What Are Micronutrients?

Overview

What are micronutrients?

Micronutrients are minerals and vitamins that your body requires in very small amounts. Micronutrients are used by your body to make substances in your body, such as hormones (chemical messengers), and enzymes which are needed for healthy growth and development, which are essential processes for life.

Why are micronutrients important for your health?

With your body only requiring micronutrients in small doses, you may ask what is their significance. Well, a deficiency in a micronutrient can be detrimental to your health, resulting in severe and possibly life-threatening conditions.

Types of micronutrients

Vitamins

1. Water-soluble vitamins

Vitamin C

Vitamin C is a water-soluble vitamin that has a role in immune function and support. Vitamin C does this in several ways¹:

• Vitamin C supports your epithelial barrier function: your epithelial cells cover both the inside and outside surfaces of your body. Vitamin C helps the epithelial barrier to prevent harmful microorganisms from entering your body or organs and causing potential infection
• Phagocytic cell function: Your phagocytic cells accumulate vitamin C. Phagocytic cells (a type of immune cell) ingest harmful microorganisms that cause infection in a process called phagocytosis, which is one of your body’s defences against microorganisms
• Antioxidant function: Vitamin C’s role in your body is not limited to supporting the immune system. Vitamin C is also a key antioxidant which neutralises free radicals, which are molecules that have the ability to harm your cells

B Vitamins

The group of B vitamins consists of 8 water-soluble vitamins which have an essential role in the body.²

The 8 B vitamins are as follows:

• Thiamine (B₁): Vitamin B₁ has a role in keeping your nervous system healthy and aiding your body in releasing energy via the breakdown of food
• Riboflavin (B₂): Riboflavin, similar to thiamine, keeps your nervous system healthy and aids in the release of energy from the breakdown of foods. However, riboflavin’s role extends to keeping your eyes and skin healthy
• Niacin (B₃): Similar to riboflavin and thiamine, niacin (vitamin B3) keeps the skin and nervous system healthy, and aids in the breakdown of food
• Pantothenic acid (B₅): Pantothenic acid (Vitamin B₅)helps to release energy from the breakdown of food in your body
• Pyridoxine (B₆): Pyridoxine (Vitamin B₆) helps your body to form red blood cells, which are essential to life, as they allow oxygen to be carried around your body to different cells. Pyridoxine also helps your body to use and store energy from carbohydrate and protein sources
• Biotin (B₇): Biotin is needed in small amounts to help your body make fatty acids
• Folate (B₉): Folate is needed for the formation of healthy red blood cells, and also prevents the formation of spina bifida in unborn babies
• Cobalamin (B₁₂): Vitamin B₁₂ is needed for your body to produce red blood cells and prevents you from developing anaemia

2. Fat-soluble vitamins

Vitamin A

Vitamin A is an essential fat-soluble micronutrient, which is responsible for the following³:

• Maintaining your vision
• Promoting growth and development in your body
• Enhancing immune function, which is critical in your body’s defence against harmful microorganisms
• Protecting your epithelium, which surrounds your body’s outer and inner surfaces. Your epithelium acts as a barrier, preventing harmful microorganisms from entering your body and causing infection³

Vitamin D

Vitamin D is another essential fat-soluble micronutrient that is produced in the human skin when you come into contact with UV radiation. Vitamin D can be obtained via food sources too and is essential for life. It performs the following functions in the body⁴: 

• Maintaining calcium levels in the body at the optimum physiological range. Calcium is necessary for a wide range of cellular and metabolic processes within your body
• Bone fracture healing
• Reducing the risk of falling over 

Vitamin E

Vitamin E is another fat-soluble micronutrient which has an important antioxidant function within your body, as well as contributing to immune function and your inflammatory response. Observational studies have demonstrated the joint benefit of both vitamin C and vitamin E in reducing the risk of metabolic diseases.⁵

Vitamin K

Vitamin K₁ and Vitamin K₂ both have antioxidant properties. Vitamin K also has an anti-inflammatory effect and may have a protective role in age-related diseases, such as cardiovascular diseases.⁶

3. Minerals

Macro-minerals

Macro-minerals are required in a large amount, greater than 100 mg per day. Macro-minerals include the following⁷:

