1830
During the 1830s Jean Baptiste Boussingault, Gerrit Mulder, Justus von Liebig all suggested that the nitrogen content of food could serve as an indicator of its nutritive value. Liebig went further and suggested that "muscular motion can be produced only by the oxidation of protein." The protein era had begun. The majority of all dietary recommendations in the nineteenth century were based on Liebig's concerns about meeting the need for protein and energy.
Whorton, J. (1982) Crusaders for fitness: the history of American health reformers. Princeton University Press. USA
Around 1830, Sylvester Graham regarded by many as the originator of the modern American food fad, produced the Science of Human Life, his prescription for health and morality. A Presbyterian minister, Graham warned of the dangers of meat, pastries and highly spiced foods and proposes that the only way to avoid the conditions such as indigestion or dyspepsia and attain true happiness is through natural living. He cites the two major dangers to a natural life as improper diet and sexuality. Graham criticised modern, commercially produced white bread and advocates a return to "traditional" homemade, whole-wheat varieties (which coincidentally he marketed as Graham Bread). Strangely, his argument against white bread was that it was too nutritious for the body to digest. Stephen Nissenbaum suggests that Graham's aversion to processed flour was less to do with dietary concerns and more centred on his distrust of modern production and a longing to return to a more natural subsistence lifestyle.
Nissenbaum, S. (1980) Sex, diet and debility in Jacksonian America: Sylvester Graham and health reform. Chicago
According to Whorton, Graham was "the man who conferred on unbolted flour its status as a health food" and by 1835, he had become known across the US as the prophet of bran bread.
Whorton, J. (1982) Crusaders for fitness: the history of American health reformers. Princeton University Press. USA
Dietary fibre – William Beaumont, the physiologist, in the 1830s suggested that the ingestion of "innutritious substance" was essential to the prevention of disease and the improvement of human health.