The processed food industry's name for food with nutritional
Orange juice with added calcium is a good example. Those nasty "milkshake" drinks for weight gain, weight loss, and senior nutrition are also functional foods. Bodybuilders' energy bars definitely qualify as functional food.
I've seen caffeinated water, sodas with guarana and gingko biloba, and even granola with various herbs.
Personally, I prefer to eat non-processed foods. If I need a vitamin or mineral supplement, I can take a multivitamin.