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Iron 101: RDA, Iron-Rich Foods, and Supplementation

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Iron 101: RDA, Iron-Rich Foods, and Supplementation

Iron is a multipurpose mineral that aids in many vital processes of human function. Iron’s involvement ranges from supporting cognitive abilities to carrying oxygen through our circulatory system and even contributing to DNA function. In this article, you understand the need for iron, what this mineral depletion can look like, how to test your iron levels, and avenues to restoring this essential nutrient properly.


What is Iron?

Iron is a mineral that is essential for human function and health. Its primary role is in the production of red blood cells. Iron makes the protein hemoglobin, which carries oxygen throughout the body and into tissues. Myoglobin is another essential protein that requires iron to get oxygen into muscles. Aside from its role in oxygen transport, it’s vital for neurological growth, hormone production, functions within our cells, and physical development. Iron is acquired through our diet as heme iron and non-heme iron. Heme iron is animal-derived from seafood, poultry, and red meat. Non-heme comes from both iron-fortified foods such as bread and from plants.

What is Iron’s Role in the Body?

Iron plays a vital role in the daily function of the human body. These areas include oxygen transportation and storage, DNA synthesis, energy metabolism, immune function support, and neurocognitive processes. Iron is absorbed through the intestinal tract and then bound to transferrin, a transport protein. Transferrin delivers iron to hemoglobin, myoglobin, ferritin storage destination, and other tissues requiring iron. Approximately 75% of iron is bound to hemoglobin and myoglobin for oxygen transportation in red blood cells and muscle tissue, a small portion is readily used in essential functions, and the remaining 10-20% is stored as Ferritin in the liver and heart.

At a cellular and DNA level, iron aids in the formation of specific enzymes such as oxidases, cytochromes, and peroxidases. It also forms proteins, DNA, RNA, and gene expression. Since these processes occur in every cell, you can see how essential iron is to all tissues in the body. The immune system's necessity for iron is a double-edged sword. To have proper communication amongst immune system cells like lymphocytes and natural killer cells, iron is needed to produce Interleukin-2, all of which is necessary to mount an immune response to invading pathogen. On the other hand, infectious agents such as bacteria and parasites, along with dysfunctional cancer cells, will sequester iron for their proliferation.

In addition to the immune system, the brain needs iron to run background processes such as neurotransmitter production and utilization. Dopamine, serotonin, GABA, and norepinephrine are vital neurotransmitters that require iron input. Iron is also necessary for the myelination of our nerve cells, which allows for the transmission of nerve impulses from the brain to organ systems.

Lastly, the mitochondria, which are heavily abundant in the human brain due to the high oxygen and energy demand, require continuous iron to maintain energy (in the form of ATP) needs. 

Iron Deficiency Symptoms 

When iron is not adequately obtained through diet or not absorbed, a deficiency can occur, leading to a manifestation of signs and symptoms. Investigating this is vital, as Iron Deficiency Anemia is the leading cause of anemia in the United States. These are common symptoms to be aware of when it comes to depleted iron levels:

  • Fatigue
  • Muscle weakness
  • Pale skin
  • Dark under-eye circles
  • Hair loss
  • Brittle nails
  • Non-nutritive food cravings (PICA) like ice chips
  • Shortness of breath
  • Cold feet or hands

How to Test Iron Levels 

Evaluating your iron status can be done through a blood draw and diagnostic testing. While evaluating iron alone is possible, taking a functional medicine approach and testing associated biomarkers is beneficial. These additional tests reveal if there is anemia, how well iron is utilized, and assess your iron storage. 

Complete Blood Count (CBC)

A CBC will evaluate your red and white blood cells. It can reveal imbalances in iron status by assessing hemoglobin (which utilizes iron), along with evaluating your Red Blood Cell count (RBC), Hematocrit (Hct), Mean Corpuscular Volume (MCV), Mean Corpuscular Hemoglobin (MCH), Mean Corpuscular Hemoglobin Concentration (MCHC) and Red Cell Distribution Width (RDW). Low values in these markers, or a combination of these markers, can indicate iron deficiency. Boston Diagnostics offers a CBC that will provide this valuable information.

Iron Panel

While an iron deficiency can be red-flagged by deficiencies on a CBC, measuring iron will give a definitive answer. Iron is considered deficient in adults at less than 10 umol/L. Access Medical Labs has an Iron + Total Iron Binding Capacity test that measures iron, transferrin saturation, total iron binding capacity, and unsaturated iron-binding capacity (UIBC). It will tell you how much free-floating iron is present, the transferrin percentage occupied by iron, and the amount of unbound transferrin present. This whole picture provides you and your practitioner with valuable information.

