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Iron is an essential mineral crucial for various physiological functions in the human body, including oxygen transport, DNA synthesis, and energy metabolism. Understanding iron metabolism is vital for maintaining optimal health, as imbalances can lead to significant health issues such as anaemia and impaired immune function. In this blog, we will delve into the intricacies of iron metabolism, focusing on the difference between heme and non-heme iron, and the benefits of incorporating heme iron-containing foods into our diets. Additionally, we will explore the role of various factors such as Hepcidin, Vitamin A, Copper, Vitamin C, and dietary components like tannins and phytates in iron absorption and utilisation.

Heme vs. Non-Heme Iron

Iron in the diet exists in two main forms: heme and non-heme iron. Heme iron is found predominantly in animal-derived foods such as meat, poultry, and fish, while non-heme iron is present in plant-based foods like legumes, grains, and leafy greens. The primary difference between heme and non-heme iron lies in their chemical structure and bioavailability.

Heme iron, bound within the heme molecule of hemoglobin and myoglobin, is more readily absorbed by the body compared to non-heme iron. The absorption of heme iron is estimated to be around 15-35%, whereas non-heme iron absorption typically ranges from 2-20% (Collings et al., 2017). This difference in absorption efficiency is attributed to the presence of heme-binding proteins in the intestinal mucosa that facilitate the uptake of heme iron into enterocytes.

Symptoms of Low Iron

  • Fatigue and weakness: Feeling unusually tired or lacking energy, even after adequate rest.
  • Shortness of breath: Difficulty breathing, especially during physical activity or exertion.
  • Pale skin: A noticeably paler complexion, often accompanied by paleness of the lips, inner mouth, and nail beds.
  • Dizziness or lightheadedness: Feeling faint, dizzy, or experiencing sensations of spinning.
  • Cold hands and feet: Persistent feelings of coldness or numbness in the extremities.
  • Headaches: Frequent or severe headaches, sometimes accompanied by dizziness.
  • Brittle nails: Weak, fragile nails that may become thin, ridged, or prone to breaking.
  • Hair loss: Experiencing increased shedding or thinning of hair, particularly in women.
  • Restless legs syndrome: Uncomfortable sensations in the legs, often described as aching, tingling, or itching, especially at night.
  • Palpitations: Irregular or rapid heartbeats, often accompanied by a feeling of fluttering or pounding in the chest.
  • Difficulty concentrating: Reduced ability to focus, remember, or perform cognitive tasks.
  • Cravings for non-food items (pica): Unusual cravings for substances such as ice, dirt, or starch, which may indicate an iron deficiency.
  • Weakness and soreness of the tongue: A swollen or sore tongue, accompanied by a sensation of burning or tingling.
  • Poor immune function: Increased susceptibility to infections or prolonged recovery from illness due to compromised immune function.
  • Impaired exercise performance: Decreased endurance, stamina, and athletic performance during physical activities.

Understanding the Intricacies of Iron Metabolism

Optimising your iron status and anemia is more complicated than simply focusing on getting more iron in your diet. In fact, adding additional iron may actually worsen your health as excess free iron is highly oxidative and can cause damage to your tissues. This is why it’s important to understand WHY you may have low iron and how best to fix it. This includes looking at important cofactors for iron utilisation and recycling and reasons why your body may have low iron in the first place. 

Reasons Why Your Iron Could Be Low

  • Insufficient Intake: the first and most obvious reason to address is if you’re simply not getting enough iron in your diet. This is very common in vegetarians and vegans as they don’t have any source of heme iron in the diet.
  • Poor Absorption: the next thing to consider is an issue with absorbing your iron. This is most often from gut damage preventing your gut lining from absorbing iron such as leaky gut or celiac disease. It could also because of excess intake of plant anti-nutrients like tannins or phytates covered below
  • Excessive Loss of Iron: you may also be losing iron through excess bleeding. This is most common in menstruating women due to their monthly period. However, there could also be internal bleeding in the gut or other areas of the body. It is also common in endurance athletes to lose excess iron through hemolysis (breakdown) of red blood cells through impact and activity.
  • Pathogens: the last and often overlooked reason for low iron is that you may have an underlying parasite or infection that it using up the iron for its own metabolism or your body is choosing not to absorb iron to try and prevent these pathogens from utilising it.

Copper’s Role in Iron Absorption

Copper is another micronutrient that interacts with iron metabolism, albeit indirectly. Copper is essential for the activity of ceruloplasmin, a ferroxidase enzyme that converts ferrous iron (Fe2+) to ferric iron (Fe3+), facilitating its binding to transferrin for transport in the bloodstream. Thus, adequate copper levels are necessary for efficient iron transport and utilisation within the body.

Vitamin A and Iron Metabolism

Vitamin A, an essential fat-soluble vitamin, also plays a role in iron metabolism. Studies have shown that Vitamin A deficiency can impair iron mobilisation from hepatic stores and decrease erythropoiesis, leading to anemia (Semba et al., 2012). Furthermore, Vitamin A supplementation has been found to improve iron status and reduce the risk of anemia, particularly in populations at risk of deficiency.

