My doctor's advice, which I have taken, is to eat sardines or mackerel on toast once a week, and my health is excellent. I chop up the fish with diced tomatoes, add black pepper and microwave for a minute and put it on one round of wholemeal toast. A very cheap, tasty and nutritious meal. I don't take any supplements as I think they can be dangerous, as they are not subject to the stringent laws that govern food and drink. They are also very bad for your budget.