Nutritional guidelines based on this concept, however, face three fundamental problems. First, a vitamin or mineral deficiency is much different from an insufficiency. Second, the widely accepted concept of biochemical individuality, developed in the 1950s by Roger Williams, Ph.D., holds that individuals are biochemically unique. Williams showed that same-species' nutritional needs can vary up to 40 times. Genetic variation results in variable enzyme activity.
Enzymes are the proteins that drive biochemical reactions.
The level of enzyme activity in the body determines many things such as hormone production, fat metabolism, energy supply and antioxidant activity. For instance, one person may require 2 mg of vitamin B5, while another needs 80 mg to achieve the same level of a certain enzyme activity. Third, we all live in different environmental situations and are subjected to different stresses, so quite naturally we may have different nutritional needs. Researchers know, for instance, that our ability to detoxify a variety of environmental toxins is based, in part, on certain key nutrients. People exposed to high levels of pollutants may have increased demands for specific nutrients.