一道SAT OG语法题Eating garlic has long been regard as a means of

一道SAT OG语法题
Eating garlic has long been regard as a means of warding off malaise,and scientific research has shown that it does have some therapeutic value.
为什么这道题是No error.
as a means 这里没有错误么?为什么是means
Eating garlic has long been regarded as a means of warding off malaise,and ceientific resrearch has shown that it does have some therapeutic value.