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Back to Roles on Certain Health Conditions

Probiotic Milk Products and Digestive Health

Probiotic products consist of specific strains of live bacteria that have potentially favourable health effects. A number of studies provide evidence that milk products with probiotics may be beneficial for digestive health and may improve various digestive problems.

Highlights

  • Fermented dairy products with active bacterial cultures are one of the most common sources of probiotics;
  • Probiotic milk products may be beneficial in alleviating symptoms for a number of gastrointestinal conditions, including Helicobacter pylori infection, irritable bowel syndrome and antibiotic-associated diarrhea;
  • Milk products with probiotics may improve gut microbiota, have an immunomodulatory effect, and thus maintain overall health.

Probiotics are defined as “live microorganisms which, when administered in adequate amounts, confer a health benefit on the host.”1 This term refers to specific strains of bacteria, and typical probiotics include lactic acid bacteria such as Lactobacillus and Bifidobacterium. These strains are widely used in the fermentation of dairy products, such as yogurt, cheese and kefir. Fermented dairy products with active bacterial cultures are therefore one of the most common sources of probiotics. These types of probiotic-containing milk products may be beneficial for a number of gastrointestinal and digestive conditions.2,3

The Evidence

Helicobacter pylori Infection
A 2009 systematic review and meta-analysis of randomized controlled trials evaluated the effect of fermented milk products enriched with probiotics on Helicobacter pylori infection. A total of 10 eligible studies, which included 963 adults and children, were assessed. It was found that fermented milk-based probiotic preparations reduce Helicobacter pylori infection rates by approximately 5% to 15%.4

A prospective study published in 2012 examined the effect of probiotic-containing yogurt on systemic immunological response among 38 children with Helicobacter pylori infection. The study concluded that intestinal microbiota balance can be maintained and humoral and cellular immunity can be stimulated in children who regularly consume yogurt.5

Irritable Bowel Syndrome
A review of 42 trials systematically examined the role of lactic acid bacteria, such as lactobacilli, bifidobacteria, enterococci, streptococci and bacilli, on irritable bowel syndrome. A majority of the clinical trials reviewed showed that lactic acid bacteria alleviate abdominal pain and discomfort. Both single- and multi-centre studies have shown that lactic acid bacteria may improve abdominal bloating and distension. Out of 24 trials, improvements in bowel habit satisfaction were found in 13 studies, and 16 trials reported improvements in symptom severity.6

A 2013 randomized controlled trial investigated the efficacy of a probiotic yogurt in irritable bowel syndrome. A total of 83 Korean adults were randomized to the treatment or control group. The treatment group was assigned a probiotic plain liquid yogurt containing Lactobacillus rhamnosus GG twice daily over 6 weeks, while the placebo group consumed plain liquid yogurt without probiotics. There was an overall improvement in the symptoms of patients who consumed the probiotic yogurt. As well, the consumption of probiotic yogurt led to beneficial changes for certain types of gut microbiota. The control group also had some improvements, although fewer than the treatment group.7

Another multi-centre, double-blind, randomized controlled trial, also published in 2013, was conducted in England to evaluate the effect of a probiotic versus non-probiotic yogurt in irritable bowel syndrome with constipation. The study consisted of 179 adults who were randomized to consume one of these two products twice daily over 12 weeks. Significant improvements were observed for both groups but there was no difference between groups.8

Inflammatory Bowel Disease
Probiotics could have beneficial effects on inflammatory bowel disease, but the evidence is limited. According to a systematic review and meta-analysis, the effects could differ depending on disease subtype and probiotic strain.9 In addition, findings from a cohort study of middle-aged women living in France indicate that milk products are a protein source that does not increase the risk of inflammatory bowel disease.10

Antibiotic-Associated Diarrhea
Evidence demonstrates that probiotics are associated with reduced antibiotic-associated diarrhea. In a meta-analysis of 82 randomized controlled trials, a statistically significant association was found between the administration of probiotics and the reduction of antibiotic-associated diarrhea. Various studies included in the meta-analysis consisted of interventions with probiotic milk products, which showed that probiotic milk products may be efficacious in preventing antibiotic-associated diarrhea.11

Constipation
A 2013 meta-analysis of randomized controlled trials indicated that short-term probiotic supplementation reduces intestinal transit time. Greater effects were observed among adults who were older or constipated. Certain probiotic strains, such as strains of Bifidobacterium lactis, appear to be more efficacious.12

Lactose Intolerance
In an evidence-based report on lactose intolerance and health published in 2010, a systematic review of the literature indicated that there was insufficient evidence to determine the effectiveness of yogurt and probiotics in alleviating the symptoms of lactose intolerance.13 However, many people who have difficulty digesting milk find that they can digest yogurt. This is because beneficial bacteria in yogurt have lactase activity and thus help in lactose digestion.14

