Micronutrients are the nutrients in your food that do not account for calories. Micronutrients are all the vitamins and minerals which a food contains. For example, potatoes are extremely high in micronutrients, perhaps even one of the highest in the world of food. Take a look at the profile and you’ll get the idea.
Micronutrients are used for staving off malnutrition related diseases. Think scurvy, which only occurs when the body is at a severe deficiency of vitamin C. It’s the same with all micronutrients like iron and iron deficiency. Generally, if you lack micronutrients you also probably lack macronutrients and vice versa. This is not because the two are necessarily connected, but just that people who do not eat enough probably don’t have a complete micronutrient intake, and people who do eat enough probably have an adequate micronutrient intake. This is a rule of thumb and does not account for specific instances. For example: if someone were only to eat a potato with butter and cheese everyday, they would most likely have healthy levels of micronutrients in their body. However, due to the severe lack of macronutrients, their body would be withering away.
This is why it is important to get a good variety of food so that you can make sure to get a healthy amount of micronutrients.