And if food is anything you eat, it gives you a nutrient, then basically everything satisfies the criteria for food; not everything in the world, but most things would.

若不论吃什么,只要提供营养就是食物,那基本上没有什么不满足食物的定义,倒不是说一切东西,至少绝大部分都满足

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

So nutrition is really what people are eating; and that overlaps with the concept of diet, which is when people are making specific choices about what to eat, how do they partition their nutrients.

营养学研究的是人们吃的东西,及其与饮食概念的交叉学科,也就是人们决定吃什么之后,如何区分其中的营养素

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选