I like yogurt and I try and eat a half cup a day of low fat plain organic of the stuff. You are seeing more and more claims everyday about the health benefits of yogurt and other foods with "probiotics" but there is some doubt about whether these “friendly” bacteria in yogurt and other foods actually do anything for you healthwise. We know they help yogurt taste good but what else? Tara Parker-Pope has a summary of the state of the research on probiotics in today’s New York Times.
If you follow the link you'll find that the short answer is kind of wishy-washy. In a nutshell it is probably yes for infant diarrhea and, maybe, irritable bowel syndrome, and maybe or no for just about everything else. Personally, I think yogurt helps keep your system in better tune and I know I seem to have less trouble with my digestion if I keep to my regular yogurt habit. This is especially true if I do bad things like eat too much raw veges or too many beans. Though I must admit that since I have been eating more veges(including beans) and a lot less meat I seem more able to handle the digestion side of the equation, yogurt or not.
According to the article consumers just won a large class-action settlement – $35 million – against Dannon for claiming that Activia yogurt promotes immunity. According to one news account, Dannon spent $100 million marketing the immunity-promoting effects of Activia ignoring the results of its own company-sponsored research which inconveniently showed few benefits.