21. What do some nutritionists say about a strict vegetarian diet?

21.关于一个严格的素食食谱，一些营养学家说了什么？

However, some nutritionists advise against switching to a totally strict vegetarian diet.

然而，一些营养学家对转向完全严格的素食食谱表示反对。

However, some nutritionists advise against switching to a totally strict vegetarian diet. They believe such a diet which includes no products from animal sources can be deficient in many of the necessary vitamins and minerals our bodies need.

然而，一些营养学家不建议人们变成绝对的素食主义者。他们认为这样的饮食不利于人类从动物身上摄取必要的维他命和矿物质。