Iron deficiency and vitamin C

Consider dietary iron intake as well as iron loss, says Dr Nick Summerton.

Drinking orange juice with a meal can significantly improve iron absorption
Drinking orange juice with a meal can significantly improve iron absorption

Eighteen hundred years ago, an individual with severe anaemia visited the Roman temple of Nodens at Lydney Park in Gloucestershire.

The man would have gone there to take advantage of the iron-rich waters, to undergo dietary therapy and, perhaps, to participate in various Aesculapian rituals, including dream therapy.

In appreciation of his successful treatment, he left behind a small offering to the god Nodens, in the form of a model forearm. As can be seen, the fingernails exhibit the typical spoon-shaped koilonychia characteristic of iron deficiency anaemia.

Iron deficiency

Today, iron deficiency is one of the most common micronutrient disorders, affecting around 30% of the world's population. In industrialised countries such as the UK, iron deficiency is most prevalent among pregnant women, children under five years old, women of reproductive age and the elderly.

The most common consequence of iron deficiency is microcytic anaemia but, importantly, iron deficiency without anaemia (as assessed by the ferritin level) can have adverse effects on cognitive function, immune status and physical performance. In one study, non-anaemic adolescent girls consuming a diet supplemented with iron felt less fatigued, their ability to concentrate in school increased and their mood improved.

Lack of iron may be due to bleeding (acute or chronic), poor diet or an inability to absorb iron from food.

It is easy to focus on blood loss (for example, due to heavy menstrual bleeding, ulcers, polyps, malignancy or medication) or malabsorption (for example, from Crohn's disease or coeliac disease) and, unlike our Roman forbears, forget to consider the patient's oral intake of iron.

Dietary iron sources

Iron in food occurs in two main forms, haem and non-haem. The major sources of haem iron are haemoglobin and myoglobin from meat, poultry and fish.

Non-haem iron consists mainly of iron salts, derived from plant and dairy products.

However, certain other dietary elements can enhance iron absorption, whereas others will inhibit it. For example, drinking tea with a meal inhibits iron absorption, as does drinking milk and eating cheese.

According to the WHO, iron absorption can vary from 1-40%, depending on the mix of enhancers and inhibitors in a meal. Simple alterations in meal patterns can significantly enhance iron absorption (see box).

Simple alterations to enhance iron absorption
  • Separate tea drinking from mealtimes - have a cup of tea one to two hours later.
  • Include fruit juices, such as orange juice, in the meal.
  • Eat milk, cheese and other dairy products as a between-meal snack, rather than at mealtimes.
  • Consume foods containing inhibitors at meals that are lowest in iron content; for example, breakfast with a low-iron cereal consumed with tea or milk products can provide adequate calcium without hampering iron nutrition.

Iron absorption

Non-haem iron normally constitutes more than 90% of the iron we eat. Unfortunately, absorption of non-haem iron is much less than haem iron, owing to its tendency to revert to the insoluble Fe3+ (ferric) form.

However, consuming a reducing agent (electron donor) such as vitamin C (ascorbic acid) with a meal promotes non-haem iron absorption by maintaining the iron in its Fe2+ (ferrous) state. As a reducing agent, ascorbic acid is special because it can transfer a single electron, yet also form a stable, non-reactive ion, dehydroascorbate.

Studies have demonstrated that iron absorption can be increased 1.5-10 fold as a consequence of consuming orange juice with a meal (up to the maximum daily recommended dose of vitamin C for the individual). Moreover, the promotion of iron absorption in the presence of vitamin C seems to be particularly pronounced in meals containing inhibitors of iron absorption. Vitamin C may also be involved in the transfer of iron into the blood, as well as mobilising it from iron stores.

  • Dr Summerton is a GP and NHS appraiser in East Yorkshire

Resources

  • WHO. Iron Deficiency Anaemia.

Assessment, Prevention and Control. Geneva, WHO, 2001.

  • European Food Safety Authority. EFSA Journal 2009; 7(9): 1226.
  • Summerton N. Medicine and Health Care in Roman Britain. Colchester, Shire Archaeology, 2007.

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