Capsaicinoids – a potential role for weight management

Whiting, Stephen John (2016) Capsaicinoids – a potential role for weight management. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

The prevalence of overweight and obese individuals has risen dramatically in populations around the world over the last 30 years (Popkin et al., 2012) representing a rapidly growing burden to public health services (Wang et al., 2011). Reliance on lifestyle modification, although initially promising, has proven to be unsuccessful over the longer term (Barte et al., 2010) and there are currently a lack of successful treatment options. Capsaicinoids are a bio-active group of compounds, naturally occurring in the fruit of the plant from the genus capsicum. Initial research suggests these compounds may have beneficial effects on weight loss outcomes when ingested (Lejeune et al., 2003). A systematic review of the available literature on capsaicinoids found evidence that ingestion may increase energy expenditure by around 210kJ/day and lipid oxidation by around 20%. Ingestion may also reduce energy intake although evidence has been conflicting and the size of the effect unclear. To further aid understanding, a meta-analysis was undertaken involving intervention trials assessing the effects of capsaicinoids on energy intake. Analysis suggested capsaicinoid ingestion prior to a meal reduced ad libitum energy intake energy intake by 251kJ (60kcal) per meal (95% confidence interval of 337 – 166kJ) p < 0.001. Caution should be applied to this result however, due to the small size of the reduction and the short term nature of the trials involved. Longer term trials are needed to assess potential changes in body composition as a result of capsaicinoid interventions. To this end, a six-week placebo control intervention study was conducted to assess changes in body fat in 60 Caucasian women. Results of a sensitivity analysis found a small, statistically significant decrease in body fat percentage (0.64%, p = 0.022) and total body fat (0.67kg, p = 0.007) in the intervention group. However, the robustness of these findings are called into question by the results of an interaction analysis which of observed no significant difference between placebo control and intervention groups over time for these outcomes. The effect was also small and therefore longer term supplementation would be required to produce a medically beneficial changes in body composition.