title: Naringin does not alter caffeine pharmacokinetics, energy expenditure, or cardiovascular haemodynamics in humans following caffeine consumption.
abstract: 1. Naringin, a grapefruit constituent interacts with many medications including caffeine, a popular weight loss supplement. The purpose of the current study was to identify changes in caffeine pharmacokinetics, resting energy expenditure (REE), oxygen consumption (VO(2)) and respiratory exchange ratio (RER) after an acute dosage of caffeine and naringin. 2. Using a double-blinded, counterbalanced design, REE, VO(2), and RER were measured before and systematically for 8 h after a single dosage of caffeine (CAF, 200 mg) with and without naringin (100 mg (CN100) or 200 mg (CN200)) in 10 apparently healthy individuals. A standardized meal was provided following 240-minute measurements (400 kcals; 35 g carbohydrate; 27 g protein; 7 g fat). 3. Caffeine, CN100, CN200 did not alter VO(2) or VO(2) area under the curve (137 301 +/- 8318, 139 729 +/- 9300, 134 297 +/- 8318, mL/480 min). Resting energy expenditure (k/cals) was 10.0 +/- 1.4% higher with CAF versus CN200 (6.0 +/- 1.4%) and CN100 (6 +/- 1.5%) at 240 min (P = 0.07) which was then negated following a standardized meal. Percent change in RER from pre to 240 min and pre to 480 min was not different between the CAF, CN100, or CN200 (-0.2 +/- 1.7%, 1.7 +/- 1.7%, -2.8 +/- 1.9%). 4. Although caffeine alone suggests a trend of increased REE, the results of the present study indicate that concurrent consumption of caffeine with naringin in acute dosages does not affect RER, VO(2), and prevents the increase of REE in adult humans. The results suggest that the interaction of grapefruit juice and caffeine may be due to constituents of grapefruit juice other than naringin or in addition to naringin.
authors.affiliation: South Dakota Health Promotion and Research Program, Applied Physiology Laboratory, South Dakota State University, Brookings 57007, USA.
authors.forename: Tasha L P
authors.initials: TL
authors.lastname: Ballard
authors.forename: Fathi T
authors.initials: FT
authors.lastname: Halaweish
authors.forename: Cheryl L
authors.initials: CL
authors.lastname: Stevermer
authors.forename: Puja
authors.initials: P
authors.lastname: Agrawal
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Vukovich
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D000924:Anticholesteremic Agents / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D002110:Caffeine / Q000493:pharmacokinetics*; D000697:Central Nervous System Stimulants / Q000493:pharmacokinetics*; D004347:Drug Interactions; D004734:Energy Metabolism / Q000187:drug effects*; D005260:Female; D044950:Flavanones / Q000494:pharmacology*; D006207:Half-Life; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects
chemical_list: D000924:Anticholesteremic Agents; D000697:Central Nervous System Stimulants; D044950:Flavanones; D002110:Caffeine; C005274:naringin