On Food and Cooking

milks eliminate toxic microbes in our
digestive system that otherwise shorten our
lives. Hence Dr. James Empringham’s
charming title of 1926: Intestinal
Gardening for the Prolongation of Youth.
Metchnikov was prescient. Research
over the last couple of decades has
established that certain lactic acid bacteria,
the Bifidobacteria, are fostered by breast
milk, do colonize the infant intestine, and
help keep it healthy by acidifying it and by
producing various antibacterial substances.
Once we’re weaned onto a mixed diet, the
Bifidobacterial majority in the intestine
recedes in favor of a mixed population of
Streptococcus, Staphylococcus, E. coli, and
yeasts. The standard industrial yogurt and
buttermilk bacteria are specialized to grow
well in milk and can’t survive inside the
human body. But other bacteria found in
traditional, spontaneously fermented milks
— Lactobacillus fermentum, L. casei, and