Functional foods containing bacteria with beneficial health effects, or probiotics, have long been very popular in Canada and the U.S. They are boosted into natural foods found predominantly in the daily section — yogurt, being the big one. But to benefit you, the probiotic bacteria must survive hostile conditions in your digestive tract. A new study attempted to see which strains survive better, and which are more worthy of your money.
Norwegian scientists developed a new system to see which survive in the human digestive system. They found that some probiotic strains survive better when consumed as fermented milks.
They tested five “Lactococcus” strains,three “Lactobacillus” strains and one “Enterococcus hirae” strain. Could the strains survive exposure to acidic conditions and bile salts — the traditional method of evaluating the potential of probiotic bacteria? The bacteria were also subjected to a process that mimicked the human digestive system, incubating the bacteria in human gastric and duodenal juices at body temperature. The bacterial strains were tested both as pure cells from cultured media and in the form of fermented milk.
They first found that Lactobacillus strains had a significantly higher acid tolerance than the others. The Lactobacillus strains showed the highest survival rate in the model digestive system, whereas the Lactococcus strains, with some exceptions, performed similarly in both systems. Interestingly, while none of the Lactococcus stains or the E. hirae strain survived in significant numbers after exposure to stomach acid, they numbers increased in the small intestine. This is interesting, because it is in the intestine that probiotics help people.
Did fermented milk protect bacteria through the digestive tract? Well, the results were mixed. The Lactococcus strains Af-1 and ML-8 and paracasei INF448 showed lower numbers compared with the digestion of pure bacterial cells. The other strains showed higher numbers of viable cells in comparison. In particular, the fermented milk improved the viability of the Lactococcus strains Ar-1, Bf- 2, and E. hirae INF E1 during incubation under gastric conditions.
The results here seem to confirm that foods, such as fermented milks, could help probiotics survive and thus give our bodies the great benefit they are known to give. What appears to be the main point of this study is that, if you are choosing between several different yogurts, you should go for the ones that feature Lactococcus bacteria.
There is so much more to learn about the amazing natural remedy probiotics. These are some powerful friends for us all.
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