What is iron in nutrition?

Iron is an essential mineral, classified as a micronutrient, which the body essentially needs for its growth and development. It helps maintain a healthy blood picture.

It performs important functions in the body and there is a required daily intake amount you have to take through your food or supplement.

There are various foods that are rich in this mineral and they are both of animal and vegetable origin.

Its deficiency in the body can lead to anemia. Iron deficiency is the most common nutritional deficiency worldwide, causing extreme fatigue and dizziness.

Iron does not contain calories, carbohydrates, proteins, or fats.

What happens to iron in the body?

Your body recycles iron obtained from the food that you eat and stores it in the liver, spleen, muscle tissue, and bone marrow as Ferritin.

In the blood, a protein called transferrin plays a central role in its metabolism and binds to it, and transports it to various tissues, such as the liver, spleen, and bone marrow.

Most of the transferrin-bound iron in the blood is used for the synthesis of hemoglobin by developing erythroid cells in the bone marrow, which rapidly develop into mature erythrocytes (red blood cells) in the blood. About two-thirds of the iron in the body is present as hemoglobin.

Hemoglobin, an iron-containing protein is present in the red blood cells and carries oxygen from the lungs to all parts of the body, and myoglobin, a protein that provides oxygen to muscles.

When in the oxygenated state, it is called oxyhemoglobin, when it is carrying oxygen through the arteries Therefore, arterial blood is bright red.

In the reduced state, when it is carrying deoxygenated blood from the tissues and organs back to the lungs for oxygenation, it is purplish blue.

A globular protein called myoglobin is present in the muscles and functions to store oxygen in the muscle cells. This stored oxygen is used by the muscles for doing different activities. About 5 to 10% of the iron in the body is present as myoglobin.

Therefore, while hemoglobin functions as an oxygen carrier from the lungs to the entire body, myoglobin functions as a storage tank of oxygen in the muscle cells, making the oxygen available whenever the muscles require it.

Functions of iron in the body

Iron plays a pivotal role in many biochemical processes in the body. These include oxygen transport and storage, improving immunity, and contributing to the functioning of enzyme systems.

  • Is an important element of hemoglobin, which facilitates its most important function to facilitate the transport of oxygen by hemoglobin in the body to all parts of the body such as tissues and organs, thereby helping to alleviate fatigue and tiredness.
  • Helps store oxygen through its compound myoglobin within the striated muscles, which the muscles use during increased metabolic demands at the time of muscle contraction.
  • Aids in the conversion of blood sugar into energy when you require it.
  • Is fundamental to the creation of enzymes, which facilitate the production of new cells, amino acids, hormones, and neurotransmitters.
  • Boosts the immune system. Evidence shows that iron is a vital element for the normal development of the immune system and its effective function.
  • Is necessary for brain metabolism and function and aids cognitive function. Its deficiency can contribute to impaired cognitive function.
  • Promotes healthy skin by supporting enzymes that are involved in the synthesis of collagen and elastin.
  • Helps your hair to become vibrant and shiny and prevents hair loss. Iron deficiency is a common cause of people losing hair.
  • Prevents the nails from becoming brittle and dry by keeping them strong and moist.

How much do you need?

How much iron you need depends on your age, sex, and lifestyle. Generally, women need more of it than men due to more requirements during menstruation, pregnancy, and breastfeeding.

The Daily Recommended Dietary Allowance (RDA) for:

  • Adults 19-50 years old is 8 mg daily for men, 18 mg for women, 27 mg for pregnancy, and 9 mg for lactation. The higher amounts in women and pregnancy compensate for blood loss through menstruation and for the rapid growth of the fetus requiring extra blood during pregnancy.
  • Rapidly growing adolescents 14-18 years old need more iron: 11 mg for boys, 15 mg for girls, 27 mg for pregnancy, and 10 mg for lactation.
  • For menopausal women above 51 years the need drops to 8 mg. However, if they are still menstruating at this age, they should continue to follow the RDA for younger women until they attain menopause.

The Tolerable Upper Intake Level is the maximum daily intake that will not cause any harm to your health. It is 45 mg daily for all males and females ages 14+ years.  For younger ages, the UL is 40 mg.

Food sources

Iron is toxic to the body in its free state. It comes from food in two forms: heme and non-heme.

Heme comes from foods of animal origin while the non-heme type is found in plant foods

Meats, poultry, and seafood are rich sources of heme iron, while fortified grains, nuts, seeds, legumes, and vegetables contain non-heme iron.

Non-heme iron is also found in animal flesh (as animals consume plant foods with non-heme iron) and fortified foods.

However, bread, cereals, and infant formulas come fortified with iron.

Common sources of heme iron:

  • Oysters, clams, mussels
  • Organ meats such as Beef or chicken liver
  • Canned sardines
  • Poultry
  • Canned light tuna

Common sources of non-heme iron:

  • Fortified breakfast cereals
  • Beans
  • Dark chocolate
  • Lentils
  • Spinach
  • Potato with skin
  • Nuts
  • Seeds

Certain factors can facilitate or inhibit the absorption of non-heme iron.

  • Heme iron is better absorbed in the body than non-heme
  • Vitamin C and heme iron consumed together at the same meal can improve its absorption.
  • Bran fiber and too much calcium especially from supplements can inhibit the absorption of non-heme iron.

What happens if I don’t get enough iron?

According to NIH, iron deficiency anemia is the most common nutritional deficiency in the world, with 30% of the population being anemic.

Even in the United States, iron deficiency is quite common, especially among young children, women under 50, and pregnant women.

It is mostly seen in people who

  • do not eat meat, poultry, or seafood
  • lose blood
  • have diseases that interfere with nutrient absorption
  • eat poor diets

A small deficiency or short-term deficiency does not cause any symptoms, because the body uses its stored reserves in muscles, liver spleen, and bone marrow for its need.

It is only when the stored reserves become low that iron deficiency anemia sets in. Red blood cells become smaller in size and the hemoglobin levels become less.

As a result, the oxygen-carrying capacity of the blood becomes less and there is a poor supply of oxygen to various parts of the body.

Symptoms of anemia include GI upset, weakness, fatigue, exhaustion, and cognitive problems with concentration and memory. Immunity falls and anemic people are more prone to fever and infections.

During pregnancy and lactation, getting too little iron during pregnancy makes the woman prone to anemia. Her baby can be at risk of low birth weight and can be born prematurely.

Getting too little of this mineral might also harm the baby’s brain development. Pregnant and lactating women should take its supplement, which an obstetrician or a health care provider prescribes.

Iron deficiency anemia in infancy can lead to delayed mental development and less ability to pay attention. During the first year of infancy, full-term infants are at risk of becoming anemic and should, therefore, be given enriched solid foods or drink its fortified fluids.

What happens if I get too much iron?

The normal serum iron value range is 60 to 170 micrograms per deciliter (mcg/dL), or 10.74 to 30.43 micromoles per liter (micromol/L).

  • Peak serum iron levels below 350 micrograms/dL are associated with minimal toxicity.
  • Levels between 350 to 500 micrograms/dL are associated with moderate toxicity.
  • Levels above 500 micrograms/dL are associated with severe systemic toxicity.

Mild symptoms that occur within hours include vomiting, diarrhea, abdominal pain, and drowsiness and are due to moderate toxicity. In more severe cases, symptoms can include tachypnea, low blood pressure, seizures, or coma. If left untreated, iron poisoning can lead to multi-organ failure that can result in death.