How much iron supplement should a man take?

Written by Ben Bunting: BA, PGCert. (Sport & Exercise Nutrition) // British Army Physical Training Instructor // S&C Coach

Iron is a mineral that is essential to muscle function and oxygen transportation. Iron-deficiency can affect athletes' performance if they do not have adequate levels of iron.

A number of studies have examined iron status in athletes with iron deficiency and the effects of iron supplementation. They also determined that physical strain could alter iron balance, as well as markers related to iron status.

Iron supplementation was most effective in athletes who had a low iron status. The greatest improvements in physical performance were seen in athletes who started out with a deficiency.

Even athletes with normal iron levels at baseline may benefit from iron supplementation for a better erythropoietic reaction during altitude training. However, this should be done with caution.

The hepcidin response may alter the iron reserves available for erythropoiesis. The amount of energy consumed and carbohydrates available may affect the hepcidin post-exercise response.

Vitamin D and B12 at optimal levels may contribute to iron status, and thereby, avoidance of anemia.

If you are an athlete or a person with a rigerous training routine, you may need to increase your iron intake. Military Muscle provides a small dose of iron with each daily serving to ensure you can perform to your best.

Quick Bite:

  • Iron deficiency is common in athletes, particularly in endurance athletes
  • Iron supplementation is most effective in improving the performance of athletes with low ferritin levels
  • This shows significant improvements for iron-deficient individuals

Iron and its Role

Iron is a mineral that is essential. Its main function involves reversible oxygen transport in the hemoglobin molecules of red blood cells, and in the myoglobin of muscle cells.

Other important roles include electron transport, DNA synthesis and energy metabolism.

Iron is used in the hemoglobin and myoglobin molecules as heme, which is iron bound to porphyrin.

Iron is mainly used by the body to make hemoglobin and myoglobin.

The iron storage in men is about 4 g and in women is 2.5 g. However, only 1-2mg is lost each day because of intestinal iron absorption.

Iron intake is usually around 10-15mg per day.

However, only 10% of this iron is absorbed in normal conditions. This is because iron loss is only small due to minor bleeding and epithelial dequamation. 

The peptide hormone hepcidin is produced by hepatocytes, the cells of the liver.

Hepcidin production is increased when serum ferritin levels are high. It is also regulated by erythropoiesis, which requires iron. 

Hepcidin blocks iron absorption by binding to ferroportin, which transports Fe 2+ out of enterocytes and into the plasma.

Interleukin-6, which is upregulated after training and causes inflammation, has been shown to stimulate hepcidin.

This response also depends on the ferritin baseline levels before training. Athletes with lower ferritin have a reduced hepcidin reaction after training.

Recent studies have examined the possibility of a different hepcidin reaction with a low energy diet (LEA), a low carbohydrate diet, or a ketogenic one. 

It has been highlighted that an increased response to hepcidin under both LEA conditions and low carbohydrate conditions among athletes. 

Iron Deficiency

An iron deficiency is posible if you have anemia or not.

Iron deficiency without anemia (IDNA)

IDNA is diagnosed when ferritin (30mg/L) levels are low but hemoglobin (>130/120g/L for men/women) levels are normal. 

According to the WHO, iron deficiency is characterized by low ferritin levels that lead to low hemoglobin levels (130/120 g/L for men/women).

IDNA can have negative effects on multiple functions because iron is involved in many biological processes. IDNA does not only carry oxygen in hemoglobin molecule.

IDNA can affect metabolic systems that contain iron-containing proteins, for example, reactions in the respiratory system where iron acts as a cofactor.

This reduces oxidative capability, which then decreases the ability of the muscles to use oxygen.

IDNA can cause symptoms such as fatigue and reduced concentration. It can also affect physical performance.

Iron deficiency with anemia (IDA)

The hemoglobin level is lower when IDA occurs. 

It reduces the physical abilities of the person because oxygen is not reaching all cells of the body. This includes working muscles when exercising.

Iron supplementation in IDA athletes may lead to an increase of hemoglobin, and therefore, an increase in VO 2max, and endurance.

Athletes and Iron Deficiency

Iron deficiency is common in athletes. This can be due to a number of factors, such as increased iron losses during training, caused by micro-ischemia and hemolysis.

Women are also more susceptible to this disease than men due to menstrual bleeding.

It is possible that athletes with low energy availability have a poor iron status, because their iron intake may be insufficient.

Increased IL-6 levels and hepcidin, which are triggered by training, allow for less iron to be absorbed and recycled.

Iron is also used more for the increased erythropoiesis, and to rebuild tissues as a result.

The increase in hemoglobin is due to the increase in EPO production after training and living in altitude or hypoxic environments.

