the china study

Principle #02 (from The China Study)
Vitamin supplements are not a panacea for good health.

Because nutrition operates as an infinitely complex biochemical system involving thousands of chemicals and thousands of effects on your health, it makes little or no sense that isolated nutrients taken as supplements can substitute for whole foods. Supplements will not lead to long lasting health and may ...cause unforeseen side effects. The dangers of a Western diet cannot be overcome by consuming nutrient pills.
As I have watched the interest in nutrient supplements explode over the past twenty to thirty years, it has become abundantly clear why such a huge supplement industry has emerged. Huge profits are an excellent incentive, and new government regulations have paved the way for an expanded market. Furthermore, consumers want to continue eating their customary foods, and popping a few supplements makes people feel better about the potentially adverse health effects caused by their diet. Embracing supplements means the media can tell people what they want to hear and doctors have something to offer their patients. As a result, a multi-billion dollar supplement industry is now part of our nutritional landscape, and the majority of consumers have been duped into believing that they are buying health. 

 The China Study: Startling Implications for Diet, Weight Loss, and Long-Term Health (T. Colin Campbell and Thomas M. Campbell)