Iron Deficiency Anemia
Iron Deficiency Anemia
Prevalence of Iron Deficiency
According to the World Health Organization (WHO), more than 2 billion people worldwide suffer from iron-deficiency. In the US, 2% of adult men, 12% white women, and 20% black & Mexican American women of child-bearing age are anemic due to iron-deficiency. Further, WHO estimates that as many as 80% of the world population have suboptimal concentrations of iron.
Symptoms of Iron Deficiency
Symptoms of anemia include: fatigue, shortness of breath – especially when exercising, skin pallor, lightheadedness & dizziness, fast heartbeat and palpitations, brittle nails, and headaches. These generalized symptoms often go undiagnosed and contribute to significant morbidity and discomfort.
Sources & Types of Iron
There 3 main sources of iron: plants, meat, and supplements.
Of these sources, the main types include: elemental iron, Ferrous2+iron, Ferric3+iron, large iron complexes – like ferritin, and heme iron. Ferrous2+and Ferric3+iron are both easily absorbed, whereas elemental iron needs to be converted to Ferrous2+or Ferric3+iron via digestive acids and enzymes. Heme iron, which is found solely from meat, is readily absorbed. Ferritin is the body’s storage form of iron. When consumed from animal sources, it is also readily absorbed without the need for conversion.
Enhancers
There are a number of enhancers that aid in the absorption of iron. These are mainly acids, especially vitamin C (ascorbic acid), but also those acids found in tomato sauces, vinegar, lemon juice, etc. These enhancers increase the solubility of iron, block inhibitors (which we’ll discuss next), and facilitate the conversion of Ferric3+to Ferrous2+iron to increase overall absorption.
Inhibitors.
The main inhibitors of iron are phytates and polyphenols. Phytates are the storage form of phosphorus in plants. They are typically found in cereal grain, like wheat, and bind to iron thereby preventing absorption in the intestines. Polyphenols are found in coffee, tea, cocoa, and red wine. Similarly, they bind and prevent that absorption of iron. Generalized inflammation also reduces the bioavailability of iron (bioavailability is the body’s ability to readily absorb a certain nutrient or compound). Proteins in milk and eggs, and calcium also interfere with the absorption of iron. To maximize absorption, especially when taking supplemental iron, avoid taking with dairy or calcium supplements.
Absorption
In the lumen (central cavity) of the intestines, Ferric3+iron is converted to Ferrous2+iron. It is then absorbed. Heme and ferritin are absorbed intact through transporters specialized for its absorption. Inside the intestinal cell, the various iron forms are either converted to ferritin, a storage form to be used for later, or released into the blood stream. In the blood stream the iron binds to transferrin, a protein that carries the iron to the liver or the bone marrow. Inside the bone marrow the iron can then be used to make hemoglobin and red blood cells. (Hemoglobin is the molecule inside red blood cells that attaches to oxygen and releases it to muscles/tissues that need it). Iron in the liver is converted to ferritin, another storage facility for later iron-distribution.
Importance of Iron Regulation
If there is too little iron in the body, then anemia develops. Anemia is defined as the underproduction of red blood cells or hemoglobin. Though there are other causes besides a deficiency in iron that can contribute to anemia, iron-deficiency is the most common. Conversely, too much iron is also problematic. Bacteria in the body can feed on iron, thereby increasing the risk of infection if there is an iron overload. Iron also increases the oxidative stress on the body – think rusty metal. We eat blueberries and try to increase our anti-oxidants to combat cancer-causing oxidation. Too much iron can contribute to this oxidative stress. Additionally, there is a condition called, Hemochromatosis, that affects 1:200-300 people of Northern European descent. It is marked by an increase in the absorption and concentration of iron stores in the body. It can be suspected via routine blood screening and you can have your genetics run to determine if you’re at risk for the condition. There is a spectrum of those affected ranging from homozygous (full-blown hemochromatosis) to heterozygous (partial hemochromatosis).
Measuring Iron Status
The best test to run to measure iron status is a serum ferritin. Low ferritin levels indicate the early stages of iron-deficiency. If detected and treated, anemia can be prevented.
Bioavailability of Iron in Food Sources
The most absorbable form of iron from food is heme iron. Heme is only found in animal sources, none come from plants. Of the iron in meat, up to 40% is in the form of heme, which contributes to meats substantially greater iron bioavailability compared to plants. For instance, steak provides 14x the bioavailability of iron as that from cooked spinach. As discussed, certain enhancers increase the absorption of iron – namely vitamin C. It is estimated that 20mg of vitamin C will aid in the absorption of 3mg of iron. Meat tissue also contains an iron enhancer that isn’t yet fully understood, but further aids in the absorption of iron. The phytates and polyphenols that inhibit iron absorption can also be mitigated to some degree. Soaking, sprouting, or fermenting these foods, i.e. cereal grains like oats, reduce phytate concentrations and increase the availability or iron.
Iron Supplements
There are several different forms of iron supplements on the market, but the two I want to discuss are ferrous sulfate and iron bisglycinate. Ferrous sulfate is the most popular form of iron, often conventionally prescribed for those with iron deficiency. It has a high degree of bioavailability, but often causes stomach discomfort and is constipating. Iron bisglycinate is iron complexed with two molecules of glycine, an amino acid. It is much gentler on the digestive system and has an even superior absorption level compared to ferrous sulfate. Most patients prefer this form of iron, as it’s non-constipating.
Causes of Iron-Deficiency
There are many potential causes for iron deficiency. There is a reduced concentration of iron in the food supply as compared to what it was 50 years ago. People most at risk are those on a vegetarian or vegan diet, as the diets provide little to no heme iron, the most absorbable form from natural sources. Inflammation reduces the absorption of iron, and with the overwhelming prevalence of chronic disease in modern society, generalized inflammation throughout the body is rampant. Women of child-bearing age lose blood every month during the menstrual cycle. If iron from food or supplementation does not replete these stores, then iron-deficiency is likely to develop. It is particularly important for women attempting to become pregnant to have their iron levels checked, as proper iron status is vitally important for a developing fetus. Older men who present with iron-deficiency should be evaluated for certain types of cancer or internal bleeding, as low levels are rarer in this population.
Takeaway
Eating a well-balanced diet with plenty of meat and vegetables should provide enough iron for the majority of the population. Nevertheless, serum ferritin should be run on labs to ensure proper iron status.
References:
https://medium.com/@learngirl/iron-supplements-explained-61c1ce570313