1 - Statistical evaluation of bioavailability assays

Abstract

Publisher Summary Bioavailability of a nutrient in a test substance, relative to its bioavailability in a standard substance, is usually defined as the ratio of the amounts of the standard and test substances required to produce equivalent responses. Bioavailability assays are based on experimental data, and properly designed experiments should be conducted to obtain valid and efficient assays. The slope ratio assay is the most common form of assay used in recent bioavailability experiments. Values of independent and dependent variables are determined from each experimental unit. For relative bioavailability value (RBV) estimates must be meaningful, and the assumptions regarding linearity and intersection of the regression lines must hold. Statistical tests can be used to check the validity of the assumptions. The three-point design, as the name implies, relies on only three design points to estimate RBV. It can be used in the case of either the assumption for the slope ratio or the parallel lines assays, but it must be known in advance which assumption is valid. The standard curve assay is a compromise between the three-point assay and the slope ratio or parallel lines assays. It requires more than three data points, but usually not as many as the slope ratio or parallel lines assays. Some experiments have been conducted in which two or more sources of a nutrient were tested without a basal control group, which is needed to make a three-point comparison.