In some cases, people who feel tired and unproductive are suffering from an iron deficiency. Iron deficiency most often comes from eating an iron-poor diet over a period of time. Currently, 10% or more of the population may be deficient in iron. Women are at a greater risk.

Sources of Iron

Iron comes in three forms:

heme: found only in animal sources
non-heme: found in plants
additive iron: iron is "added" to foods in which iron is not naturally found

Functions of Iron

The main role of iron in the body is its function in hemoglobin. Hemoglobin helps carry oxygen in your blood to your lungs and to all body cells.
Some vitamin C rich foods help absorption of iron. Good sources include: citrus fruits and juices, dark green vegetables, cauliflower, cabbage, tomatoes, cantaloupe, and strawberries. These foods can substantially increase absorption of non-heme (iron from plants) and additive iron.

Anemia

The first thing that happens when you don't get enough iron is that your stores are depleted. This can eventually result in anemia which is when blood hemoglobin drops, and red blood cells become small and pale. The symptoms of anemia usually come on slowly and can include fatigue, irritability, headaches, lack of energy, and tingling of the hands and feet. Feelings of weakness and fatigue, however, shouldn't trigger you to start taking iron supplements. Consult your physician first.

How to Increase Iron Intake

Eat a small amount of meat several times a week.
Consume iron and vitamin C rich foods at the same meal. Vitamin C enhances iron absorption.
Buy enriched and fortified foods. Read the labels!
Go easy on coffee and tea. Coffee can decrease iron absorption by as much as 39% and tea, by 87%, when consumed with a meal.

Iron amounts in foods

The list below shows the amount of total iron in food. Remember, iron from most animal sources is usually better absorbed by the body than iron from plant sources.

Food Source	Iron in milligrams
Lean ground beef (3oz) Skinless chicken breast, broiled (3oz) Lean pork, roasted (3oz) Salmon, canned with bones (3oz) Fortified breakfast cereal, serving size Pretzels (1/2 cup) Enriched rice (1/2 cup) Raisins, seedless (1/3 cup)	1.8 1.1 1.0 0.7 4.5-18 1.3 1.2 1.1