Iron: What Does It Do For Your Body?

Iron is an essential micromineral.  This means the body needs in small amounts, but excessive amounts can be problematic.  

What Does Iron Do for the Body?

Although we don’t need much iron, it has several key roles in the body.

Iron is an essential component of haemoglobin or the substance in red blood cells that carries oxygen from your lungs to the rest of your body.  Haemoglobin makes up about two-thirds of your body’s iron stores.

If you don’t have enough iron, your body can’t make enough oxygen-carrying red blood cells.  This means your tissues and muscles won’t get enough oxygen to function optimally. 

Along with iodine, iron is required to make thyroid-stimulating hormone (TSH).  Inadequate iron can cause hypothyroidism. 

Iron is critical to making up many proteins (e.g. haemoglobin, myoglobin, neuroglobin) and enzymes (e.g., cytochromes, peroxidases) in the body that regulate various functions.

We require iron for the synthesis and repair of DNA.

To an extent, iron is considered an antioxidant that protects against damaging substances like heavy metals.  However, when you have excess iron, it can become an oxidant or a damaging substance in and of itself.

Iron helps regulate cognition and behaviour and has been shown to play a role in attention and concentration.

Iron is vital for creating energy and transporting electrons through the electron transport chain.

Iron is also critical to maintaining strong bones, detoxifying, regulating immune function, skin and nail formation, and synthesising neurotransmitters in your brain. 

Heme Iron vs Non-Heme Iron

There are two forms of iron found in foods:

  • non-heme iron, which is found in plant and animal foods, and
  • heme iron which is found exclusively in animal foods.

Animal foods containing heme iron have a higher bioavailability and are absorbed more readily, as it does not require cofactors that enhance uptake.  Approximately 15-35% of heme iron sources are absorbed.

On the other hand, non-heme iron is less bioavailable and requires different nutrients to assure absorption.  As a result, only around 2% of non-heme iron is absorbed.  Hence, you may be at risk of anemia if you are a strict vegan

However, while some people like to make a big deal of the bioavailability of iron in plants vs animal products, super high iron absorption is not necessarily a good thing either.

If you consume an omnivorous diet, you are unlikely to have significant issues with low iron levels unless you have digestive problems, consume a lot of grains, or consume minimal amounts of vitamin C. All of these factors will affect absorption.

Iron-Rich Foods

Some popular foods that contain higher iron per calorie are listed below. 

Animal (heme and non-heme)

  • chicken liver
  • lamb liver
  • beef liver
  • animal heart
  • venison
  • bison
  • lamb
  • pork
  • kangaroo
  • whole egg
  • ground beef 
  • octopus

In terms of animal foods, the iron content is generally higher in redder meats, which contain haemoglobin which give the red colour.

Vegetables (non-heme)

  • parsley
  • dried fruit
  • nettle
  • asparagus 
  • sauerkraut
  • lettuce
  • kale 
  • spinach
  • chard
  • broccoli 
  • zucchini
  • cucumber
  • green peppers
  • cauliflower
  • raspberries
  • garlic
  • flax seeds
  • sweet potato 
  • butternut squash
  • cabbage
  • onion
  • kiwifruit
  • blueberries
  • grapes
  • cashews
  • almonds
  • walnuts

For more iron-rich foods, see top foods high in iron over at Nutrient Optimiser

Iron-Rich Recipes

Some of our most iron-rich NutriBooster recipes include:

Factors That Increase Iron Absorption

Your gut will absorb more iron in your intestines if you need more of it.  On the contrary, your body will let it pass through if you have adequate amounts in your system. 

To increase the bioavailability of non-heme iron, there are certain compounds in other foods that act as ‘enhancers’ to absorption.

Vitamin C, fructose, and sodium increase the absorption of dietary iron.  Therefore, if you are getting less vitamin C, sodium, or fructose, you may not be absorbing as much iron as you otherwise would.  Iron supplements often include vitamin C for this reason.

