What determines whether a mineral is macronutrient and a micronutrient?

Answer 1

Macronutrients are either proteins, carbohydrates, or fats. They are considered macro because the body needs them in pretty large amounts. Vitamins and minerals are considered micronutrients, because the body only needs them in small amounts.

Answer 2

The need for a macronutrient vs micronutrient is based solely on the animal's need for that nutrient. For a human, we need a large (macro-) amount of proteins, carbohydrates and fat, so these are the human's macronutrients. Examples of micronutrients (micro = little) for the human are the vitamins, minerals such as iron, calcium, iodine and sodium, and organic acids such as acetic acid, citric acid and lactic acid. Generally minerals are not considered macronutrients, unless you are breaking the macronutrient glucose into its mineral components -- carbon, oxygen, hydrogen.

Answer 3

First a macronutrient is a substance that is needed in large quantities by the animal or plant; whereas, a micronutrient is necessary but needed in small quantities. For a human, the macronutrients are carbohydrates, proteins and fats, and the individual minerals are part of the micronutrient needs.

This is different in a plant. There are 3 classes each having 3 minerals which are considered macronutrients because a plant uses all 9 in very large quantities.