Metabolic Costs Associated with the Ingestion of Plant Phenolics by Microtus pennsylvanicus

We measured the basal metabolic rate of meadow voles, Microtus pennsylvanicus, before and after incorporating the phenol gallic acid (6% by dry mass) into the diet. After phenolics were added, basal metabolic rates increased by 13.6–22.6%. This indicates that there are measurable metabolic costs associated with feeding on plants that contain phenolics. These costs may be associated with detoxification and tissue repair, but their cause is not known.