Sources of vitamins
Vitamins and minerals are essential for the maintenance of good health and the prevention of a number of diseases. In this article we look at the properties of vitamins A, B, C, D, E, K, and common food sources.
Types of vitamins
There are two types of vitamins:
- water-soluble vitamins B and C
- fat-soluble vitamins A, D, E and K.
Water-soluble vitamins cannot be stored in the body, so you need to get them from food every day. They can be destroyed by overcooking.
Vitamins and minerals are found in a wide variety of foods and a balanced diet should provide you with the quantities you need.
Vitamin A (retinol)
This vitamin is essential for growth and healthy skin and hair. It is a powerful antioxidant that plays a key role in the body's immune system. Vitamin A is found in the following animal products:
- milk, butter, cheese and eggs
- chicken, kidney, liver, liver pate
- fish oils, mackerel, trout, herring.
Another source of vitamin A is a substance called beta-carotene. This is converted by the body into vitamin A. It is found in orange, yellow and green vegetables and fruits.
Vitamin B Complex
The complex of B vitamins includes the following group of substances:
- B1 - thiamine
- B2 - riboflavin
- B3 - nicotinic acid
- B6 - pyridoxine
- B12 - cobalamin
- folate - folic acid.
The body requires relatively small amounts of vitamins B1, B2 and B3.
Vitamins B6 and B12 help the body to use folic acid and are vital nutrients in a range of activities such as cell repair, digestion, the production of energy and in the immune system. Vitamin B12 is also needed for the breakdown of fat and carbohydrate. Deficiency of either vitamin will result in anaemia.
Vitamin B6 is found in most foods, so deficiency is rare.
Vitamin B12 deficiency can occur in vegans because all dietary sources are animal in origin.
The British Vegan Society recommends foods fortified with vitamin B12 such as:
Lack of folic acid is one of the main causes of anaemia, particularly in people whose diet is generally poor. Vitamins B6 and B12 help the body use folate, so are often given alongside folic acid supplements.
In pregnancy, low folate levels increase the risk of the baby's spinal cord system not developing completely (spina bifida). All women are now advised to take folic acid supplements in the first three months of pregnancy and preferably before conception.
Folate occurs naturally in most foods but often in small amounts.
Other sources of folate are dried beans, fresh orange juice, tomatoes, wheat germ (wholemeal bread and cereal) and wholegrain products (pasta and brown rice).
We need vitamin C for growth, healthy body tissue, wound repair and an efficient immune system. In addition, it's thought vitamin C can reduce cholesterol levels and regulate your blood pressure and your body's absorption of iron.
The action of sunlight on the skin enables the body to manufacture vitamin D – even on a cloudy day. For this reason, most people will get enough vitamin D through their everyday activities.
Foods rich in vitamin D are oily fish, liver, cod liver oil and dairy products.
Vitamin E
The following foods are rich in vitamin E:
Your body also makes vitamin K in the large intestine, through the activity of 'healthy bacteria'. For this reason, there is no recommended daily amount.
These bacteria are also referred to as the gut flora. They form part of our defence against more harmful organisms.
Diets rich in fatty and sugary foods can adversely change the balance of the gut flora, as can the additives and pesticides that are often a part of modern food production.
Other articles in this series
Folic acid (folate)
Folic acid works closely in the body with vitamin B12. It is vital for the production of healthy blood cells.
Liver contains the greatest amount of folic acid, with lower levels found in beef, lamb and pork and a range of green vegetables and citrus fruits.
Vitamin C
Food
Serving size
Amount of folate
Asparagus
115g
132mcg
Black beans
115g
128mcg
Breakfast cereal
30-40g
80-120mcg
Brussels sprouts
115g
47mcg
Chicken liver
100g
770mcg
Chick peas
115g
180mcg
Cooked broccoli
115g
47mcg
Cooked spinach
115g
131mcg
Cooked white rice
170g
60mcg
Kidney beans
115g
115mcg
Oranges
1 medium
47mcg
Pasta
55g
100-120mcg
Tomato juice
1 cup (225ml)
48mcg
Wheat germ
2 tbsp
38mcg
Vitamin C is one of the most potent antioxidant vitamins.
Vitamin D (calciferol)
Food
Serving size
Amount of vitamin C
Strawberries
1 bowl
70-120mg
Kiwi fruit
1 fruit
50mg
Steamed broccoli
1 serving (80g)
50mg
Orange
1 large
70mg
Mango and passion fruit smoothie
250ml glass/bottle
48mg
Frozen peas, cooked
1 serving (85g)
17mg
Vitamin D is essential for healthy bones and teeth. It helps the body to absorb calcium.
Vitamin E is important in cell maintenance and also plays an active role in the maintenance of a healthy heart, blood and circulation. It is one of the body's main antioxidants.
Vitamin K
Vitamin K is involved in the blood clotting process and in the maintenance of strong bones. It is found in small quantities in meat, most vegetables and wholegrain cereals.
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