I use the following two supplements:
-- Life Extension Cat Mix powder (taurine, probiotics, arachidonic acid, alpha lipoic Acid, folic acid)
-- Missing Link Feline Formula (Omega-3 and fiber via flaxseed powder)
Community warning: If you use the Missing Link Feline Formula, beware of changes made to the nutritional value between the bright gold, smaller label package and the Missing Link Ultimate Feline formula which the front is mostly purple and the label takes up the whole side of the bag.
The Omega-3 concentration and minimum guaranteed level has been dramatically lowered, going from 1000mg/teaspoon down to 312.5mg/teaspoon comparing the ingredients of the two packages. I have not ran out of the older mix yet and source this via Amazon or the local pet store.
So either the formulation changed, the minimum guaranteed analysis on the old was incorrect, or they are "making up" the lack of Omega-3 with some other nutrient 'filler' and the primary reason why Omega-3 is helpful is it's mostly limited to seafood nutritional sources. Even humans on a pure seafood diet still have a higher concentration of Omega-6 in their diet by a factor of 2:1 and good nutrition means bringing these ratios closer to balance for skin, coat, and organ health. And I'm allergic to seafood so my boys don't get it any other way outside of canned seafood.