348 Chapter 13 Nutrition Copyright Goodheart-Willcox Co., Inc. Osteoporosis Osteoporosis is a disease that weakens bones, often causing severe fractures. It occurs primarily in people over 50 years of age. Osteoporosis is caused from a depletion of calcium in the body. This results in porous and brittle bones that break easily. Osteoporosis is more common in women than in men. Almost all cells of the body require calcium. The body absorbs calcium directly from the food consumed. However, if there is insuffi cient calcium in food, the body will withdraw calcium from the bones. When supplies are insuffi cient, the body will also slow the loss of calcium through the urine. Gradual loss of calcium in bones is a normal part of aging. A diet rich in calcium and vitamin D promotes healthy bones, 13-15. This can slow bone loss and lessen the risk of fracture. Cancer Cancer refers to a disease in which abnormal cells divide uncontrollably and invade other body tissues. The abnormal cells may also spread to other parts of the body. The development of abnormal cell masses are called tumors. In some cases, no tumors develop. Instead, uncontrolled cell growth occurs in the blood and blood system. In most cases it is not known what causes cancer, but there are risk factors that are often associated with an increased prevalence. One such risk is a diet high in fat. The American Cancer Society recommends that you eat an abundance of fruits and vegetables each day, as well as whole grains and beans. Limit fat intake, especially animal fat. Use alcohol in moderation or not at all. It is also recommended that you stay active and maintain a healthy weight. Reading Review 1. Why do pregnant teenagers have more difficulty meeting the needs of their developing babies than pregnant adults? 2. Of the four types of vegetarianism, what distinguishes one type from another? 3. What are the four particular needs that an athlete’s diet must address? 4. True or false. Adults need more calories than teenagers. 13-15 Milk and other dairy products provide calcium needed to fight osteoporosis.