They appear in food in pretty small amounts which is why they're the micronutrients;, but they're vital for health, so if you're deficient in micronutrients you've got big problems.

它们在食物中所占比重很小,这也是称它们为"微量元素"的原因,但它们对健康的意义却是至关重要的,如果缺乏微量元素的话会很糟糕

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

This is less of a problem in modern life then it used to be, but because things are supplemented and fortified-- overly so in some cases-- but still the deficiencies are less common then they used to be.

相比过去,这在现代社会中已不太多见,因为如今很多食物有人工添加的微量元素,有些甚至是过度添加了,但相比过去,缺乏微量元素已不那么常见了

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选