Heme Iron vs. Synthetic Iron

synthetic iron vs heme iron

Iron is probably the most common word used in the emails we receive. There's a lot of confusion in terms of wanting to access the most effective, absorbable form that doesn't come with a range of side effects, hence this article ...

Iron stands as one of the fundamental nutrients vital for various bodily functions, such as oxygen transport, energy production, and DNA synthesis. Its importance in maintaining overall health cannot be overstated. When discussing iron, two primary forms come into focus: heme iron and synthetic iron. Understanding their differences in bioavailability, potential side effects, and best sources is crucial for making informed dietary choices.

Heme Iron vs. Synthetic Iron: Unraveling the Distinctions


Heme iron and synthetic iron exhibit differences in how effectively the body absorbs and utilises them. Heme iron, predominantly found in animal-based foods, boasts higher bioavailability compared to synthetic iron. Bioavailability refers to the amount of a nutrient that the body can absorb and use effectively.

The unique structure of heme iron found in hemoglobin and myoglobin in animal tissues allows for efficient absorption in the intestines. This characteristic absorption mechanism enables the body to utilise a more substantial portion of heme iron consumed compared to its synthetic counterpart.

Conversely, synthetic iron, often in the form of supplements or fortified foods, contains non-heme iron. This form of iron doesn't absorb as efficiently as heme iron. Factors such as the presence of inhibitors in certain foods and lower absorption rates contribute to the decreased bioavailability of synthetic iron.

Side Effects

Synthetic iron supplements can cause gastrointestinal discomfort, including nausea, and abdominal pain. One of the most common side effects of synthetic iron is constipation. Iron supplements can slow down bowel movements and cause stools to become hard and difficult to pass.

The form in which synthetic iron is presented in supplements can be harsh on the digestive system. Some forms of iron, such as ferrous sulfate or ferrous fumarate, can irritate the stomach lining, causing discomfort, nausea, or even gastritis.

Heme iron, found in animal-based foods, has fewer side effects due to better absorption and its natural form, minimising gastrointestinal issues.

Optimal Sources of Heme Iron

When it comes to obtaining iron from dietary sources, heme iron predominantly comes from animal-derived foods, such as red meat, poultry, and fish. Beef, in particular, stands out as a significant source of heme iron, with the lesser-known beef spleen containing exceptionally high iron content. Learn more about iron rich foods here

Best Food Sources of Heme Iron

  1. Red Meat: Beef, lamb, and pork contain substantial amounts of heme iron. These cuts of these meats provide a nutrient-dense source of iron.

  2. Poultry: Chicken and turkey serve as good sources of heme iron. 

  3. Fish: Certain types of fish, such as salmon and tuna, offer heme iron along with popular omega-3 fatty acids.

  4. Beef Spleen: While less commonly consumed, the beef spleen presents the richest source of heme iron in the beef organs space.


Heme iron and synthetic iron differ significantly in their bioavailability, potential side effects, and dietary sources. While heme iron, predominantly found in animal-based foods, boasts higher bioavailability, synthetic iron, often in supplements or fortified foods, offers an alternative for individuals with specific dietary needs.

Understanding these differences enables individuals to make informed choices about their iron intake. Incorporating a balanced diet with various heme iron sources, including the often-overlooked beef spleen, can contribute significantly to meeting daily iron requirements without solely relying on synthetic supplements.

How to Supplement with Freeze-Dried Beef Spleen

beef liver capsules

If you are looking for a natural, whole food and bio-available supplement to boost your iron that includes a myriad of critical nutrients look no further than desiccated beef spleen. 

Our Primal Iron Beef Spleen supplements are organic, 100% hormone, antibiotic and GMO-free. Available in capsules or powder form, they provide nose to tail nourishment, are freeze-dried to preserve nutrients and are 100% grass-fed and grass-finished from the pristine Tasmanian pastures.


You can find out more about them here 

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