Micronutrient - Magnesium, Potassium And Selenium

In this article on our short series on Micronutrients, we will be focusing on Magnesium, Potassium and Selenium.

Micronutrients are vitamins and minerals that are needed by the body in small amounts. They are essential to include in your diet to maintain good health. Micronutrients are different to macronutrients – fat, carbohydrates, and protein, which make up a larger proportion of our diets.

You need to ensure that you are eating a balanced diet to include as many different micronutrients as possible. Below we have focused on three micronutrients which can support heart and brain health.


Magnesium plays an important role in the movement of calcium and potassium across the cell membranes throughout our body. This contributes to maintaining a steady heartbeat, maintaining normal blood pressure, and helps the heart contract to pump blood round the body. Magnesium is also important for the conduction of electrical pulses along nerves., which ensures that nerves function properly.


This micronutrient is the third most abundant in the body. Along with sodium and chloride, potassium is constantly moving in and out of our cells. This movement is responsible for the creation of nerve impulses, which help our muscles to contract, including our heart. These nerve impulses also carry information between the brain and the rest of the body. Potassium also helps to regulate the fluid balance in our body and blood pressure.  

Too much potassium (> 3,700mg/day) can lead to symptoms of sickness, diarrhoea, and stomach pain.


Selenium is used to form selenoproteins, a group of proteins that play important roles in our body such as protecting tissues from inflammation. This includes the brain, heart, and blood vessels therefore it is important in both brain and cardiovascular health.  



Daily recommended intakes

So how much should you be eating of each micronutrient?


Should I take supplements?

Supplements of either one single micronutrient, or multiple micronutrients are readily available in pharmacies, supermarkets, and health food shops. However, if you eat a healthy, balanced diet you should not need to take supplements, unless directed by your health professional.

Exceptions to this are:

  • folic acid (a form of folate) supplements for women who are trying to get pregnant or during the first 12 weeks of pregnancy.
  • Vitamin D tablets between October and March (in the UK) containing no more than 10µg.



British Nutrition Foundation (2024) Vitamin and Minerals

Calderón-Ospina CA, Nava-Mesa MO. B (2020) Vitamins in the nervous system: Current knowledge of the biochemical modes of action and synergies of thiamine, pyridoxine, and cobalamin. CNS Neurosci Ther

Gröber U (2020) Brain nutrients: Cerebral metabolism and micronutrients

Narayanam H, Chinni SV, Samuggam S. (2021) The Impact of Micronutrients-Calcium, Vitamin D, Selenium, Zinc in Cardiovascular Health: A Mini Review. Front Physiol.

NHS (2024) Vitamins and Minerals

NIH. (2024) Magnesium: Fact Sheet for Health Professionals

NIH. (2024) Potassium: Fact Sheet for Health Professionals

Tangvoraphonkchai K, Davenport A. (2018) Magnesium and Cardiovascular Disease. Adv Chronic Kidney Dis.

Torres Daniel J. , Alfulaij Naghum , Berry Marla J. (2021) Stress and the Brain: An Emerging Role for Selenium


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