Gastric Cancer
It has been postulated that probiotics may help in gastric cancer prevention, but the evidence so far is mainly based on experimental in-vitro data. For instance, a study was conducted on fermented milk containing Propionibacterium freudenreichii as microbiota, and it was demonstrated that this probiotic fermented milk had pro-apoptotic effects on human gastric cancer cells.15

Potential Mechanisms

Probiotics, such as lactic acid bacteria, are active bacterial cultures with unique characteristics that allow them to survive in the gastrointestinal tract and compete with other enteric microorganisms. Thus, they help to maintain the natural balance of the microbiota and overall health.2,3

Additionally, probiotics may promote immunomodulation by attaching to gut epithelial tissue, interacting with the immune system and producing antimicrobial substances.2,3 Dairy lactobacilli, as part of a regular diet, may also modulate innate immune responses.16,17 Furthermore, probiotics may suppress the growth of bacteria that convert procarcinogens into carcinogens.18

Conclusion

Evidence suggests that probiotic milk products enhance digestive and overall health by improving gut microbiota and promoting immunity. These products may be beneficial in Helicobacter pylori infection and irritable bowel syndrome and could prevent antibiotic-associated diarrhea.

Further research, including large randomized controlled trials and long-term cohort studies, is needed to confirm these findings. As well, more research is needed to elucidate the role of probiotic milk products in lactose intolerance and gastric cancer.

For more information, see the article Gut Microbiota and Milk Products: Implications for Health.

References

  1. Food and Agriculture Organization and World Health Organization Expert Consultation. Evaluation of health and nutritional properties of powder milk and live lactic acid bacteria. Córdoba, Argentina: Food and Agriculture Organization of the United Nations and World Health Organization; 2001.
  2. Balakrishnan M and Floch MH. Prebiotics, probiotics and digestive health. Curr Opin Clin Nutr Metab Care 2012;15(6):580-5.
  3. Hosseini A et al. Probiotics use to treat irritable bowel syndrome. Expert Opin Biol Ther 2012;12(10):1323-34.
  4. Sachdeva A and Nagpal J. Effect of fermented milk-based probiotic preparations on Helicobacter pylori eradication: a systematic review and meta-analysis of randomized-controlled trials. Eur J Gastroenterol Hepatol 2009;21(1):45-53.
  5. Yang YJ and Sheu BS. Probiotics-containing yogurts suppress Helicobacter pylori load and modify immune response and intestinal microbiota in the Helicobacter pylori-infected children. Helicobacter 2012;17(4):297-304.
  6. Clarke G et al. Review article: probiotics for the treatment of irritable bowel syndrome--focus on lactic acid bacteria. Aliment Pharmacol Ther 2012;35(4):403-13.
  7. Lee J et al. Effects of probiotic yoghurt on symptoms and intestinal microbiota in patients with irritable bowel syndrome. Int J Dairy Tech 2013;66(2):245-55.
  8. Roberts LM et al. A randomised controlled trial of a probiotic ‘functional food’ in the management of irritable bowel syndrome. BMC Gastroenterology 2013;13:45.
  9. Jonkers D et al. Probiotics in the management of inflammatory bowel disease: a systematic review of intervention studies in adult patients. Drugs 2012;72(6):803-23.
  10. Jantchou P et al. Animal protein intake and risk of inflammatory bowel disease: the E3N prospective study. Am J Gastroenterol 2010;105(10):2195-201.
  11. Hempel S et al. Probiotics for the prevention and treatment of antibiotic-associated diarrhea. JAMA 2012;307(18):1959-69.
  12. Miller LE and Ouwehand AC. Probiotic supplementation decreases intestinal transit time: meta-analysis of randomized controlled trials. World J Gastroenterol 2013;19(29):4718-25.
  13. Wilt TJ et al. Lactose intolerance and health. Agency for Healthcare Research and Quality Publication; 2010.
  14. Rabot S et al. Guidance for substantiating the evidence for beneficial effects of probiotics: impact of probiotics on digestive system metabolism. J Nutr 2010;140(3):677S-89S.
  15. Cousin FG et al. Milk fermented by Propionibacterium freudenreichii induces apoptosis of HGT-1 human gastric cancer cells. PLoS ONE 2012;7(3):e31892.
  16. Santos Rocha C et al. Anti-inflammatory properties of dairy lactobacilli. Inflamm Bowel Dis 2012;18(4):657-66.
  17. Wang S et al. Fermented milk supplemented with probiotics and prebiotics can effectively alter the intestinal microbiota and immunity of host animals. J Dairy Sci 2012;95(9):4813-22.
  18. Kumar M et al. Cancer-preventing attributes of probiotics: an update. Int J Food Sci Nutr 2010;61(5):473-96.

Keywords: probiotics , microbiota


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