What Are Red Blood Cells?

Red blood cells play an important role in your health by carrying fresh oxygen throughout the body. The oxygen gives your blood its bright red color.

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Red blood cells are round with a flattish, indented center, like doughnuts without a hole. Your doctor can check on the size, shape, and health of your red blood cells using tests such as the complete blood count screening.

Red blood cells at work

Hemoglobin is the protein inside red blood cells that carries oxygen. Red blood cells also remove carbon dioxide from your body, transporting it to the lungs for you to exhale.

Red blood cells are made inside your bones, in the bone marrow. They typically live for about 120 days, and then they die.

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Nutrition and red blood cells

Foods rich in iron help you maintain healthy red blood cells. Vitamins are also necessary to build healthy red blood cells. These include vitamin E, found in foods such as dark green vegetables, nuts and seeds, mango, and avocados; vitamins B2, B12, and B3, found in foods such as eggs, whole grains and bananas; and folate, available in fortified cereals, dried beans and lentils, orange juice, and green leafy vegetables.

Illnesses of the red blood cells

Most people don't think about their red blood cells unless they have a disease that affects them. Problems with red blood cells can be caused by illnesses or a lack of iron or vitamins in your diet. Some diseases of the red blood cells are inherited.

Diseases of the red blood cells include many types of anemia, a condition in which your body can't produce enough normal red blood cells to carry sufficient oxygen throughout the body. People with anemia may have red blood cells that look normal, larger than normal, smaller than normal, or have an unusual shape.

Symptoms of anemia include tiredness, irregular heartbeats, pale skin, feeling cold, and, in severe cases, heart failure. Children who don't have enough healthy red blood cells grow and develop more slowly than other children. These symptoms demonstrate how important red blood cells are to your daily life.

These are common types of anemia:

• Iron-deficiency anemia. If you don't have enough iron in your body, your body won't be able to make the hemoglobin that helps red blood cells carry oxygen. Iron-deficiency anemia is the most common form of anemia. Among the causes of iron deficiency are a diet low in iron, a sudden loss of blood, a chronic loss of blood (such as from heavy menstrual periods), or the inability to absorb enough iron from food.

• Sickle cell anemia. In this inherited disease, the red blood cells are shaped like half moons rather than the normal indented circles. This change in shape can make the cells "sticky" and unable to flow smoothly through blood vessels, causing a blockage in blood flow. This blockage may cause pain and can also lead to infection or organ damage. Sickle cells die much more quickly than normal blood cells – in about 20 days instead of 120 days – causing a shortage of red blood cells.

• Normocytic anemia. This type of anemia occurs when your red blood cells are normal in shape and size, but you don't have enough of them to meet your body's needs. Diseases that cause this type of anemia are usually long-term conditions, like kidney disease, cancer, or rheumatoid arthritis.

• Hemolytic anemia. This type of anemia occurs when red blood cells are destroyed by an abnormal process in your body before their lifespan is over. As a result, your body doesn't have enough red blood cells to function, and your bone marrow cannot make enough to keep up with demand.

• Fanconi anemia. This is a rare inherited disorder in which your bone marrow isn't able to make enough of any of the components of blood, including red blood cells. Children born with this disorder often have serious birth defects because of the problems with their blood and may develop leukemia.