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10.5: Iron-Deficiency Anemia

Learning Objective

  1. Discuss why iron-deficiency anemia is the most prevalent nutritional deficiency worldwide, its impacts on human health, and possible solutions to combat it.

Iron-Deficiency Anemia: Signs, Symptoms, and Treatment

Iron-deficiency anemia is a condition that develops from having insufficient iron levels in the body resulting in fewer and smaller red blood cells containing lower amounts of hemoglobin. Regardless of the cause (be it from low dietary intake of iron or via excessive blood loss), iron-deficiency anemia has the following signs and symptoms, which are linked to the essential functions of iron in energy metabolism and blood health:

  • Fatigue
  • Weakness
  • Pale skin
  • Shortness of breath
  • Dizziness
  • Swollen, sore tongue
  • Abnormal heart rate

Iron-deficiency anemia is diagnosed from characteristic signs and symptoms and confirmed with simple blood tests that count red blood cells and determine hemoglobin and iron content in blood. There are three stages of iron deficiency.  The first stage is iron depletion in which iron stores become low, and ferritin levels are reduced. Usually, there are no accompanying signs or symptoms that iron levels are being depleted.  In the second stage, iron deficiency erythropoiesis, transferrin levels decrease resulting in reduced iron transport.  Production time for heme is reduced.  Feelings of a low energy level, reduced capacity to do physical work, slow cognitive function are signs that anemia is developing.  In some rare instances, pica may occur which is the appetite for ice, clay, paste, and other non-food items.  The last stage is iron deficiency anemia.  It is characterized by a low hemoglobin concentration with small (microcytic), pale (hypochromic) RBCs. Symptoms include fatigue upon exertion, weakness, headaches, apathy, pallor, poor resistance to cold temperatures, low physical work capacity, and poor immune function. 

Several different blood tests are needed to assess iron status.  The clinician must decide if the anemia is the result of an iron deficiency or other nutrients such as folate or vitamin B12. These include the following:

  • Serum iron which is poor measure of iron status
  • Serum ferritin which indicates storage status and is a good measure of early deficiency
  • Transferrin which can provide clues on a progressing deficiency.  Total iron-binding capacity and transferrin saturation may be measured
  • Hematocrit which is not a good measure of iron status
  • Hemoglobin which is late indicator of iron deficiency
  • Erythrocyte protoporphyrin which measures the non-heme, non-complexed protoporphyrin in blood.  Used to measure if blood has too little iron or too much lead.
  • Mean cell volume (MCV) measures the average size of the RBC.  Several anemias have smaller RBC.
  • Mean corpuscular Hb concentration (MCHC)
  • Liver and bone marrow biopsies - very invasive and rarely done to assess iron status.

Several different groups are at risk of developing anemia. Iron is lost through the gastrointestinal tract, urine, sweat or skin.  If you have chronic changes in one of these systems, you could be at risk of developing an iron deficiency.  Menstruating women and growing individuals such as infants, children, adolescents, and pregnant women have increased needs for iron that are not always met by their diet. A chronic anemia of exercise has been reported but the cause is unknown.  It may be due to an increase in blood volume, damage to RBCs (foot-strike hemolysis), or sweat loss. People with excessive blood loss can develop anemia.  Ulcers, wounds, surgery, infections and regular blood donation can contribute to excessive blood loss.  Vegetarians require more iron than individuals who include animal products in their diet and must be careful to eat enough iron. Finally, people who live in developing countries are more likely to develop an iron deficiency.  

Anemia is most often treated with iron supplements and increasing the consumption of foods that are higher in iron. Iron supplements have some adverse side effects including nausea, constipation, diarrhea, vomiting, and abdominal pain. Reducing the dose at first and then gradually increasing to the full dose often minimizes the side effects of iron supplements.

See Table 10.5.1 for good dietary sources of iron. The absorption of iron changes with your body's need; it is higher if your iron stores are low.  Even though your body can modulate iron absorption, less than 35% of what you eat is absorbed and ranges between 2 - 35%. Heme iron is more efficiently absorbed, 25%, than non-heme iron, 17%.  There are several things you can do to improve non-heme iron absorption. Avoiding foods and beverages high in phytates and also tea (which contains tannic acid and polyphenols, both of which impair iron absorption), is important for people who have iron-deficiency anemia. Eating a dietary source of vitamin C at the same time as iron-containing foods improves absorption of nonheme iron in the gut. Additionally, unknown compounds that likely reside in muscle tissue of meat, poultry, and fish (MFP factor) increase iron absorption from both heme and nonheme sources. These factors have not been identified. See Table 10.6.2 for more enhancers and inhibitors for iron absorption.

