Micronutrients defined

What are micronutrients

Nutrition is more complex than simply having enough to eat. It is a critical part of staying healthy at all life stages ¹. Nutrients can be divided into macro and micronutrients. They provide energy, the building blocks for protein to grow and maintain muscle mass and maintain normal bones, and are essential for controlling all the chemical processes that take place in our bodies ². Making sure that our intake of macronutrients or micronutrients is optimal through good dietary choices is a great start to look after your health and well-being.

Macronutrients are required by the human body in large quantities (macro means large) and are used for energy production as well as for growth and maintenance, transport and making more complex molecules. They make up the bulk of our food and it is not hard to get enough of them. There are only three types of macronutrient; they are proteins, carbohydrates and fats ³ although fibre is often also included.

In contrast, micronutrients (sometimes called vitamins and minerals) are required in very small amounts but benefit the body in very important ways. Because they make up such a small fraction of what we eat, and because there are 27 different types, it can be hard to make sure that we get enough of them. Apart from vitamin D, they cannot be made by the body and must be derived from our diet ⁴.

What are micronutrients?

The World Health Organisation micronutrients definition is:

“vitamins and minerals needed by the body in very small amounts”

It is also stressed that the benefit of micronutrients on the body is critical as they perform a range of functions, including enabling the body to produce enzymes, hormones and other substances needed for normal growth and development ⁵.

Both macro and micronutrients are essential but with micronutrients but as the name suggests, tiny quantities play a vital role in maintaining a healthy body. Vitamins and minerals are classified as micronutrients and common micronutrients examples include vitamin C and iron.

What are the functions of micronutrients?

Micronutrients are used for a huge range of different functions and the full extent of their role is still being discovered. They are used in all the vital processes that the body carries out. For example, magnesium is used for electrolyte balance, energy-yielding metabolism and many other functions ⁶.

The proven functions of some of the main micronutrients are detailed in the tables below ⁶.

What are the different types of micronutrients?

Micronutrients can be classified as water-soluble vitamins, fat-soluble vitamins, microminerals and trace minerals. There are Nutrient Reference Values given for 13 vitamins and 14 minerals and these are used for food labelling. They are EU guidance levels on the daily amount of vitamin or mineral that the average healthy person needs. This is based on detailed reviews of the research and are applied to all products for adults ⁷. The values are given here together with the foods that contain them.

Water-soluble vitamins – functions and sources

These vitamins can be dissolved in water which means that any excess is flushed out of the body and they need to be replenished through the diet daily.

