Most yogurts are full of sugars, which could be a problem and the quality brand. I add my own sweetener. But of course there are many people that are sensitive to milk products, even if it is cultured (I have a harder time with milk, but luckily take well to yogurt, kefir, cheese, etc.). You can try soy yogurt, but taking a supplement is also a good idea. Whatever works best for you. There was much written on this in another post, similar in topic, on kefir vs. probiotics:
https://www.healingwell.com/community/default.aspx?f=38&m=1012753