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Last Updated: October 04, 2017

Micronutrients

Overview

Micronutrients are those nutrients we require in relatively small quantities. They are vitamins and minerals, and our good health requires them in milligram and microgram amounts. Recall that fats, carbohydrates and proteins are macronutrients, meaning that we require them in relatively large quantities. We consume the macronutrients in gram amounts. For example, we might have 200 grams of carbohydrate, 100 grams of protein and 50 grams of fat, yet only 18 mg of iron and 400 micrograms of folate.

Vitamins are carbon-containing molecules and are classified as either water-soluble or fat-soluble. They can be changed and inactivated by heat, oxygen, light and chemical processes. The amount of vitamins in a food depends on the growing conditions, processing, storage and cooking methods. Minerals do not contain carbon, and are not destroyed by heat or light. Unlike other nutrients, minerals are in their simplest chemical form. Minerals are elements. Whether found in bone, seashells, cast iron pots or the soil, they are they same as the minerals in our food and our bodies. The mineral content of plant foods varies with the soil content and the maturation of the plant.

On This Page

  1. Water-Soluble Vitamins
  2. Fat-Soluble Vitamins
  3. Major Minerals
  4. Trace Minerals

Water-Soluble Vitamins

Assortment of vitamin and supplement pills of varying size and color

If you look to vitamins for a jolt of energy, you are looking in the wrong place - even if a supplement bottle says, “promotes energy,” or makes some other similar vague statement. Vitamins are not energy boosters. Many B vitamins do, however, participate in energy-yielding chemical reactions in the body. This is confusing because calorie is another word for energy. It’s clearer to say that B vitamins help the body get calories from food. While you’re unlikely to get more pep by taking vitamins, eating vitamin-rich foods will certainly help you maintain health.

Vitamin B1 - Thiamin

Vitamin B1 assists in carbohydrate and amino acid metabolism.

Vitamin B2 - Riboflavin

A few crimini mushrooms, one of them sliced in half

Riboflavin assists in carbohydrate and fat metabolism. - Recommended Intakes of Riboflavin: The RDA for riboflavin also reflects energy needs with higher riboflavin intakes recommended for those whose calorie needs are higher. The RDA for adult women and men is 1.1 and 1.3 mg, respectively. - Sources of Riboflavin: Diary products, fortified cereals and enriched grains are major contributors of dietary riboflavin. Mushrooms and organ meats such as liver are additional sources. - When You Get Too Much or Too Little Riboflavin: The body readily excretes excess riboflavin, so there are no apparent toxicity symptoms. Like thiamin deficiency, riboflavin deficiency is uncommon, but alcoholism increases an individual’s risk. The symptoms include swollen mouth and throat, dermatitis and anemia.

Niacin - Nicotinamide, Nicotinic Acid

Niacin assists in carbohydrate and fat metabolism; helps with cell differentiation; and participates in DNA replication and repair.

Vitamin B6 - Pyridoxine, Pyridoxal, Pyridoxamine

A bowl of chickpeas

Vitamin B6 assists in protein and carbohydrate metabolism; and supports blood cell synthesis and neurotransmitter synthesis.

Vitamin B12 - Cobalamin

Vitamin B12 participates in the metabolism of folate. It helps protect the myelin sheath, the coating that surrounds and protects nerve fibers.

Folate - Folic Acid (Synthetic Form)

One glass of orange juice

Folate assists in DNA synthesis and cell division; participates in amino acid metabolism; and is required for the maturation of cells including red blood cells.

Vitamin C - Ascorbic Acid

A kiwi cut in half

Vitamin C is important for many reasons. It enhances iron absorption. It helps with collagen synthesis. It acts as an antioxidant and plays a role in immune function. It also regenerates vitamin E and assists in the synthesis of neurotransmitters, DNA and hormones.

Fat-Soluble Vitamins

Fat-soluble vitamins accumulate in the liver and fat tissues. These reserves may be released when dietary intakes are low. There is research, however, suggesting that blood levels of vitamin D may be low even in the presence of significant storage in the fat.

