2.7  Micronutrients in detail

2.7.1  Vitamins

Vitamins are groups of related substances present in small amounts in foodstuffs and are necessary for the body to function normally. Vitamins are also called protective foods. They are grouped together because, as their name implies, they are a vital factor in the diet.

Classifications of vitamins

Vitamins are classified into two groups:

Fat soluble vitamins (vitamins A, D, E and K) are soluble in fats and fat solvents. They are insoluble in water. So these are utilised only if there is enough fat in the body.

Water soluble vitamins (vitamins B and C, and folic acid) are soluble in water and so they cannot be stored in the body.

The best sources of micronutrients in our diets are fruits and vegetables. These two food groups contain essential vitamins and minerals. Animal sources of foods are also both good sources of micronutrients. However, an adequate micronutrient intake can only be achieved through sufficient intake of a balanced diet that includes plenty of fruits and vegetables. Table 2.1 overleaf sets out the functions of some of the important vitamins and examples of sources of food for each of these.

Table 2.1  Functions and sources of vitamins.

Vitamins FunctionFood sources
Vitamin A

Night vision

Healing epithelial cells

Normal development of teeth and bones

Breastmilk, tomatoes, cabbage, lettuce, pumpkins

Mangoes, papaya, carrots

Liver, kidney, egg yolk, milk, butter, cheese cream

Vitamin D

Needed for absorption of calcium from small intestines

Calcification of the skeleton

Ultra violet light from the sun

Eggs, butter, fish

Fortified oils, fats and cereals

Vitamin KFor blood clotting

Green leafy vegetables

Fruits, cereals, meat, dairy products

B complexMetabolism of carbohydrates, proteins and fats

Milk, egg yolk, liver, kidney and heart

Whole grain cereals, meat, whole bread, fish, bananas

Vitamin C

Prevention of scurvy

Aiding wound healing

Assisting absorption of iron

Fresh fruits (oranges, banana, mango, grapefruits, lemons, potatoes) and vegetables (cabbage, carrots, pepper, tomatoes)

Breastmilk

Epithelial cells form the thin layer of tissue lining the gut, respiratory and genitourinary systems.

Calcification refers to the hardening of bones by calcium deposits.

Scurvy is a disease caused by vitamin C deficiency which leads to sore skin, bleeding gums and internal bleeding.

2.6  Including fibre in the diet

2.7.2  Minerals