Our body contains at least 10 times as many bacteria as human cells, and new research is documenting the dramatic impact that these microbes have on our health.

The human microbiome was the subject of an international Gut Microbiota for Health meeting in Barcelona this March and a featured lecture by Mark Heiman, Ph.D, vice president and chief science officer for MicroBiome Therapeutics at the IFT Annual Meeting & Food Expo in Chicago this July. Research on the human microbiome is demonstrating that reduced microbial diversity is associated with many different diseases and suboptimal health conditions. One way to bolster the diversity of the gut is to consume fermented foods, including dairy foods that contain probiotics.

Benefits to digestive health

One of the most promising areas for probiotic health benefits is in digestive health. A recent meta-analysis evaluating results of 84 trials on over 10,000 individuals concluded that probiotics had positive significant effects for pouchitis, infectious diarrhea, irritable bowel syndrome, helicobacter pylori, clostridium difficile disease and antibiotic-associated diarrhea. Longer treatment periods showed significantly higher efficacy. The authors concluded that the type of disease and the probiotic species (strain) were both important factors to consider when choosing probiotics for the treatment or prevention of gastrointestinal disease.

Supporting the immune system

Immune function is another area where probiotic dairy products currently exist. Dannon uses the strain, L caseiimmunitas in DanActive in the United States and Actimel worldwide. However, the market for DanActive is significantly smaller than the market for Activia. But other strains are showing an immune effect.

“In the world’s largest clinical study of the immune effects of probiotics in adults, Lactobacillus casei 431 was shown to shorten the duration of common cold and influenza-like illness,” noted Mirjana Curic-Bawden, senior scientist at Chr. Hansen, Milwaukee.

In this study, involving more than 1,000 individuals, the number of sick days from influenza-like illness was reduced from eight to five in individuals that consumed a daily dairy beverage containing L. casei 431.

Gut-brain axis

“We have heard of the gut-brain axis, and one of the most exciting areas of probiotic research involves the role of live microbes on brain function,” said Mary Ellen Sanders, PhD, of Dairy and Food Culture Technologies, Centennial, Colo.

One study from the Netherlands explored how multispecies probiotic supplementation could reduce cognitive reactivity to sad mood. The strongest effects were for reduced rumination and reduced aggressive thoughts. Another study in Finland followed up on children who were given the probiotic Lactobacillus rhamnosus GG in the first six months of life.

Weight management

Probiotics also show promise in the fight against obesity. Research has shown that certain probiotic strains can affect the microbial ecology which may lead to functional shifts in the microbiota that could contribute to the obese phenotype. The distal gut microbiota of lean, wild-type mice and obese mice showed consistent differences in the two major bacterial phyla, Bacteroidetes and Firmicutes. Firmicutes were higher whereas the Bacteroidetes were correspondingly reduced in obese mice despite a similar diet and activity level, explained Suja Senan, Ph.D. post doc research associate at South Dakota State University.

Challenges of clinical research

In order to make a probiotic claim, the Food and Drug Administration and the Federal Trade Commission have requirements for substantiation of all structure function claims.

“About one-and-a-half years ago we changed how we communicate the benefits of Activia to our consumers,” noted Miguel Freitas, Dannon’s vice president of health affairs, White Plains, N.Y.

Combined benefits with dairy

Traditionally, scientists have looked at the way in which prebiotics provide synergies to probiotics. But several studies have shown or are exploring synergies of probiotics with dairy protein. Recent research revealed that GanendenBC30 combined with dairy protein showed performance benefits such as reduction of muscle soreness, faster recovery and an increase in power.

 Although probiotics are finding their way into nondairy beverages, juices, protein shakes, confectionary, chocolate, granola bars, and dietary supplements, dairy continues to dominate the application space for probiotics.