Unlike vitamins (organic compounds made of carbon, hydrogen, and oxygen), minerals are inorganic substances composed of only one kind of atom. Another name for minerals is elements.
Minerals occur naturally in nonliving things, such as rocks and metal ores. True, there are minerals in plants and animals, but they're imported. Plants get minerals from soil, and animals get minerals by eating the plants.
Nutritionists classify the minerals essential for human life into one of two categories, depending on how much of the mineral you store in your body and how much you have to consume each day to maintain a steady supply:
Major minerals: You store more than 5 grams (about one-sixth of an ounce) of each of the major minerals and must take in more than 100 mg a day of each to keep your supply level.
Trace elements: You store less than 5 grams of each of the trace elements, so you can hold this supply steady with a daily consumption of less than 100 mg of each trace mineral.
Meeting the majors
The major minerals are calcium, phosphorous, magnesium, sulfur, and the electrolytes sodium, potassium, and chloride.
Although sulfur, a major mineral, is an essential nutrient for human beings, you don't find it listed in most nutrition textbooks. Why? Because sulfur is an integral part of all proteins, so any diet that provides adequate protein also provides adequate sulfur.
You know that calcium builds strong bones and teeth, reducing your risk of osteoporosis and maybe lowering your dental bills. But do you also know that this mineral helps regulate the amount of water in and around your cells and keeps your muscles from cramping? Or that researchers have recently discovered that a calcium-rich diet may reduce your risk of high blood pressure while lowering your risk of colon cancer by stopping the creation of too many colon cells linked to a high-fat diet? No wonder this is a major mineral!
The best dietary sources of calcium are milk and milk products. There is calcium in some plant foods, such as broccoli, but the calcium is bound tight to other substances, making it hard for your body to grab hold of the calcium.
Like calcium, phosphorus is essential for strong bones and teeth. You also need phosphorous to metabolize carbohydrates, synthesize proteins, and transport fats to your organs and tissues, and protect myelin, the fatty sheath covering each nerve cell. Best of all, phosphorus plays a role in transmitting the genetic code (genes and chromosomes that carry information about your special characteristics) from one cell to another when cells divide and reproduce.
The best sources of phosphorous are high protein foods such as meat, fish, poultry, and dairy products.
You need magnesium to build body tissues, especially bone; three-quarters of the ounce of magnesium in an adult human body is in the bones. Magnesium is also a constituent of more than 300 different enzymes that trigger the countless chemical reactions throughout your body. And you use magnesium to ship nutrients in and out of body cells, send messages between cells, and — like phosphorous — to transmit your genetic code.
Plant foods, especially bananas and dark green veggies, are good sources of magnesium.
Tracking the traces
Don't be fooled by their name. Trace minerals may sound like small potatoes, but these guys deliver big benefits.
Very small amounts of trivalent chromium, a digestible form of the shiny metal that decorates your car and household appliances, is essential for building bones and teeth, helping blood clot, regulating your use of glucose, and telegraphing messages back and forth among nerve cells.
Dietary sources of chromium are cereals, meat, fish, poultry, and — three cheers! — beer.
Copper promotes bone growth, protects nerve cells, enables your body to use iron, and acts as an antioxidant in enzymes that demobilize free radicals and make it possible for your body to use iron.
Organ meats (such as liver and heart), seafood, nuts, seeds, and whole grains are natural sources of copper.
Fluoride is the fluorine ion in drinking water. You store fluoride in bones and teeth. Is fluoride an essential nutrient? Nobody knows. But the mineral does harden dental enamel, reducing your risk of cavities, and some researchers suspect (but can't prove) that some forms of fluoride strengthen bones.
Fluoride occurs naturally in some ground water supplies in the western part of the United States, but the common source is artificially fluoridated water.
Iron is an essential constituent of two pigmented proteins, hemoglobin and myoglobin. The first carries oxygen around your body; the second stores oxygen in your muscles. Iron is also part of various enzymes that facilitate body chemistry.
The best naturally occurring source of this mineral is heme iron, the form of iron found in food from animals (meat, fish, poultry, and dairy products). Non-heme iron, the form of iron found in plants, is more difficult to absorb.
Iodine is a component of thyroid hormones that regulate chemical processes inside body cells and play an essential role in the synthesis of proteins, the formation and growth of healthy nerves and bones, and the functions of the reproductive system.
Iodine occurs naturally in saltwater fish and plants grown near the ocean, but most Americans get theirs from iodized salt.
Manganese, an essential constituent of the enzymes that metabolize carbohydrates and synthesize fats (including cholesterol), is vital for a healthy reproductive system. During pregnancy, it speeds the proper growth of fetal tissue, particularly bones and cartilage.
You find manganese in nuts, beans, whole grains, and tea.
You need molybdenum to build several enzymes that metabolize proteins.
Foods containing molybdenum include nuts, grains, and beans.
Selenium regulates thyroid hormones. Like vitamin C it's an antioxidant.
You find selenium in organ meats, seafood, and plants grown in high-selenium soil.
Zinc insures healthy growth, protects nerve and brain tissue, and strengthens the immune system. It's a constituent of digestive enzymes and hormones, but most of the zinc in any male body is in the testes, where zinc is used to make a continuing supply of testosterone, the male hormone.
Yes, oysters dish up zinc. So do meat, liver, and eggs. Take your pick for a tasty meal.