Why iron?

Iron is needed to make haemoglobin, a pigment found in red blood cells that transports oxygen around the body, releasing it where it's needed.
Oxygen is needed to "fuel" the body, so if the oxygen doesn't get to where it should be, your body's cells will feel "starved" and you will feel tired and run down.

The main diet-related cause of fatigue is iron-deficiency anaemia. However, a lot of people have low iron store not enough to make them anaemic, but enough to cause fatigue and lethargic. If that's the case, you should ask your doctor if you should take iron supplement. You shouldn't take them without advice as too much iron isn't good for you either.
You can simply increase the amount of iron-rich foods in your diet.
Some people are more at risk from anaemia and low iron levels: women lose iron every month when they have their periods; children and specially teenagers, need extra iron because of the muscle they are gaining; and pregnant women need more to build up their babies' s muscle and red blood cells.
If your iron levels need boosting, try to increase your intake of iron-rich foods.
Iron from animal source is easier to be absorbed and used by your body and you can get it from liver (should be avoided by pregnant women), red meat and eggs. Iron from vegetarian sources, such as beans, spinach and other green leafy vegetables, and apricots, is less available to your body, so vegetarians need to make sure they maximize their absorption of this vital mineral. One way is to eat vitamin C rich foods or drink a glass of orange juice with your meal as these will help iron absorption.

Some foods help your absorption of iron, while others makes it more difficult.

• vitamin C eaten at the same time as your iron-containing foods really boosts your iron uptake, so drink a glass of orange juice with your meal.
• high-fibre diets, especially insoluble fibre such as bran, makes it more difficult to absorb iron. But fibre is good for you, and vegetarian iron sources are high in fibre themselves. To maximize your iron absorption, just don't add extra fibre to your meals, for example by sprinkling wheat brn on them.
• tea and coffee contain tannins, which interfere with iron uptake. Don't drink them with meals, and save them for occasional between-meal treats.
• spinach and rhubarb contain plant chemicals called oxalates, which also makes iron absorption difficult. Don't serve them with iron-rich foods.