The effectiveness of an extract from the fruit of black pepper, consisting of a minimum of 98.0% pure alkaloid piperine, was evaluated for its ability to improve serum response of beta-carotene during oral supplementation using a double-blind, crossover study design. Subjects were randomly selected to ingest a daily beta-carotene dose (15 mg) either with 5 mg of piperine or placebo during each of two 14-day supplementation periods. Inter-subject variability in pre-supplementation serum beta-carotene levels was minimized by limiting the selection of volunteers to healthy, adult males with fasting serum beta-carotene values <20 μg/dL. The results indicate that significantly greater increases (P<0.0001) in serum beta-carotene occurred during supplementation with beta-carotene plus piperine (49.8+/-9.6μg/dL vs. 30.9+/-5.4μg/dL) compared to beta-carotene plus placebo. Supplementation with beta-carotene plus piperine for 14-days produced a 60% greater increase in area under the serum beta-carotene curve (AUC) than was observed during supplementation with beta-carotene plus placebo. We suggest that the serum response during oral beta-carotene supplementation is improved through the non-specific, thermogenic property(s) of piperine, described in this paper as thermonutrient in action.