Calcium is used as a pharmacological agent in humans almost entirely to remedy deficiency. Adequate calcium in the blood is so vital to a wide variety of bodily functions that our internal biochemistry will not tolerate a deficiency even for short periods.
Vitamin-C is an essential component of the diet as man can not synthesize vitamin-C. It is a very powerful reducing agent. Vitamin-C plays an important part in the response of the body to stress. It is important in the defense against infection.