Connie: Dear friends, thank you for joining us again this Saturday evening. Today, we invited our old friend Dr. Hofstadter to the program. In the last program, we learned about the many applications of probiotics. And for today’s program, we will continue to explore the characteristics of standard probiotics. Thank you for being here today, Dr. Hofstadter?
Dr. Hofstadter: Thank you for inviting me, Connie. Good evening, everyone. It is quite nice to see you again. I’m very glad to be here.
Connie: Now that with more research focus on probiotics, its potential sources have also been carefully studied in order to produce inexpensive and easily available probiotic products. Probiotic microorganisms are derived from fermented food, breast milk, etc. These bacteria are called “good bacteria” and exist in the human intestinal tract through various dietary sources, showing the benefits of anti-inflammatory, anti-cancer, and immunity enhancement. So next, let’s focus on the selection criteria of probiotics. In other words, how do we choose the right probiotics with appropriate functions? Do you know if we have a systematic approach to follow to select the probiotic strains for human use?
Dr. Hofstadter: Yes, to select the right strains for human use, we definitely need to follow a systematic approach. Because we need to deliver safe and required probiotic products to the end-user. Before selecting probiotic strains, general aspects should be considered, such as the source of probiotics, genus and strain identification, biological safety, functional aspects, health aspects, and production aspects. We need a “step-by-step” method to test the functional capabilities of probiotics.
Connie: Which probiotics should be used by humans? And why?
Dr. Hofstadter: It is recommended to isolate the strain only from the target animal. which means that the probiotics used in humans should ideally be separated from the human intestine or breast milk because they are better able to adhere to the intestinal wall and have been shown to be safer for humans. Probiotics can also be separated from various fermented foods.
Connie: What characteristics should a microorganism have to be used as a probiotic?
Dr. Hofstadter: The first is host-related stress tolerance. Probiotics should be able to maintain in different parts of the digestive tract after ingestion and be able to withstand various stress conditions in the human body, like the action of various digestive enzymes such as lysozyme, amylase, pepsin, and chymotrypsin. The strain should have acid resistance and bile resistance and have a slight tolerance to heat shock caused by body temperature.
Connie: Any tolerance range for the strain?
Dr. Hofstadter: That’s a good question. Yes, different probiotics have different degrees of resistance to stress conditions. In general, probiotics should be able to tolerate bile concentrations of 0.3 to 2 percent and a pH range of 2 to 5.
Connie: Any other important characteristic that a probiotic strain should have?
Dr. Hofstadter: Adhesion should definitely be counted as one. The adhesion of probiotic strains to the intestinal wall is very important to determine their probiotic potential. Because the adhesion ensures that the bacteria will not be washed away and gather together to increase their cell density and biomass in the digestive tract.
Connie: Do you mean the adhesion is important to ensure better interaction between microbial cells and human epithelial cells?
Dr. Hofstadter: That’s right. Adhesion is also important for probiotics to produce various host-related functional effects on the host. And another important feature of probiotics is their antibacterial activity. That is, the strains should be able to fight against potentially pathogenic microorganisms that may exist in the intestines and survive.
Connie: Isn’t the survival of pathogens in the intestine affected by the profitable bacteria?
Dr. Hofstadter: Exactly. The prevention of pathogen survival in the intestine is related to the competitive behavior of probiotic strains. Probiotics secrete lactose, bacteriocin, lactic acid, and antibodies to prevent pathogens from adhering to human epithelial cells. Probiotics are also used to increase leukocyte phagocytic activity, increase transepithelial resistance, enhance cytoskeleton and tight junction protein phosphorylation activity to kill various pathogenic bacteria.
Connie: Since probiotics can inhibit the survival of pathogens, does it mean that probiotics can regulate the host’s immune response?
Dr. Hofstadter: That’s right. We briefly mentioned this in the previous episode. Probiotics can modulate the immune response. Probiotic strains should participate in the production of metabolites to stimulate the maturation and function of immune cells. These bacteria promote the secretion of immunoglobulin and the production of cytokines. So probiotic strains should be selected according to the target host to stimulate the systemic immune response.
Connie: That makes sense. What other criteria are used to select microorganisms as probiotics?
Dr. Hofstadter: We all know that one of the most important characteristics of probiotics is that they can provide health benefits to the host. Therefore, the selection of probiotics should be based on the host-related functional criteria.
Connie: What kind of functional activities should probiotics provide for the host?
Dr. Hofstadter: It’s expected that they should protect the host against irritable bowel syndrome, gastroenteritis and inflammatory bowel disease, diarrhea, infant allergies, cancer, lactase digestion, diabetes, and hyperlipidemia. Not only that, but probiotics should also provide the host with anti-cancer, anti-cholesterol, anti-depressant, anti-anxiety, anti-obesity, anti-diabetic and antioxidant activities.
Connie: Wow, it’s amazing that probiotics can be so helpful. I’m really curious how to choose probiotics with anti-cancer activity?
Dr. Hofstadter: Choose the ones that can inactivate enzymes related to the activation of precancerous substances. For example, nitrate reductase, β-glucosidase, β-glucuronidase. In addition, probiotic strains secreting conjugated linoleic acid and apoptosis-inducing activity should be screened for possible anti-cancer activity.
Connie: I heard that the effectiveness of probiotic strains in reversing depression and anxiety can also be studied in vivo in animal models. So did we include all the criteria for the selection of probiotics?
Dr. Hofstadter: Almost. There is one last one, good technical characteristics. The extent to which probiotics can effectively deliver their benefits to the host will depend on the strain’s ability to survive and maintain the same efficiency and vitality during the storage period. Probiotics should be able to grow quickly under different nutritional supplements, preferably cheap fermentation media, food substrates, and microaerobic conditions. Very importantly, bacterial strains should be able to adapt to the pressure of different physical processing techniques during food processing without losing their activity and efficiency.
Connie: So we can conclude from today’s discussion that in the absence of any regulatory guidelines governing the probiotic industry, it is likely that counterfeit products with low or no health benefits are being sold to end-users. A product must meet the prerequisites we talked about today before it can be labeled as “probiotics”. So much for this episode. You, Dr. Hofstadter, for your insightful input. And thanks everyone for listening. We will continue our discussion on probiotics next Saturday evening. See you then.
Dr. Hofstadter: Thanks everyone. I hope we will see you next time.