Can 10month old baby drink Yakult?

I'd say it's too young, and more importantly, things like Yakult and Vitagen have more sugar than pre/probiotics so I'll say to just stay away from them as much as possible - even for adults! If you're looking to introduce more pre/probiotics, you can look into other alternatives like yoghurt or those supplements suitable for younger ones - although I'd think that most of them requires minimum 1 year old. If bowel movement is an issue, try other things like introducing more fibre (fruits and veg) or food known to help like prunes!