Iron

Anaemia and iron overload are two of the most prevalent disorders worldwide and affect over a billion people.” Anderson and Shah, 2013.

It’s a myth that you need to eat meat to get iron. One of the largest studies of vegetarians and vegans, The European Prospective Investigation into Cancer and Nutrition (EPIC) Oxford study, compared over 33,000 meat-eaters, 18,000 vegetarians and 2,500 vegans and fo­und that vegans had the highest intake of iron, followed by vegetarians with meat-eaters coming last (Davey et al., 2003). The American Dietetic Association state that iron deficiency is no more common among vegetarians than meat-eaters (Craig and Mangels, 2009).

The meat industry tries to reinforce the idea that you need to eat meat to get iron. A small number of industry-funded studies have fed in to the confusion. The authors of one such study, commissioned by the Meat and Livestock Commission, expressed concern about iron intakes in relation to falling meat intake (Gibson and Ashwell, 2003). The authors (who both run ‘independent’ nutrition consultancies that have worked with Kelloggs, Danone, Glaxo SmithKline, Coca-Cola, PepsiCo as well as the Meat and Livestock Commission) said that low consumption of red and processed meat has implications for iron intakes and iron status in men and women.

However, contrary to the idea that meat is the main source of iron in a meat-eater’s diet, research shows that cereals and cereal products (bread and fortified breakfast cereals) are the principal source of iron in the average UK diet. One study found that the main contribution of iron in a large British cohort was from cereal foods, including breakfast cereals, bread and other cereal products such as pasta, rice, cakes, biscuits and puddings, followed by fruit, nuts and vegetables and then meat coming in last (Johnston et al., 2007). The 2014 NDNS was in agreement – cereals and cereal products were the largest contributor to iron intake for all age groups (Bates et al., 2014). People who don’t eat meat can easily get sufficient iron from cereal, pulses and vegetable sources that also provide healthy fats and valuable fibre.  

The Reference Nutrient Intake (RNI) is the amount of a nutrient which is sufficient for most people. The RNI for iron is 8.7 mg per day for men and 14.8 mg per day for women up to the age of 50 (Department of Health, 1991). Women have higher requirements as they lose iron during menstruation. If iron intake is low, the amount of haemoglobin in the red blood cells can fall leading to iron-deficiency anaemia. Symptoms include tiredness, weakness, feeling cold and an inability to concentrate.

As mentioned previously, iron occurs in two forms; haem iron and non-haem iron. Haem iron is found in animal tissue as it is a component of haemoglobin (oxygen-carrying protein in the blood) and myoglobin (oxygen-carrying molecules in muscle) and makes up around half the iron found in red meat, poultry and fish. Most iron in the diet is non-haem iron (5-10 per cent comes from haem iron in diets containing meat). Haem iron is more readily absorbed; 20-30 per cent of haem iron eaten is absorbed. Absorption of non-haem iron is more variable with 1-10 per cent of non-haem iron absorbed because non-haem iron absorption is subject to a range of influences including a number of dietary factors that can increase or inhibit it (see Table 4.0).

Vitamin C found in abundance in fruit and vegetables, can increase the amount of iron absorbed considerably by converting it into a soluble, more readily absorbable form and by preventing it from forming complexes with phytate or tannin (Fairweather-Tait, 2004). The amount of vitamin C in eight strawberries or 200ml of orange juice can increase iron absorption three- to four-fold (Craig, 1994). To increase your iron absorption substitute your morning cup of tea or coffee with a glass of freshly squeezed orange juice. Combine vitamin C-containing foods with iron-rich meals (beans on toast with apple juice or watercress salad with dates, toasted pumpkin seeds and slices of orange). 
Phytate found in unrefined grains, seeds and pulses (which are also a rich source of iron) can bind to iron, calcium, magnesium and zinc and reduce absorption. Soaking pulses and discarding the water can help as can sprouting pulses and grains (Gibson et al., 2014). CookingSprouting can increase iron absorption by 20-62 per cent (Hemalatha et al., 2007). Increasing the amount of time bread is fermented can help. Remember though, wholemeal bread and brown rice contain around two to three times the amount of iron found in white bread and rice (Craig et al., 1994). So even though the percentage of iron absorbed from wholegrain foods may be lower, the total amount of iron absorbed is similar, making wholegrain foods the healthier option as they also contain more vitamins, minerals and fibre.
Polyphenols are chemical substances in plants that possess antioxidant properties that may reduce the risk of CVD and cancer. Tannins are a type of polyphenol found in tea and red wine that bind non-haem iron and may reduce iron absorption. So tea (including herbal teas), coffee, cocoa and red wine may inhibit iron absorption. Research shows that tea-drinking does not influence iron status in healthy people who eat a well-balanced diet and have adequate iron stores (Temme and Hoydonck, 2002; Nelson and Poulter, 2004). Try switching to fresh fruit smoothie (as its vitamin C content increases the absorption of iron) and wait at least one hour after eating before drinking tea.
Calcium may inhibit iron absorption, but research suggests that over time, calcium has a limited effect on iron absorption (Saunders et al., 2013). Calcium inhibition may be counteracted by the addition of vitamin C (Walczyk et al., 2014). This doesn’t mean you should limit your calcium intake; calcium is a very important mineral. Avoid drinking cow’s milk and taking calcium supplements with food (Mangels et al., 2011).
Oxalic acid is a compound found in spinach, Swiss chard and beetroot leaves as well as tea, chocolate and other cocoa products. Some research suggests that oxalic acid may reduce iron absorption. However, recent evidence suggests that it is of minor relevance in iron nutrition (Bonsmann et al., 2008).

