All of the body functions, including the healing of wounds, immune system function and oxygen movement round the body, are made possible by vitamins and minerals. Vitamins and minerals are referred to as essential nutrients because they are important for numerous roles that help the body to function properly. Vitamins and minerals are essential nutrients your body needs in small amounts to work properly. It is thus important to get familiar with these nutrients and know their basic functions.
The difference between vitamins and minerals
Vitamins are organic substances (made by plants or animals) and as such can be broken down by heat, air or acid. Minerals are inorganic elements (from the soil and water and are absorbed by plants or eaten by animals) and retain their chemical structure. This basic difference is that minerals in soil and water find their way into the body through plants, animals, fish and fluids consumed. However, vitamins from food and other sources find it tougher to get to the body because storage, cooking and even exposure to air can distort the fragile compounds.
Vitamins are classified as either fat soluble or water soluble.
These vitamins dissolve in fat and are mainly found in fatty foods and animal products, such as oily fish, eggs, milk and dairy foods, liver, vegetable oils and butter.
Although these vitamins are needed every day for the body to work properly, you don't need to eat foods containing them every day because the body can store these vitamins in the liver and fatty tissues for future use. These stores can build up so they are there when you need them. However, fat-soluble vitamins can be harmful if you have much more than you need. The fat- soluble vitamins are A, D, E, and K.
Preformed vitamin A is also known as retinol and vitamin A can be formed from Beta-Carotene. Vitamin A helps the immune system to work properly against infections, helps vision in dim light and keeps skin and the linings of some parts of the body (such as the nose) healthy.
Recommended daily dose: 0.7mg a day for men
0.6mg a day for women
Sources include: Many breakfast cereals, juices, milk and yoghurt, cheese, eggs, oily fish, fortified low-fat spreads, and other foods fortified with retinol. Many fruits (such as mango, melon and apricots) and vegetables (such as spinach, carrots and red peppers), and some supplements also contain beta-carotene and other vitamin A precursors, which the body can turn into vitamin A.
Extremely high doses (>9000 mg) can cause dry, scaly skin, fatigue, nausea, loss of appetite, bone and joint pains and headaches.
Research has shown that an average consumption of vitamin A above 1.5mg a day over many years may affect the bones, making them susceptible to fracture in old age. If you eat liver more than once a week, you may be getting too much vitamin A.
Therefore, it is advisable to make sure daily vitamin A intake from food and supplements does not exceed 1.5mg.
Vitamin D helps to regulate the amount of calcium and phosphate in the body which are needed to keep bones and teeth healthy.
Recommended daily dose: 5mg per day
Most people should be able to get all the vitamin D they need by eating a healthy balanced diet and by getting some summer sun.
Good sources of vitamin D include dairy products and breakfast cereals (both of which are fortified with vitamin D), and fatty fish such as salmon and tuna.
A lack of vitamin D can lead to bone deformities such as rickets in children, and bone pain and tenderness as a result of a condition called osteomalacia in adults. Large doses (>50mg) obtained from food can cause eating problems and ultimately disorientation, coma and death
Vitamin E mainly functions in the body as an antioxidant, scavenging loose electrons (“free radicals”) that can damage cells. This helps to maintain healthy skin, eyes and strengthens the immune system.
Recommended daily dose:
· 4mg a day for men
· 3mg a day for women
You should be able to get all the vitamin E you need from your daily diet.
Any vitamin E your body doesn't need is stored immediately for future use, so you don't need it in your diet every day.
The richest sources are plant oils such as soya, corn and olive oil. Other sources include nuts and seeds, and wheat germ – found in cereals and cereal products.
Vitamin K is needed for blood clotting, which means it helps wounds to heal properly. There's also some evidence that vitamin K is needed to help keep bones healthy.
Recommended daily dose: Adults need approximately 0.001mg a day of vitamin K for each kilogramme of their body weight.
For example, if you weigh 65kg, you’ll need 0.065mg a day of vitamin K, and if you weigh 75kg you’ll need 0.075mg a day.
You should be able to get all the vitamin K you need by eating a varied and balanced diet.
Good sources of vitamin K include green leafy vegetables – such as broccoli and spinach, vegetable oils and cereal grains. Small amounts can also be found in meat and dairy foods.
Any vitamin K your body doesn't need immediately is stored in the liver for future use, so you don't need it in your diet every day.
Water-soluble vitamins will be discussed in the next article…