Nutritional influences of overfeeding on experimental outcomes in laboratory mice: consequences for gut microbiota and other functional studies.

Data from literature suggests that laboratory mice are often overfed and malnourished. This might have several reasons, including: (i) we usually offer an ad libitum diet, which is not the natural way of feeding for a wild mouse; (ii) many commercial diets we use contain rather high amounts of carbohydrates, particularly of sugars, and low amounts of fat; and (iii) laboratory mice live in a warm and constricted environment in which energy expenditure is lower than in the wild. Such selective or global overfeeding in laboratory mice, which resembles the widespread overfeeding in humans, although it does not always result in overweight, likely affects a number of outcome variables analyzed in laboratory mice, such as microbiota composition and function, metabolic alterations, longevity, intestinal permeability and inflammation. Therefore, a careful selection of experimental diets and their way of administration, as well as detailed documentation, is mandatory in order to understand and compare scientific data obtained from different mouse experiments.