There are some useful history books on this subject:

Warren Belasco's _Appetite for Change: How the Counterculture Took on the
Food Industry_ views the food reform movement of the 1960s and 1970s as many
of the previous respondents do: as a leftist, pro-environmental,
anti-corporate crusade against agribusiness and the food industry.

James Whorton's _Crusaders for Fitness_ looks at the health reform tradition
in America that originated in the first half of the 19th century. (He
discusses Graham, Kellogg, etc.) Although the book does not go beyond the
1920s, in the book's conclusion and in other writings, he links the
post-1960s food reform movement to this tradition. He sees the movement as
basically concerned with health and, in particular, with fears about the
impact of urban-industrial society on health.

Next month, I believe, an article that I wrote on the subject will be
published in Robert Johnston's _Politics of Healing_, an anthology of
articles on alternative medicine in the US in the 20th century. I examine
(what I call) the modern health foods movement, which originated in the
1930s in the wake of the discovery of vitamins and related nutritional
matters. (The organic foods movement in the US was one part of this
movement.) I discuss both the scientific aspect of the movement, and the
ideological aspect (which is definitely anti-modernist and
pro-environmental, but not fundamentally leftist -- in the 1950s the
movement had close links to the far right). Although my articles stops in
1965, I believe that the food ideas embraced by the youth counterculture in
the 1960s came mainly from the post-1930s health foods movement. (One
difference: the post-1960s movement endorsed vegetarianism, while the
earlier movement did not.)

I'd also like to disagree with those who claim that the countercultural food
movement died after the 1970s. Organic/sustainable agriculture, opposition
to bioengineered foods, the slow-foods movement, etc. are all in the same
anti-modernist ideological tradition as both the pre-and-post-1960s health
foods movement.

Michael Ackerman
Grad Student, Dept. of History
University of Virginia