There are many minerals in the body that science is just beginning to understand. You may be surprised to know that you’ve got gold, silver, and even arsenic floating around inside your body. The purpose of many of these minerals is still a mystery. Scientists know you need them, but they don’t always know why. There are, however, a few of these minerals that are well understood.

Iron

Humans are not often deficient in minerals, except for iron. Iron is a crucial element in each red blood cell. Each molecule of hemoglobin has four iron atoms attached. The quantity of iron determines the quantity of oxygen in the rest of the body.

Oxygen attaches to the iron and is carried in the blood to where it is needed. There, it is swapped with carbon dioxide and returned to the lungs where it is exhaled. Too little iron means too few red blood cells. This results in anemia, shortness of breath, fatigue, and paleness.

Deficiency occurs long before symptoms are noticeable. It is common in adult and teenage women (due to the menstrual cycle), and those that lose an excessive amount of blood through surgery or accident. Anyone with poor diet, including picky kids, extreme dieters, and the elderly with loss of appetite, are at risk for deficiency.

Vitamin C is important for the absorption of iron, so those with low C intake are also at risk for deficiency. Good sources of iron include meat and poultry, prunes, and oysters, as well as spinach, legumes, and molasses. Another good way to get iron is to cook in it. Food cooked in cast iron absorbs the iron, especially if the food is acidic.

Zinc

Thousands of proteins in your body contain zinc, and it is crucial to the formation of enzymes and hormones, wound healing, DNA synthesis, and a healthy immune system. Normal growth relies on zinc, as it helps utilize proteins, fat, and carbohydrates.

Zinc is found in beans, nuts, and seeds, but the zinc in animal protein is absorbed at a higher rate. Deficiency is rare, but is sometimes found in vegetarians. A vegetarian diet is not simply lacking in meat. It is commonly high in fiber. Excessive fiber binds to zinc and blocks absorption, which can cause various problems.

Selenium

This mineral is an important component of the enzymes that form antioxidants. Working in conjunction with vitamin E, it protects cells from the damage of free radicals. It also plays a role in cell growth and the healthy functioning of the thyroid gland and immune system. The antioxidant and immune system functions of selenium are being studied in relationship to cancer and HIV/AIDS. Seafood is especially rich in selenium, as is meat and poultry. Smaller amounts can be found in grains and nuts. The exception is the Brazil nut, which has the highest levels of selenium of all foods.

Copper

Copper helps make enzymes that function in energy production. It helps form collagen, connective tissues that support bones, teeth, and muscles. It keeps your arteries flexible, and insulates your nerves. Because copper helps in the absorption of iron, it is crucial in the formation of hemoglobin.

Good sources of copper include shellfish, organ meat, legumes, avocados, whole grains, and nuts. Deficiency is rarely caused by diet, but it is sometimes seen as a genetic condition. Toxicity is uncommon, but can cause nausea and damage to the nervous system.

Iodine

This mineral is needed to form the thyroid hormone called thyroxin, which regulates metabolism, or how fast energy from food is used. In general, metabolism refers to a set of reactions that occur in living cells, allowing them to grow, maintain their structure, and react to situations that occur in their environment. But when people speak of their metabolism, they are referring to the way their body burns energy to maintain itself.

Iodine deficiency results in a condition known as hypothyroidism, which is a shortage of thyroid hormone. The body slows the rate at which calories are burned, and in response, the thyroid tries to make more hormone. In doing so, the thyroid swells into a lump known as a goiter.

Iodine is found in seafood and seaweed. Because of low levels of iodine in the Midwestern U.S. soil, and a lack of seafood in the diet, instances of goiters were common in that area. The conditions disappeared in the 1920s when iodine was first added to table salt.

Chromium

This mineral is important in the balance of blood sugar levels, working with insulin to take glucose from the blood to the body cells. Without it, insulin is blocked and blood sugar level is raised. It is also important in the metabolism of fats and proteins. Chromium has been used by bodybuilders and dieters as a way to lose weight and add muscle, and it has been touted as a treatment for diabetes. Such effects have been studied, but have never been proven.

Good sources of chromium include whole grains and lean beef. Brewer’s yeast is the most potent source. Only about 2 percent of the chromium you eat is absorbed. Vitamins C and B3can help absorption, but most is excreted. When chromium is excreted by excessive sweating, common with extreme exercise, deficiency can occur. Diets with excessive sugar and fat may not include sufficient chromium to balance blood sugar and are therefore deficient. Symptoms include high blood cholesterol, increased arterial plaque, and high blood pressure. Toxicity is rare.

Fluoride

Fluoride is a mineral that your body does not need, but it helps fight tooth decay by hardening tooth enamel. In cities that add fluoride to the water supply, instances of cavities are reduced as much as 40 percent. People that use fluoride toothpaste increase their protection even more. Fluoride is also shown to work in conjunction with calcium, phosphorus, magnesium, and vitamin D to strengthen bones, and it may help in the fight against osteoporosis. Bottled water is not a significant fluoride source.