Resting Metabolic Rate is Synergistically Stimulated by a Single Bolus Lycium barbarum Fruit Juice Intake Combined With Indigestible Dietary Fiber in Healthy Human Adults

Lycium barbarum ( L.barbarum ) fruit (goji) increases resting metabolic rate (RMR), and reduces body weight in rodents and central adiposity in humans. To investigate the possible synergistic effect of L.barbarum on RMR with various doses of dietary fiber, human adult subjects (n=8, age=45±5 y) randomly took a single bolus serving of 1 of 4 different doses (0, 1, 5 and 10 g) of indigestible soluble dietary dextrin fiber with a placebo or a low dose of L.barbarum in a form of fruit juice (15 ml of commercially available GoChi ® juice) in a randomized, double‐blind, placebo‐controlled, multiple‐period crossover design. RMR was measured by breath oxygen volume immediately before (baseline), 1, 2 and 4 h after sample intake. Each test sample was randomly tested at weekly interval following an overnight fast. Average baseline RMR was 1,544 kcal/day and control nutritional beverage (360 kcal) increased RMR by about 4.8% from baseline level. All doses of dietary fiber intake did not statistically change RMR from control level. However, the addition of L.barbarum increased RMR proportionally with the dose of fiber. RMR 0 to 4 h post‐intake of 5 and 10 g dietary fiber plus L.barbarum were significantly increased by 7.2 and 8.4%, respectively, from the baseline level and statistically higher than the control level (P<0.05). These results show that L.barbarum synergizes with indigestible dietary fiber to increase metabolic rate.