
Connie: Also, I believe there is research using a probiotic mix, including L. Plantarum, L. Fermentum, B. Longum with prebiotic Triphala, showing beneficial effects on physical obesity indicators including a decrease in overall weight, triglyceride and glucose levels.
Dr. Hofstadter: And here is an even more interesting one. In a different study, adult mice nursed with L. casei fermented milk were observed with decreased body weight as well as an increased number of immunoglobulin cells and macrophages in the small intestine. Another research using two L. plantarum and L. curvatus probiotic strains showed a decline in adipose tissue and liver fat accumulation. Similarly, probiotic supplementation of B. longum reduced fat, size of adipocyte, expression of lipoprotein lipase, modulated leptin level and increased receptor-activated adiponectin and peroxisome proliferator-activated receptors-g expression in diet-induced obese rats. These results may reveal the mechanism of probiotics reducing obesity at the cellular level.
Connie: I’m really excited to hear that there are so many studies around reducing obesity using probiotics. Ok, that’s it for our content today. Thanks, Professor Hofstadter for your time and great input. And thanks everyone for listening. We will continue our discussions next week. See you then!
Dr. Hofstadter: Thanks, everyone. I hope we will see you next time.