The best yoghurts are those with live bacteria, Tesco seems the only own brand without it when I did my first shops.
Taken from the lady who's guiding me on clean eating: On the label it should say lactobacillus acidophilus and/or strep thermophillus.... These good bugs help our digestive system and keep the bad bugs under control.
Sainsburys own brand is 49p a big tub and has the goodness in