The α-eleostearic acid (α-ESA) in bitter melon seed oil (BMSO) is efficiently converted by the body into rumenic acid. The objective of this study was to investigate effects of BMSO on skeletal muscle fiber-type switch and endurance capacity in mice, with or without exercise training. In a 3 x 2 factorial design, C57BL/6 J mice were fed a 30% high-fat diet composed of soybean oil, butter or a 1:1 mixture of BMSO and soybean oil, i.e. SB, BT and BM diets respectively and were allocated to be sedentary or undergo exercise (Ex). The Ex groups received a 15-min training regimen on a motorized treadmill 5 times a week. After 3-wk intervention, endurance capacity was evaluated (total running time and distance until exhaustion). Mice fed a BM diet had significantly less body fat, with increased muscle percentage and improved endurance capacity. Combining sedentary and Ex groups, mice fed a BM diet ran 33% longer and 50% further than those fed SB, or 25% longer and 36% further than those fed BT (P<.01). The BM diet-increased gastrocnemius cytochrome c protein and mitochondrial DNA content was more prominent in sedentary than in trained mice. Histochemical staining shows sedentary BM-fed mice had a higher succinate dehydrogenase activity among groups. Based on a reporter assay, rumenic acid, rather than α-ESA itself, activated PPARδ ligand binding domain. We concluded that BMSO, improved endurance capacity via stimulation of mitochondrial biogenesis and function, potentially influencing muscle metabolism and fiber-type composition in sedentary mice.

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Date of publication: 6 June 2018; The Journal of Nutritional Biochemistry

Author information: Fei Koon Chan (1); Chin Hsu (2); Tsai-Chung Li (3,4); Wen-Hung Chen (5); Kuo-Tang Tseng (5); & Pei-Min Chao (1)

(1) Department of Nutrition, China Medical University, Taichung, Taiwan
Department of Exercise Health Science, National Taiwan University of Sport, Taichung City, Taiwan
Department of Public Health, College of Public Health, China Medical University, Taichung, Taiwan
Department of Healthcare Administration, College of Medical and Health Science, Asia University, Taichung, Taiwan
Aquavan Technology Co., Ltd., Taipei City, Taiwan