Probiotics as functional foods.

Probiotic products have been widely used in Japan and Europe for years. Probiotics are now emerging as an important category of food supplement in the United States. Questions about the biologic nature, available products, claimed health benefits, and safety and regulation of probiotics are important for both consumers and nutrition professionals. Probiotics can be considered functional foods because they provide health benefits beyond the traditional nutrition function. With few exceptions, most probiotic products currently available contain lactic-acid-producing bacteria, which mainly belong to the genera Lactobacillus and Bifidobacterium. We reviewed the scientific papers published in major nutrition journals and abstracts available on the PubMed website regarding probiotics. Evidence suggests the following beneficial effects of probiotics: normalization of the intestinal microflora, ability to block the invasion of potential pathogens in the gut, prophylactic or therapeutic treatment for several types of diarrhea, relief of symptoms of irritable bowel syndrome and inflammatory bowel disease, amelioration of lactose intolerance, prevention of colon cancer, modulation of immune function, inhibition of Helicobacter pylori, and possible enhancement of calcium absorption and reduction of blood cholesterol levels. Mechanisms for the above benefits have been proposed, but none has been proven. An adequate level of viable bacteria in a probiotic product and an appropriate daily dose are critical to achieve a health benefit. Because probiotics are not known to be pathogenic and their upper tolerable level is high, they could be promoted as a beneficial food supplement. Currently, no disease-prevention or therapeutic claim for probiotics is legally allowed.     

The application of probiotics in cancer

Lactic acid bacteria (LAB) are present in many foods such as yoghurt and are frequently used as probiotics to favour some biological functions in the host. Many investigators have evaluated the therapeutic effects of yoghurt and LAB commonly used in yoghurt production against diseases such as cancer, infection, and gastrointestinal disorders. The increase of immune cell activity in the prevention of cancer by LAB consumption has also been described. Another possible explanation for the preventive effect of probiotics on carcinogenesis is their effect on other bacteria in the intestine. Probiotics may suppress the growth of bacteria that convert procarcinogens into carcinogens, thereby reducing the amount of carcinogens in the intestine. The present review is focused on two types of cancer in which milk fermented by LAB may show a beneficial effect: colon cancer and breast cancer.     

Probiotiques et cancer colorectal

The fecal flow conveys many carcinogens, and the intestinal flora plays a major role in colon health. Thus it has been suggested that some bacterial species could modulate in a positive way the mechanisms of intestinal carcinogenesis. The present article summarizes the main arguments in favor of a positive role of probiotics on the risk of colorectal tumors. Available arguments are mostly experimental, with the limits of extrapolating experimental data to human carcinogenesis. However, some studies in humans also suggest a potential beneficial effect, as for example an intervention study on adenoma recurrence. Most probably, according to the strain, probiotics exert different effects along the various steps of carcinogenesis. The most studied probiotics are lactic acid bacteriae with special interest for lactobacilli and bifidobacteriae. It has been suggested that probiotics modulate the activities of the intestinal microflora via at least three diffent mechanisms: competition and shifting of other constituents of the microflora; production of antibacterial agents thus controlling the growth of other constituents of the microflora; production of lactic acid and other organic acids, thus decreasing the intestinal pH and modulating the enzymatic activity. On-going studies, especially European studies, should enable us to better determine the potential benefits of probiotics in colorectal cancer prevention in the next few years.     

Probiotics and their potential health claims

Many studies have attempted to identify specific positive health effects of probiotics. One of the challenges in generalizing health effects of probiotics is that different strains exert disparate effects on human health. As a result, the efficacy of one strain or species cannot necessarily be inferred from another. The objective of this review is to examine the current scientific literature that could be used as the basis for potential health claims. More specifically, this paper will review existing evidence of different probiotic strains to prevent and treat diarrhea, treat irritable bowel syndrome (IBS), treat inflammatory bowel disease, and prevent colon cancer. The strongest evidence is related to the use of Lactobacillus rhamnosus GG in the prevention and treatment of rotavirus-associated diarrhea. Further examination of the literature also shows promise in the treatment of some forms of IBS with probiotics. Future studies that use consistent supplementation regimes will allow more definitive conclusions to be drawn on the effects of probiotics on IBS, inflammatory bowel disease, and colon cancer.     

