American Medical Association Family Medical Guide - American Medical Association [36]
Minerals play a significant role in good nutrition. Some minerals, such as chromium, selenium, and zinc, are needed in such tiny amounts that they are called trace minerals. Your body needs other minerals in higher amounts. Magnesium, found in grains, vegetables, and meats, regulates your heartbeat and stimulates the activity of many enzymes (proteins that trigger chemical reactions). Iron, contained in red meat, spinach, and fortified cereals, helps carry oxygen from your lungs to every other part of your body.
Calcium: Essential at All Ages
Calcium, found in dairy products and calcium-fortified orange juice and other foods, is essential for strong bones and teeth and helps regulate the heartbeat and lower blood pressure. To build strong bones and teeth, children from birth to 6 months should get 400 milligrams of calcium a day, 600 milligrams a day from 7 to 12 months of age, and 800 milligrams a day from 1 to 10 years. Older children, adolescents, and young adults (ages 11 to 24, when the bones reach their peak density) should take in between 1,200 and 1,500 milligrams a day. Adult women and men need about 1,200 milligrams a day. Postmenopausal women need to consume 1,500 milligrams a day (1,000 milligrams daily if they are taking a bone-building medication); men should consume 1,200 milligrams a day after age 50.
Some people need more of certain vitamins and minerals and other nutrients than other people do. For example, children, teenagers, and adults over age 50 have an especially high requirement for calcium to build bones and to keep bones strong. To ensure proper brain development and to meet their rapid growth requirements, infants and toddlers need to consume more fat than older children and adults. Girls and women who are menstruating need adequate amounts of iron to replace that lost during menstruation. Women of childbearing age should make sure they get enough of the B vitamin folic acid (400 micrograms a day) to prevent birth defects.
Water
Water is an important but often overlooked nutrient. It does not provide energy or calories but, like fiber, it plays a critical role in the body’s ability to function normally. Water helps your body distribute nutrients to cells, regulate body temperature, and eliminate waste. Drink six to eight glasses of water each day—more if you consume drinks that contain caffeine or alcohol, both of which increase water loss from the body. Vigorous exercise and hot, humid weather can rapidly use up your body’s supply of fluid and increase your need for water, but they are not the only dehydrating factors. Living in a dry climate and dry, indoor heating in the winter can also increase the risk of dehydration and boost your water requirements.
Fluoridated water helps prevent tooth decay. Some parts of the United States have water supplies with naturally occurring fluoride; in others, municipalities add the mineral to the water supply. Many people drink bottled water because they think it’s safer. However, most bottled waters do not contain fluoride or naturally occurring minerals. Some supplemented bottled waters contain various nutrients, but they can be expensive and may not be as healthy as water from the tap.
The US government regulates the safety of American drinking water through established standards for water purity. Most public water supplies meet these standards. However, if water treatment systems break down, bacteria and other contaminants can reach unsafe levels. In these situations, local officials usually advise residents to boil their tap water before drinking it or using it for cooking. Lead that leaches from plumbing pipes, solder, or well pumps also can contaminate tap water, especially in older homes. To minimize the level of lead in the tap water in