Iron is a mineral your body needs to make healthy blood. It is a key part of hemoglobin, the protein in red blood cells that carries oxygen from the lungs to the rest of the body. When you have enough iron, your cells can get the oxygen they need for energy, growth, learning, and physical activity.
Low iron can lead to tiredness, weakness, pale skin, or trouble concentrating, so iron is important for everyday health.
Understanding Iron and Healthy Blood
Your body manages iron carefully because both too little and too much can cause problems. After iron is absorbed from food, it travels in the blood attached to a transport protein called transferrin. Much of it goes to the bone marrow, the soft tissue inside certain bones where new red blood cells are made.
Extra iron can be stored in a protein called ferritin, mainly in the liver, spleen, and bone marrow. These stores act like a reserve supply when food intake changes for a short time.
Each red blood cell contains many hemoglobin molecules. In the lungs, oxygen enters the blood and attaches to the iron-containing part of hemoglobin. This attachment is reversible.
In body tissues that are using oxygen, conditions encourage hemoglobin to release it. Active muscles release more carbon dioxide and become warmer, which helps them receive oxygen during exercise. Red blood cells are well suited to this job because their shape gives a large surface area and lets them move through very narrow blood vessels.
Iron from animal foods is called heme iron. The body usually absorbs it more easily than non-heme iron, which comes from plant foods and fortified products. Absorption of non-heme iron can vary a lot from one meal to another.
Vitamin C can improve it by changing iron into a form that the intestine can take in more easily. Eating peppers, oranges, berries, tomatoes, or broccoli with beans, lentils, or cereal can help.
Tea and coffee contain compounds that can reduce iron absorption when they are consumed with a meal. Calcium can have a similar effect for some people.
Iron needs can rise during periods of rapid growth. This includes childhood and the teenage years. People who menstruate lose blood regularly, so they often need more iron than people of the same age who do not.
Endurance athletes may need careful food planning because training increases red blood cell turnover and can cause small iron losses through sweat or the digestive system. A varied diet matters more than relying on one food. Vegetarians and vegans can meet their needs, though they need regular sources of beans, lentils, tofu, whole grains, nuts, seeds, and fortified foods.
Low iron is not always the same as iron deficiency anemia. Stores can become low before the number or quality of red blood cells changes enough to cause anemia. A clinician can use blood tests, including ferritin and hemoglobin, to investigate symptoms and find the cause.
Fatigue has many possible causes, so it should not be assumed to mean low iron. Iron supplements are useful for some people, but taking them without advice can be unsafe and can hide an underlying health issue. When learning this topic, pay attention to the difference between eating iron, absorbing iron, storing iron, and using iron to make new blood cells.
Key Facts
- Iron helps hemoglobin bind oxygen so red blood cells can deliver it throughout the body.
- Hemoglobin is found inside red blood cells and contains iron in its heme groups.
- Oxygen transport can be summarized as lungs to red blood cells to body cells.
- Iron-rich foods include lean meat, poultry, fish, beans, lentils, tofu, spinach, fortified cereals, nuts, and seeds.
- Vitamin C helps the body absorb non-heme iron from plant foods, such as beans or spinach.
- The body loses some iron over time, so it must be replaced through food or supplements if a health professional recommends them.
Vocabulary
- Iron
- Iron is a mineral the body uses to make hemoglobin and support oxygen transport in the blood.
- Red blood cell
- A red blood cell is a flexible blood cell that carries oxygen from the lungs to body tissues.
- Hemoglobin
- Hemoglobin is an iron-containing protein in red blood cells that binds and carries oxygen.
- Oxygen
- Oxygen is a gas that body cells need to release energy from food.
- Anemia
- Anemia is a condition in which the blood has too little hemoglobin or too few healthy red blood cells to carry enough oxygen.
Common Mistakes to Avoid
- Thinking iron is the same thing as blood is wrong because iron is only one nutrient used to build hemoglobin inside red blood cells.
- Ignoring plant sources of iron is wrong because foods like beans, lentils, tofu, spinach, and fortified cereals can contribute important iron.
- Forgetting vitamin C with plant-based iron is wrong because vitamin C can help the body absorb non-heme iron more effectively.
- Taking iron supplements without advice is wrong because too much iron can be harmful, and supplements should be used when recommended by a healthcare professional.
Practice Questions
- 1 A cereal serving has 8 mg of iron. If a student eats 2 servings, how many milligrams of iron do they get?
- 2 A meal has 3 mg of iron from beans and 2 mg of iron from spinach. If adding a vitamin C-rich fruit helps absorption but does not change the amount of iron in the food, how many milligrams of iron are in the meal?
- 3 Explain why a lunch of lentils with orange slices may support healthy blood better than lentils alone.