Although nutrition, as a science, has always been part of conventional medicine, doctors are not taught, and therefore do not practise, much in the way of nutritional therapeutics. Dieticians in conventional settings tend to work mainly with particular patient groups–such as those with diabetes, obesity, digestive or swallowing problems, or cardiovascular risk factors. Apart from the treatment of gross nutritional deficiencies and rare metabolic disorders, other nutritional interventions generally fall outside the mainstream and can therefore be described as complementary medicine.

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.”

Nutritional interventions

Unconventional nutritional interventions can be broadly divided into three categories: nutritional supplements, dietary modification, and therapeutic systems.