鱼_鱼

百度上说:
因为红薯含有一种氧化酶，这种酶容易在人的胃肠道里产生大量二氧化碳气体，如果红薯吃得过多，会使人腹胀、打嗝、放屁。其次，红薯里含糖量高，吃多了，可产生大量胃酸，使人感到“烧心”。胃由于受到酸液的刺激而加强收缩，此时胃与食管连接处的贲门肌肉放松，胃里的酸液即倒流进食管，人就吐酸水了。同时，糖分多了，身体一时吸收不完，剩余的在肠道里发酵，也会使肚子不舒服。

知乎上说:
红薯富含膳食纤维，可以促进肠道蠕动，促进排便。对于预防便秘、消化不良、痔疮有很好效果。被誉为“肠道清道夫”，排毒小帮手。红薯富含淀粉，但是膳食纤维的存在让人产生饱腹感，当主食可以减肥。红薯也被成为“穷人的食物”。

yahoo上说:
问:Why do we fart more if we eat sweet potato? What is the scientific reason behind?
Chinese medicine practitioners say it is good for liver. Just wondering whether it is related to farting or not.

答:The main component of sweet potato that causes flatulence (that’s fart for you) is carbohydrates. Especially oligosaccharides such as raffinose & stachyose. Beans and such are loaded with these particular type of carbohydrates.
Humans & some other animals (pigs, poultry etc.) do not possess the necessary enzymes to digest these types of carbohydrates and thus the oligosaccharides pass undigested through the stomach and upper intestine. In the lower intestine they are fermented by gas-producing bacteria which make carbon dioxide, methane, and/or hydrogen — leading to the flatulence.