Because they can be stored so readily, the fat-soluble vitamins may be toxic in large doses.

Vitamin A - Retinol, Retinal, Retinoic Acid, Provitamin A - Carotenoids

Egg yolk sitting in a half of an egg shell

Our bodies require vitamin A for night vision and color vision, but that’s not all. We need it for for cell differentiation and bone health too. It supports immune function. Vitamin A also aids both male and female reproductive processes.

Vitamin D - Cholecalciferol

Two salmon steaks with a lemon wedge garnish

Cholecalciferol regulates blood calcium levels and supports bone health.

Vitamin E - Tocopherol

Tocopherol protects cell membranes from oxidation.

Vitamin K - Phylloquinone, Menaquinones

Small pile of Brussels sprouts

Vitamin K plays a role in blood clotting and aids bone formation.

Major Minerals

Major minerals are the ones that the body requires in amounts of at least 100 milligrams per day. They are sodium, potassium, chloride, phosphorus, calcium, magnesium and sulfur. The first four are included in the discussion of fluid and electrolytes.

Calcium

An opened can of sardines

You may know about calcium as a major component of bones and teeth, but did you know that it’s required for muscle contraction as well as nerve transmission? It even plays a role in cellular metabolism and helps with blood clotting.

Magnesium

People are often less familiar with the role of magnesium, though it assists enzymes in more than 300 chemical reactions in the body. Like calcium, it is a component of bone, participates in muscle contraction and aids in blood clotting. Magnesium supports cell activity, too.

Sulfur

A component of some vitamins and amino acids, sulfur helps maintain acid-base balance and assists in some of the liver’s drug-detoxifying pathways.

Trace Minerals

The minerals that the body requires in amounts less than 100 milligrams per day are referred to as trace minerals. They are chromium, copper, fluoride, iodine, iron, manganese, molybdenum, selenium and zinc. Because iron metabolism is the most complicated of the nine, it will be discussed in greater detail.

Iron

Chicken livers on a cutting board

Iron carries oxygen throughout the body - a pretty big responsibility! It assists in energy metabolism and other enzyme-mediated chemical reactions. Iron not only participates in the development of the brain and nervous system, but it’s also involved in the production of neurotransmitters, chemicals that carry messages between nerve cells. It supports immune function as well.

The UL for males and females aged 14 and above is 45 mg. It is 40 mg for younger individuals. Side effects of too much iron are gastrointestinal and include nausea, vomiting, diarrhea and constipation. Accidental overdose of multivitamin/mineral supplements or other iron-containing products is the leading cause of poisoning deaths among young children in the U.S. Immediate emergency medical care is critical because death can occur quickly. In addition to gastrointestinal symptoms, the child may experience rapid heartbeat, dizziness and confusion.

Hemochromatosis is a genetic defect that causes excessive iron absorption. Over time, iron can accumulate in and cause damage to various parts of the body. The result could be diabetes, liver cancer, cirrhosis of the liver and joint problems.

Iron deficiency is the most common nutrient deficiency throughout the world. In the U.S., individuals experiencing rapid growth or blood losses are at increased risk for deficiency. These include young children over 6 months of age, adolescents, menstruating women and pregnant women. Because they consume no heme iron, vegetarians are also at increased risk. Iron deficiency results in anemia with symptoms ranging from fatigue to rapid heart rate to decreased tolerance to cold to decreased athletic performance. Pica, the eating of clay, paper, ice and other non-food items, especially during pregnancy, may also be a symptom of iron deficiency.

Chromium

Stacked dark chocolate bars containing nuts

Chromium enhances the effects of insulin, and may thus, play a role in the development of glucose intolerance and type 2 diabetes. Whole grains, brewer’s yeast, nuts and dark chocolate are sources of chromium. Clinical assessment of chromium status is difficult.  

Copper

Copper assists with the transport of iron. Rich sources of copper include liver, shellfish, legumes, nuts and seeds. Deficiencies or excesses of copper are rare in healthy people.

