When doctors start talking about diet, patients are well advised to head for the door. A glance at the history of medicine reveals that doctors have always resorted to recommending diets when they have had no effective treatments — a state of affairs that prevailed from antiquity until the 1930s. Dietary protocols for numerous conditions, from insulin-dependent diabetes to pernicious anaemia, have disappeared with the development of new drugs or other forms of therapy. Take peptic ulcers. Patients survived for decades on fish and milk and other grim regimes, all prescribed in dogmatic detail and all of negligible benefit. Yet once effective acid-blockers appeared in the 1970s all talk of diet ceased, or at least migrated to the alternative health fringe.
Today, in relation to common conditions, such as coronary heart disease and cancer, where the scope for both preventive and therapeutic interventions is limited, doctors find themselves thrown back on dietary measures. Just as doctors have done through the ages, we issue detailed dietary instructions with a level of authority and conviction that goes far beyond the scientific rationale for them — and any evidence of their efficacy. Things were bad enough when such dietary dogma was largely confined to the surgery. Since it has been elevated to become a central feature of government public health propaganda, in programmes such as the ‘5-a-day’ fruit and vegetable promotion, the adverse consequences have become much worse.
Last year the government published Choosing a better diet: a food and health action plan as part of its wider public health policy.1 This emphasises the need to promote ‘healthy lifestyle choices’, including the provision of personal trainers in disadvantaged communities to help people to draw up ‘personalised plans’ to encourage them to eat less junk food, more fruit and veg, and take more exercise. In Getting personal: shifting responsibilities for dietary health, the Food Ethics Council accurately identifies the way in which government policy now ‘treats food like medicine and society like a hospital’.2 This is bad for science (nutritional and medical) and bad for society.
From any objective assessment of health trends in the industrialised world over the past half century it is readily apparent that diet plays a marginal role in both the causation and the prevention of disease. There is a consensus that since the Second World War we have all been eating too much saturated fat, too many refined carbohydrates, too much salt, indeed too much of everything, including diverse toxins and pollutants. Yet life expectancy has increased by about 10 years over this period — and it continues to increase. While prophets of doom promote nightmare scenarios resulting from epidemics of obesity and diabetes, death rates from coronary heart disease continue to decline — and rival gloom-mongers raise the spectre of a demographic timebomb of the elderly.
The public has been exhorted to follow a low fat diet, but this has little effect on circulating cholesterol and less on rates of heart disease. The evidence that any dietary intervention has a significant impact on the incidence of cancer is poor. But government dietary policy is not only scientifically irrational, it is also socially authoritarian.
In Britain school meals have become a major political issue and popular television shows feature celebrity nutritionists haranguing hapless parents about what they should be feeding their children, lest they condemn them to a premature death. Politicians desperately seeking ways of making contact with the public have hit on health in general (and food in particular) as means through which they can show they care about people's welfare and impose some authority over their behaviour. Yet, as Getting personal points out, this approach reduces the social activity of eating food to a personalised quest for individual survival. It implies that disease is the universal default status and that health can only be maintained by the scrupulous pursuit of an ascetic lifestyle. By medicalising diet, the government's intrusive and moralistic dietary policy diminishes individual autonomy and is more likely to make people ill than to improve public health.
- © British Journal of General Practice, 2006.