Ingredients	Nutrient Reference Values (NRV) for adults⁷	Food source examples⁸	Function⁶
Vitamin B1 (thiamine)	1.1 mg/day	Peas, Bananas, Wholegrain breads, Nuts	Energy yielding metabolism, Function of the nervous system, Normal psychological function, Cardiac function
Vitamin B2 (riboflavin)	1.4 mg/day	Milk and plain Yoghurt, Eggs, Mushrooms	Contribution to normal energy-yielding metabolism, Maintenance of the normal function of the nervous system, Maintenance of normal red blood cells, Maintenance of normal skin and mucous membrane,s Maintenance of normal vision, Contribution to normal metabolism of iron, Protection of DNA, proteins and lipids from oxidative damage, Reduction of tiredness and fatigue
Vitamin B3 (niacin)	16mg/day	Meat, Fish, Eggs, Wheat flour	Contribution to normal psychological functions, Contribution to normal energy-yielding metabolism, Function of the nervous system, Maintenance of normal skin and mucous membranes, Reduction of tiredness and fatigue
Vitamin B5 (pantothenic acid)	6mg/day	Chicken, Beef, Eggs, Mushrooms	Energy-yielding metabolism, Mental performance, Synthesis and metabolism of steroid hormones, vitamin D and some neurotransmitters, Reduction of tiredness and fatigue
Vitamin B6 (pyridoxine)	1.4mg/day	Meat and poultry, Peanuts, Soya beans, Bananas	Contribution to normal cysteine synthesis, Contribution to normal energy-yielding metabolism, Function of the nervous system, Contribution to normal homocysteine metabolism, Protein and glycogen metabolism, Contribution to normal psychological functions, Red blood cell formation, Function of the immune system, Reduction of tiredness and fatigue, Regulation of hormonal activity
Vitamin B7 (biotin)	50µg/day	Wide range of foods at very low levels	Energy-yielding metabolism, Function of the nervous system, Contribution to normal macronutrient metabolism, Contribution to normal psychological functions, Maintenance of normal hair, Maintenance of normal skin and mucous membranes
Vitamin B9 (folate or folic acid) *	200µg/day	Green vegetables such as broccoli, cabbage and spinach, Chickpeas and kidney beans	Maternal tissue growth during pregnancy, Contribution to normal amino acid synthesis, Blood formation, Homocysteine metabolism, Contribution to normal psychological functions, Function of the immune system, Reduction of tiredness and fatigue, Cell division
Vitamin B12 (cobalamin)	2.5µg/day	Meat, Fish, Milk and cheese, Eggs	Energy-yielding metabolism, Contribution to neurological and psychological function Contribution to normal homocysteine metabolism, Contribution to neurological and psychological function, Red blood cell formation, Function of the immune system, Reduction of tiredness and fatigue, Cell division
Vitamin C (ascorbic acid)	80mg/day	Citrus fruits and juice, Peppers, Blackcurrants	Function of the immune system during and after extreme physical exercise, Collagen formation, Contribution to normal energy-yielding metabolism, Function of the nervous system, Contribution to normal psychological functions, Maintenance of the normal function of the immune system, Protection of DNA, proteins and lipids from oxidative damage, Reduction of tiredness and fatigue, Regeneration of the reduced form of vitamin E, Non-haem iron absorption

* it is recommended that women trying to become pregnant or who are pregnant take a 400µg folic acid supplement daily until the 12th week of pregnancy.

Fat-soluble vitamins - functions and sources

Fat-soluble vitamins are absorbed through the gut with the help of fat. They can be stored in the liver and fatty tissue until the body needs them.

Ingredients	Nutrient Reference Values (NRV) for adults⁷	Food source examples⁸	Function⁶
Vitamin A	800µg/day	Cheese, Eggs, Oily fish, Milk	Metabolism of iron, Maintenance of normal skin and mucous membranes, Maintenance of normal vision, Maintenance of the normal function of the immune system, Cell differentiation
Vitamin D (Cholecalciferol)	10µg/day	Oily fish such as salmon and mackerel, Red meat, Egg yolks	Absorption and utilisation of calcium and phosphorus and maintenance of normal blood calcium concentrations, Maintenance of bones and teeth, Normal muscle function, Normal function of immune system and inflammation response, Cell division
Vitamin E	12mg/day	Plant oils such as sunflower and olive oil, Nuts and seeds Wheatgerm	Protection of DNA, proteins and lipids from oxidative damage
Vitamin K	75µg/day	Green leafy vegetables such as broccoli, Cereal grains	Blood coagulation, Maintenance of bones

Microminerals - functions and sources

These are minerals that the body requires in larger amounts, these are sometimes called macrominerals. ¹²

We need 100s or 1,000s of milligrams (mg) every day to carry out specific roles.

Ingredients	Nutrient Reference Values (NRV) for adults⁷	Food source examples⁸	Function⁶
Calcium	800mg/day	Dairy products, Green leafy vegetables such as curly kale and spinach	Blood coagulation, Energy-yielding metabolism, Muscle function and neurotransmission, Function of digestive enzymes, Regulation of cell division and differentiation, Maintenance of normal bones and teeth
Phosphorus	700mg/day	Red meat and poultry, Dairy products, Fish	Energy-yielding metabolism, Function of cell membranes, Maintenance of bone and teeth
Magnesium	375mg/day	Spinach, Nuts, Wholemeal bread	Reduction of tiredness and fatigue, Electrolyte balance, Energy-yielding metabolism, Neurotransmission and muscle contraction including heart muscle, Protein synthesis, Contribution to normal psychological functions, Maintenance of bones, Maintenance of teeth, Cell division
Potassium	2000mg/day	Bananas, Vegetables such as broccoli and parsnips, Beans, pulses, nuts and seeds	Muscular and neurological function, Blood pressure

Trace minerals - functions and sources

Trace minerals are required in extremely small amounts but are crucial for essential life processes. Our bodies need just tens of milligrams or even just micrograms every day.