Probiotics: Interaction with gut microbiome and antiobesity potential

Obesity is a metabolic disorder afflicting people globally. There has been a pivotal advancement in the understanding of the intestinal microbiota composition and its implication in extraintestinal (metabolic) diseases. Therefore, any agent modulating gut microbiota may produce an influential effect in preventing the pathogenesis of disease. Probiotics are live microbes that, when administered in adequate amounts, have been shown to confer health benefits to the host. Over the years, probiotics have been a part of the human diet in the form of different fermented foods consumed around the world. Their influence on different physiologic functions in the host is increasingly being documented. The antiobesity potential of probiotics is also gaining wide attention because of increasing evidence of the role of gut microbiota in energy homeostasis and fat accumulation. Probiotics have also been shown to interact with the resident bacterial members already present in the gut by altering their properties, which may also affect the metabolic pathways involved in the regulation of fat metabolism. The underlying pathways governing the antiobesity effects of probiotics remain unclear. However, it is hoped that the evidence presented and discussed in this review will encourage and thus drive more extensive research in this field.     

Human gut microbiota and its relationship to health and disease

Probiotics are live microorganisms that confer a health benefit on the host when administered in appropriate amounts. Over 700 randomized, controlled, human studies have been conducted with probiotics thus far, with the results providing strong support for the use of probiotics in the clinical prevention or treatment of gastrointestinal tract disorders and metabolic syndrome. The present review is based on webinar presentations that were developed by the American Gastroenterological Association (AGA) in partnership with the International Scientific Association for Probiotics and Prebiotics (ISAPP) and the North American branch of the International Life Sciences Institute (ILSI North America). The presentations provided gastroenterologists and researchers with fundamental and current scientific information on the influence of gut microbiota on human health and disease, as well as clinical intervention strategies and practical guidelines for the use of probiotics and prebiotics.     

Probiotic use in clinical practice: what are the risks?

Probiotics have been advocated for the prevention and treatment of a wide range of diseases, and there is strong evidence for their efficacy in some clinical scenarios. Probiotics are now widely used in many countries by consumers and in clinical practice. Given the increasingly widespread use of probiotics, a thorough understanding of their risks and benefits is imperative. In this article we review the safety of probiotics and discuss areas of uncertainty regarding their use. Although probiotics have an excellent overall safety record, they should be used with caution in certain patient groups-particularly neonates born prematurely or with immune deficiency. Because of the paucity of information regarding the mechanisms through which probiotics act, appropriate administrative regimens, and probiotic interactions, further investigation is needed in these areas. Finally, note that the properties of different probiotic species vary and can be strain-specific. Therefore, the effects of one probiotic strain should not be generalized to others without confirmation in separate studies. Careful consideration should be given to these issues before patients are advised to use probiotic supplements in clinical practice.     

Probiotics for human use

Probiotics have become a popular approach for managing digestive and immune health and are being recommended more frequently as effective therapeutic interventions by medical professionals. Introduced early in the 20th century, the science of probiotics has advanced considerably, especially in the past two decades. Researchers have adopted a consensus definition, begun to understand many of the mechanisms of action, defined characteristics important to probiotic function and have obtained clinical evidence supporting probiotic health benefits and product quality. Nonetheless, a need remains for clear, evidence‐based communications to consumers on the role of probiotics in a healthy diet and to healthcare providers regarding clinical use. However, regulatory frameworks in many countries have restricted progress on this front. There is a need for additional research to further clarify the most effective probiotics for given health outcomes and to identify people most likely to respond to specific probiotic interventions. This review provides current perspective on the probiotic concept, discusses evidence‐based probiotic interventions, considers fermented foods with regard to probiotics and addresses some regulatory challenges facing the probiotic field.     

Essential fatty acids as possible enhancers of the beneficial actions of probiotics

I investigated whether there is a common link between essential fatty acids and probiotics, which have similar actions and benefits in atopy.I made a critical review of the literature pertaining to the actions of essential fatty acids and probiotics on immune response and the interaction between them with particular reference to atopy.Colonization of the human gastrointestinal tract occurs in the first months and years of life. Probiotics are cultures of beneficial bacteria of healthy gut microflora, which reduce dietary antigen load and thus protect against atopy. A significant reduction in the risk of childhood asthma and other atopic conditions was reported in children who were exclusively breast-fed for at least 4 mo after birth. This beneficial action can be attributed to the immunomodulatory, nutritional, or other components of human milk Human breast milk is rich in long-chain polyunsaturated fatty acids (LCPUFAs), which have immunomodulatory actions. Probiotics and LCPUFAs modulate T-helper 1 and 2 responses, show antibioticlike actions, and alleviate changes related to allergic inflammation. LCPUFAs promote the adhesion of probiotics to mucosal surfaces, which augments the health-promoting effects of probiotics. In view of the similarity in their actions and because LCPUFAs promote the actions of probiotics, I believe that a combination of LCPUFAs and probiotics offer significant protection against atopy. It is likely that breast-feeding and probiotics are two naturally occurring, appropriate events in early human life that have significant health benefits.     

