Natural vitamin C is derived from citrus fruits, ascerola cherries, amla berries, rose hips, red and green peppers and other fruits and vegetables. Be sure to check labels for sources as some vitamin C supplements are labeled "natural and organic" because they are synthesized from corn sugar (gulcose), which technically fits that definition but is not the same as a natural vitamin C complex from whole food.
Synthetic and natural vitamins interact differently with minerals in the body. For example, many nutritionally oriented physicians warn their patients not to take ascorbic acid because it depletes copper levels. Natural vitamin C does not. When beta carotene failed to protect heavy smokers from heart attacks, head lines condemned vitamin therapies without mentioning that the supplement tested was synthetic, not natural. Hundreds of studies have shown that people who eat foods rich in beta carotene have lower heart attack and cancer rates than those who don't.