326 Chapter 13 Nutrition Copyright Goodheart-Willcox Co., Inc. poor utilization of some vitamins. Of the fats needed in the diet, fi sh, nuts, and seeds are good sources. However, excessive amounts of any fat can cause weight problems. People who eat such amounts tend to eat less of other needed foods. This should be avoided because a well-balanced diet is important for good health. Minerals Minerals are inorganic substances needed for building tissues and regulating body functions. They are an essential part of bones, teeth, and red blood cells. Minerals also aid in the proper functioning of muscles and nerves and in the clotting of blood. Like proteins, minerals are needed for growth and repair of body tissues. Unlike the nutrients already discussed, minerals do not provide the body with energy. They do not need to be broken down by digestion for the body’s use. Your body can absorb minerals directly from the foods you have eaten. Calcium and Phosphorus Calcium and phosphorus are the most abundant minerals in the body. Reserves are stored in the bones. Calcium and phosphorus are also found in teeth, soft tissues, and body fl uids. If a person’s diet is low in calcium, his or her bones will serve as a reserve to fi ll immediate calcium needs. However, a low calcium intake over a long period could lead to osteoporosis. This is a disease characterized by weak, brittle bones, which are more likely to fracture. As osteoporosis progresses, bones become too weak to support the body’s weight. They are unable to withstand force from routine chores like lifting and bending. See 13-3. Fluoride Fluoride is needed for the proper development of bones and teeth. When added to the diets of children, it helps reduce tooth decay. Fluoride is not readily available in foods. Therefore, many cities add fl uoride to the supply of drinking water. Iodine Iodine is present in very small amounts in the body, but it is essential for good health. Iodine is used to make thyroxine. Thyroxine is a hormone produced by the thyroid gland, which is located at the base of the neck. Thyroxine controls the rate at which the body uses nutrients. When the diet is low in iodine, the thyroid gland enlarges. This condition is called a goiter. Write a report on osteoporosis. What affect does calcium intake before age 30 have on this disease? Wellness Awareness 13-3 Osteoporosis weakens bones and can cause an increased risk of fractures and curving of the spine.