Now that we’ve covered the Macronutrients (Carbohydrates, Protein and Fat), let’s take a look at the Micronutrients (Vitamins and Minerals) we need in our diet. They are named this because we only need minute amounts of them in order to have a healthy, balanced diet but they are still vital for various different reasons. Vitamins and Minerals are gauged in grams (g), milligrams (mg) and micrograms (mcg or µg).
1g = 1000mg
1mg = 1000µg
Vitamins are complex organic substances which are found in our food. They support almost every system in the body including the immune system, brain and nervous system. There are two subgroups of vitamins; water-soluble and fat-soluble.
This group of vitamins can be excreted in the urine if consumed in excess. This group includes all the B Vitamins and Vitamin C.
Vitamin C – Also known as Ascorbic Acid. It is an antioxidant which helps with the repair of blood vessels, cells, gums, bones and teeth. It also helps with immune function and our resistance to infection. It is necessary for the absorption of iron. Sources include citrus fruits, broccoli, tomatoes, cauliflower, potatoes, dark green leafy vegetables, brussel sprouts and cabbage. The Recommended Daily Amount (RDA) is 80mg.
B1 Thiamin – This is used in energy metabolism for the nerves, tissue, heart, brain and muscles. It is also necessary for the conversion of carbohydrates to energy. Sources include dried yeast, beans, whole grains, oatmeal, pork, vegetables, milk, brown rice and enriched cereal. The RDA is 1.1mg.
B2 Riboflavin – This is used in energy metabolism, supports healthy skin, hair and nails and supports vision. Sources include milk, liver, eggs, meat, leafy green vegetables, fish, whole grains, enriched bread and cereal. The RDA is 1.4mg.
B3 Niacin – This is used in energy metabolism, supports healthy skin, nervous system and digestive system. It is also needed for synthesis of sex hormones, cortisone, thyroxin and insulin. Sources include liver, lean meats, whole grains, peanuts, fish, eggs, avocados, sunflower seeds, prunes, enriched bread and cereal. The RDA is 18mg.
Pantothenic Acid – This is essential for carbohydrate conversion to energy, synthesis of antibodies and produces anti-stress hormones. Sources include meat, whole grains, wheat bran, liver, eggs, nuts, yeast and green vegetables. The RDA is 6mg.
B6 Pyridoxine – This is used in amino acid and fatty acid metabolism, helps form red blood cells and antibodies, supports a healthy nervous system and helps the body to absorb zinc. Sources include avocados, bananas, fish, wheat bran, liver, cantaloupe, cabbage, milk, eggs and seeds. The RDA is 1.4mg.
Vitamin B12 – This helps form new cells, supports a healthy nervous system, regenerates new blood cells and is necessary to utilise fats, proteins and carbohydrates. Sources include liver, beef, cheese milk, kidneys, yoghurt and eggs. The RDA is 2.5µg.
Biotin – This is used in energy and amino acid metabolism and fat synthesis and breakdown. Sources include liver, egg yolk and green vegetables. The RDA is 50µg.
Folic Acid – This is essential for the division of body cells, the production of nucleic acids and for forming red blood cells. Sources include legumes, liver, leafy green vegetables, beans and nuts. The RDA is 200µg.
This group of vitamins are found in their greatest quantities in fatty or oily foods. The body has the ability to store these vitamins in the liver and adipose tissues (fat deposits around the body). These vitamins cannot be excreted through the urine as they are not water soluble. This means that they can accumulate in the body, particularly the liver. Therefore, high intakes of these vitamins may be harmful, especially vitamins A and D.
Vitamin A – Also known as Retinol. It aids hormone synthesis, is necessary for healthy eyesight, is important for mucous membranes, aids synthesis of protein and aids tissue development. Sources include fortified milk, cheese, butter, liver, eggs, dark green leafy vegetables and deep orange fruits and vegetables. The RDA is 800µg.
Beta Carotene – This is converted to Vitamin A by the liver. It is an antioxidant and aids in the prevention of infections. Sources include carrots, apricots, cantaloupe, parsley, spinach, kale and sweet potatoes. There is no RDA.
Vitamin D – This is important to help develop strong bones and teeth, is necessary for the absorption of Magnesium, Calcium, Zinc, Iron and Phosphorous, and helps the body to absorb and digest Vitamin A. Sources include milk and dairy products, oily fish, fish-liver oils and sunlight. The RDA is 5µg.
Vitamin E – This is an antioxidant which helps with the development and maintenance of nerves and muscles, slows the aging process and improves the immune activity in the body. Sources include wheatgerm, soybeans, vegetable oils, broccoli, leafy green vegetables, whole wheat, eggs, oats, almonds, butter, peanuts, sunflower oil and seeds. The RDA is 12mg.