Ingredients	Nutrient Reference Values (NRV) for adults⁷	Food source examples⁸	Function⁶
Iron	14mg/day	Red meat, Beans such as red kidney beans and chickpeas, Nuts and dried fruit	Cognitive function, Contribution to normal energy-yielding metabolism, Formation of red blood cells and haemoglobin, Oxygen transport, Function of the immune system, Reduction of tiredness and fatigue, Cell division
Manganese	2mg/day	Bread, Nuts, Green vegetables such as peas	Contribution to normal energy-yielding metabolism, Maintenance of bones, Contribution to normal formation of connective tissue, Metabolism of fatty acids
Copper	1mg/day	Nuts, Shellfish	Maintenance of connective tissues, Contribution to normal energy-yielding metabolism, Maintenance of the normal function of the nervous system maintenance of skin and hair pigmentation, Iron transport, Maintenance of the normal function of the immune system, Protection of DNA, proteins and lipids from oxidative damage
Zinc	10mg/day	Meat, Shellfish, Dairy products	DNA synthesis and cell division Acid-base metabolism, Contribution to normal carbohydrate metabolism, Cognitive function, Fertility and reproduction, Contribution to normal macronutrient metabolism, Maintenance of normal serum testosterone concentrations, Vitamin A metabolism, Contribution to normal protein synthesis, Maintenance of bones, Maintenance of normal hair, normal nails, normal skin Fertility and reproduction, Maintenance of vision, Function of the immune system, Protection of DNA, proteins and lipids from oxidative damage, DNA synthesis and cell division
Iodine	150µg/day	Sea fish and shellfish	Contribution to normal cognitive and neurological function, Contribution to normal energy-yielding metabolism, Maintenance of skin, Contribution to normal thyroid function and production of thyroid hormones
Selenium	55µg/day	Brazil nuts, Fish and meat, Eggs	Spermatogenesis, Maintenance of normal hair, Maintenance of normal nails, Maintenance of the normal function of the immune system, Thyroid function, Protection of DNA, proteins and lipids from oxidative damage

Some micronutrients are considered to be antioxidants due to one of their roles being to protect cells from oxidative stress. These micronutrients are vitamins C and E, Riboflavin, Selenium, Zinc, Copper and Manganese ^{9, 10} There are further micronutrients such as chromium, and molybdenum that play an important role in the body.

Why take micronutrient supplements?

It is not always easy to calculate micronutrients in food items accurately to be sure we are getting adequate amounts in our diet. Making sure our body has enough of these essential nutrients is vital to ensure it is working at its best. Some groups of people need more of certain nutrients than others, for example, women trying to get pregnant or who are pregnant are advised to take 400µg Folic Acid supplement.

You can have confidence that your body is well-fuelled by eating a balanced diet that includes five portions of fruit and vegetables, high fibre starchy foods, dairy (or dairy alternative), protein from meat, beans, pulses, fish or eggs and unsaturated oils ¹³.

However, our nutritional needs are constantly changing due to ageing, diet changes and exercise changes and our demanding lifestyles mean that it can be difficult to maintain the correct micronutrients daily intake. A micronutrient supplementation program is a safe and convenient way to top up our intake of these essential nutrients.

Take away message for micronutrients

Micronutrients are substances that are needed in very small quantities by the body and are sometimes referred to as vitamins and minerals. They fulfil a vital role which enables the proper function of our bodies. They are present in a wide range of foods and you can also get them from supplements. However, micronutrient supplements should not be used as a replacement for a balanced diet. Before beginning supplementation, speak to a health care professional.

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