Possibly synonymize them, but maybe make a [nutrients] tag?
Micronutrients are not exactly equal to vitamins and minerals, though they are a bit of a subset.
Micronutrients are defined as:
a chemical element or substance required in trace amounts for the normal growth and development of living organisms.
Note the "trace amounts".
Vitamins & minerals are defined as:
vitamins are organic substances (made by plants or animals), minerals are inorganic elements that come from the soil and water and are absorbed by plants or eaten by animals
I'm not meaning either of these to be full exhaustive authoritative definitions, but I do believe they're pretty darn good ones.
What's the difference between the two? One of the only two differences I see is the "chemical element or substance" vs "organic substance..., inorganic substance". However, these are pretty much two ways to say the same thing.
The other is a bit more complicated. The "trace amounts" part. As I understand it, this means that all micronutrients are vitamins or minerals that are just needed in small amounts.
As such, I'd be in favor of synonymizing micronutrients with vitamins-and-minerals, but it might also be a good idea to make a brand-shiny-new nutrients tag.
We already have a nutrition tag, but that may end up being for nutrition in general as opposed to specific nutrients.
Proteins are essential nutrients for the human body.
Fat also supplies the body with energy. It contains more energy than any other nutrient
Carbohydrates are energy-providing nutrients.
These are the 3 things currently covered under macronutrients. All of them are, well, macro-nutrients, and I'd be in favor of also synonymizing this tag with nutrients. However, we may also want separate tags for protein, possible fat, and carbohydrates/carbs if they become common enough.