The Impact of Diet on Lab Results and Research Outcomes

Abstract

Nutritional physiology plays an important role in the functional outcome of studies performed with rodent models. This is important generally in safety and efficacy studies performed to support health claims, but when obesity, type 2 diabetes, or cardiovascular diseases are taken into consideration, it becomes even more important. Several examples are given to illustrate that dietary intervention studies in wild-type mice and rats give relatively small effects compared to in vitro or human studies on parameters such as lipoprotein profiles, biomarkers of inflammation and gene expression responses (P. M. Hoevenaars et al., 2012). Generally applied “standard” chow diets usually contain poorly specified ingredients that may strongly vary in composition between batches and between suppliers. Even diets prepared by the same supplier may differ significantly in composition. Since rodents are often used to study functional effects of individual nutrients or groups of nutrients, it is important to use diets that are as much as possible controlled for their composition. This necessity is now widely recognized among researchers employing rodents to unravel molecular mechanisms underlying functional effects of nutritional components. Semi-purified control and experimental diets based on the recommendations of the American Institute of Nutrition for the AIN93 semi-purified rodent diets are increasingly used (Gkiouras et al., 2022). These diets contain purified ingredients of desirable quality, resulting in diets with more defined and controlled composition. Unfortunately, at present there are as many different formulations as there are different research groups. Consequently, a need to further standardize diets has been expressed that would make comparisons of study outcomes easier and would increase efficiency of use of both resources and animals. Despite this need, trying to agree on one formulation for a standard diet has proven to be extremely difficult.