Iron is among the best -known and most important mineral substances in the body. To produce haemoglobin, which transports oxygen we need iron. In the case of iron deficiency, cells don’t get enough oxygen, which eventually leads to fatigue, then anaemia. Iron has many other functions as well, it’s indispensable for the production of certain enzymes and the satisfactory functioning of the antioxidant system.  

However, iron is a double-edged sword. Excess intake can lead to numerous health problems. Supplementation is especially dangerous, as iron can foster certain infections and can increase the oxidative load. (1) Supplementation is only advised under specific, rare  circumstances when iron deficiency can be definitely diagnosed, as numerous studies found it to have neutral or even negative effects. Even in these cases, it’s best to ingest iron from food sources and avoid taking supplements.  

How much iron do we need?  

The necessary daily intake of iron was prescribed as 11 mg by the European Food Safety Authority for men and older women, while the American NIH only recommends 8 mg for this age group. Younger women who still menstruate are prescribed 16-18 mg by both organizations, as they generally lose a much larger amount of iron. (2,3) 

Typical iron intake is higher in most countries, though iron deficiency is quite common in certain groups, such as children or pregnant women. In impoverished countries where famines occur frequently even today iron deficiency is common. (4) 

Animal source foods contain a form of iron which is better utilized than the form found in plants. Moreover, plant based foods contain additional substances which further decrease iron absorption, so those who don’t eat meat must take better care of their iron intake. (5) 

Regular blood donors also need more iron depending how much blood they donate and how often; iron deficiency was detected in over half of participating donors in a large-scale study. (6) Thankfully, iron supplies are easy to determine from blood work, but all values must be considered, since that’s the only way to get a complete picture of the body’s iron supplies. Blood donation is the best way to decrease excess iron, but can lead to iron deficiency especially  in the case of young women.  

How to provide sufficient intake? 

The best sources of iron are animal source foods, as they contain a form of iron that’s easily utilizable. Beef, and especially beef liver are outstanding examples. Sea food, fish and other types of meat count as good iron sources too. Among plant based foods, spinach, quinoa, pulses, dark chocolate and nuts contain higher amounts of iron. (7) 

There are many ways to increase or decrease the absorption of iron depending on whether one wants to increase or decrease their iron intake. The following strategies help increase the amount of absorbed iron:  

• Eating citrus or vitamin C with meals (8) 

• Eating animal protein, meat, fish or eggs in addition to plant based food (this increases the utilization of iron from plant based foods as well) (9, 10) 

• Supplementing vitamin A on its own increases ferritin and haemoglobin levels (11) 

The following methods help decrease the amount of absorbed iron:  

• Eating calcium rich food, such as dairy with meals (12) 

• Drinking coffee or tea with meals (13) 

• Fiber from whole wheat grains significantly decrease the amount of absorbed iron (14) 

• Avoiding iron cooking pots (15) 

How to prevent iron deficiency?  

Unlike deficiencies of most mineral substances and trace elements , iron deficiency only affects few  people:  regular meat eaters won’t be affected. It’s more common in certain groups, such as the above-mentioned blood donors, young women, followers of plant-based diets or babies with low birth weight. 

Iron deficiency should first be treated by eating iron-rich food and using the strategies listed above; iron supplements should be a final resort. Unnecessary or rash iron supplementation can lead to various problems.  

Be careful with iron supplementation 

Iron is one of those micronutrients which are easy to ingest in excess, especially for those who already have an iron-rich diet but take iron supplements as well. As the body cannot easily dispose of it, excess iron, just like iron deficiency, can cause various health problems. Excess levels can only be significantly lowered through bleeding, which is why menstruating women and blood donors are less prone to having excess iron. From an evolutionary perspective, men likely lost more blood through scratches and scars, but it’s no longer the case nowadays.  

To an extent, the body can regulate how much iron is  absorbed from food depending on the available iron. A rare genetic defect, which causes these systems regulating iron absorption to fail and iron to accumulate more easily in the body, perfectly demonstrates how damaging excess iron can be. Due to this genetic mutation, iron may accumulate in organs over time, damaging the liver and the cardiovascular system, which can lead to death in severe cases. (16) When diagnosed in time, the illness can thankfully be controlled through blood donation.  

Excess iron supplementation can lead to immediate poisoning: doses over 20 mg/kg can cause nausea, digestive pain and cramps, and a bit more can induce a life-threatening condition. (17) With long term use, even smaller quantities can be problematic. All it takes is regularly eating iron-enriched food or ingesting dietary iron supplements daily.  

Through supplementing iron, a considerable amount of free iron gets into the digestive system, then from there into the blood, where a very low amount is  present under normal circumstances. This is unfortunately ideal for infection, as microorganisms need iron to stay alive. Withdrawing iron is a part of the body’s immune response to infection, which is blocked by iron supplementation. (18) Several studies observed that the risk of certain infections and their severity increase with iron supplementation. (19,20) 

While we need an optimal amount of iron for the function of the antioxidant system, excess intake has negative effects. A high amount of free iron circulating in the bloodstream increases the production of free radicals and thus the oxidative load, which damages cells and tissues in the long run. This is probably why high iron intake increases the risk of various types of cancer. (21) 

[The cover photo of the note shows a beef steak. 100 grams of beef contains 6.2 mg of iron, which provides half of the daily iron requirement.]