Table 4.0 Factors that enhance or inhibit iron absorption.

Table 4.0 shows that vitamin C and some unknown component in muscle tissue can increase iron absorption while phytates (from high fibre foods), polyphenols found in tea, coffee and red wine, calcium and oxalic acid may inhibit it.

Non-haem iron absorption is also affected by iron status – how much iron you already have in the body. People with low iron stores or higher physiological need for iron will tend to absorb more iron and excrete less (Saunders et al., 2013). Haem iron constitutes a smaller part of dietary iron than non-haem iron, but is more bioavailable with 20-30 per cent of haem iron being absorbed in the gut – whether it is needed or not. A high absorption rate is not necessarily a good thing as the body has no mechanism for disposing of excess iron. Indeed, excessive iron levels (iron overload) are linked to heart disease, diabetes and bowel cancer. It is well known that many meat-eaters are oversupplied with iron, increasing the risk of heart disease and cancer (Leitzmann, 2005). So, iron from plant foods is more beneficial to the body because its absorption remains safely regulated, whereas iron from meat can accumulate to levels which could be harmful. 

That said, iron deficiency is a concern in both developing and industrialised countries; and young women are particularly vulnerable. The NDNS found that iron intakes among some groups in the UK are below the RNI, girls and women are particularly affected. The average iron intake among women aged 19-64 was 78 per cent of the RNI, among girls aged 11-18 it was only just over half of the RNI at 57 per cent. When the group surveyed was reassessed taking supplements into account, the average intake across the whole group (including those not taking supplements) increased to 91 per cent of the RNI (Bates et al., 2014).

The Lowest Recommended Nutrient Intake (LRNI) is the amount of a nutrient which is sufficient for only a few individuals. Habitual intakes below the LRNI will almost certainly be inadequate for most people. Nearly half the girls (46 per cent) and almost a quarter of women (23 per cent) in the survey had an iron intake below the LRNI.  There was evidence of anaemia plus low iron stores indicative of iron deficiency in nearly five per cent of girls and women. They were not a group of vegetarians or vegans, so clearly being a meat-eater does not guarantee protection against low iron intakes. 

Contrary to the idea that meat is the best source of iron in a meat-eater’s diet, grains and cereal products (bread and fortified breakfast cereals) were the main source of iron in the diet, followed by meat and meat products then vegetables. People who don’t eat meat can easily get sufficient iron from cereal, pulses, nuts, seeds and vegetable sources that also provide many vitamins, other minerals, healthy fats and valuable fibre. 

Food (medium portions) Iron (mg)
RNI: 8.7mg/day for men and 14.8 mg/day for women
Tesco Malt Wheats, Sainsbury’s Wholegrain Malties or Waitrose Malted Wheats (40g) 4.8
Medium steak, fried (144g) 4.3
Tofu, fried (100g) 3.5
Wholemeal Spaghetti, boiled (220g) 3.1
Pumpkin seeds (1 handful/35g) 3.1
Red lentils, boiled (120g) 2.9
Figs (three dried fruits 60g) 2.5
Quarter pounder beef burger, grilled (78g) 2.0
Baked beans (135g) 1.9
Curly kale, boiled (95g) 1.9
Kidney beans, canned (90g) 1.8
Lamb chop, grilled (edible portion 70g) 1.5
Spinach, boiled (90g) 1.4
Sesame seeds (1 tbsp/12g) 1.2
Prunes (six dried fruits 48g) 1.2
Cashew nuts (20 nuts ~ 20g) 1.2
Brown rice, boiled (180g) 0.9
Broccoli, boiled (85g) 0.9
Wholemeal bread (36g) 0.9
*Alpro Soya milk (200ml) 0.7
Chicken breast, grilled (130g) 0.5
Bacon, grilled (46g) 0.5

Table 5.0 The iron content of selected foods.

Source: FSA, 2002 and Alpro*.

Table 5.0 shows the iron content of medium-sized portions of selected foods including different types of meat, fruit, vegetables, pulses and wholegrain foods. The RNI for women under 50 is 14.8mg per day. This amount of iron can be obtained from a bowl of cereal with fruit (blueberries or strawberries) for breakfast, lentil and pasta salad for lunch and smoked tofu stir-fry with brown rice, broccoli and pumpkin seeds for dinner. Alternatively, scrambled tofu and wholemeal toast for breakfast with orange juice, lentil soup for lunch and chickpea and spinach curry for dinner would provide plenty of iron. Including vitamin C-containing foods with your iron-rich meals can boost the amount of iron you absorb substantially.