the problem of choosing the possessive properly.
The value of a particular food is an estimation of how good it is, based on its level of vitamins, minerals, or calories.

I think "Its" of "its level" indicates vitamins, minerals, or calories. Then, should it be "their levels"?

Question

the problem of choosing the possessive properly.
The value of a particular food is an estimation of how good it is, based on its level of vitamins, minerals, or calories.

I think "Its" of "its level" indicates vitamins, minerals, or calories. Then, should it be "their levels"?

Answer

No. "Its" is correct. The sentence is talking about the value of a PARTICULAR FOOD (singular). Therefore, "it" is referencing the food.

The word "food" be plural can sometimes, but the word "particular" shows that it is singular in this case.