Can food change a cat?

[LenaLoyd]

My cat is a really fussy eater, she spends most of her time loitering and being grumpy. We've tried lots of brands, but at best she'll eat chicken mixed with a few biscuits (she even turns her nose up at the chicken sometimes). I was given some Purina One Dual Nature to trial, my expectations were low (I've tried her on other expensive brands) but she happily ate it. Since she's been eating she's like a changed cat in her personality, she's really playful and happy, could this be the change in food? Can food actually make a difference like this? I've presumed that being grumpy was her personality, but has she been this happy cat all along and the foods bought it out? The new food contains spirulina.