Excess dietary calcium, zinc, phosphorus, and manganese can interfere with iron absorption.  Antacids increase stomach pH which decreases iron absorption.  Remember, acid converts the ferric state of iron to ferrous which improve water solubility and absorption.

Another way to increase iron intake is to cook using iron cookware but the amount of iron leached from the pan into your food depends on several factors.  First, the acidity of the food; the more acidic the food, more iron will be released into the food. Second, the longer you leave the food to cook in iron cookware, more iron will be imparted to the food.

White flour is fortified with iron which can contribute significant amounts of iron to one's diet if you eat a lot of foods made with fortified white flour. Otherwise, there are better iron sources.

 

Table 10.5.1: Dietary Sources of Iron
Food Milligrams per serving Percent RDA (males) Percent RDA (females)
Oysters (3 oz.) 13.20 165 73
Beef liver (3 oz.) 7.50 94 42
Prune juice (½ c.) 5.20 65 29
Clams (2 oz.) 4.20 53 23
Walnuts (½ c.) 3.75 47 21
Chickpeas (½ c.) 3.00 38 19
Bran flakes (½ c.) 2.80 37 16
Pork roast (3 oz.) 2.70 34 15
Raisins (½ c.) 2.55 32 14
Roast beef (3 oz.) 1.80 23 10
Green peas (½ c.) 1.50 19 8
Peanuts (½ c.) 1.50 19 8
Green beans (½ c.) 1.00 13 6
Egg (1) 1.00 13 6

 

Table 10.5.2 Enhancers and Inhibitors of Iron Absorption
Enhancer Inhibitor
Meat Phosphate
Fish Calcium
Poultry Tea
Seafood Coffee
Stomach acid Colas
  Soy protein
  High doses of minerals (antacids)
  Bran/fiber
  Phytates
  Oxalates
  Polyphenols

Iron Deficiency: A Worldwide Nutritional Health Problem

The Centers for Disease Control and Prevention reports that iron deficiency is the most common nutritional deficiency worldwide.Centers for Disease Control and Prevention. “Iron and Iron Deficiency.” Accessed October 2, 2011. http://www.cdc.gov/nutrition/everyone/basics/vitamins/iron.html. The WHO estimates that 80 percent of people are iron deficient and 30 percent of the world population has iron-deficiency anemia.The World Bank. “Anemia.” Accessed October 2, 2011. http://web.worldbank.org/WBSITE/EXTERNAL/TOPICS/EXTHEALTHNUTRITIONANDPOPULATION/EXTPHAAG/0,,contentMDK:20588506~menuPK:1314803~pagePK:64229817~piPK:64229743 ~theSitePK:672263,00.html. The main causes of iron deficiency worldwide are parasitic worm infections in the gut causing excessive blood loss, and malaria, a parasitic disease causing the destruction of red blood cells. In the developed world, iron deficiency is more the result of dietary insufficiency and/or excessive blood loss occurring during menstruation or childbirth.

At-Risk Populations

Infants, children, adolescents, and women are the populations most at risk worldwide for iron-deficiency anemia by all causes. Infants, children, and even teens require more iron because iron is essential for growth. In these populations, iron deficiency (and eventually iron-deficiency anemia) can also cause the following signs and symptoms: poor growth, failure to thrive, and poor performance in school, as well as mental, motor, and behavioral disorders. Women who experience heavy menstrual bleeding or who are pregnant require more iron in the diet. One more high-risk group is the elderly. Both elderly men and women have a high incidence of anemia and the most common causes are a dietary iron deficiency and/or a chronic disease such as ulcer, inflammatory diseases, and cancer. Additionally, those who have recently suffered from traumatic blood loss, frequently donate blood, or take excessive antacids for heartburn need more iron in their diet.

Video 10.5.1 Iron Deficiency  (click to see video)

This video provides a brief overview on how good nutrition can prevent the development of iron-deficiency anemia.

Iron Toxicity

The body excretes little iron and therefore the potential for accumulation in tissues and organs is considerable. Iron accumulation in certain tissues and organs can cause a host of health problems in children and adults including extreme fatigue, arthritis, joint pain, and severe liver and heart toxicity. In children, death has occurred from ingesting as little as 200 mg of iron and therefore it is critical to keep iron supplements out of children’s reach. The IOM has set tolerable upper intake levels of iron (Table 10.5.3 "Tolerable Upper Intake Levels of Iron"). Mostly a hereditary disease, hemochromatosis is the result of a genetic mutation that leads to abnormal iron metabolism and an accumulation of iron in certain tissues such as the liver, pancreas, and heart. The signs and symptoms of hemochromatosis are similar to those of iron overload in tissues caused by high dietary intake of iron or other nongenetic metabolic abnormalities but are often increased in severity.