Serum Ferritin

Ferritin is an iron-storage protein. Measuring iron and ferritin simultaneously can provide a full scope of knowing the blood's iron levels and how much reserve is present. Access Medical Labs also offers the Ferritin test

What is the Recommended Daily Allowance (RDA) For Iron? 

Obtaining adequate iron through nutrition is necessary for building and maintaining iron in the body. The RDA varies depending on age and gender. Here are recommended dosages to acquire from foods or supplementation. 

Infants to 13 Years of Age RDA for Iron 

Adolescent & Adult RDA for Iron

Which Foods Have Iron in Them? 

Consuming iron-rich foods will support optimal iron levels. Consuming both heme iron food categories and non-heme sources of iron will provide various options to support the various physiological processes that require this mineral. When optimizing iron levels, an additional avenue is to consider foods high in Vitamin C. This vitamin assists in absorbing non-heme iron, bringing it into the bloodstream, where it can be transported to hemoglobin, myoglobin, storage, or other tissues. Here are the top foods to consume to acquire iron through nutrition. 

Top 10 Common Heme Iron Sources 

Top 10 Common Non-Heme Iron Sources

When Are Iron Supplements Appropriate? 

Supplementing with Iron is indicated in situations of primary deficiency and secondary results of a chronic health condition. Cases of iron deficiency anemia warrant iron supplementation until you can restore both ferritin and iron levels and have symptom relief in health conditions such as malabsorption or inflammatory conditions such as inflammatory bowel disease (IBD).

During specific stages of life, the requirement for iron can increase, which means supplementation may be necessary. Menstruating women, pregnant women, and those breastfeeding may require a boost of iron. Infants born early, with low birth weight or young children, could be at risk for low iron due to growth needs and or feeding patterns. Suppose you are in one of these stages of life and have iron deficiency symptoms. In that case, it’s best to consult your healthcare practitioner for appropriate testing and recommendations. 

When taking exogenous iron, you mustn’t over-supplement. Regularly monitoring your status every 3 months helps find your optimal dose and when supplementation is no longer necessary. Iron overload is a risk for those with a hereditary condition called hemochromatosis. This predisposes them to absorb too much iron through their diet, which can lead to organ damage. 

What Are the Different Forms of Iron Supplements? 

There are a variety of iron forms. The standard forms of iron supplementation include ferrous sulfate, ferrous gluconate, ferric citrate, ferric sulfate, ferrous bisglycinate, iron glycinate, and iron chelate. Each form contains a different amount of elemental iron. Depending on your case and how severe your deficiency is, your healthcare provider may recommend one form of iron over another to ensure you get an adequate amount. 

Iron is typically bound to salt in supplements to make up an ingestible compound, i.e., Ferrous sulfate. Ferrous forms of iron are typically more bioavailable, meaning the body can absorb and use these forms more readily. When looking for a liquid form of iron, instead of a tablet, it is usually in the form of Ferrous gluconate.

It’s important to note that iron supplements can cause gastrointestinal upset and bowel discomfort, such as constipation. This can be offset by adding more fiber to the diet or a stool softener; however, a different form of iron, such as iron glycinate or iron chelate, may also be preferred. Studies reveal that ferrous bisglycinate is effective and causes fewer gastrointestinal symptoms therefore, this form is often used in pregnancy and with children. 

Who Should Not Take Iron Supplements? 

There are instances when supplementing with iron may be contraindicated. If you are suspicious of iron deficiency, it is recommended that you get tested before supplementing with any form of iron. If you are chronically depleted, it may be warranted to do further investigation to see if you have a genetic issue with acquiring or utilizing iron properly. Conditions in which you should avoid iron supplementation with hereditary hemochromatosis and with individuals not diagnosed with iron deficiency. Men do not typically require exogenous iron support unless they have chronic health issues that impact their iron status. The same goes with post-menopausal women since they are no longer menstruating and their iron has been balanced. This situation has nuances and exceptions, so working with your healthcare provider is the best way to see if iron supplementation is proper for you. 


Iron 101: Key Takeaways

Iron is a necessary mineral that the body needs to function appropriately and execute physiological processes. This nutrient is vital for carrying blood to organs and tissues, supporting cognitive function, and producing energy for the body. If you are showing symptoms of iron deficiency, or your diet lacks food that is reached, it may be time to evaluate your levels. It is beneficial to work with a holistic practitioner who can run comprehensive labs for iron and markers related to iron while also providing an action plan to get any deficiencies that may present themselves. Seeking professional guidance on nutrition and the supplementation form and dosing can assist you in safely rebuilding iron in your body. 

The information provided is not intended to be a substitute for professional medical advice. Always consult with your doctor or other qualified healthcare provider before taking any dietary supplement or making any changes to your diet or exercise routine.
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