An increase in EPO stimulates erythropoiesis, the production of red cells in the bone-marrow. For endurance athletes, living and/or exercising at altitude can increase their oxygen-carrying capability of blood and endurance.

Iron stores are essential for hematological adaptation to hypoxia. Prior to altitude training it is recommended to have ferritin levels > 50 ng/mL due to the need for iron in such environments.

In a retrospective and prospective study, it was demonstrated that iron deficiency inhibited the erythropoietic response to altitude-training and highlighted the importance iron supplementation for achieving optimal adaptation.

Iron deficiency affects several abilities athletes need, outside of their aerobic abilities. These include those related to strength and fatigue.

These factors can all affect performance, including endurance as well as power and speed. They also influence coordination, concentration, recovery and other sports variables.

Iron deficiency is a common problem among endurance athletes, due to the role iron plays in aerobic metabolism and its high prevalence.

Does Iron Supplementation Improve Performance?

Some research found that after four weeks of altitude exercise only those with normal ferritin had an improved VO 2max.

Those with low ferritin showed no improvement. In the prospective study VO 2max increased among athletes who were training at altitude while supplementing iron.

Those who train at sea level and take iron supplements did not improve.

The athletes who received IV iron or oral iron supplementation saw a significant increase in their hemoglobin (3.7% and 3.2%), while those on placebo did not see any increase.

Both studies showed that iron supplements are necessary to maintain ferritin levels in hypoxic environments, even if the levels were sufficient prior to altitude.

They also pointed out an increased iron use for accelerated erythropoiesis in these conditions.

Okazaki et al. Calculated an additional need of 4.9 mg iron per day for altitude runners, on top of the daily requirements: 1.9 mg/day (for women) and 2.3mg/day (for men) when training at sea-level.

Only two other studies in which athletes were supplemented in environments without altitude showed a slight increase in performance. 

The effect was more noticeable in athletes with lower ferritin levels. The iron supplementation period was associated with increased strength.

No other study has shown a direct improvement in performance in athletes who are iron deficient when iron is supplemented in normal conditions.

These studies found that supplementation can prevent a decrease in iron stores caused by hard physical strain, and also have a positive effect on mood and fatigue.

Iron Supplementation Timing

Iron absorption improves after morning exercise compared to afternoon or when you are rested.

The researchers found that hepcidin levels were higher and accumulated in the afternoon. This suggests a transient mechanism, which promotes iron absorption better in the morning.

The increase in hepcidin occurred 3 hours after training regardless of whether it was morning or afternoon training.

How to Improve Iron Levels

The recommended daily allowance (RDA) for iron in the US for the general public is 18mg per day for women, and 8mg per day for men.
In the UK it is 14.8mg and 8.7mg respectively.
Iron is recommended for pregnant women at 27mg.
However, there's no official recommendation for athletes.
Some women endurance athletes may need up to 70% more than 18mg.


Treatment of iron deficiency in sports can be accomplished through dietary adjustments and if necessary using oral supplementation, or supplementation intravenously/intramuscularly.

It is important for athletes to consume meat, fish, grains and vegetables. Vitamin C-rich foods can enhance iron absorption while polyphenols, found in tea, coffee and some plants, can inhibit it.

The first step in treating iron deficiency is to correct the diet.

Aim for 14 mg of iron per day.

Oral supplementation should be done with caution because of its potential side effects and the possibility that hepcidin will increase as a result of elevated iron levels.

A dose of 40-60 mg elementary iron per day is recommended for athletes who have an iron deficiency.

One body of research found that a single dose of iron per day was found to be superior to a divided dose for increasing hemoglobin levels during altitude training.

Possible Side-Effects

Oral iron supplements can cause gastrointestinal problems such as nausea, abdominal discomfort, and constipation.

It is important to be aware of these side effects, which can affect daily performance. Oral supplements are most commonly used ferrous sulphate, along with ferrous fumarate or gluconate.

If oral iron supplementation does not result in an increase in ferritin, if the treatment is not tolerated, or if a rapid recovery is needed, intravenous iron supplementation may be considered.

In terms of iron status, intravenous supplementation did not show any additional benefits over oral supplementation. 


Iron deficiency is common in endurance athletes.

It is possible that the protocol for optimizing iron status in athletes could be one of many factors contributing to a better physical performance.

Iron supplementation is most effective for athletes who have lower ferritin concentrations.

This shows significant improvement in iron deficient athletes, while athletes with adequate iron stores only see a limited benefit.

There are no clear guidelines on how to achieve a ferritin level that is narrower and optimal for athletes, other than maintaining levels above the iron deficiency threshold.

Recent research has also shown that athletes and coaches need to pay attention to the fact that maintaining a diet with adequate carbohydrates and energy is important to avoid increased levels of hepcidin after training.

Iron status can be improved by ensuring adequate vitamin D and vitamin B12 intake.


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