One thing I used to take was malt extract. Just a teaspoonful a day. I also had one with added cod liver oil. You cant taste it, I promise!
Nowadays I take vitamins, c, d, e, zinc, iron, garlic oil, and extra raw veg on my plate.
Raw onion, red cabbage, and carrot , and /or or salad leaves (spinach, watercress and rocket) with every meal, either as a coleslaw or, just as a veg accomplament. Cooking veg can destroy some goodness, so I often have raw veg...except potatoes! they definitely need cooking!