What you need to know about IRON
- Iron deficiency is on the increase.
- You may be at risk of deficiency if you are vegetarian or vegan, a frequent runner, suffer with IBS or any kind of bowel disorder or are over the age of 70.
- Too much iron is extremely toxic and causes significant damage to our cells.
- Iron levels in vegetables have decreased by 50% since the 1950s.
- Iron from meat and fish is up to 35 times more absorbable than iron from plant foods.
- You can absorb up to three times as much iron from plant foods when you add vitamin C to your meal.
Iron is an essential mineral. This means it has to come from our diet. We cannot make it.
Deficiency of iron can lead to anaemia, which is on the increase in the western world. In the UK, around 4 million people including 10% of women, have iron-deficient anaemia. However, many more may be living with suboptimal iron levels, contributing towards poor health.1-3
Iron performs hundreds of different functions, but is best known for its role in red blood cells, where it is used to transport oxygen around the body. When the body is deficient or low in iron, we can experience a range of symptoms:4,5
- Fatigue, low energy, listlessness
- Heavy periods in women (when iron levels are normalised periods may be shorter and lighter)
- Heart palpitations or breathlessness on exertion
- Brittle nails
- Sore mouth
- Pale skin (pallor)
- Frequent infections or illnesses
- Thinning hair or hair loss
- Restless legs
- Hypothyroidism (low thyroid function)
- ADHD or hyperactivity in children
Why you may be at risk of iron depletion.3,6
- Intensive farming is estimated to have reduced the levels of iron in vegetables by around 50% since the 1950s.
- If you suffer with a gut disorder such as irritable bowel syndrome, bowel disease, undiagnosed coeliac disease, or if you regularly use antacids, you may have trouble absorbing the iron in your food.
- If you eat a diet high in processed foods, ready meals and sugary snacks.
- If you are vegetarian or vegan (see, how we get iron from our diet).
- If you participate in high impact sports or endurance sport. In one study 28% of female recreational marathon runners were found to be iron depleted.7
- If you suffer with chronic inflammation.
- If you have a genetic predisposition.8
Warning! Iron overload.
Before you reach for your supplement pot you need to know that too much iron acts as a free radical. This means it is highly reactive in the body (particularly with oxygen), extremely toxic and can cause major damage to our cells.
It is estimated that around 250,000 people in the UK have a genetic predisposition for iron overload (this is more common in men, particularly those of Celtic descent).9,10
Symptoms of iron overload can include:9,10
- Extreme fatigue, weakness and lethargy.
- Joint pain or arthritis (particularly of the knuckle and joint in the index and middle fingers).
- Abdominal pain.
- Mood swings, irritability, depression and manic episodes in bipolar.
- Loss of body hair.
- Irregular or absent periods in women.
- Erectile dysfunction in men.
For any signs and symptoms of iron deficiency or iron overload always speak to your GP.
Your GP will be able to test your iron levels. However, it is worth knowing that the reference range (normal levels) for ferritin (our stored iron) is extremely wide. It varies between labs but broadly speaking falls between 15ug/L – 300ug/L. If you are within this range but at the low end, you may not be diagnosed with a deficiency, however you may still not be getting enough iron from your diet to support optimal health.3
A comprehensive iron test will check a number of different iron markers. There are various companies offering private, at home, finger-prick blood tests (see resources).
Which foods do we get iron from?
Dietary iron comes in two different forms, haem iron and non-haem iron. Meat and seafood contain both forms of iron. Plant foods only contain non-haem iron.
A healthy digestive system will absorb approximately 35% of haem iron but only 1% – 3% of non-haem iron. This is because non-haem iron is in a form that is naturally less-easily absorbed. In addition, many foods high in non-haem iron also contain inhibitors which further reduce absorption.
Inhibitors of non-haem iron absorption include phytates (compounds found in legumes, grains, nuts and seeds), polyphenols (in particular tannins in tea and coffee) and oxalates (high in rhubarb, spinach, beetroot and tea), although evidence for the effects of oxalates on absorption is contradictory. Calcium (high in dairy products) and egg may also inhibit absorption.11-14
Promoters of iron absorption include meat (eating meat with iron rich vegetables, can increase the uptake of non-haem iron) and vitamin C, which acts as a significant promoter of non-haem iron absorption. There is also some evidence that beneficial gut bacteria (Lactobacillus Plantarum) may positively influence non-haem iron absorption, although this is yet to be proven. What is undeniable is that good gut health is paramount for all nutrient absorption, iron included.11-15
The UK recommended reference nutrient intake (RNI) per day for Iron is:4
Adult males over 18yrs. 8.7mg
Adult females age 19-50yrs. 14.8mg (iron requirement is increased in pregnancy)
Adult females over 50yrs. 8.7mg
However, it is important to remember that we are all unique, and as such our individual requirements may differ considerably.