MFP Factor is a peptide found in meat, fish, and poultry.  It has been shown to increase the absorption of non-heme iron by almost threefold.

Factors That Decrease Iron Absorption

Phytates are plant compounds found in grains, vegetable protein, legumes and green leafy vegetables known as ‘antinutrients’.  These are known to decrease the absorption of iron.

Similarly, plant compounds like lectins and polyphenols like tannins are known to inhibit the uptake of iron in the body’s digestive tract. 

Oxalate, or oxalic acid, is known to decrease iron absorption from non-heme foods.  Many plant foods like kale and spinach high in oxalate are also high in iron.

Consuming large amounts of calcium and (or) copper in the diet alongside iron-rich foods decreases iron absorption.

Factors Increasing Iron Demand

You may need more iron in your diet if you:

If you are female and have low energy levels, check for low ferritin levels on your standard blood tests. 

Practical steps you can take to increase your iron levels include:

  • modifying your diet to improve your iron intake,
  • taking iron supplements,
  • minimising calcium and copper intake around high-iron foods,
  • consume more heme iron vs non-heme,
  • ensuring you are getting adequate vitamin C (which assists iron absorption), and
  • reducing phytates, oxalates, and lectins (e.g., grains and legumes). 

Can You Get Too Much Iron?

Iron is one nutrient that menstruating women require significantly more of.  However, men who tend not to bleed as frequently in the modern day are more prone to accumulating excessive amounts of iron.  This condition is known as haemochromatosis or iron overload, and it affects around one in three hundred people. 

While adequate iron helps you manage oxidation, excess iron can bind to proteins and act as a pro-oxidant.  Here, it causes your tissues to oxidise (or rust).

If left untreated, the excess iron can increase your risk of diabetes, cirrhosis of the liver, heart disease, neurodegeneration, and a host of other chronic diseases. 

Symptoms of Iron Overload

Symptoms of iron overload include:

Although men seem to have a greater risk of developing haemochromatosis, you should watch for elevated ferritin levels, regardless of whether you are male or female.  If they are high, consider regular blood donations.  Blood donation is not just good for you.  It could be a matter of life or death for someone in need. 

What Foods to Avoid if You Have Hemochromatosis

  • Iron toxicity and its symptoms can be improved by ensuring you are getting a nutrient dense diet overall, particularly adequate niacin, tryptophan, zinc, manganese, copper, and lipoic acid.
  • To support your body against hemochromatosis, it can be helpful to decrease your intake of high-iron foods like red meat and organ meats.
  • Avoiding the consumption of vitamin C alongside iron-rich meals can decrease the amount of iron you’ll absorb.
  • Reducing your intake of bread, cakes, cereals, and cookies fortified with iron can remove a considerable amount of iron from the diet.

If you have high ferritin levels, you can flag this in your settings Nutrient Optimiser settings to de-emphasise dietary iron.  But in reality, it can be difficult to significantly reduce iron in your diet without compromising many other nutrients, so you should only de-prioritise a nutrient if you have test results showing your levels are high. 

However, the good news is, if you are using Nutrient Optimiser and already getting plenty of iron, the foods and meals prioritised for you will not prioritise additional iron.  Nutrient Optimiser will highlight other foods and meals that contain the nutrients you need more of. 

What Foods to Eat if You Have Hemochromatosis

While ‘antinutrients’ are often seen as ‘bad’ for health, this is where incorporating more oxalate, lectin, and phytate-containing foods (if you tolerate them) can actually be helpful as they are known to inhibit iron absorption.

  • Consuming foods higher in calcium and copper can also help decrease iron levels and its uptake.
  • Coffee and tea contain tannins which help to inhibit the absorption of iron.
  • Consuming more fish, white meat (as in chicken), and plant proteins can decrease your dietary iron while still supplying you with ample, bioavailable protein.
  • Proteins found in eggs are known to inhibit the absorption of iron, which can be helpful for someone looking to reduce their iron levels.
  • Because the liver is in charge of recycling this micromineral, supporting the liver is often essential to regulating iron stores.  So, working to have great overall health and excellent liver function is a crucial part of making sure your body can get rid of the iron it doesn’t require.

