What are the best food supplements?

So there's loads of debate around food supplements, particularly multivitamin tablets and whether very much of it gets absorbed and benefits you. ​ I've had tons of success however taking fish oil supplements, as it has been the only thing to clear up my eczema. I've decided to switch to cod liver oil once I finish the fish oil capsules, as cod liver oil also has the benefit of vitamin D & A. ​ I've been thinking perhaps the success I've had with the fish oil is due to it being closer to a whole food format? ​ I was just wondering if anyone can think of any other supplements that would be similar to a whole food format like fish oils? I was thinking of organ meat, but I don't think I can source it other than at the supermarket. I'd just like to hit some more nutrient requirements than just omega 3s, and vitamin A & D.