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.
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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
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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.
Also note:
Proteins are essential nutrients for the human body.
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Fat also supplies the body with energy. It contains more energy than any other nutrient
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Carbohydrates are energy-providing nutrients.
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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.