Superfood No. 10: Yogurt and Kefir "Probiotic" Partners in Health The origin of fermented foods and cultured milk products goes so far back that it is rumored to predate recorded history. This is perfectly in keeping with my philosophy that the most ancient foods have survived for a reason—they continue to be instrumental to the survival of our species. Fermented and cultured foods may well represent our first experience with what researchers now call "functional" foods—foods that actively promote optimal health. The fermented foods scientists consider "probiotic" are primarily yogurt and kefir. Learn more about the benefits of yogurt and kefir: What are probiotics, and what do they do? Yogurt versus obesity All about kefir Get more of Dr. Perricone's 10 superfoods.