Table 10.5.3: Tolerable Upper Intake Levels of Iron
Age Males (mg/day) Females (mg/day) Pregnancy (mg/day) Lactation (mg/day)
7–12 months 40 40 N/A N/A
1–13 years 40 40 N/A N/A
14–18 years 45 45 45 45
19+ years 45 45 45 45

Preventing Iron-Deficiency Anemia

In young children, iron-deficiency anemia can cause significant motor, mental, and behavior abnormalities that are long-lasting. In the United States, the high incidence of iron-deficiency anemia in infants and children was a major public-health problem prior to the early 1970s, but now the incidence has been greatly reduced. This achievement was accomplished by implementing the screening of infants for iron-deficiency anemia in the health sector as a common practice, advocating the fortification of infant formulas and cereals with iron, and distributing them in supplemental food programs, such as that within Women, Infants, and Children (WIC). Breastfeeding, iron supplementation, and delaying the introduction of cow’s milk for at least the first twelve months of life were also encouraged. These practices were implemented across the socioeconomic spectrum and by the 1980s iron-deficiency anemia in infants had significantly declined. Other solutions had to be introduced in young children, who no longer were fed breast milk or fortified formulas and were consuming cow’s milk. The following solutions were introduced to parents: provide a diet rich in sources of iron and vitamin C, limit cow’s milk consumption to less than twenty-four ounces per day, and a multivitamin containing iron.

Figure 10.5.1: While supplementation may be necessary for acute situations, the best way to boost your iron intake is through good eating habits.

In the third world, iron-deficiency anemia remains a significant public-health challenge. The World Bank claims that a million deaths occur every year from anemia and that the majority of those occur in Africa and Southeast Asia. The World Bank states five key interventions to combat anemia:The World Bank. “Anemia.” Accessed October 2, 2011. http://web.worldbank.org/WBSITE/EXTERNAL/TOPICS/EXTHEALTHNUTRITIONANDPOPULATION/EXTPHAAG/0,,contentMDK:20588506~menuPK:1314803~pagePK:64229817~piPK:64229743 ~theSitePK:672263,00.html

  • Provide at-risk groups with iron supplements.
  • Fortify staple foods with iron and other micronutrients whose deficiencies are linked with anemia.
  • Prevent the spread of malaria and treat the hundreds of millions with the disease.
  • Provide insecticide-treated bed netting to prevent parasitic infections.
  • Treat parasitic-worm infestations in high-risk populations.

Also, there is an ongoing investigation as to whether supplying iron cookware to at-risk populations is effective in preventing and treating iron-deficiency anemia.

Key Takeaways

  • Iron-deficiency anemia is a condition that develops from having insufficient iron levels in the body, resulting in fewer and smaller red blood cells containing lower amounts of hemoglobin. It is diagnosed from characteristic signs and symptoms and confirmed with simple blood tests that count red blood cells and determine hemoglobin and iron content in blood. Anemia is most often treated with iron supplements and increasing the consumption of foods that are higher in iron.
  • The main causes of iron deficiency worldwide are parasitic-worm infections in the gut (causing excessive blood loss), malaria, a parasitic disease causing the destruction of red blood cells, and insufficient iron in the diet.
  • Infants, children, adolescents, and women are the populations most at risk worldwide for iron-deficiency anemia by all causes.
  • In America in the past, iron-deficiency anemia was prevalent in infants and young children. After the introduction of infant screening, fortification of formulas and foods, and educating parents on providing an iron-rich diet, iron-deficiency anemia significantly declined in this country.
  • In the third world, iron-deficiency anemia remains a significant public-health challenge. Solutions to reduce the prevalence of iron-deficiency anemia in the developing world include providing supplements to target populations, fortifying foods with iron and other blood-healthy micronutrients, preventing the spread of malaria, treating parasitic infections, and giving iron cookware to high-risk populations.
  • The body excretes little iron and therefore the potential for accumulation in tissues and organs is considerable. Iron accumulation in certain tissues and organs can cause a host of health problems in children and adults, including extreme fatigue, arthritis, joint pain, and severe liver and heart toxicity.

Discussion Starters

  1. Come up with a hypothesis or two on why it is vital that blood is continuously renewed.
  2. Discuss the effectiveness and cost of some possible solutions for eliminating iron-deficiency anemia worldwide.