Background

There is a wide spectrum of complementary nutritional practices. These range from specific, well researched, biochemically understood treatments that are given by well trained practitioners to unresearched, biochemically implausible interventions popularised by spectacular claims in the lay press and largely used without professional supervision.

Just which treatments are “conventional” and which are “complementary” is subject to debate. Some, such as fish oil supplements for patients with rheumatoid arthritis, have many of the features of a conventional medical treatment—a biochemical mechanism and support from randomised trials— but are, none the less, often considered unconventional. Other interventions were originally considered “complementary” but are now part of conventional practice. Probably the best example is the high fibre diet, rich in fruit and vegetables. “Alternative” practitioners of the 19th century, such as John Kellogg, advocated such a diet at a time when conventional nutritional authorities tended to see meat and potatoes as the best food, even to the extent of denigrating the importance of vegetables and describing wheat bran as “refuse.”

In the Hay diet proteins and starch must be eaten separately, though fruit and vegetables can be eaten with either

Nutritional interventions

Unconventional nutritional interventions can be …