In the 1980’s, Dr. William Shive, a biochemist and researcher in the field of nutrition at the University of Texas, Austin, realized that serum tests for many vitamins and minerals did not adequately reflect the biological efficacy or functionality of these nutrients within the body. Serum levels of nutrients were felt to inadequately reflect the true state of a person’s nutrition for the following reasons:
- Serum measurements are transient—they represent a snapshot rather than a history of nutrient intake.
- Serum measurements are heavily influenced by a patient’s recent nutrition—thus, a temporary change in diet prior to the test can present a skewed view of the patient’s normal nutrient intake.
- Serum levels may not reflect intracellular nutrient status. Patients may have biochemical differences with respect to the transport of different nutrients from their blood into their cells. For example, two patients may show similar serum measurements for folic acid, but may differ with respect to the capacity of their cells to take up folic acid. Thus, one patient would have a functional deficiency of folic acid that would not be revealed by serum measurements.
In an effort to overcome the above deficiencies inherent in serum determinations, Dr. Shive invented a test that could reveal the function of a specific accumulated nutrient within human cells. This comprehensive assay takes into account all of the factors affecting nutritional status: age, genetic and individual biochemistry, environmental and physical stressors, and the cumulative effect of diet over a longer period of time than just a few days.