Intake of medium-chain fatty acids induces myocardial oxidative stress and atrophy

BACKGROUND: Oral intake of medium-chain fatty acids (MCFAs) reportedly suppresses the accumulation of visceral fat and has antitumor effects in tumor-bearing animals. MCFAs penetrate the mitochondrial membrane in a carnitine shuttle-independent manner and are metabolized more quickly than long-chain fatty acids. Based on these characteristics, MCFAs may have pronounced effects in mitochondria-rich tissues, such as the myocardium. We examined the effect of oral intake of MCFAs on the heart. METHODS: We fed BALB/c mice with a control diet supplemented with 0%, 2%, 5%, or 10% lauric acid (LAA; a 12-carbon saturated MCFA). After euthanasia, the hearts, both sides of quadriceps femoris muscle (QFM) and epididymal fat pad (EFP) were excised and weighed. Then myocardial tissue morphology, oxidative stress accumulation, and mitochondrial volume were observed by histological analysis. The expression levels of myosin light chain 1 were measured by ELISA. RESULTS: There were no differences among the groups in food and calorie intake, but the intake of LAA increased with the dietary proportion. The 10%-LAA-fed mice experienced significant weight loss and became moribund on day 6. The body, cardiac and EFP weights of the mice fed 5% and 10% LAA were lower than those of the control group. And 10% LAA fed group showed significant decrease of the QFM weights. Protein analysis of the excised hearts revealed higher expression of myosin light chain 1 in the 5% group than in the control group. Histological examination of the hearts revealed myocardial atrophy and accumulation of oxidative stress in the 10% group. Fewer mitochondria were observed with increased LAA intake. CONCLUSIONS: Excessive LAA consumption may damage the myocardium and the damage might result from oxidative stress accumulation and cellular atrophy.