Mighty Microminerals

Minerals are among the six groups of nutrients that you must get from your diet, and there are about 20 that you need each day. The minerals you need in larger amounts — like calcium, sodium, potassium, and iron — are known as macrominerals. Those necessary but in smaller quantities — like zinc, magnesium and copper — are called microminerals, or trace elements.

Only a few micrograms of these microminerals are usually required, but that doesn't mean they aren't important. Your body needs them as much as the better-known macrominerals — just in smaller quantities.

What are these microminerals? What foods contain them? What follows is a guide to some of the microminerals that you might want to start paying attention to in your diet. If you are concerned you might be deficient in one or more microminerals, first try eating more of the foods discussed below that contain them. As you will see, over-supplementation of trace minerals brings its own dangers. Check with your doctor or registered dietitian before deciding if supplements are necessary.

Most of the magnesium we consume is used to maintain healthy bones, but the rest resides inside cells where it helps over 300 enzymes do their jobs in the body — everything from making sure your nerves and muscles work properly to creating body proteins that help cells divide properly.

If you live in an area that is plagued with hard water, take heart. That hard water is a significant source of magnesium.

You need 300 to 400 milligrams per day, depending on your age and gender. Include leafy green vegetables, whole grains, beans, nuts and seeds, and bananas in your diet regularly, and you should have no problem hitting the mark.

Processing food often removes the magnesium, a good reason to limit the amount of processed foods you eat. If you live in an area that is plagued with hard water, take heart. That hard water is a significant source of magnesium.

Zinc is especially important for pregnant women, infants, and children because it’s necessary for proper growth and development. The recommended intake is 8 milligrams a day for women and 11 milligrams for men and pregnant women. This mineral also aids the immune system in fighting off viruses and bacteria, and it is used to make body proteins and DNA.

Animal sources of zinc are absorbed better than plant sources because plants contain phytates that tend to bind zinc. Oysters are the best source, but red meat, crab, and fortified breakfast cereals are also excellent sources. Beans, nuts, eggs, yogurt, milk, whole grains, spinach, and potatoes also contribute significantly to your intake of zinc.

The amount of copper needed by adults is very small, 900 micrograms a day. It is necessary for organs to function properly and for metabolic processes to proceed normally. The formation of hemoglobin and iron metabolism depend on copper, too. This means that some forms of anemia can actually be related to a copper deficiency.

Organ meats are the richest source, but you also get copper when you eat seafood, nuts and seeds, and whole grains. If you’re a chocolate lover, you’ll be glad to know that it is a good source of copper, too. An ounce of 70 percent dark chocolate contains 500 micrograms of copper, but its overall nutritional contribution pales in comparison to other sources of copper.

Selenium's importance to nutrition wasn’t discovered until the 1970s. It is a key part of the body’s antioxidant defense system and is found in grains, seeds, dairy foods, beef, poultry, and seafood. Fruits and vegetables contribute less selenium, but they still contain some.

The selenium content of food depends on the soil where the food was grown or the amount of selenium in the feed given to animals. So getting enough selenium could be an issue for people who only eat foods grown in one area with low amounts of selenium in the soil. However, because we generally eat foods that are grown or raised in a variety of places, that is an unlikely problem.

Getting enough selenium could be an issue for people who only eat foods grown in one area with low amounts of selenium in the soil.

It is possible to have too much selenium. People who over-supplement can end up with selenium toxicity or selenosis which can cause fatigue, hair loss and abnormal nail growth. If you are concerned about selenium, it's wiser to eat a Brazil nut rather than to take a supplement. You only need 55 micrograms per day.

The one exception to this may be in people with Crohn's disease and other gastrointestinal disorders. They may have difficulty getting enough selenium, despite a healthy diet and may need to take selenium supplements with a doctor's guidance.

Iodine is an important component of your thyroid hormones that regulate growth and development, synthesis of body proteins, and your metabolic rate. You need 150 micrograms a day, and these are easily obtained if you purchase iodized salt, the most common source of iodine in the American diet.

Like selenium, the amount of iodine in foods depends on the soil that plants grow in or where animals graze. It is a natural component of seawater, so seafood and plants grown near the coast are high in iodine, while the foods from inland areas contain less.

Chromium’s role in the body is related to the metabolism of carbohydrate, fat, and protein. It is believed to enhance the action of insulin, but chromium’s precise role in the body is not fully understood.

The mineral is widely available in our food supply¸ but agricultural practices and manufacturing processes affect the amount that is available. Adults require 25 to 30 micrograms a day, and those over 50 slightly less since food intake and metabolism generally decrease with age.

If you are concerned you might be deficient in one or more microminerals, try eating more of the foods that contain them. Over-supplementation brings its own dangers.

Chromium may help with polycystic ovary syndrome (PCOS), which is linked to insulin resistance.

Whole grains, liver, and nuts are reliable sources of chromium, but the mineral is lost in refined carbohydrates, like white bread and pasta. If you cook in stainless steel pots and pans, you will increase your intake since chromium leaches from the steel and ends up in your food.

While these are relatively unknown and rarely considered minerals, their importance should not be underrated. Deficiencies of any of them can lead to health problems. The best way to assure yourself that you aren’t missing out of any of these important minerals is to eat a wide variety of foods from all the food groups and from within all the food groups.

You can learn more at the US National Library of Medicine’s website.