Dr. David Hegsted, professor emeritus of nutrition at Harvard, suggested that RDA values should be retired because they are unusable and inaccurate. I believe the system is not only unworkable but no-one knows how to use RDAs. We tend to use RDA values as the first approximation of desirable nutrient intake. Often RDA values overestimate the number of calories required and underestimate values for some vitamins and minerals. Wild diets with total calories in excess of 3000 Kcal per day tend to supply all vitamins and minerals at RDA levels and higher.
Nutrient disproportion is common with some nutrient in extreme excess and others just adequate.
As the total caloric intake drops, calculated nutrient deficiencies begin to appear, although the overall effect of the food choices may be quite positive. One of the dogmas of standard dietetics is that all nutrients should be obtained from food. The recommendation to increase food intake sufficient to achieve RDA levels of nutrients may be counter-productive. The prescription of a reasonable nutrient supplement permits food selection, free of this nutrient-deficiency concern. Proper supplementation is a safe, cost-effective, intelligent way to assure optimal nutrient intake without compromising safe food choices.