Vitamin K – This is required for bone calcification and mineralization (these are essential for the formation and hardening of the bones), is essential for the formation of prothrombin (a protein present in blood plasma which is produced in the liver in the presence of Vitamin K) and is a blood clotting chemical. Sources include yoghurt (live) alfalfa, egg yolks, broccoli, brussel sprouts, leafy green vegetables, green tea, kelp, wholegrains, liver, tomatoes, fish-liver oils and is made by bacteria in the intestines. The RDA is 75µg.
Minerals are elemental sources. They are found in the soil and are absorbed by plants which we eat or are eaten by animals – which we then eat. This means we can get minerals from animal and vegetable sources. Minerals have many different roles such as, structural role (i.e. calcium in bones and teeth) or regulatory roles (i.e. sodium in fluid balance). There are two subgroups of minerals; macro minerals and trace minerals.
There are five main minerals in this group and they are called “macro minerals” because we need relatively high amounts each day.
Calcium – This is needed for strong bones and teeth, muscle contraction and relaxation, blood clotting, nerve function, regulating blood pressure and helps metabolise iron. Sources include milk products, dark green leafy vegetables, broccoli, shrimp, salmon, clams, fortified orange juice, legumes and tofu. The RDA is 800mg.
Magnesium – This is needed for the development of bones and teeth, to transmit nerve impulses, for muscle contraction and to activate enzymes needed for energy. Sources include whole grains, nuts, legumes, dark leafy green vegetables, bananas and dark chocolate. The RDA is 375mg.
Phosphorous – This is needed for strong bones and teeth, buffer in acid-base balance, helps to emulsify and transport fat and to oxidise carbohydrates. Sources include meat, eggs, poultry, milk products, legumes and nuts. The RDA is 700mg.
Potassium – This is needed for fluid balance, transmission of nerve impulses and helps in the making of protein. Sources include legumes, meat, vegetables, bananas, milk and fruit. The RDA is 2000mg.
Chloride – This is needed for fluid balance, acid-base balance and transmission of nerve impulses. The main source of this is salt. The RDA is 800mg.
This group contains the remaining minerals which we only need small amounts of each day.
Chromium – This is associated with the hormone insulin and is needed for the release of energy from glucose. Sources include meat, vegetable oil and whole grain cereals. The RDA is 40µg.
Copper – This is needed for the production of haemoglobin (the protein molecule in the red blood cells which carries oxygen from the lungs to the body’s tissues), helps make red blood cells and helps with several other enzyme functions. Sources include organ meats, shellfish, legumes and nuts. The RDA is 1mg.
Fluoride – This is needed for the formation of bones and teeth, and prevents the decay of teeth. Sources include fluoridated water and toothpastes, and seafood. This RDA is 3.5mg.
Iodine – This is needed for the production of thyroid hormone. Sources include iodised salt and seafood. The RDA is 150µg.
Iron – This helps produce haemoglobin which carries oxygen from the lungs to body cells and assists in extraction of energy from food. Sources include red meat, organ meat, egg yolk, legumes, enriched cereals and breads, green leafy vegetables and dried fruits. The RDA is 14mg.
Manganese – This works with enzymes to help with many cell processes. Sources include whole grains, vegetables and nuts. The RDA is 2mg.
Selenium – This has antioxidant properties and works with Vitamin E. Sources include brewers yeast, raw wheatgerm, seafood, tuna, onions, nuts and seeds. The RDA is 55µg.
Molybdenum – This aids in enzyme activity, the conversion of purines to uric acid and cell repair. Sources include beans, peas, lentils, milk, almonds, peanuts, eggs, seeds, tomatoes, yoghurt, liver and carrots. The RDA is 50µg.
Zinc – This activates enzymes for important functions (particularly those in growth and nerve development), involved in production of insulin, making of sperm and aids blood clotting and wound healing. Sources include meat, poultry, fish, whole grain cereals and breads, legumes and nuts. The RDA is 10mg.
The bottom line
Eating a well-balanced diet containing fresh and unprocessed foods should help you meet the requirements you need. Some people may need higher requirements – i.e. if they are sick, on certain drugs or pregnant – so may need to increase their intake of these foods or may require supplementation. This should ideally be discussed with a doctor, dietitian or registered nutritionist. To get the most vitamins and minerals out of your food:
- Eat food as fresh and unprocessed as possible and eat a variety of foods from across the food groups
- Use cooking methods such as microwaving, steaming or pressure-cooking as they are less likely to destroy the vitamin content in food
- Try and choose fruit and vegetables which have been locally produced rather than those that have had to travel from the other side of the world before getting to your supermarket shelves
- Try and eat more raw or lightly cooked veg
- Use vegetable cooking water for stock rather than meat juices
- Keep fresh food in airtight containers or in the fridge to avoid being exposed to the air
Do not knock these micronutrients. They are important to your health so make sure you include them in your diet.