Limited Probiotic Success for Obesity

by Janice Haney of CDC (public domain)
Enterococcus faecalis by Janice Haney of CDC

In this installment, an Enterococcus works to prevent allergy, Bifidobacteria interact with the immune system and Lactobacilli take a bite out of obesity.

Allergic rhinitis is a growing problem for residents of the developed world. Researchers from China wondered if heat-killed Enterococcus faecalis FK-23 (LFK) might help prevent the problem. To test their idea, the dead bacteria were given orally to mice for six weeks before and during the induction of allergy. The dead probiotics helped reduce the severity of the allergy and there were hints that it was due to the development of an anti-inflammatory immune response.

Immune System Regulation
Probiotics are known to influence the immune system through the direct interaction with immune cells. To learn more about how probiotics affect the immune system during food poisoning, a group of Spanish researchers decided to look at how Bifidobacterium breve CNCM I-4035 and its secreted products would affect immune cell behavior when introduced together with Salmonella. The researchers chose to look at the specific effects of these bacteria on dendritic cells, a type of cell that is particularly important in initiating immune responses. Salmonella normally causes dendritic cells to react in a way that enhances the immune response. They found that when the Bifidobacteria was added to the mix, the response of the dendritic cell was more pronounced. Yet, the secreted products of the probiotic had a different effect; causing a reduction in the response and an initiation of an anti-inflammatory one. The differences could represent different levels of threat to the immune system. Direct interaction between a dendritic cell and probiotic bacteria is still something that shouldn’t occur under normal circumstances, while exposure to bacterial products may be typical under healthy conditions.

Researchers in Korea speculate that probiotics might influence weight. One group, working for Yakult, looked at the ability of Lactobacillus curvatus HY7601 and Lactobacillus plantarum KY1032 to influence obesity in mice. The mice were first made obese and then treated with probiotics for ten weeks. The results were encouraging, the mice gained less weight than their untreated counterparts. The other group was busy with a clinical trial in obese humans using Lactobacillus gasseri BNR17. The participants were treated for twelve weeks with the probiotic. Although, only slight reductions in weight parameters were found, the group still felt that this method of treatment had potential.