Writing in the International Journal of Obesity, lead author Anita Belza from the Royal Veterinary and Agricultural University in Denmark said: "The combination of these bioactive food ingredients may be of value in supporting weight management after a weight reduction."
The retail market for weight management products was estimated by Euromonitor International to be worth US$0.93bn (€0.73) in Europe in 2005 and $3.93bn in the US, indicating that call to slim down or face the health consequences is being heeded by a slice of the overweight population at least.
The Danish researchers recruited 80 overweight and obese subjects (average BMI 31.2 kg per sq. m) for an initial four-week hypocaloric diet (3.4 MJ/day) to induce weight loss, and were then randomly assigned to receive the combination supplement (57 participants receiving a daily dose of 1500 mg green tea extract, 1218 mg L-tyrosine, 302 mg caffeine, 1.2 mg capsaicin, 2000 mg calcium) or placebo (23 participants).
The double-blind, eight-week trial measured the thermogenic effect, blood pressure, heart rate, body weight and composition.
The researchers report that average weight loss during the initial four-week diet phase was 6.8 kg. At the end of the supplementation/ placebo phase average body mass in the supplemented group was 0.9 kg less than the placebo group.
"The supplementation increased four-hour resting metabolic rate (RMR) by 90 kJ more than placebo, and the study extends previous findings by showing that the effect was maintained after eight weeks, and was accompanied by a slight reduction in fat mass," wrote Belza.
No effect was observed on blood pressure, heart rate or faecal fat excretion, said the researchers.
"The thermogenic effect is likely to exceed 300-400 kJ per day when the supplement is taken three times per day, without any detectable hemodynamic effects," they said.
The mechanism behind the effects is proposed to be due to the effect of the active ingredients on boosting activity of the sympathetic nervous system (SNS). Both green tea catechins, particularly epigallocatechin gallate (EGCG), and capsaicin have been linked to these in previous studies, said the researchers.
Previous studies have also reported that calcium can increase faecal fat excretion, but this was not supported by the findings of this study. "The effect off calcium may be dependent on calcium being ingested as a supplement or as part of a calcium-rich meal in order for calcium to bind to fatty acids in the gut," wrote Belza.
While the supplement, formulated by Salt Lake City-based Alpine Health Products, is not currently commercially available, the combination of these ingredients to promote thermogenesis, coupled with the lack of adverse effects over the eight-week period, shows the potential of these bioactives for supporting weight management after a weight reduction..
"Further investigations are needed to evaluate the long-term use of the compound," concluded the researchers.
Over 300m adults are obese worldwide, according to latest statistics from the WHO and the International Obesity Task Force. About one-quarter of the US adult population is said to be obese, with rates in Western Europe on the rise although not yet at similar levels.
Source: International Journal of Obesity Volume 31, Pages 121-130 "Body fat loss achieved by stimulation of thermogenesis by a combination of bioactive food ingredients : a placebo-controlled, double-blind 8-week intervention in obese subjects" Authors: A. Belza, E. Frandsen, J. Kondrup