Increased intake of dietary carbohydrate that is fermented in the colon by the microbiota has been reported to decrease body weight, although the mechanism remains unclear. Here we use in vivo11C-acetate and PET-CT scanning to show that colonic acetate crosses the blood–brain barrier and is taken up by the brain. Intraperitoneal acetate results in appetite suppression and hypothalamic neuronal activation patterning. We also show that acetate administration is associated with activation of acetyl-CoA carboxylase and changes in the expression profiles of regulatory neuropeptides that favour appetite suppression. Furthermore, we demonstrate through 13C high-resolution magic-angle-spinning that 13C acetate from fermentation of 13C-labelled carbohydrate in the colon increases hypothalamic 13C acetate above baseline levels. Hypothalamic 13C acetate regionally increases the 13C labelling of the glutamate–glutamine and GABA neuroglial cycles, with hypothalamic 13C lactate reaching higher levels than the ‘remaining brain’. These observations suggest that acetate has a direct role in central appetite regulation.

參考譯文：
科學家發現，食物中的膳食纖維在腸道中經一些微生物發酵后能產生一種“抗食欲”分子——醋酸，這對于節食者來說將是個好消息。
多吃膳食纖維有助于減肥，這點已為人們所知。最近，研究者們使用同位素示蹤的方法發現：有些糖類膳食纖維在小鼠的大腸中經微生物發酵產生醋酸，醋酸根進入血液并到達腦部透過血腦屏障。下丘腦醋酸根濃度的升高使小鼠的食欲受到抑制。給小鼠的腹腔內注射醋酸鹽也能起到類似抑制食欲的作用，這也為這個新發現提供了證據。
不過，易發酵的膳食纖維才有這個作用，不易發酵的如纖維素則沒有。
 
原始來源：http://www.nature.com/ncomms/2014/140429/ncomms4611/full/ncomms4611.html