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What are micronutrients?

This article will focus on micronutrients, namely minerals and vitamins; describing what they are, and what their function is in the body.
© EIT Food

Intake requirements of minerals and vitamins vary from nutrient to nutrient and may also depend on an individual’s age, sex or physiological state (e.g. pregnant, lactating or other health conditions).

When inadequate levels of minerals or vitamins are consumed it results in a deficiency disease.


Minerals are inorganic substances required by the body in relatively small amounts. They cannot be synthesised in the body, so they need to come from the diet.
They play a key role in a variety of functions e.g.

  • Formation of bones and teeth
  • Enzyme systems
  • Nerve function
  • Controlling fluid in cells

At least 15 minerals are essential in the diet, although it is argued that more should be considered essential. Some are needed in very low amounts, these are termed the ‘trace minerals’.

Mineral Dietary sources
Sodium Salt
Potassium Fruit and vegetables
Magnesium Green leafy vegetables, nuts wholegrain, fish, meat, dairy
Calcium Dairy, fish, green vegetables
Phosphorus Dairy, seafood, chicken
Selenium (tr) Meat and cereals
Fluoride (tr) Some water, some toothpaste
Chloride Salt
Iodine (tr) Seafood
Chromium (tr) Meat, wholegrain
Manganese (tr) Vegetables, wholegrain, nuts, tea
Iron (tr) Red meat, green leafy vegetables
Copper (tr) Shellfish, nuts, wholegrain
Zinc (tr) Meat, wholegrain, pulses
Molybdenum (tr) Nuts, vegetables, wholegrain

tr= trace mineral

Mineral deficiencies

Iron and iodine deficiencies are the most common mineral deficiencies worldwide. Inadequate amounts of iron in the body lead to iron deficiency anaemia, a recent World Health Organisation (WHO) report suggests that 25% of the world population are anaemic; with prevalence highest in young women and children.

Anaemia in adults leads to fatigue and in children can lead to developmental delays. Iodine is a key constituent of thyroid hormones that regulate metabolic functions. Deficiency in iodine results in an enlarged thyroid gland (called goitre) and hypothyroidism in adults and is the most common preventable cause of cognitive impairment in infants.

Mineral excess

There are also cases where excess is more of an issue than deficiency; most minerals exhibit toxicity at high levels. Sodium is an example of this, unfavourably high intakes of sodium are observed all around the world, which leads to high blood pressure resulting in an increased risk of cardiovascular disease.

Decreasing salt intake to below the recommended levels could save 2.5 million lives a year according to the WHO.


Vitamins are organic substances that are required by the body. Most vitamins cannot be synthesised in the body and those that can, are not necessarily produced at levels to meet the demands of the body and so, like minerals, it is important to consume vitamins from a varied diet.

The 13 vitamins are divided into fat-soluble or water-soluble vitamins. Excessive consumption of water-soluble vitamins in the diet is not usually a problem as they are easily excreted, however, fat-soluble vitamins are not easily cleared and can build up leading to toxicity.


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Why do we need minerals?

Vitamins are required by the body for specific biochemical functions; they act as antioxidants to prevent damage from free radicals, are involved in enzymes systems and pro-hormone mechanisms.

Internationally, vitamin A is the most common vitamin deficiency and is most prevalent in low- and middle-income countries; low levels of vitamin A can lead to night blindness, and eventually permeant blindness.

In the current day, deficiency diseases in developed countries are rare, although vitamin D deficiency is a global public health issue, especially in countries where sun exposure is limited.

Due to its role in calcium regulation, deficiency in vitamin D leads to bone deformities, such as rickets and osteomalacia; for this reason, many countries recommend taking vitamin D supplements through the winter months.

Author: Dr Charlotte Mills

© University of Reading
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