I just came home very late from a dinner party; when you meet up with a bunch of people to share and enjoy food, you don’t think about the fact that we actually eat to survive. Food contains nutrients which our bodies use to build, to repair, to regulate and to manufacture energy. All living organisms need to sustain themselves by ingesting the necessary substances.
When you think of what nutrients actually are, the usual suspects are groups of chemical compounds such as proteins, fats and carbohydrates. All of these provide energy for the body, and they’re organic by their origin.
However, there is a fourth group of organic nutrients that is surprisingly different, and these are vitamins. For starters, vitamins do not provide energy, but are vital nutrients, meaning the organism requires them in particular — usually small — amounts so that it can carry out particular chemical reactions. The functionality of vitamins is biochemically complex, ranging from anti-oxidant activity to cell growth regulation.
A most interesting aspect is the fact that vitamins are not even a group in its own right. An organic nutrient is a vitamin only if the organism doesn’t produce enough of it, so that the bulk of the vitamin needs to come from food.
For example, vitamin C or ascorbic acid is a ‘vitamin’ for humans, because we don’t synthesise enough of it in the body. However, for a cat there is often plenty of ascorbic acid produced in their liver, so they don’t need to ingest any extra. Therefore vitamin C wouldn’t count as a ‘vitamin’ for cats.
The stuff that goes under the label ‘vitamin’ is in fact a medley of chemical diversity; a nice reminder that sometimes concepts are more useful than true-to-life categories.