You would be surprised but actually the cat's body and human body are not very different from each other. I mean to say that the function of both depends heavily on nutrition that the body is getting with the intake of health vitamins. Just like human beings ,the cats whether pet or stray needs vitamin and mineral supplements , but the type and quantity of course will depend on the diet they are being given and their health quotient.
Similarly cats too require all kinds of vitamins like vitamin A,B,C,D etc ,that is both the groups of vitamins viz fat as well as water soluble is equally demanded by the cat's body. Actually cats and other pets tend to get frequent bruises and cuts, so if their body contains adequate amount of vitamins and minerals, they get easily repaired.
In fact naturally the cat's body is build in a way that they can absorb vitamins readily, on the other hand giving them minerals might depend on their health condition. All the major minerals including calcium, sodium chloride etc is required by cats' body but then if your pet is suffering from ill health then chances are high that it won't be bale to absorb the minerals effectively.
Luckily the pet foods available are market today has proper combination of all the minerals and vitamins that your cat requires. So choose any one of these foods that your cat eat happily or take advice from a specialist, to give your cat the complete nutrition. But remember that these foods too when kept for longer period looses some amount of vital minerals and vitamins. Therefore, while buying food for your cat, remember to purchase in small quantities and once it gets finished again visit the store.
These where some points that you must take care while feeding your pet cat ,but what if you come across a stray one and want to help ? In that case consult a professional who can tell you what's is the actual health condition of that cat and then give nutritional supplements ,only after getting full nutrition guide from the expert, because if you try to act as a doctor yourself then you might be putting the life of that cat in risk. As some minerals and vitamins is given unlimited or in higher quantities can behave as toxic material in the body, hence be careful.