Increased dietary fiber consumption has been associated with many beneficial effects, including amelioration of obesity and insulin resistance. These effects may be due to the increased production of short chain fatty acids, including propionate, acetate and butyrate, during fermentation of the dietary fiber in the colon. Indeed, oral and dietary supplementation of butyrate alone has been shown to prevent high fat-diet induced obesity and insulin resistance. This review focuses on sources of short chain fatty acids, with emphasis on sources of butyrate, mechanisms of fiber and butyrate metabolism in the gut and its protective effects on colon cancer and the peripheral effects of butyrate supplementation in peripheral tissues in the prevention and reversal of obesity and insulin resistance.

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Skeletal muscle mitochondrial dysfunction, evidenced by incomplete beta oxidation and accumulation of fatty acid intermediates in the form of long and medium chain acylcarnitines, may contribute to ectopic lipid deposition and insulin resistance during high fat diet (HFD)-induced obesity. The present review discusses the roles of anterograde and retrograde communication in nucleo-mitochondrial crosstalk that determines skeletal muscle mitochondrial adaptations, specifically alterations in mitochondrial number and function in relation to obesity and insulin resistance. Special emphasis is placed on the effects of high fat diet (HFD) feeding on expression of nuclear-encoded mitochondrial genes (NEMGs) nuclear receptor factor 1 (NRF-1) and 2 (NRF-2) and peroxisome proliferator receptor gamma coactivator 1 alpha (PGC-1α) in the onset and progression of insulin resistance during obesity and how HFD-induced alterations in NEMG expression affect skeletal muscle mitochondrial adaptations in relation to beta oxidation of fatty acids. Finally, the potential ability of acylcarnitines or fatty acid intermediates resulting from mitochondrial beta oxidation to act as retrograde signals in nucleo-mitochondrial crosstalk is reviewed and discussed.

The effect of pornography on sexual response is understudied, particularly among women. A multinational, community-based sample of 2433 women at least 18 years of age completed a 42-item, opt-in questionnaire collecting information on demographic and sexual history characteristics, use of pornography during masturbation, frequency of pornography use, and sexual response parameters. Pornography use and average frequency were compared across demographic variables. We also examined how pornography frequency predicted differences in self-reported arousal difficulty; orgasmic difficulty, latency, and pleasure; and the percent of sexual activities ending in orgasm during both masturbation and partnered sex. On average, women using pornography were younger, and reported more interest in sex. Pornography frequency differed significantly by menopausal status, sexual orientation, anxiety/depression status, number of sexual partners, and origin of data collection. During masturbation, more frequent pornography use predicted lower arousal difficulty and orgasmic difficulty, greater pleasure, and a higher percentage of masturbatory events leading to orgasm. Frequency of pornography use predicted only lower arousal difficulty and longer orgasmic latencies during partnered sex, having no effect on the other outcome variables. Pornography use frequency did not predict overall relationship satisfaction or sexual relationship satisfaction. Overall, more frequent pornography use was generally associated with more favorable sexual response outcomes during masturbation, while not affecting most partnered sex parameters. Several demographic and relationship covariates appear to more consistently and strongly predict orgasmic problems during partnered sexual activity than pornography use.