Use of Probiotics in the Management of Chemotherapy‐Induced Diarrhea: A Case Study

Gastrointestinal disturbances (particularly diarrhea) are often induced in response to cancer treatments such as chemotherapy or radiation. Oral chemotherapeutic agents can induce diarrhea by damaging the intestinal lining. Two common oral drugs used in cancer treatment that are known to have gastrointestinal side effects are capecitabine and lapatinib. In this brief communication, the authors discuss a case study of a stage IV breast cancer patient whose chemotherapy‐induced diarrhea was treated successfully with a multispecies combination of probiotics. This is a unique study in which grade 3 chemotherapy‐induced diarrhea (characterized by 7–9 stools per day and associ ated with incontinence and abdominal cramping) was treated with only a multispecies combination of probiotics. Probiotics have been used to treat diarrhea in patients with irritable bowel syndrome, ulcerative colitis, pouchitis, and Crohn's disease. More recently, probiotics have been used to treat chemotherapy‐induced diarrhea in colon cancer patients. This case study demonstrates that the probiotics can also be used to treat severe cases of chemotherapy‐induced diarrhea in breast cancer patients. The use of different probiotics in gastrointestinal diseases is an increasingly important area of study, and more research into this area is needed. This study demonstrates that probiotics should be considered for advanced breast cancer patients with chemotherapy‐induced diarrhea.     

The clinical use of probiotics for young children

Probiotics are live microorganisms that occur naturally in the human digestive system. They chiefly colonise the colon and benefit the health of the individual by acting as a digestive aid and boosting the immune response. Low levels of beneficial bacteria and microorganisms in the colon provide a greater opportunity for pathogenic bacteria to become established. Probiotics may be beneficial in reducing the severity and incidence of gastroenteritis, diarrhoea, and colic in babies. They can also benefit children's health by supporting the developing immune system but should not be seen as a panacea or as an alternative to a healthy lifestyle or diet. The level of probiotics in the colon can be boosted by a healthy diet containing plenty of grains, fruit and vegetables. It can also be boosted by probiotic supplementation. Supplementation by the probiotic L. reuteri has been studied in major scientific trials and proven to be safe and effective with no reported side effects.     

Role of microecology in chronic inflammatory bowel diseases

Inflammatory bowel diseases (IBD) are chronic conditions of unknown etiology. Current therapy mitigates the severity of acute bouts of mucosal inflammation but an eradication therapy is lacking. Growing incidence of IBD is associated with social development. Epidemiology suggests a relationship between the establishment of the individual gut flora and the risk of developing IBD. Patients show an impaired tolerance towards commensal bacteria of the resident flora. Unrestrained activation of the intestinal immune system against some commensal bacteria appears to be responsible for the characteristic relapsing course of these diseases. Wide-spectrum antibiotic therapy reduces bacterial load and mitigates intestinal inflammation in human IBD and in animal models. Current research aims at the identification of probiotics for bacterial antagonism therapies. Probiotics are living microorganisms which upon ingestion in certain numbers exert health benefits beyond inherent basic nutrition. Colonization with a Lactobacillus reuteri strain can prevent the development of colitis in genetically susceptible mice. Other studies have used a bacterium genetically engineered to secrete the antiinflammatory cytokine IL-10 and demonstrated a therapeutic effect in animal models of colitis. Moreover, some probiotics may naturally exhibit antiinflammatory properties when interacting with the human gut mucosa. Prebiotics such as inulin have also been shown to prevent colonic inflammation in animal models. Preliminary clinical trials with probiotics in IBD are encouraging. Probiotics offer a valuable tool for the prevention and control of inflammatory bowel diseases.     