Vitamin C and Iron Absorption

Vitamin C, also known as ascorbic acid, enhances non-heme iron absorption by reducing ferric iron (Fe3+) to ferrous iron (Fe2+), a more soluble form that is readily absorbed by enterocytes. Additionally, Vitamin C forms stable complexes with non-heme iron in the intestinal lumen, protecting it from oxidation and improving its bioavailability.

However, it’s important to note that while Vitamin C can enhance non-heme iron absorption, it may not have the same effect on heme iron absorption due to differences in their chemical structures and absorption mechanisms.In the end, you’re better off just trying to get heme-iron sources (ie animal based).

Role of Hepcidin in Iron Metabolism

Hepcidin, a key regulator of iron homeostasis, plays a crucial role in controlling iron absorption and distribution in the body. Produced by the liver, hepcidin acts by regulating the activity of ferroportin, a transmembrane protein involved in the export of iron from enterocytes into the bloodstream and from macrophages into circulation.

When iron levels are high, hepcidin synthesis is upregulated, leading to the internalisation and degradation of ferroportin, thereby reducing iron absorption and sequestering iron within macrophages. Conversely, when iron levels are low, hepcidin production is suppressed, allowing for increased iron absorption and release from macrophages to meet the body’s demands.

This is important to understand because if you are supplementing or infusing excess iron into your body through supplementation or IV (because of iron deficiency) you will actually increase hepcidin and thus reduce actual iron utilisation in your body – the opposite of what you want to happen!

Dietary Inhibitors: Tannins and Phytates

Tannins and phytates are dietary components commonly found in plant-based foods that can inhibit iron absorption by forming insoluble complexes with iron in the intestinal lumen, thereby reducing its bioavailability. Tannins are polyphenolic compounds present in foods such as tea, coffee, and certain fruits, while phytates are found in whole grains, legumes, nuts, and seeds.

To mitigate the inhibitory effects of tannins and phytates on iron absorption, it is recommended to consume heme iron-containing foods alongside plant-based sources of non-heme iron. Additionally, various food processing methods such as soaking, sprouting, and fermenting can help reduce the levels of tannins and phytates, thereby enhancing iron bioavailability.

The Benefits of Heme Iron

Incorporating heme iron-containing foods into our diets offers several advantages for maintaining optimal iron levels and overall health. Firstly, heme iron is more efficiently absorbed by the body, making it a reliable source of iron for individuals at risk of deficiency, such as pregnant women and young children.

Moreover, heme iron is less influenced by dietary inhibitors commonly found in plant-based foods, such as tannins and phytates, which can hinder the absorption of non-heme iron. Additionally, heme iron is less affected by other dietary factors that can either enhance or inhibit iron absorption, such as Vitamin C, copper, and certain dietary components.

Best Sources of Heme-Iron and Cofactors

The following are the absolute best sources of heme-iron and the important cofactors listed above:

  • Beef Spleen
  • Beef Liver (or Chicken)
  • Beef Whole Blood
  • Oysters and other Molluscs 

Thankfully you can get all of the beef organ products in our Ancestral Woman organ blend! Specifically designed to help women optimise their iron and nutrient status to support energy, mood and hormone balance.


In conclusion, iron metabolism is a complex process influenced by various factors, including the form of iron consumed, dietary enhancers and inhibitors, and regulatory proteins such as hepcidin. While both heme and non-heme iron contribute to overall iron status, heme iron from animal-derived foods offers superior bioavailability and is less affected by dietary inhibitors. However, incorporating a diverse range of iron-rich foods into the diet, including both heme and non-heme sources, along with adequate intake of enhancers such as Vitamin C and copper, is essential for maintaining optimal iron levels and overall health.


  1. Collings R, Harvey LJ, Hooper L, Hurst R, Brown TJ, Ansett J, King M, Fairweather-Tait SJ. The absorption of iron from whole diets: a systematic review. Am J Clin Nutr. 2017 Mar;105(3):746-757. doi: 10.3945/ajcn.116.146241. Epub 2017 Feb 8. PMID: 28179226.
  2. Semba RD, Shardell M, Sakr Ashour FA, Moaddel R, Trehan I, Maleta KM, Ordiz MI, Kraemer K, Khadeer MA, Ferrucci L, Manary MJ. Child Stunting is Associated with Low Circulating Essential Amino Acids. EBioMedicine. 2016 Mar;6:246-52. doi: 10.1016/j.ebiom.2016.02.030. Epub 2016 Mar 1. PMID: 27077105; PMCID: PMC4800818.
  3. Young I, Parker HM, Rangan A, Prvan T, Cook RL, Donges CE, Steinbeck KS, O’Dwyer NJ, Cheng HL, Franklin JL, O’Connor HT. Association between Haem and Non-Haem Iron Intake and Serum Ferritin in Healthy Young Women. Nutrients. 2018 Jan 12;10(1):81. doi: 10.3390/nu10010081. PMID: 29329258; PMCID: PMC5793309.
  4. Hooda J, Shah A, Zhang L. Heme, an essential nutrient from dietary proteins, critically impacts diverse physiological and pathological processes. Nutrients. 2014 Mar 13;6(3):1080-102. doi: 10.3390/nu6031080. PMID: 24633395; PMCID: PMC3967179.

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