Let us start with a brief history of Medicine and Nutrition -

Patient "I am sick".

Physicians responses: 
3500 years ago - "Here eat this root" 
2500 year ago - "That root is heathen - say this prayer" 
150 years ago - "That is superstition - drink this potion" 
50 years ago - "That potion is snake oil - take this pill" 
15 years ago - "That pill is no good, take this antibiotic" 
Today - "that is not natures way - here eat this root"