It all depends on your metabolic type.
You also have to look at your background, where do you originate from, from what part of the globe because of your ancestors.
For exemple if you give a Eskimo a orange or a fruit like a watermelon this could make him very sick and if you give a Indian raw seal you will also make him very sick. I know that this is a extreme example but we are all in between.
Everybody has its own biochemical individuality. Meat is compressed plants and it has been showed that plants suffer also.