Natural food sources of iron:16
|Haem & Non-haem Iron||Level||Per|
|Clams – cooked||28.0mg||100g|
|Liver – calf||11.5mg||100g|
|Mussels – steamed||6.7mg||100g|
|Prawns – cooked||3.0mg||100g|
|Sardines (tinned in oil)||2.3mg||100g|
|Beef sirloin steak*||1.3mg||100g|
|Non-Haem Iron only||Level||Per|
|80% Dark chocolate||9.1mg||100g|
|Cashew nuts plain||6.2mg||100g|
|Spirulina powder||5.8mg||20g (4 teaspoons)|
|Blackstrap Molasses||4.2mg||1 Tablespoon|
|Puy lentils cooked||3.5mg||100g|
|Almonds with skin||3.4mg||100g|
|Red lentils cooked||2.4mg||100g|
|Quinoa tri cooked||2.3mg||100g|
|Sesame seeds||2.3mg||2 Tablespoons|
|Spinach mature cooked||2.2mg||100g|
|Egg||2.0mg||100g (2 medium eggs)|
|Spinach baby raw||1.9mg||100g|
|Dried mixed herbs||0.5mg||Teaspoon (1)|
*Organic grass-fed beef may provide higher levels of iron. There is research demonstrating increased levels of beneficial fatty acids, vitamins E & A, CoQ10 and taurine in organic beef, but I could find no studies comparing iron content between conventionally raised and organic beef.17
To support iron absorption & get more iron into your diet
- Avoid drinking tea and coffee within one hour of meals, preferably two hours.
- Include a wide variety of iron-rich food groups in your diet, and include both raw and cooked leafy green vegetables (the iron in spinach may be better absorbed after cooking).
- Soak beans and pulses prior to cooking to reduce the levels of phytates present.
- Eat a small amount of meat or fish with non-haem foods.
- Include vitamin C rich foods with non-haem foods (red peppers, kale, broccoli, watercress, red cabbage, citrus fruits). Add a squeeze of lemon or orange juice to veg and salads or drink a small glass of fresh orange or apple juice with your meals.
- Use dried herbs in cooking and sprinkle fresh parsley on to meals.
- Sweeten foods with blackstrap molasses instead of honey, syrup or sugar.
- Optimise your digestion by eating your meals in a relaxed environment, eat slowly and chew food well. Focus on your food and really savour it.
If you have been diagnosed as iron deficient you may need to take a supplement. Some supplements can cause an upset stomach including stomach cramps, constipation or diarrhoea. Iron bisglycinate is generally better tolerated than other forms of iron supplementation, resulting in fewer gut symptoms.18
And before I leave you, a quick reminder that food is so much more than its individual nutrients, and great health is so much more than just the food that we eat.
Thanks for reading!
Finger-prick blood tests are available from Medichecks (medichecks.com) and Thriva (Thriva.co).
Haemochromatosis UK (http://haemochromatosis.org.uk/).
- Sant-Rayn Pasricha (2014) Anemia: a comprehensive global estimate. Blood, 123: 611 – 612
- Anaemia Manifesto (https://anaemiamanifesto.com/manifesto/introduction/)
- SACN (2010) Scientific Advisory Committee on Nutrition [Online] (https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/339309/SACN_Iron_and_Health_Report.pdf) Accessed: 10th March 2019
- NHS (2017) Vitamins and Minerals, Iron. [Online] (https://www.nhs.uk/conditions/vitamins-and-minerals/iron/)
- Camaschella C (2017) New insights into iron deficiency and iron deficiency anaemia. Blood Reviews, 31: (4) 225 – 233
- Galloway S (2016) Iron Deficiency. The Diagnosis and Treatment of Common Functional Illnesses. 1st, UK. SureScreen Scientifics
- Mettler S, Zimmerman Mb (2010) Iron excess in recreational marathon runners. European Journal of Clinical Nutrition, 64: (5) 490 – 494
- Blanco-Rojo R et al., (2011) Four variants in transferrin and HFE genes as potential markers of iron deficiency anaemia risk: an association study in menstruating women. BioMed Central, [Online] (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3195693/) Accessed: 10th March 2019
- org (undated) Symptoms [Online] (http://haemochromatosis.org.uk/haemochromatosis/symptoms/) Accessed: 9th March 2019
- NHS (2016) Health overview: Haemochromatosis [Online] (https://www.nhs.uk/conditions/haemochromatosis/) Accessed: 9th March 2019
- Hurrell R (2010) Iron bioavailability and dietary reference values. The American Journal of Clinical Nutrition, 91: (5) 1461 – 1467
- MacPhail A (2012) Iron. The Essentials of Human Nutrition. 4th, Oxford. Oxford University Press
- Noonan SC (2002) Oxalate content of foods and its effect on humans. Asia Pacific Journal of Clinical Nutrition, 8: (1) 64 – 74
- Storcksdieck S et al., (2008) Oxalic acid does not influence nonhaem iron absorption in humans: a comparison of kale and spinach meals. European Journal of Clinical Nutrition, 62: 336 – 341
- EFSA (2016) Lactobacillus plantarum 299v and an increase of non‐haem iron absorption: evaluation of a health claim pursuant to Article 13(5) of Regulation (EC) No 1924/2006 [Online] (https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2016.4550) Accessed: 10th March 2019
- Nutrition analysis software for professionals [Online] (https://www.nutritics.com/p/home) Accessed: 10th March 2019
- Ribas-Agusti A et al., (2019) Nutritional properties of organic and conventional beef meat at retail. The Journal of the Science of Food and Agriculture. [Epub ahead of print] (doi: 10.1002/jsfa.9652)
- Youssef AM et al., (2014) A Comparative Study of Efficacy, Tolerability, and Compliance of Oral Iron Preparations for Iron Deficiency Anemia in Pregnant Women. American Journal of Medicine and Medical Sciences, 4: (6) 244 – 249