Overweight people who drank 120 ml per day of the goji berry juice in combination with calorie restriction lost an average of 5.5 cm on their waistlines in 14 days, compared with people who drank placebo and adhered to the same calorie-controlled diet.
The researchers also report that a single intake of the goji juice boosted energy burning by 10%, compared with placecbo, according to findings presented in the Journal of the American College of Nutrition.
The study used a commercial goji (Lycium barbarum) product by FreeLife International Inc., and the Phoenix, AZ, based company funded the study and first author Haru Amagase, PhD, is FreeLife’s chief scientific officer.
The pilot study was also very small – including only eight participants – and longer and larger studies are required to support this study’s findings.
“Although the present preliminary studies are the first clinical report to show various unique metabolic effects of L. barbarum, there are limitations in these studies because (1) each study had a small number of the subjects, and (2) the studies were short in duration, a 14-day intervention or a single-bout intake,” wrote Amagase and his collaborator, Dwight Nance from the University of California at Irvine and a scientific advisor to FreeLife.
“Therefore, a larger and more long-term study is required to clarify further the effects of L. barbarum on body weight, metabolic syndrome, and glucose and fat metabolism in humans in order to confirm the efficacy and to identify the mechanisms of actions of L. barbarum.”
Goji, or lyceum barbarum, has been used in Asian countries such as China, Korea and Japan for over 2500 years, where it is thought to have health benefits including anti-aging, vision, kidney and liver function.
A recent review paper by Dr Amagase and the late Prof Norman Farnsworth from the University of Illinois at Chicago in Food Research International concluded that “L. barbarum is an interesting herb and food, and has wide variety of biological effects shown in various human clinical, in vivo animal and in vitro studies.
Commenting on the potential stimulation of metabolism, Prof Farnsworth and Dr Amagase cite data from ‘preliminary’ studies (all performed by Dr Amagase) and not that “these did not include any functional measurements of substrate utilization, heart rate, muscle activity, temperature or respiratory quotient”.
“However, the absence of these additional measures does not diminish the clear functional and statistical significance we observed in the present studies in terms of postprandial energy expenditure,” they wrote.
The new study included eight overweight individuals with an average age of 35 and an average BMI of 29 kg/m2. Two studies were performed: The first investigated the effect of a single intake of three doses of goji juice (30, 60, and 120 ml) and placebo on energy expenditure. Results indicated a 10% increase in the high dose group, but no significant effect for the two lower doses.
The second study investigated the effects of 14 days of goji juice consumption (120 ml per day) or placebo on waist circumference.
Results for this study suggested that the goji juice product was associated with a decrease in waist circumference of about 5.5 cm or 2.16 inches, compared with 0.9 cm or 0.35 inches in the placebo group.
However, no changes in body weight or BMI were recorded in either group.
“These are the first randomized clinical trials to evaluate the role of L. barbarum in the metabolic parameters in humans,” wrote Drs Amagase and Nance.
“Our results suggest that L. barbarum may stimulate metabolic rate, and these effects may be related to the changes in waist circumference produced by daily consumption of L. barbarum in the form of fruit juice (GoChi) for 14 days.”
Source: Journal of the American College of Nutrition
Volume 30, Pages 304-309
“Lycium barbarum Increases Caloric Expenditure and Decreases Waist Circumference in Healthy Overweight Men and Women: Pilot Study”
Authors: H. Amagase, D.M. Nance