What are the health benefits of iron?

Iron deficiency anemia is the world's most common nutritional deficiency disease and is most prevalent among children and women of childbearing age. Anemia develops due to an inadequate amount of iron in the diet or poor iron absorption.

Iron deficiencies can be caused or exacerbated by injury, blood loss, hemorrhage or gastrointestinal diseases that impair iron absorption. Inadequate intake of folate, protein and vitamin C can also contribute to iron deficiency.

This article provides an in-depth look at recommended intake of iron, its possible health benefits, foods high in iron and any potential health risks of consuming iron.

Recommended intake

The Recommended Daily Allowance (RDA) for iron depends on age and gender.

Inadequate intake of folate, protein and vitamin C can contribute to iron deficiency.

Children:

• 1-3 years - 7 milligrams
• 4-8 years - 10 milligrams.

Males:

• 9-13 years - 8 milligrams
• 14-18 years - 11 milligrams
• 19 years and older - 8 milligrams.

Females:

• 9-13 years - 8 milligrams
• 14-18 years - 15 milligrams
• 19-50 years - 18 milligrams
• 51 years and older - 8 milligrams.

Pregnancy:

• 27 milligrams.

An estimated 8 million women of childbearing age in the US suffer from iron deficiency severe enough to cause anemia. Iron deficiency during pregnancy may raise the risk for preterm delivery.

Iron supplements are available, but it is best to obtain any vitamin or mineral through food first. It is not the individual vitamin or mineral alone that make certain foods an important part of our diet, but the synergy of the foods nutrients working together. It has been proven time and again that isolating certain nutrients in supplement form will not provide the same health benefits as consuming the nutrient from a whole food. First focus on obtaining your daily iron requirement from foods then use supplements as a backup.

Possible health benefits of consuming iron

Iron deficiency can cause many health problems. Common difficulties associated include delayed cognitive function, poor exercise performance and lowered immune function. In children, iron deficiency anemia can cause psychomotor and cognitive abnormalities resulting in future learning difficulties.

Healthy pregnancy

Low iron intakes increase a woman's risk of premature birth and the risk of her infant having low birth weight, low iron stores and impaired cognitive or behavioral development.

More energy

Not getting enough iron in your diet can affect how efficiently your body uses energy. Iron carries oxygen to the muscles and brain and is crucial for both mental and physical performance. Low iron levels may result in a lack of focus, and an increase in irritability.

Better athletic performance

Iron deficiency is more common among athletes, especially young female athletes, than sedentary individuals. Iron deficiency in athletes decreases athletic performance and weakens immune systems. A lack in hemoglobin iron can greatly reduce physical work performance via a decrease in oxygen transport to exercising muscle.

Foods high in iron

Iron has a low bioavailability, meaning that it has poor absorption within the small intestine and low retention in the body, decreasing its availability for use. The efficiency of absorption depends on the source of iron, foods consumed with the iron, and overall iron status of the person. In many countries, wheat products and infant formulas are fortified with iron.

There are two types of dietary iron - heme and non-heme. Most animal products and seafood contain heme iron, which is easier to absorb than non-heme. Non-heme iron sources include beans, nuts, vegetables and fortified grains. The recommended iron intake for vegetarians is 1.8 times higher than for those who eat meat in order to make up for the lower absorption level from plant-based foods.

Proton pump inhibitors (lansoprazole [Prevacid®] and omeprazole [Prilosec®]) used to reduce the acidity of stomach contents can inhibit the absorption of iron. The polyphenols and tannins in coffee and tea also decrease non-heme iron absorption. Eating foods that are high in vitamin C, on the other hand, help to increase iron absorption.

Clams contain a significant 24 mg of iron per 3 oz.

• Clams, canned, 3 oz: 24 milligrams
• Cereal, fortified, one serving: 1-22 milligrams
• White beans, canned, 1 cup: 8 milligrams
• Chocolate, dark, 45-69% cacao, 3 oz: 7 milligrams
• Oysters, cooked, 3 oz: 6 milligrams
• Spinach, cooked, 1 cup: 6 milligrams
• Beef liver, 3 oz: 5 milligrams
• Blueberries, frozen, ½ cup: 5 milligrams
• Lentils, boiled and drained, ½ cup: 3 milligrams
• Tofu, firm, ½ cup: 3 milligrams
• Chickpeas, boiled and drained, ½ cup: 2 milligrams
• Tomatoes, canned, stewed, ½ cup: 2 milligrams
• Ground beef, lean, 3 oz: 2 milligrams
• Potato, baked, medium: 2 milligrams
• Cashew nuts, roasted, 1 oz: 2 milligrams
• Egg, 1 large: 1 milligram.^1,2

Potential health risks of consuming iron

The tolerable upper intake level for iron is between 40-45 milligrams. Adults with healthy functioning gastrointestinal systems have a very low risk of iron overload from dietary sources.

Taking iron supplements of 20 milligrams or more on a frequent basis can cause nausea, vomiting and stomach pain, especially if the supplement is not taken with food. In severe cases, iron overdoses can lead to organ failure, coma, seizure, and even death.

Some studies have suggested that excessive iron intake can increase the risk of coronary heart disease and cancer.

Iron supplements can interact with several medications, including levodopa (used to treat restless leg syndrome and Parkinson's) and levothyroxine (used to treat hypothyroidism, goiter, and thyroid cancer).

It is the total diet or overall eating pattern that is most important in disease prevention and achieving good health. It is better to eat a diet with a variety than to concentrate on individual nutrients as the key to good health.

References:

1.        Mahan, L. Kathleen and Escott-Stump, Sylvia. Krause’s Food & Nutrition Therapy, 12th edition. Saunders Elsevier, St. Louis, MS. Copyright 2008.
2.        Dietary supplement fact sheet: iron, National Institutes of Health, U.S. Department of Health and Human Services, reviewed 08 April 2014, accessed 15 December 2014.
3.        Iron status and exercise, Beard, John and Tobin, Brian, Am J Clin Nutr, August 2000, accessed 15 December 2014.