Scientists are now one step closer to understanding why people who frequently eat yogurt have healthier teeth and gums. Previous research has shown that there is a decreased incidence of periodontal disease among those who frequently consume dairy products, but did not identify which products are most beneficial. Now, Japanese researchers are reporting that lactic acid foods like yogurt provide mouths with the greatest protection, while foods like milk and cheese are not associated with better periodontal health. They suggest that the probiotic effect of the lactobacilli found in those foods may hinder the progression of periodontal disease.