Wednesday, March 11, 2009

Dietary supplement increases plasma norepinephrine, lipolysis, and metabolic rate in resistance trained men

Richard J Bloomer, Kelsey H Fisher-Wellman, Kelley G Hammond, Brian K Schilling, Adrianna A Weber and Bradford J Cole

Background: Dietary supplements targeting fat loss and increased thermogenesis are prevalent within the sport nutrition/weight loss market. While some isolated ingredients have been reported to be efficacious when used at high dosages, in particular in animal models and/or via intravenous delivery, little objective evidence is available pertaining to the efficacy of a finished product taken by human subjects in oral form. Moreover, many ingredients function as stimulants, leading to increased hemodynamic responses. The purpose of this investigation was to determine the effects of a finished dietary supplement on plasma catecholamine concentration, markers of lipolysis, metabolic rate, and hemodynamics. Methods: Ten resistance trained men (age = 27 ± 4 yrs; BMI = 25 ± 3 kg· m-2; body fat = 9 ± 3%; mean ± SD) ingested a dietary supplement (Meltdown®, Vital Pharmaceuticals) or a placebo, in a random order, double blind cross-over design, with one week separating conditions. Fasting blood samples were collected before, and at 30, 60, and 90 minutes post ingestion and were assayed for epinephrine (EPI), norepinephrine (NE), glycerol, and free fatty acids (FFA). Area under the curve (AUC) was calculated for all variables. Gas samples were collected from 30–60 minutes post ingestion for measurement of metabolic rate. Heart rate and blood pressure were recorded at all blood collection times. Results: AUC was greater for the dietary supplement compared to the placebo for NE (1332 ± 128 pg·mL-1·90 min-1 vs. 1003 ± 133 pg·mL-1·90 min-1; p = 0.03), glycerol (44 ± 3 ìg·mL-1·90 min-1 vs. 26 ± 2 ìg·mL-1·90 min-1; p< p =" 0.0003)."> 0.05). For all variables, values were highest at 90 minutes post ingestion. Total kilocalorie expenditure during the 30 minute collection period was 29.6% greater (p = 0.02) for the dietary supplement (35 ± 3 kcal) compared to placebo (27 ± 2 kcal). A condition main effect was noted for systolic blood pressure (p = 0.04), with values increasing from 117 ± 2 mmHg to 123 ± 2 mmHg with the dietary supplement, while remaining unchanged for placebo. No other hemodynamic changes were noted (p > 0.05).
Conclusion: The dietary supplement results in an acute increase in plasma NE and markers of lipolysis, as well as metabolic rate. This occurs without altering hemodynamic variables in a clinically significant manner. Intervention studies to determine the impact of this dietary supplement on weight/fat loss are warranted.

My Take:
It appears that during this study Meltdown was successful at increasing plasma Norephinrine (NE) levels which coincided with the increase of glycerol. NE is a key factor in the breakdown of triglycerides into fatty acids and glycerol (lipolysis). It appears from this study that these effects take 90 minutes to begin working. I am sure that on the bottle of the product it recommends that you ingest 90 minutes prior to exercise to maximize your body's utilization of those liberated fatty acids. The authors also noted in their conclusion that this product increase
in metabolic rate despite a minimal increase in heart rate and systolic blood pressure. This may be beneficial to some people who avoid taking supplements because of the rapid heart rate and inc. in blood pressure that gives them headaches. However I caution that this study was designed using resistance trained males, so females keep that in mind.


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