I’m quite worried about my mummy as I believe she fell victim to marketing and advertising promoting supplements and superfoods for pets. Lately she behaves very strange and our kitchen start looking like an apothecary, if you know what I mean!
We cats are carnivores with a digestive system that is designed to eat the bodies of rodents, birds and insects. That means not just their flesh but their innards, their skin, their bones, etc. We probably eat a little green stuff in the rodent gut and we definitely eat grass occasionally.
An all-flesh diet of something like steak doesn't give us everything we need. Nor does an all-vegetable diet. Nor does an all-fish diet. An all-liver diet can kill us with hypervitaminosis. Feeding a home-made diet is complicated.
In the past we cats were fed scraps and milk and fish (those two items used to be cheap) and we supplemented our diet with catching mice and birds. Cats fed odd diets by their owners can still do that, as long as they have a cat flap. But cats that live indoors without a cat flap cannot do that.
So supplements for cats on home-made diets are a good idea. Which ones? Your owner should ask a qualified vet for advice and follow it. It's probably better to choose a well qualified vet and stick to their advice, rather than taking a piece of advice here and another there and maybe getting muddled. As for TV commercials, Youtube "influencers," pet shops, etc - these are not the right places to get advice. They do not know enough.
You've gone through so much, you need the best, Chico.