• Chloride: Chloride has roles in digestion, water balance, and muscular activity, to name a few
• Sodium: Sodium has many different roles within your body, including maintaining water balance and innervating your nerves. Sodium also has a role in muscle contraction
• Phosphorus: Phosphorus is a key component of different structures in your body, including your teeth and your skeleton (similar to calcium). phosphorus is also found within your DNA
• Calcium: Calcium is a key mineral needed in many different structures in the body, including your teeth and your skeleton
• Magnesium: Magnesium has many different roles in your body, including energy storage, bone development, and a role in signalling pathways in your body
• Potassium: Similar to sodium, potassium also has a role in muscle contraction, as well as a role in nerve innervation and water balance

Micro-minerals

Compared to macro-minerals, micro-minerals are required in a smaller amount (less than 100 mg per day). Micro-minerals include the following⁷:

• Selenium: Selenium has a role in antioxidant defence, and in anabolic processes (the process of making complex molecules) within your body
• Iron: Iron has a key role in oxygen being transported around your body in red blood cells. Transportation of oxygen ensures that your body cells and the tissues and organs that these cells make up can survive
• Copper: Copper is an essential element of many different proteins which make up your body
• Zinc: Zinc is important for many different enzymes in your body, which help to speed up chemical reactions 
• Iodide: Iodine is needed for making thyroid hormones within your body, which regulate your body temperature, heart rate and blood pressure 

Dietary sources of micronutrients

Vitamins

Fruits and vegetables

Typically, the water-soluble vitamins (vitamin C and B vitamins) are sourced from fruit and vegetables. 

• Vitamin C: this can be sourced from citrus fruits, broccoli, blackcurrants, strawberries and peppers to name a few (NHS)
• B vitamins: B vitamins can be sourced from peas, bananas and oranges (NHS)
• Vitamin A: this can be sourced from mangos, apricots, papaya, spinach (green leafy vegetables), sweet potatoes, red peppers and more (NHS)
• Vitamin K: this can be sourced from green leafy vegetables, which include spinach and broccoli (NHS)

Animal products

Vitamins that can be sourced from animal products are listed below, with some suggestions of which animal products they can be sourced from:

• Vitamin B1: sourced from meat and fish
• Vitamin B2: sourced from lean beef and pork, organ meats, chicken breast, eggs, and milk to name a few
• Vitamin B3: sourced from red meat, poultry, and fish
• Vitamin B5: sourced from organ meats, chicken breast, and dairy products
• Vitamin B6: sourced from tuna, salmon, poultry and beef liver
• Vitamin B7: sourced from beef liver, salmon and pork
• Vitamin B9: sourced from eggs and liver
• Vitamin B12: this can be sourced from animal products such as meat, poultry, eggs and dairy products such as milk⁸
• Vitamin A: sourced from beef liver, milk and eggs
• Vitamin D: best sourced from fatty fish and fish oils
• Vitamin E: best sourced from liver, egg yolk, meats and eggs

Minerals

Plant-based sources

• Calcium: Found in leafy green vegetables
• Magnesium: Sourced from spinach, legumes, and broccoli
• Potassium: Found in a variety of fruits and vegetables
• Iron: Found in fruits and green vegetables

Animal-based sources

• Calcium: Sourced from cheese, milk, salmon, yoghurt
• Potassium: Found in meats and milk
• Copper: Sourced from shellfish
• Iodide: Sourced from seafood
• Iron: Red meat, eggs, and poultry are sources
• Selenium: Found in seafood and organ meat

Recommended daily intake

Recommended dietary allowances (RDAs) and upper limits

The recommended daily intake of micronutrients for adults, with their upper limits can be found at this link to the Harvard website.

Deficiency and excess

Micronutrient deficiency disorders

Micronutrient deficiencies can cause several diseases, which include the following⁹:

• Acute respiratory infections 
• Cancer 
• Rickets 
• Loss of vision 

Micronutrient toxicity

Micronutrient toxicity is when toxic levels of a nutrient or vitamin build up in your body, which can have adverse effects. One example is vitamin D toxicity, which is caused by taking too much vitamin D via vitamin supplements, which can cause bone and kidney problems.

Summary

Micronutrients are nutrients or vitamins that your body requires in small doses and are crucial to your body’s everyday functioning. Micronutrients can be sourced from both animal and plant sources, depending on the nutrient/vitamin. The recommended daily amount of micronutrients varies for each vitamin/nutrient. Not taking enough of the recommended daily amount of micronutrients or taking too many may cause deficiencies or result in toxicity, both of which have adverse effects