Health benefits of lactic acid bacteria in fermented milk

Lactic acid bacteria do more than just pre-digest lactose and produce yogurt. Back in the early 1900s, the Russian immunologist Ilya Metchnikov proposed that lactic acid bacteria in fermented milks help eliminate toxic microbes in our digestive system. To support Mr. Metchnikov’s prescient claim, research in recent decades suggests that Bifidobacteria, fostered in breast milk, colonizes the infant intestine and keep it healthy through acidification and production of antibacterial substances. Once the infant is weaned, the Bifidobacteria recede in favor of a mixed population of Streptococcus, Staphylococcus, E. coli, and yeasts.

Bacteria such as L. fermentum, L. casei, L. brevis, and L. acidophilus adhere to the human intestinal wall. Their presence shields it from other microbes by the secretion of antibacterial compounds, and by boosting the immune response to infection. Furthermore, research suggests that these bacteria also dismantle cholesterol and reduce the production of carcinogens.

The consumption of fermented milks for health purposes, however, is debatable. At the time of Mr. Metchnikov’s claim, milk fermentation involved a dozen or more microbes. Industrial versions nowadays usually limit it to two or three. This biological narrowing does not only affect flavor and consistency, but its health value as well. In addition, live cultures in industrial buttermilk and yogurt grow well in milk but cannot survive in the human body. Some manufacturers are adding "probiotic" Lactobacilli and Bifidobacteria to their cultured milk products in an attempt to mimic the original fermented milks. Such products are advertised for the health benefits afore noted.