Fluoride

Fluoride helps prevent dental caries. Nearly 99% of the body’s fluoride resides in the bones and teeth. The main source of fluoride is municipal water supplies that add fluoride to the water. Excess fluoride discolors and damages teeth.

Iodine

Iodine is a component of the thyroid hormones, which regulate metabolic rate and body temperature. Sources of iodine include saltwater fish, liver, legumes, potatoes, iodized salt and dairy products. Iodine deficiency inhibits the synthesis of thyroid hormones resulting in hypothyroidism and it’s typical problems including fatigue, weight gain and intolerance to cold. Inadequate iodine intake is fairly common in some parts of the word and may affect as much as 30% of the world’s population. In recent years, the use of iodized salt has decreased deficiency cases. Under different circumstances, excess iodine can cause either hyperthyroidism or hypothyroidism. Both too little and too much iodine can cause goiter, an enlargement of the thyroid gland.

Manganese

Manganese is important in many enzyme-mediated chemical reactions including enzymes involved in the synthesis of cartilage in skin and bone. Tea and coffee are significant sources of manganese in the American diet. Additional sources are nuts, whole grains, legumes and some fruits and vegetables. Magnesium deficiency is rare. Toxicity is also uncommon and is most frequently the result of exposure to airborne manganese dust. The UL for manganese is 11 mg per day.

Molybdenum

Molybdenum assists several enzymes including one required for the metabolism of sulfur-containing amino acids. Peas, legumes and some breakfast cereals supply molybdenum. Both molybdenum deficiency and toxicity are rare. High doses of molybdenum, however, inhibit copper absorption.

Selenium

Selenium is required for immune function and for the synthesis of thyroid hormones. Additionally, this mineral assists enzymes in protecting cell membranes from damage. Depending upon the soil in which they are grown, Brazil nuts are one of the richest sources of selenium. Organ meats, seafood, other meats and whole grains are additional sources. Low selenium intake may decrease an individual’s ability to fight viral infections. Some research also links low intakes to some cancers. Toxicity causes brittle hair and nails and is most likely to occur with supplements.

Zinc

Zinc is critical for normal growth and sexual maturation. It plays a role in the immune system and is important to the proper function of at least 70 enzymes including one that helps protect cells from damage. Oysters, beef and clams are rich sources of absorbable zinc. Whole grains also contain zinc, but it is less available for absorption. Zinc deficiency causes delayed growth and sexual development, decreased immune function, altered sense of taste, hair loss and gastrointestinal distress. Zinc deficiency is uncommon in healthy people in the U.S. It is more common among populations that consume cereals as their primary source of nutrition. Zinc toxicity is rare.

For your overall health, each nutrient is as important as the next. Whether they are macronutrients or micronutrients, vitamins, major minerals or trace minerals, they each have a unique role. A deficiency in any will impact your wellbeing. Eating a diet with both a variety of food groups and a variety within food groups is your best protection against nutrient imbalances.

Next Nutrition Guide:

WATER: IT’S MORE THAN JUST A DRINK

Sources

  1. Arunabh S, Pollack S., et al. Body Fat Content and 25-Hydroxyvitamin D Levels in Healthy Women. The Journal of Clinical Endocrinology and Metabolism. 2003; 88:157-161.
  2. Linus Pauling Institute Micronutrient Information Center of the Oregon State University: http://lpi.oregonstate.edu/infocenter/ Accessed March and April 2012.
  3. Office of Dietary Supplements, National Institutes of Health:http://ods.od.nih.gov/factsheets/list-all/ Accessed March and April 2012.
  4. Insel Paul, Ross Don, McMahon Kimberley and Bernstein Melissa. Nutrition 4th ed. Jones and Bartlett Publishers. 2011.
  5. Thompson Janice L, Manore Melinda M and Vaughan Linda A. The Science of Nutrition. 2nd ed. Benjamin Cummings. 2011.

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Authored by: Jill Weisenberger, MS, RD, CDE