Synthetic vitamin C is really just ascorbic acid, comparable to the outer skin of an orange; 90 percent of the ascorbic acid in the United States is manufactured at a facility in Nutley, New Jersey, owned by Hoffman-LaRoche. In this plant the ascorbic acid is derived from cornstarch, corn sugar, and volatile acids mixed in a fermentation process. Most U.S. vitamin companies purchase this ascorbic acid, bottle it, and attach their own labels before selling it as vitamin C. Even less well known, most synthetic vitamin E comes from an Eastman Kodak plant, where it is a by-product of an emulsification process used to manufacture film. After purification it is sold to the supplements industry.
At the level of molecules seen under an electron microscope, synthetic and natural vitamins may look similar to some chemists, but they don’t assimilate the same way in the human body. Studies of both vitamin C and vitamin E show that the naturally occurring forms are more absorbable by the body and more biologically active than synthetics.
The Hundred Year Lie by Randall Fitzgerald, pg. 136