Both sources are limited in a bodybuilding diet because they aren't very calorie-dense and the point is after all to get in as much calories as you can use. So its always wise to supplement these two. All B-vitamins improve the use of macronutrients, and individually they can give energy, speed up digestion and a zillion other useful things. The C-vitamin is both anabolic and anti-catabolic. It functions as an important enzyme in many anabolic processes and acts like an anti-oxidant as well as support the action of other anti-oxidants.