Probiotics: A potential immunomodulator in COVID-19 infection management

COVID-19 caused by SARS-CoV-2 is an ongoing global pandemic. SARS-CoV-2 affects the human respiratory tract's epithelial cells, leading to a proinflammatory cytokine storm and chronic lung inflammation. With numerous patients dying daily, a vaccine and specific antiviral drug regimens are being explored. Probiotics are live microorganisms with proven beneficial effects on human health. While probiotics as nutritional supplements are long practiced in different cuisines across various countries, the emerging scientific evidence supports the antiviral and general immune-strengthening health effects of the probiotics. Here, we present an overview of the experimental studies published in the last 10 years that provide a scientific basis for unexplored probiotics as a preventive approach to respiratory viral infections. Based on collated insights from these experimental data, we identify promising microbial strains that may serve as lead prophylactic and immune-boosting probiotics in COVID-19 management.     

Probiotics: considerations for human health

Evidence for the role of probiotics in maintenance of health or prevention of disease is mounting and is supported in some cases by blinded, placebo-controlled human trials. Today, in an era of antibiotic-resistant pathogens and other looming microbial threats, the value of prevention of infection is recognized. Probiotics may play an important role in helping the body protect itself from infection, especially along the colonized mucosal surfaces of the gastrointestinal tract. Probiotic products are available in many different forms worldwide, including pills, powders, foods, and infant formula. In some cases, general health claims are made that cannot be substantiated for the specific strains and levels being used and consumers must therefore beware.     

Should yoghurt cultures be considered probiotic?

Probiotics are live micro-organisms that when administered in adequate amounts confer a health benefit on the host. Consumption of yoghurt has been shown to induce measurable health benefits linked to the presence of live bacteria. A number of human studies have clearly demonstrated that yoghurt containing viable bacteria (Streptococcus thermophilus and Lactobacillus delbrueckii sp. bulgaricus) improves lactose digestion and eliminates symptoms of lactose intolerance. Thus, these cultures clearly fulfil the current concept of probiotics.     

Probiotics and health: a review of the evidence

Probiotics are live microorganisms – mainly bacteria – which when administered in adequate amounts confer a health benefit on the host. There is rising interest in this area, but reports in the media are often conflicting. The aim of this review is to consider the current evidence on the effects of probiotics on health, focusing on gut‐related health issues and the immune system, with the objective to provide a clearer picture of whether and how probiotics can be beneficial for health. The outcomes of this review are based on more than 100 original studies, meta‐analyses and systematic reviews. A variety of different strains have been used in studies on probiotics, and it is important to remember that the effectiveness of probiotics is strain‐specific, which means that each single probiotic strain has to be tested to assess its potential health benefits. Overall, despite the diversity of strains used in the studies included in this review, there is evidence that probiotics have the potential to be beneficial for our health. Studies in patients with inflammatory bowel disease show probiotic strains to be able to decrease the recurrence of ulcerative colitis and occurrence and recurrence of pouchitis, however, current evidence suggests that probiotics are ineffective in treating patients with Crohn's disease. Patients with irritable bowel syndrome show a reduction in symptoms when treated with selected probiotic strains, but high placebo effects have been reported as well. The evidence of the efficacy of probiotics in patients suffering from constipation is limited, but the evidence seems promising for some strains to bring relief to patients suffering from constipation. There is good evidence that a number of probiotic strains are effective in preventing antibiotic‐associated diarrhoea. The most commonly studied strains are Lactobacillus rhamnosus GG (LGG) and Saccharomyces boulardii, but other strains and mixtures of strains seem to be effective as well. There is also promising evidence of a preventive effect of probiotics in Clostridium difficile‐associated diarrhoea, although some studies have been too small to obtain statistically significant findings. The effect of probiotics in acute diarrhoea, particularly in children, is well studied. Selected probiotic strains seem to be effective in reducing the duration of acute diarrhoea. LGG and S. boulardii are again the most commonly used strains and a number of studies have shown them to be effective, although one meta‐analysis showed that the effect of LGG was only significant in children in Western countries, not in children in developing countries, which may be due to different causes of diarrhoea in these regions. Studies investigating the preventive effect of probiotics in the context of common cold and flu infections show that the studied strains failed to lower the incidence of episodes but that they have the potential to decrease the duration of episodes, which suggests that the immune system may be more efficient in fighting off common cold and flu infections after consuming these strains. The evidence so far does not suggest that probiotics are effective in preventing or treating allergies or in treating eczema. However, some probiotic strains seem to lower the risk of developing eczema if taken by pregnant women and their infants in early life.     

Probiotics and prebiotics: A brief overview.

