In general,a complete diet should provide all the vitamins a body needs in their natural form.

VOA: special.2009.04.21

But it's also helpful to think just for health and well-being in general, what might be done to improve the diet and this will be a good way to try to get at that.

但如果出于健康考虑,想想如何能改善饮食,也是很有益处的,这次的作业就是一个改善饮食的好方式

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选