I think two daily multi-vitamins, about 12 hours apart will do the trick. How did our ancestors do it, aside from making sure they ate from a wide variety of foods.
Imagine...
Until the beginning of the 20th century, the soils weren't as depleted, and there was frontier available. The air wasn't contaminated. The fruits, vegetables, fish, fowl and meat had been developed by nature to survive; weak species died off. There were no chemical food additives or colorings. There were no processed foods or fats. People ate local, organic and seasonal foods all the time, because that's all there was.