Trace Minerals – Selenium and More

Selenium Functions

Selenium is a trace mineral that works with vitamins C and E as an antioxidant to protect cells from damage caused by harmful free radicals. It also supports immune and thyroid function. Selenium can play a role in reducing the risk or growth of some cancers.

Selenium is found in a variety of foods, such as seafood, organ meats, nuts, and grains, though nothing tops the notable Brazil nut for selenium content. So much so, you should not eat more than two Brazil nuts per day.

Although rare, selenium deficiency can occur in those who have Crohn’s disease or other severe digestive disorders or conditions or who rely on total parenteral nutrition (TPN), a method of feeding intravenously. Symptoms of a deficiency can include heart problems, hypothyroidism, and a weakened immune system. Low levels of selenium can predispose children to a rare form of heart disease and is also associated with a higher risk of cancer.

Too much selenium in the blood from foods or supplements can cause selenosis. Symptoms include gastrointestinal problems, hair loss, brittle nails, fatigue, irritability, and mild nerve damage.


Copper is a trace mineral with many important functions in the body. It’s part of an enzyme involved in iron metabolism and helps make red blood cells. It is also a part of enzymes that act as antioxidants to remove free radicals. Copper also helps keep the immune system, nerves, and blood vessels healthy. It also helps for the pigments in the skin, hair, and eyes.

Copper deficiency is rare but can occur in preterm infants and those with malabsorption conditions such as Celiac Sprue. Symptoms include anemia and bone problems.

Getting too much copper from foods or supplements can cause nausea, vomiting or diarrhea. Too much copper can also decrease iron and zinc absorption. In rare cases, excess copper intake can cause anemia and in some cases, death.


Manganese is a trace mineral that has many essential functions in the body. It is a key component of many enzymes that help form cartilage, the foundation of bones and skin, and support the metabolism of amino acids (which form proteins), cholesterol, and carbohydrates.

Various plant foods and tea contain manganese. Drinking water can also supply manganese to the diet.

It’s uncommon to be deficient in manganese, but people with epilepsy, phenylketonuria (PKU), multiple sclerosis, and some other conditions can be deficient. Symptoms include impaired growth and bone problems.

Too much manganese from foods, water, supplements, or the environment (from dust) can be toxic. High levels can lead to irritability, hallucinations, and extreme coordination problems. People with liver problems can be especially vulnerable to the negative effects of too much manganese.


Iodine is a trace mineral that is a key component of two thyroid hormones that regulate body temperature, basal metabolic rate (BMR), reproduction, and growth.

Iodine is found in foods in the form of iodide and iodates. Although there is limited information about specific amounts of iodine in foods, the richest sources include iodized salt and processed foods made with it, seafood, milk and dairy products, and some grains.

Deficiencies of iodine in America are uncommon because salt is iodized and we consume so much salt and salty foods. Iodine deficiency is still a risk, however, for many people around the world. People who consume a lot of raw vegetables such as cabbage, turnips, rutabagas, and cassava can be at risk because these foods contain goitrogens – compounds that prevent iodine from being absorbed and used properly. A deficiency of iodine overstimulates the thyroid gland and can cause goiter (enlarged thyroid gland) and symptoms such as intolerance to cold, weight gain, lower body temperature, and sluggishness. A severe deficiency of iodine in early pregnancy causes cretinism, characterized by stunted growth, deafness, and mental retardation.

Too much iodine especially from supplements can also cause goiter.


Fluoride is a trace mineral that is essential for maintaining strong bones and teeth (especially tooth enamel) and preventing dental caries.

Few foods naturally contain fluoride; however, some is found in tea, fish (with and without bones), and canned meats and poultry. Fluoride-fortified foods and supplements (available by prescription only) and toothpaste also provide fluoride. The American Dental Association (ADA) recommends fluoride supplements for children whose drinking water supplies less than 0.6 milligrams per liter.

Too little fluoride from the diet or drinking water increases the risk of tooth decay and dental caries.

Too much fluoride in the diet or from toothpaste, fortified foods, and supplements can cause fluorisis (discolored teeth with specs in them). Fluoride toxicity, which can develop in those who receive hemodialysis treatments for kidney disease, can cause headaches, nausea, and abnormal heart rhythms.


Chromium is a trace mineral that helps the hormone insulin function properly to maintain normal blood glucose levels. It also helps release energy from carbohydrates and fats. Chromium can also support immune function.

There is limited information about the content of chromium in specific foods, but very small amounts are found in a variety of foods and beverages including meats and poultry, whole grains, fruits and vegetables, spices, and beer.

Too little chromium in the diet can cause high blood sugar and insulin levels. Those on TPN who have low levels can experience brain and nerve disorders.

Excessive chromium might not be a problem for most people because it’s so poorly absorbed. However, animal studies suggest that chromium picolinate supplements can damage DNA – important genetic material.


Molybdenum is a trace mineral needed by many enzymes in the body to help them function properly. It can support a healthy nervous system, create energy in cells, and process wastes in the kidneys.

Although little is known about how much molybdenum is found in foods, legumes (beans and peas), grains (including ready-to-eat cereals), and nuts appear to be good dietary sources.

A molybdenum deficiency does not occur in people who consume a normal diet. Those on parenteral nutrition (intravenous feedings) can develop a molybdenum deficiency and experience symptoms such as weakness, mental confusion, and night blindness.

Too much molybdenum from food or supplements can lower the body’s absorption of copper, another trace mineral.

Microcytic hypochromic anemia is a type of anemia in which the red blood cells are smaller than normal and do not contain as much hemoglobin (a protein that carries oxygen) as normal; this can be caused by an iron deficiency or impaired production of hemoglobin.

Selenosis is a condition that can occur from excess dietary selenium intake; symptoms include hair loss, brittle nails, garlicky breath, intestinal problems, and mental changes

Basal metabolic rate (BMR) is the amount of energy the body expends at rest; it makes up the largest portion of total calories the body expends or burns each day.

Caries is another name for cavities or tooth decay.

Insulin is a hormone naturally made by the pancreas; it helps body cells use glucose (the key fuel for the brain and nervous system) for energy by regulating blood glucose or blood sugar levels in the body.

Dietary reference intakes (DRIs) are established for all minerals and include the following:

• Estimated average requirements (EARs)
• Recommended dietary allowances (RDAs)
• Adequate intakes (AIs)
• Tolerable upper intake levels (UL)

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