I use P@H muesli mix, which isn't recommended by many, as most prefer Harry Hamster, but mine seem to have no problem with it and are extremely healthy
Though, if they did start having problems I would change the mix immediately, or maybe just remove the pea flakes as these can have a high content of sugar which can upset some hammys tummies
I think it is the hamsters preference so you may just have to get a mix and then add fruit or vegetables to it to make the hamster more likely to eat that food
Not too much fruit and veg though
