Lost in translation: Allometric scaling of bioactive dietary n-3 and n-6 fatty acids

Abstract

Experimental animal models are the primary tool to test nutritional intervention strategies for health promotion and prevention and/or treatment of human diseases. These kinds of experiments test hypotheses that otherwise could not be done in humans. These models generate data important for pre-clinical screening purposes. However, their ability to predict human responses has been disappointing, particularly when it comes to dietary n-3 and n-6 polyunsaturated fatty acids (PUFA). Many times, it is difficult to recapitulate the data as a result of diet between pre-clinical experiments and clinical trials, in part because we lack the fundamental understanding of how to effectively translate diets between species. The diets in experiments using rodent models are preferentially designed to generate positive results (i.e., perform a dose response and pick the dose that works) with little thought on their applicability to humans. Accordingly, the levels of n-3 and n-6 PUFA used in rodent diets are typically on the extreme and rarely justified. A search of the literature reveals no guidelines establishing appropriate levels for the use of PUFA in rodent diets, although extrapolation to human conditions is quite common despite being inappropriate. The goal of this paper is to examine allometric scaling models between species for dietary PUFA using similar endpoints with the hypothesis that equivalent physiological changes in rodents and humans support the mathematical model.