英语语法分析

Pellagra is a disease that results from niacin deficiency.

糙皮病是一种由烟酸缺乏引起的疾病。

Maize contains the vitamin niacin, but not in a form the body can absorb.

玉米中含有维生素烟酸，但不以人体可吸收的形式存在。

Niacin is one of the most stable of the B-vitamins.

烟酸是最稳定的B族维生素中的一种。