Iron:Zinc Ratio

Excess iron intake can affect zinc absorption.  If your dietary ratio of iron:zinc is greater than 2:1, your zinc absorption will be reduced.  

For this reason, look to prioritise foods with favourable iron:zinc ratios and avoid excess iron supplementation and manage your intake of foods fortified with iron to ensure optimal zinc absorption.  

This is especially important for vegans and vegetarians who can find it harder to obtain iron and zinc.

How Much Iron Do You Require Per Day?

Iron is recycled by the body and is thus conserved.  Thus, repurposing iron from red blood cells and old proteins supplies the body with a generous amount of iron.  However, we still must obtain a fair amount from the diet.

Our satiety analysis of people using Nutrient Optimiser shows a moderate satiety response when people consume more iron.  People consuming more iron food tend to eat around 28% fewer calories than those who consume less iron-rich foods.

The average iron intake of Optimisers is 18 mg/day with an 85th percentile intake of 26 mg per 2000 calories.  This is considerably more than the Estimated Average Requirement for iron of 6 mg and the Recommended Daily Intake for iron of 8 mg/day.  However, this is still far less than the Upper Limit of 45 mg/day, which is set to prevent gastrointestinal issues. 

The satiety response curve below has been prepared using all data from Optimisers (including days with fortification and supplementation).  As the data indicates, we tend to eat many foods fortified with iron.  Because we crave iron in food, consuming high amounts of food products fortified with iron, but otherwise nutrient-poor with a low satiety value (like flours and breakfast cereals), may lead to overconsuming these foods.  Furthermore, we may also see a lack of cravings for foods that naturally contain iron, like meat and vegetables.

The chart below shows the distribution of iron intake with supplements and fortification included, with many people getting well in excess of the Optimal intake of 30 mg/day.

Availability of Iron in the Food System

As shown in the chart below, dietary iron availability has increased with the introduction of iron-enriched foods like breakfast cereals to combat anemia in the 1940s. 

Ironically, iron absorption is also negatively affected by phytates in the grains that cereals are made from.  In addition, the form of iron used in fortification is also not ideal.  It is known to cause constipation, feed pathogenic gut flora, and contribute to oxidative stress that actually damages the intestines.

So, if you are worried about your iron intake and the ferritin levels in your blood, be sure to avoid processed foods fortified with iron as your highest priority. For this reason, in our Micros Masterclass, we guide people to review their intake of supplements and fortified foods to ensure they are not excessive. 

Optimal Iron Intake

Based on our analysis, we have set a stretch target of 30 mg/day for both men and women. 

nutrient menwomen
iron (mg)3030

Nutrient Profile of Foods High in Iron

The nutrient fingerprint below shows the micronutrient profile of the foods that contain the most iron.  We can see that iron is easy to obtain from a nutrient-dense diet in adequate quantities.  

How Can I Calculate My Iron Intake? 

If you’re interested in checking that you’re getting enough (but not too much) iron in your diet, you can check your nutrient profile using our Free 7-Day Nutrient Clarity Challenge

After a week of tracking your current diet in CronometerNutrient Optimiser will give you a prioritised list of foods and NutriBooster recipes that will help you plug your current nutritional gaps.

Level Up Your Nutrient Density

To help you level up your nutrient density, we’ve prepared a Nutritional Optimisation Starter Pack to ensure you are getting plenty of all the essential nutrients from the food you eat every day.    

The free starter pack includes:

  • Maximum Nutrient Density Food List
  • Sample Maximum Nutrient Density Recipe Book
  • Sample Maximum Nutrient Density Meal Plan.

To get started today, all you have to do is join our new Optimising Nutrition Group here

Once you join, you will find the Nutritional Optimisation starter pack in the discovery section here.

Nutrient Density Index



Essential fatty acids                      

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