Edward Smith (physician)

"As a general definition, it may be stated that a food is a substance which, when introduced into the body, supplies material which renews some structure or maintains some vital process; and it is distinguished from a medicine in that the latter modifies some vital action, but does not supply the material which sustains such action."

"The same nutritive elements exist in both vegetable and animal foods, and … within certain limits, the two classes of food are interchangeable."

"Every … element, whether mineral or organic, which is required for nutrition is found in the vegetable kingdom."