Microplex VMz food supplement dōTERRA | 120 capsules

The name vitamin A covers retinol and its plant precursors, the carotenoids. The best known is beta-carotene, the orange pigment of carrots, which the body converts into retinol. Pale yellow and oily, vitamin A is as sensitive to light as to oxygen, hence the opaque bottle.

The calcium used here comes from fossilised coral gathered from the ground, a source naturally rich in calcium carbonate and marine trace elements. Its very fine grind makes it easy to encapsulate. It is the bulkiest ingredient of the formula, which explains the number of capsules per serving.

As ascorbic acid, vitamin C is a white, highly soluble and distinctly acidic powder: the very molecule found in citrus fruit. It breaks down with light, heat and air, which calls for tightly closed packaging.

The twelfth element of the periodic table, magnesium never occurs on its own in a food: it is always bound to an acid, citrate, bisglycinate or oxide. The form chosen changes everything, from the taste to the volume of powder needed for one and the same quantity.

Vitamin E is not one molecule but a family of eight, four tocopherols and four tocotrienols. Most supplements keep only one, alpha-tocopherol. Keeping the whole spectrum, as here, calls for a more careful extraction from vegetable oils.

K1, or phylloquinone, is found in green leaves, where it takes part in photosynthesis: that is where its name comes from. K2, or menaquinone, is produced by bacteria, notably during the fermentation of soy. Two very different origins under one and the same letter.

Thiamine was the first vitamin to be isolated, in the 1920s, which earned it the number 1. Its name comes from the sulphur it contains, thio in Greek. Highly water-soluble, it passes into the cooking water, which is why boiled foods keep little of it.

Riboflavin owes its name to the Latin flavus, yellow: it is what gives multivitamin supplements their vivid colour. Fluorescent under ultraviolet light, it also serves as a food colouring, where it carries the code E101.

Vitamin B3 comes in two forms, nicotinic acid and nicotinamide. The first was originally obtained by oxidising nicotine, hence its name, though it shares nothing else with it. It stands up well to heat, which is rare in this family.

Vitamin B6 groups three related forms, pyridoxine, pyridoxal and pyridoxamine, which the body converts into a single active form. Isolated in the late 1930s, it is found in yeast, whole grains and bananas. It dissolves in water and breaks down in light.