Acute p-synephrine ingestion increases whole-body fat oxidation during 1-h of cycling at Fatmax.
- Authors
- Type
- Published Article
- Journal
- European Journal of Nutrition
- Publisher
- Springer-Verlag
- Publication Date
- Oct 01, 2020
- Volume
- 59
- Issue
- 7
- Pages
- 3341–3345
- Identifiers
- DOI: 10.1007/s00394-019-02101-6
- PMID: 31691018
- Source
- Medline
- Keywords
- Language
- English
- License
- Unknown
Abstract
p-Synephrine, the principal alkaloid of bitter orange (Citrus aurantium), is widely used in dietary supplements for weight loss due to its purported effect of increasing fat oxidation. However, there is a paucity of scientific information about its effectiveness in enhancing fat oxidation during exercise. The aim of this investigation was to determine the effect of an acute dose of p-synephrine on substrate oxidation during prolonged and constant intensity exercise. In a double-blind and randomized experiment, 14 healthy subjects performed two acute experimental trials after ingesting either p-synephrine (3 mg kg-1) or a placebo (cellulose). Energy expenditure and fat oxidation rates were continuously measured by indirect calorimetry during 1 h of continuous cycling at Fatmax, the intensity that induces maximal fat oxidation rate. In comparison to the placebo, energy expenditure during 1 h of cycling remained unchanged with p-synephrine (698 ± 129 vs. 686 ± 123 kcal, P = 0.08). However, p-synephrine increased whole-body fat oxidation (33.6 ± 10.4 vs. 37.3 ± 9.8 g, P < 0.01) while also reducing carbohydrate oxidation (99.5 ± 30.4 vs. 85.0 ± 28.4 g, P < 0.01). However, the magnitude of the shift on substrate oxidation induced by p-synephrine was small. Acute ingestion of p-synephrine augments fat oxidation during prolonged and constant-intensity exercise.