Probiotics and prebiotics are 2 food ingredients that confer physiologic effects through the gastrointestinal tract. Probiotics have been defined as viable microorganisms that (when ingested) have a beneficial effect in the prevention and treatment of specific pathologic conditions. These microorganisms are believed to exert biological effects through a phenomenon known as colonization resistance, whereby the indigenous anaerobic flora limits the concentration of potentially pathogenic (mostly aerobic) flora in the digestive tract. Other modes of action, such as supplying enzymes or influencing enzyme activity in the gastrointestinal tract, may also account for some of the other physiologic effects that have been attributed to probiotics. Conversely, prebiotics are nondigestible food ingredients that beneficially affect host health by selectively stimulating the growth and/or activity of 1 or a limited number of bacteria in the colon. The prebiotic, fructooligosaccharide (FOS), is found naturally in many foods, such as wheat, onions, bananas, honey, garlic, or leeks. They can also be isolated from chicory root or synthesized enzymatically from sucrose. Fermentation of FOS in the colon results in a large number of physiologic effects including increasing the numbers of bifidobacteria in the colon, increasing calcium absorption, increasing fecal weight, shortening of gastrointestinal transit time, and possibly lowering blood lipid levels. Other effects that have been observed in animal models include an increase in cecal weight and an increase in fecal nitrogen excretion. The increase in bifidobacteria has been assumed to benefit human health by producing compounds to inhibit potential pathogens, by reducing blood ammonia levels, and by producing vitamins and digestive enzymes.     

肠道微生态平衡、免疫功能及对临床结局的影响

健康个体肠道中拥有数量极大的菌群,肠道菌群的平衡对机体起到良好的保护作用。机体免疫系统可识别病原体和非病原体所表达的独特分子结构。抗原提呈细胞,如树突样细胞能将细菌和其他抗原提呈至肠黏膜进行取样,激活原始T细胞并诱导其分化,产生一系列细胞因子,刺激IgA分泌,进而决定免疫反应的程度及耐受性。不良饮食习惯、肠外营养、抗生素等的使用,能破坏肠道菌群平衡,诱发肠黏膜损伤,可能与一些自身免疫性疾病,如炎性肠病的发病有关,益生菌或合生素通常可成功预防或显著减轻此类疾病的活动性。在围手术期给予重大手术患者益生菌和纤维素能有效降低术后并发症的发生率。未来提高生态学治疗效果的努力将会集中在寻找和尝试新的纤维素和益生菌以及新的给药方法,并会更加强调联合应用多株益生菌(4～5株),进一步尝试在各种疾病尤其是外科围手术期患者中的应用。     

Role of intestinal flora in inflammatory bowel disease and probiotics place in their management

The pathogenic role of certain microorganism of intestinal flora has been demonstrated in experimental colitis in animals and strongly suspected in inflammatory bowel disease in human, especially in Crohn's disease and pouchitis. Probiotics are living non pathogenic microorganisms that, upon oral ingestion exert benefits on human health by modulating enteric flora or by stimulation of local immune system. The aim of this article is to remind the role of intestinal flora in inflammatory bowel disease, the mechanism of inflammation induced by this flora and to review through the literature, the different clinical studies performed with probiotics in human.     

Emerging Roles of Probiotics in Prevention and Treatment of Breast Cancer: A Comprehensive Review of Their Therapeutic Potential

Breast cancer is the most common cancer among women. Need for novel preventive and curative approaches with more safety than the present one seems inevitable. This review is devoted to potentially favorable role of probiotics in prevention and treatment of breast cancer as well as their alleviating role regarding chemotherapy-induced side effects. Literature was searched for human, animal, and in vitro studies about the role of probiotics in breast cancer. In vitro studies showed that probiotic intervention induces cancer cells apoptosis and inhibits their proliferation. In animal models, treatment with probiotics inhibited tumor growth and reduced tumor size; also, the immunomodulatory, antiangiogenesis and antimetastatic activities of probiotics were illustrated. Human studies showed that intake of Lactobacillus casei shirota reduced the breast cancer incidence and consumption of fermented milk products and yogurt was inversely associated with breast cancer incidence; however, no study regarding the curative role of probiotics in breast cancer is available. Studies on the effect of probiotics on chemotherapy-induced side effects in breast cancer were contradictory but showed potential for more investigation. Probiotics seem to have a potential role in both prevention and treatment of breast cancer. However, more clinical studies are needed to elucidate their efficacy and safety.