Iron is an essential nutrient for growth and development, and plays a critical role in transferring oxygen around the body. It constitutes a vital part of haemoglobin, the oxygen-carrying component of red blood cells. Haemoglobin is responsible for transporting oxygen from the lungs to the body’s tissues, and carbon dioxide from the tissues to the lungs. The mineral also plays a part in energy production, muscle function, DNA synthesis and the immune system. We get most of the iron we need from food, and our body carefully monitors our iron levels, absorbing more when demand is high and less when stores are adequate. Iron is stored primarily in bone marrow and the liver.
The Nutrient Reference Intake (NRI) for women of reproductive age is 14.8mg iron per day, with an additional requirement recommended during pregnancy. For men and non-menstruating women, the requirement is 8.7mg per day.
Iron deficiency is surprisingly common in the UK, and is particularly prevalent among infants under two, teenage girls, pregnant women and the elderly. According to government surveys, the majority of menstruating women do not reach their dietary target.
Iron deficiency may be due to one or more of the following factors:
- Blood loss: this is the most common cause of iron deficiency in women of childbearing age. It is often due to excessive menstrual bleeding, but other causes of blood loss can include bleeding from peptic ulcers, haemorrhoids and donating blood.
- Increased iron requirement: periods of growth during childhood and adolescence sharply increases the need for iron. The increased need for iron during pregnancy may not be met through diet alone, so supplementation may be advised to pregnant women as necessary. If you’re pregnant and are concerned you may be deficient in iron, please consult your doctor.
- Inadequate dietary intake: it is good to remember that plant-based sources of iron are a little harder for the body to absorb, and that vitamin C aids in absorption of all forms of iron. Typical infant diets, which are high in milk and cereals, can also be low in iron. Try a cereal fortified with iron to up intake.
- Diminished iron absorption: this is often due to reduced gastric acid secretion in the stomach, which can be caused by atrophic gastritis (common in the elderly), chronic diarrhoea or prolonged use of antacids.
Periods of rapid growth (such as adolescence), heavy bleeding, a busy lifestyle and lack of iron in your diet will result in your body drawing on its iron reserve. Initially there are no symptoms, but as your iron supply dwindles, so will your body’s ability to produce healthy red blood cells. The result is low numbers of red blood cells circulating in the blood, a condition called iron-deficiency anaemia.
Symptoms of anaemia include weakness, fatigue*, pale complexion, breathlessness, palpitations and an increased susceptibility to infection. Anaemic children have difficulty concentrating, and may find it difficult to learn. Doctors can determine the levels of your body’s iron stores through a serum ferritin test.
*A note on haemochromatosis
Haemochromatosis is a specific genetic disorder in which iron builds up over time, leading to excessive levels. If you have a family member with haemochromatosis, you should be screened to determine if you are at risk.
It is hard to diagnose, but one of the symptoms is fatigue. If you are feeling very tired all the time, it is recommended that you go to your GP and have a blood test before taking iron supplements.
Read more about it at the NHS website.
Supplements and safety
Anaemia requires a careful diagnosis and treatment to correct the underlying cause. Always consult a doctor before taking an iron supplement. When prescribed by a doctor, iron is typically taken in a form called ferrous salts – ferrous sulphate, ferrous fumerate or ferrous gluconate. Side effects of iron supplements can include constipation and an upset stomach, so be cautious and do not exceed the recommended amount. Keep all supplements containing iron out of reach of children.
Friends and foes
There are two forms of iron found in food. Haem iron is found in animal products, and is the most efficiently absorbed form of iron. Non-haem iron is found in plant-based foods, and is more difficult to absorb by comparison. Vitamin C helps promote iron absorption, so when vitamin C-rich foods are combined with foods rich in iron, absorption of the iron is substantially increased.
You should also watch the amount of tea you consume, as a substance called tannin – found in tea – is thought to inhibit the absorption of iron. Be aware that decaffeinated teas contain just as much tannin as caffeinated teas. Foods high in phytates and oxylates, such as spinach, nuts, chocolate, parsley and rhubarb may also have a negative impact on iron absorption. Dairy products such as yogurt, cheese and milk, as well as eggs, can also interfere with iron absorption – that’s because casein from milk and certain forms of calcium inhibit iron absorption. It’s important to aim to eat a varied, balanced diet.
Rich sources of iron
- Liver, beef and lamb
- Clams, mussels and oysters
- Kidney beans
- Leafy green vegetables
- Dried figs and apricots
- Oatmeal and rye
- Brewer’s yeast
- Blackstrap molasses
- Pinto beans
Pregnant women should avoid liver and any related products, such as liver pâté, as these can contain high levels of vitamin A, which may be harmful to a developing baby.
Recipe suggestions for iron-rich meals
Go crazy for lentils, beans and peas with these tasty, light lunches:
Puy lentil salad with soy beans, sugar snap peas & broccoli
Lemony rice & peas
Make your own muesli:
This article was updated on 11 December 2019 by Kerry Torrens.
Kerry Torrens BSc. (Hons) PgCert MBANT is a Registered Nutritionist with a post graduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including BBC Good Food.
All health content on bbcgoodfood.com is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. If you have any concerns about your general health, you should contact your local health care provider. See our website terms and conditions for more information.