MRI 8-FX Incorporates Nutratech’s Advantra Z®

Second Haller Study Supports Advantra Z® Efficacy and Safety
Exercise Sessions Rated Easier with Dietary Supplement Use, Show No Adverse Events

WEST CALDWELL, N.J., June 10, 2008 – A new scientific study led by a staunch critic of performance-enhancing dietary supplements has found that exercise tolerance improved – and no significant adverse events occurred – following use of a performance-enhancing dietary supplement containing Advantra Z®, a patented Citrus aurantium (bitter orange) extract for weight-management and sports nutrition distributed exclusively by Nutratech, Inc.
The three-arm, double-blind, placebo-controlled, crossover study, “Human Pharmacology of a Performance-Enhancing Dietary Supplement Under Resting and Exercise Conditions,” was published online in the British Journal of Clinical Pharmacology on March 13, 2008. It was conducted by Christine A. Haller, M.D. – of the University of California, San Francisco – who has been a frequent and outspoken critic of performance-enhancing dietary supplement usage. However, this is the second study from Haller to demonstrate positive results for dietary supplements containing Advantra Z.

“This study is a ringing endorsement of sports nutrition supplements, as well as Advantra Z,” said Bob Green, Nutratech president. “The researchers found that exercising was easier 83 percent of the time when people used a leading sports nutrition supplement.”
Green noted that the study also corroborates the results of numerous safety evaluations conducted on Advantra Z since 1997 – notably analysis by independent Laboratory Chromadex, which proved Advantra Z contains the stable p-isomer of synephrine, not the m-isomer that is believed to potentially increase blood pressure in some users.
Haller found that test subjects reported exercise was less difficult after using Twinlab’s Ripped Fuel Extreme Cut®, which incorporated Advantra Z as the source for Citrus aurantium.
“Perceived exertion during exercise showed that supplement use ameliorated the increase in exertional effort reported over time with placebo …. Dietary supplement sessions were rated easier than placebo sessions 83 percent of the time.”
In addition, after the initial post-dosing increases in blood pressure, there were no increases in post‑exercise heart rate, systolic blood pressure, or temperature – and no differences in exercise‑related oxygen consumption, serum lactate, or insulin.
Haller measured plasma synephrine (the dominant amine in Citrus aurantium) and caffeine concentrations over twelve hours, and monitored vital signs, serum electrolytes, oxygen consumption, and perceived exercise exertion in ten healthy adults between the ages of 20 and 31. Subjects ingested one dose of the supplement under resting conditions and one hour prior to 30 minutes of moderate exercise on a stationary bicycle.
Haller also found that diastolic (resting) blood pressure and postprandial (after eating a meal) plasma glucose increased after exercise with supplement use and stated that dietary supplement use could be detrimental in some people.
“That conclusion seems dubious. It’s definitely an overstatement because the study doesn’t account for a number of third variables. For example, how individual metabolisms and fitness levels react differently to food and exercise,” said Green. “Most importantly, it’s common knowledge that blood pressure goes up during and after exercise, and increases in glucose are normal after eating.”
However, Green added that Nutratech has always strongly advised manufacturers to properly label their products and urge consumers – particularly those with hypertension, heart disease or other pre-existing conditions – to consult with health care providers before embarking on any dietary supplement regimen.
This is the second study from Haller to cite findings supporting Advantra Z. In “Hemodynamic Effects of Ephedra-Free Weight-Loss Supplements in Humans,” published September 9, 2005 in The American Journal of Medicine, Haller studied Xenadrine EFX, a weight-management supplement containing Advantra Z. The study found:

  1. Even in eight-fold higher dosages (40 mg synephrine per dose), Citrus aurantium (Advantra Z) did not affect blood pressure. In fact, blood pressure went down slightly.
  2. With Advantra Z, there was no central nervous stimulation.
  3. Although “ephedra-free weight loss dietary supplements have significant cardiovascular stimulant actions … these pressor effects are not likely caused by Citrus aurantium (Advantra Z).”

Efficacy and safety studies conducted on Citrus aurantium / Advantra Z from 1997
to the present can be viewed in their entirety at

Nutratech, Inc., is a premier supplier of cutting‑edge, popular, and patented nutraceutical ingredients for the weight management and sports nutrition industries. Its proprietary bitter orange extract, Advantra Z®, is the industry’s leading patented thermogenic ingredient. Headquartered in West Caldwell, N.J., the company is known for its industry advocacy and commitment to scientifically supported raw materials. For more information on Nutratech and Advantra Z, visit the company’s web site at

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Editor’s Note: Ripped Fuel Extreme Cut®, the dietary supplement featured in this study, has been discontinued. However, other sports nutrition products from Twinlab continue to incorporate Advantra Z®, including Ripped Fuel Ephedra Free, Diet Fuel Ephedra Free, and Metabolift Ephedra Free.
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