CHICAGO — The July 10th on-line issue of Applied and Environmental Microbiology, a journal of the American Society for Microbiology, included results from a study investigating the potential benefits of consuming probiotics via dairy foods, rather than a different food or supplement matrix. Findings indicate the manner in which a probiotic is delivered may influence how effective that probiotic is in delivering the desired health benefits.
The study will be published in the September 2015 print edition. It may be found on-line HERE.
Researchers investigated the probiotic strain Lactobacillus casei BL23 in a mouse model of inflammatory bowel disease. The mice that ingested the probiotic in milk had reduced symptoms compared to the control fed milk without the probiotic or the mice that received the probiotic within a non-food, supplement-like format.
Corresponding author Maria Marco, Ph.D., an associate professor in the Department of Food Science and Technology, at the University of California at Davis shared some background on the research and highlights from the study.
Food Business News: The paper explains that dairy products are common carriers of probiotics, yet the importance of consuming probiotics in dairy products as opposed to other food/beverage/supplement formats is not well understood. Why is that?
Dr. Maria Marco: It has long been assumed that the manner in which probiotics are consumed does not really make a difference for their effectiveness in the digestive tract. However, literature searches reveal that only one (underpowered) human study performed in the early 1990s and very few preclinical (rodent) studies have actually done side-by-side comparisons with probiotics in different matrices. Our paper shows that it is time to reexamine this assumption. We found that consuming L. casei in milk and not a nutrient-free matrix resulted in significantly higher levels of protection again intestinal inflammation in a mouse model of inflammatory bowel disease. An important next step will be to see if this type of result is repeatable in humans.
There are a number of reasons why dairy is commonly associated with probiotics. First, fermented dairy products such as yogurt are generally understood to contain living microbes. Hence, it is less of a stretch to accept living probiotic strains in such products. Second, unlike many other fermented foods, dairy products are typically not pasteurized or heat treated at the end of production, which ensures probiotic viability. Third, bacteria related to probiotics have been well studied for their growth and survival in dairy products hence some of that research can be applied to examine probiotic strains.
What motivated this investigation?
Dr. Marco: Knowing that bacteria can adapt to their surroundings, I was interested in quantitatively measuring whether the delivery matrix mattered at all with regard to probiotic efficacy. Dairy was the logical choice for this work because L. casei is often incorporated into dairy products.
|Maria Marco, Ph.D., associate professor in the Department of Food Science and Technology at the University of California at Davis.|
This study took place over three years and involved two of my Ph.D. students —Bokyung Lee and Xiaochen Yin — who also authored the report. We were all pleased and excited by the findings, especially in light of the fact that this type of study is rather unique.
We had hypothesized that the conditions probiotics are exposed to prior to ingestion might influence their capacity to maintain or improve human health. So for this study, we took a census of the microbiota before and after ingestion of L. casei and learned that consumption did not significantly alter the populations or diversity of most of the resident gut bacteria. This suggests that the benefits of the probiotic involve a direct effect of L. casei, or of a metabolic product of these bacteria upon the intestinal epithelium, rather than a global alteration of the indigenous intestinal microbiota.
How may the dairy industry best use the findings from this research?
Dr. Marco: The industry can discuss the role of probiotic-containing milk and other dairy products in promoting a healthy digestive tract through modulating the intestinal microbiome. The dairy industry should also be encouraged by the emerging consumer interest in fermented foods and work to educate the public on why dairy products are different than foods such as sauerkraut. The industry can also address the beneficial roles that microorganisms have in making fermented dairy foods and in human health.
Human studies are needed, however, as well are mechanistic studies. These can identify the specific cell products made by probiotics and the reciprocal host cell response pathways that recognize and respond to those cell products that ultimately result in health benefits.
We must remember, however, that while milk was a good carrier for L. casei in this study, dairy might not always be the best choice for all probiotics and health conditions.