Vitamins and minerals are known as micronutrients because they are needed in the body in small amounts (usually only a few milligrams per day).
Fat-soluble vitamins are vitamins A (retinol) and D. These are found mainly on fatty foods from animal sources, such as butter, lard, dairy foods, oily fish and liver.
Although the body needs these vitamins every day, foods containing them do not need to be consumed daily as the body will store unused fat-soluble vitamins in the liver and in fatty tissue.
Water-soluble vitamins are vitamins B1 (thiamin), B9 (folate), B12 and vitamin C (ascorbic acid). They are found mainly in fruit, vegatables and grains.
They can be destroyed by exposure to heat or air, and can also be lost in the water used for cooking. They are not stored in the body, as any excess is excreted. Therefore, these vitamins need to be consumed daily to fulfil dietary requirements.
Vitamin A: promotes healthy eyesight, healthy skin, normal growth and development, a healthy immune system, and also has antioxidant properties (protects cells from free radical damage; cancer link).
It is found as retinol in animal sources such as cheese, eggs, oily fish and liver. It is also found as beta-carotene in plant sources such as carrots, orange-coloured fruits and green leafy vegetables.
Vitamin D: helps to absorb calcium, and also helps to regulate the amount of calcium and phosphate in the body. It is needed for healthy maintenance of bones, muscles and teeth.
The body creates vitamin D from direct sunlight on the skin when outdoors. It is also found in egg yolks, oily fish, butter, red meat and fortified foods (margarine, breakfast cereals, etc.).
A vitamin D deficiency in children can lead to a spinal deficiency known as rickets which causes soft bones. In adults, it can lead to back pain and bone weakness caused by a condition called osteomalacia.
Vitamin B1: assists with the release of energy from food (carbohydrate in particular). In addition to this, it promotes functioning of the nervous system, muscles and heart.
It is found in meat, wholegrains, nuts, beans, peas and fortified cereals.
Vegetarians may be lacking this vitamin.
Vitamin B9 (Folate): forms healthy red blood cells and is required for cell division. It is important for the structure of the nervous system and is vital during pregnancy to prevent neural tube defects in the baby.
It is found in brown rice, oranges, broccoli, bananas, green leafy vegetables and fortified cereals.
A folate deficiency can cause folate deficiency anaemia. In pregnancy, it will cause an increased risk of miscarriage and may cause neural tube defects in the baby such as spina bifida.
Vitamin B12: is required in the body for energy production, the formation of red blood cells and functioning of the nervous system.
It is found in eggs, meat, fish, dairy products and fortified cereals.
Vegetarians may be lacking this vitamin.
Vitamin C: promotes the normal structure and function of blood vessels. It is also involved in wound healing, promotes the development of connective tissue, has antioxidant properties (reduces the risk of cancer and CVD) and helps to build a strong immune system.
It is found in citrus fruits, berries, kiwi fruit and vegetables such as peppers and broccoli.
A vitamin C deficiency can cause fatigue, aching joints and muscles, weakness, gum disease and possibly even scurvy (if severe). It can also prevent wounds from healing well.
When consumed alongside food containing non-haem iron, vitamin C reduces the risk of iron-deficiency anaemia by helping the body to absorb iron from food (vitamin C converts non-haem iron to haem iron). An example would be fruit juice consumed alongside breakfast cereal.
Sodium: is an electrolyte and helps to keep body fluids balanced. It also maintains nerve function.
Some good sources are table salt, salty snacks (such as nuts), processed meats, cheese and butter.
Hyponatremia, a low sodium concentration in the blood, can cause cramping, headaches, nausea, vomiting and restlessness.
Remember to moderate sodium consumption.
Calcium: is also an electrolyte, and is necessary in the body for nerve and muscle function. Furthermore, it is involved in blood clotting and the formation and maintenance of bones and teeth.
Some good sources are milk, cheese, green leafy vegetables, white bread, fish (where bones are eaten, such as sardines) and fortified soya products.
A calcium deficiency can reduce peak bone mass, which is a contributing factor to the development of osteoporosis, a systemic skeletal disorder characterized by low bone mass. It results in fragile bones and an increased risk of broken bones or fractures.
Iron: is needed in the body for the formation of haemoglobin in red blood cells, which transport oxygen around the body. It is also required for normal energy metabolism and functioning of the immune system.
It can be found as haem iron and non-haem iron. Haem iron can be found in animal sources (red meat, fish, chicken, eggs) and is easily absorbed by the body.
Non-haem iron can be found in plant sources (pulses, nuts, green leafy vegetables and dried fruit) but is not as easily absorbed by the body.
An iron deficiency leads to low iron stores in the body and can eventually cause iron-deficiency anaemia.
The absorption of non-haem iron from plant sources is affected by various factors. Dietary fibre, phytates in cereals and pulses, and tannins in tea can reduce the absorption of non-haem iron. Furthermore, remember that vitamin C converts non-haem iron to haem iron.