Human Biology

http://www.ck12.org Chapter 1. Human Biology

In the United States, 20% of all women of childbearing age have iron-deficiency anemia, compared with only 2% of
adult men. The most common cause of iron-deficiency anemia in young women is blood lost during menstruation.
Iron deficiency anemia can be avoided by getting the recommended amount of iron in one’s diet. Anemia is often
treated or prevented by taking iron supplements.

Boys and girls between the ages of 9 and 13 should get 9 mg of iron every day. Girls between the ages of 14 and 18
should get 15 mg of iron every day. Boys between the ages of 14 and 18 should get 11 mg of iron every day. Pregnant
women need the most iron—27 mg daily. Good sources of iron include shellfish, such as clams and oysters. Red
meats, such as beef, are also a good source of iron. Non-animal sources of iron include seeds, nuts, and legumes.
Breakfast cereals often have iron added to them in a process called fortification. Some good sources of iron are listed
below (Table1.5). Eating vitamin C along with iron-containing food increases the amount of iron that the body can
absorb.

TABLE1.5:Sources of Iron

Food Milligrams (mg) of Iron

Canned clams, drained, 3 oz 23.8

Fortified dry cereals, about 1 oz 1.8 to 21.1

Roasted pumpkin and squash seeds, 1 oz 4.2

Cooked lentils,^12 cup 3.3

Cooked fresh spinach,^12 cup 3.2

Cooked ground beef, 3 oz 2.2

Cooked sirloin beef, 3 oz 2.0

Sickle-Cell Anemia

Sickle-cell anemiais a blood disease that is caused by an abnormally-shaped hemoglobin protein in red blood cells.
Many of the red blood cells of a person with sickle-cell anemia are long and curved (sickle-shaped) (Figure1.49).
The long, sickle-shape of the cells can cause them to get stuck in narrow blood vessels. This clotting means that
oxygen cannot reach the cells. People with sickle-cell anemia are most often well but can occasionally have painful
attacks. The disease is not curable, but it can be treated with medicines.

FIGURE 1.49

The red blood cells of a person with

sickle-cell anemia (left) are long and

pointed, rather than straight, like normal

cells (right). The abnormal cells cannot

carry oxygen properly and can get stuck

in capillaries.