Micronutrients: an overview
The body needs vitamins and minerals in very small amounts — hence the name. This article describes how they are classified, where the familiar reference values come from and why nutrient contents in foods vary. It deliberately contains no statements about effects.
What micronutrients are
The term covers vitamins, minerals and trace elements. The distinction from macronutrients is purely one of quantity: while protein, fat and carbohydrate are measured in grams, here it is a matter of milligrams or micrograms. Micronutrients provide no energy.
What they have in common is that, with few exceptions, the body cannot produce them itself and therefore takes them in through food. One of those exceptions is vitamin D, which the body can form in the skin under the influence of sunlight — which is why specialist texts occasionally describe it as a hormone precursor rather than a vitamin in the narrow sense.
Fat-soluble and water-soluble
Vitamins are classified by solubility. Fat-soluble are A, D, E and K; they are absorbed together with dietary fats and can be stored in the body, mainly in the liver and fat tissue. Water-soluble are vitamin C and the B-group vitamins; they are stored only to a small extent, and excesses are largely excreted via the kidneys.
This distinction explains two practical observations: that fat-soluble vitamins are absorbed less well from a meal containing no fat at all, and that statutory maximum amounts in food supplements are laid down for some fat-soluble vitamins, while for water-soluble ones this is usually not the case in the same way.
Bulk and trace elements
Minerals are likewise distinguished by amount. Bulk elements include calcium, magnesium, potassium, sodium and phosphorus — a matter of several hundred milligrams up to a few grams a day. Trace elements such as iron, zinc, iodine, selenium and copper are taken in in considerably smaller amounts.
Absorption from food is not equally reliable for all of them. With iron, for instance, availability differs according to whether it comes from animal or plant foods, and it is influenced by other components of the same meal. The figure on the packaging therefore does not directly indicate how much actually arrives.
Interactions during absorption
Micronutrients are not absorbed independently of one another. A whole range of interactions is described, which can work in both directions. Vitamin C in the same meal improves the absorption of iron from plant sources; larger amounts of calcium and certain components of coffee and tea work the other way.
There is competition within a group too: some trace elements use the same transport routes in the gut, so a marked excess of one can impair the absorption of another. This is one reason maximum amounts are set for food supplements, and why a statement about your own status does not follow from a sum of individual figures.
In practice this does not mean meals have to be planned around interactions. Across a varied selection these effects largely balance out — they become relevant mainly where individual nutrients are taken deliberately and in larger amounts.
Where the reference values come from
The familiar daily figures are not individual prescriptions. They are set by professional bodies and authorities — in German-speaking countries by the nutrition societies, at European level by EFSA — for population groups, and graded by age and sex.
They are derived so as to cover the requirement of the great majority of a group. That necessarily means the value lies above the actual requirement for most individuals. Someone slightly below a reference value therefore does not automatically have too little — and someone above it does not automatically have enough. The percentages on packaging in turn refer to their own, legally defined reference amounts, which can differ from the professional bodies’ recommendations.
Why nutrient contents vary
Nutrition tables list average values. The actual content of a food depends on variety, growing conditions, time of harvest, storage duration and preparation. Water-soluble vitamins partly pass into the cooking water; heat and light act on some vitamins.
Conversely, preparation can also increase availability, for instance when cell structures are broken down. There is no general rule that “raw always means more”. In practice this mainly means: a table figure describes an order of magnitude, not the portion on your own plate.
Food supplements: what they are in law
Food supplements are legally foods, not medicines. They go through no approval procedure with proof of efficacy but are merely notified. For a number of vitamins and minerals there are maximum-amount rules and labelling requirements; which statements may appear on the pack is regulated across Europe and limited to an approved list.
This article deliberately names no amounts and no products. Whether something is lacking in an individual case cannot be read off a feeling or a table but, where appropriate, from blood values — and interpreting those belongs in medical hands. This applies particularly in pregnancy and breastfeeding, with pre-existing conditions, when taking medication and with a strongly restricted range of foods.
The key points
- Micronutrients provide no energy; the distinction from macronutrients is one of quantity.
- Fat-soluble vitamins (A, D, E, K) are stored; water-soluble ones only to a small extent.
- Availability differs by source and by the accompanying components of the same meal.
- Reference values apply to population groups and lie above actual requirements for most individuals.
- Table figures are averages; variety, storage and preparation change them.
- Food supplements are legally foods; interpreting blood values belongs in medical hands.
Last reviewed: 14.08.2026