Iron

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Iron is an essential mineral that is considered to be critical to human life. It is found in the food sources liver, meat, beans, nuts, dried fruits, poultry, fish, whole grains and enriched cereals, soybean flour and most dark green leafy vegetables. The Recommended Daily Amount (RDA) for adults in the UK is 8 mg for males and

18 mg for females. During pregnancy, this increases to 27 mg and 9 mg for lactating mothers.

What is it needed for?

Iron is an essential component of oxygen transportation between the lungs and the body’s tissues. It is also necessary for growth and development, normal functioning of the cells, and synthesis of some hormones and connective tissue. It also contributes to normal cognitive function, normal energy-yielding metabolism and the normal functioning of the immune system. Iron contributes to the reduction of tiredness and fatigue and plays a role in the process of cell division.

Deficiency

A deficiency of iron limits oxygen delivery to cells, resulting in anaemia, fatigue, poor work performance, and decreased immunity. Deficiency is common and occurs as a result of decreased dietary intake, diminished iron absorption and utilisation or blood loss or a combination of these factors. The groups at highest risk include infants under 2 years of age, teenage girls, in pregnancy and the elderly generation.

Evidence

Prevention of Iron deficient Anaemia (IDA) during pregnancy- a number of randomized controlled trials have shown that iron supplementation can prevent IDA in pregnant women and related adverse consequences in their infants (1), (2). A Cochrane review showed that daily supplementation with 9–90 mg iron reduced the risk of anaemia in pregnant women at term by 70% and of iron deficiency at term by 57% (3). In the same review, use of daily iron supplements was associated with an 8.4% risk of having a low-birthweight new born compared to 10.2% with no supplementation. In addition, mean birthweight was 31 g higher for infants whose mothers took daily iron supplements during pregnancy compared with the infants of mothers who did not take iron.

Prevention of Iron-Deficient Anaemia in infancy– Research shows that IDA in infancy can lead to potentially irreversible adverse cognitive and psychological effects, including delayed attention and social withdrawal (4), (5). A Cochrane review of 26 studies in 2,726 preterm and low-birthweight infants found that enteral iron supplementation at a dose of at least 1 mg/kg/day reduces the risk of iron deficiency (6).  

Cognitive Function- Research has found that Iron deficient anaemia may result in cognitive deficiency symptoms (7). Furthermore, a study by Murray-Kolb and Beard in 2007 (8) showed a positive effect of iron supplementation on cognitive function in healthy women between 18-35 years of age.

Our take on how Iron may help you based on EU claims;

Fatigue and Tiredness- Iron contributes to normal energy-yielding metabolism This suggests that a deficiency may be a factor in cases of tiredness and fatigue, and so a supplement may help prevent this. This may also be of value to those participating in sports activities to ensure the correct functioning of their energy metabolism to maximise performance.

Colds, Flu and Infections- Iron contributes to the normal function of the immune system This makes it a popular supplement for those looking to ward off colds, flu and other infections.

Anaemia– Iron contributes to normal formation of red blood cells and haemoglobin It is well established that an iron deficiency can lead to anaemia. A supplement may, therefore, help to guard against this and the related symptoms of fatigue, tiredness and pale skin.

Low mood and related symptoms– Iron contributes to normal cognitive function This suggests that deficiencies could lead to impaired cognitive function, and there have been studies to suggest that correcting Iron deficiency may help to improve mood in those with low Iron.

Athletic Performance– Iron contributes to normal formation of red blood cells and haemoglobin, and contributes to normal oxygen transport in the body. These processes are both important for the body’s energy supply, so guarding against deficiency may help to maximise athletic performance.

Safety and side effects

Iron is considered to be likely safe for most people when taken in appropriate amounts. However, iron has been associated with unwanted side effects mainly relating to digestive upset and may include constipation or diarrhoea, nausea, and vomiting. Side effects may be reduced if taken with food however because some foods are thought to interfere with absorption where possible iron supplements should be taken on an empty stomach. Taking iron supplements with food seems to reduce some of these side effects. However, food can also reduce how well the body can absorb iron. Iron should be taken on an empty stomach if possible. The Tolerable Upper Intake Level for adults in the UK is 45mg.

References

  1. Makrides M, Crowther CA, Gibson RA, Gibson RS, Skeaff CM. Efficacy and tolerability of low-dose iron supplements during pregnancy: a randomized controlled trial. Am J Clin Nutr 2003;78:145-53.
  2. Cogswell ME, Parvanta I, Ickes L, Yip R, Brittenham GM. Iron supplementation during pregnancy, anaemia, and birth weight: a randomized controlled trial. Am J Clin Nutr 2003;78:773-81
  3. Pena-Rosas JP, De-Regil LM, Dowswell T, Viteri FE. Daily oral iron supplementation during pregnancy. Cochrane Database Syst Rev 2012;12:CD004736
  4. Aggett PJ. Iron. In: Erdman JW, Macdonald IA, Zeisel SH, eds. Present Knowledge in Nutrition. 10th ed. Washington, DC: Wiley-Blackwell; 2012:506-20
  5. Baker RD, Greer FR. Diagnosis and prevention of iron deficiency and iron-deficiency anaemia in infants and young children (0-3 years of age). Pediatrics 2010;126:1040-50
  6. Mills RJ, Davies MW. Enteral iron supplementation in preterm and low birth weight infants. Cochrane Database Syst Rev 2012;3:CD005095.
  7. Jáuregui-Lobera I: Iron deficiency and cognitive functions. Neuropsychiatr Dis Treat. 2014 Nov 10;10:2087-95. doi: 10.2147/NDT.S72491. eCollection 2014. Review. PMID: 25419131
  8. Murray-Kolb LE, Beard JL. Iron treatment normalizes cognitive functioning in young women. Am J Clin Nutr. 2007;85:778–87