The assessment of deficiency diseases may be regarded as old-fashioned nutrition, as distinct from the modern concern with more sophisticated problems such as dietary interrelationships, treatment of genetic disease and the role of diet in such multifactorial disorders as heart disease, diverticular disease, spina bifida and a host of other disorders of the affluent communities. However, it is still possible to question whether everyone in the lands of plenty is well nourished. Group mean values provide inadequate information; the problem is that of the individuals at the lower end of the scale. However, it is extremely difficult to resolve the problem. Nutrient shortages are unlikely to be severe, biochemical indices may be in the normal or average range and clinical signs will certainly be very vague. Even if all three of these criteria indicate some degree of nutritional risk, it is difficult to demonstrate that extra nutrients confer any measurable benefit.