The main role of iron in the human body is to transport oxygen via the bloodstream.
Average 70-kg man has 4-5g of iron, mostly (60-70%) in hemoglobin form (red protein which is the oxygen's carrier), around 11-14% in mioglobin form (a muscle storage) and approximately 3% as an iron bound in enzymes (oxidases, catalases).
The rest of iron is stored in the liver, spleen, kidneys and bone marrow in the form of ferritin and hemosyderine (a degradation product of ferritin) .
Over 80% of iron in the human body retrieves from from haemolityic reactions (a destruction of red blood cells, red blood cell lives approximately 120 days), the remaining is provided from body storage and from food intake.
Humans lose only small amounts of iron in urine, faeces, the gastrointestinal tract and skin .
The most popular blood disorder anemia – which is usually defined as a decrease in the amount of red blood cells or hemoglobin in the blood, affect about quarter of people globally .
Diagnosis in men is based on hemoglobin of less than 13-14g/dl and in women, less than 12-13g/dl.
To differentiate the anemia type and find out the cause, the doctor can check the iron and ferritin level and total iron binding capacity (TIBC) .
Iron deficiency anemia
In iron deficiency( anemia), iron and ferritin level are decreased and the TIBC is elevated.
This type of anemia is more common in females (due to a menstruation) than in males, among children, during pregnacy and elderly [2,3].
The sympthoms of iron-deficiency anemia may include: fatigue, decreased work/school performance, pale skin, poor memory, irregular heart beats, difficulties with maintainging body temperature, decreased immune function and glossitis (an inflamed tongue) [1,3].
Many people when feeling tired and fatigue, go to the health store and buy an iron supplement without consulting and finding out the root cause (GP consulation).
There is a risk of masking the sympthoms of many underlying issues (i.e. hypothyroidism), in rare cases even more serious such as an undiagnosed cancer.
The excess of the iron can accelerates the formation of a free radicals, and scientific studies have shown that eleveated blood iron levels are linked with increased cancer risk .
If you have been diagnosed with the iron-deficiency anemia and been prescribed with an iron supplement i.e. iron citrate or gluconate, you might alternatively increase your iron intake through the diet as a more natural form of the treatment.
It will not give you side affects as some iron pills do,such as experiencing a stomach upset or constipation.
Iron in food is presented in two forms: heme and nonheme.
Heme one is a combination of protoporphyrin IX and iron ion, and is derived from meat, seafood and poultry.
The other source of an iron such as plants or iron-fortified foods represent nonheme group .
Iron absorbtion rate is the highest from breast milk (50%), then from heme-forms (20%) and the lowest in non-heme forms (5%).
Those rates are only approximates, and your body tries to sustain homeostasis (balance), so when it has an abundance of iron-rich food and the iron storage are full, it down-regulates the absorbtion, and contrary, when you are iron-deficient and don't provide enough iron from a diet, your digestive tract will work hard to retrieved it from even poor sources such a fruits and vegetables .
This articles will presents you 10 good sources of an iron, which can be easily introduced to a normal diet.
Those heme one will be easily absorbed, however the plant sources may require extra actions. To increase absorbtion from non-heme iron foods you might consider :
- increasing your vitamin C intake (fruits and vegetables)
- adding meat and poultry at the same meal
- lowering the pH of gastric juices (do not use Bicarbonate soda, be careful with antiacids)
- ensuring that certain aminoacids - histidine, lysine – are in the meal (in most of the cases present in animal proteins)
Bear in mind that there a few other factors which might also decrease the iron absorbtion such as :
- phytic acid (cereals, grains, beans and lentils)
- casein and whey proteins (dairy products)
- tannins (tea, coffee)
According to Food and Nutrition Board the Recommended Dietary Allowances (RDA) for nonvegetarians are presented in a table 1.
The RDAs for vegetarians are 1.8 times higher than for meat-eaters. The reason heme iron from meat is more bioavailable than non-heme plant-based equivalent.
Table 1: Recommended Dietary Allowances (RDAs) for Iron 
|Birth to 6 months||0.27 mg*||0.27 mg*|
|7–12 months||11 mg||11 mg|
|1–3 years||7 mg||7 mg|
|4–8 years||10 mg||10 mg|
|9–13 years||8 mg||8 mg|
|14–18 years||11 mg||15 mg||27 mg||10 mg|
|19–50 years||8 mg||18 mg||27 mg||9 mg|
|51+ years||8 mg||8 mg|
*Adequate Intake (AI)
Iron-rich food ranking
The ranking presented below does not try to establish an ultimate set of the iron-richest products, rather it presents a few options from various food groups which may increase your hemoblobine and iron levels.
1. Chicken liver
Chicken liver is a great source of highly bioavailable heme iron (12.9 mg/100g), folates (538 mcg/100g) and vitamin B12 (16.8mg/100g). Those three nutrients are essential for building the hemoglobine and also are present in the best chemical form.
On the other hand, there are a few concerns in regards to heavy metals,aflatoxins contaminations and high vitamin A content.
Liver, both in humans and animals is the primary organ for removing toxins and xenobiotics from the blood.
Generally, the level of heavy metals (Pb, Cd, As, Cr, Ni) and aflatoxins in a chicken liver and kidneys is higher than in other organs [6,7].
Another concern is high doses of vitamin A (in the retinol form), which can be teratogenic (may cause birth defect via a toxic effect on an embryo or festus) in pregnancy, hence why pregnant women should stay away from any kind of animal livers.
To sum up, chicken liver is a very good option for iron-deficient men and non-pregnant women, however in regards to heavy metals and aflatoxin contamination, the intake of this internal organ should be limited to maximum twice a week.
2. Black pudding (blood sausage)
Black puddings are eaten in various forms in many countries: morcilla in Spain, boudin noir in France, kaszanka in Poland.
It is made usually with pigs' blood, mixed with oatmeal and fat, before being packed in to casing.
Nutritionally, it is a great source of highly bioavailable heme iron (6.4 mg/100mg), magnesium, zinc, calcium and animal proteins.
The downsides are: quite high in fat (17.5g/100g) and salt (1.5-2.4g/100g) contents.
Generally in the comparison to animals livers' downsides, black pudding is one of the best source of iron and can help you combat the iron-deficiency anemia.
Oysters are very good source iron (7.8 mg/100g), zinc, calcium and selenium, as well as vitamin A and B12.
They are high in proteins (approximately 9g/100g of pacific oysters) and low in calories (68 kcal/100g).
Traditionally considered as an aphrodisiac as it is a good source of zinc and amino acids which affects the sex hormones.
They might be a good alternative to traditional meat (pork, beef and poultry), however make sure you do not suffer from any shellfish allergies.
4. Beef steak
Beef is rich in an easily absorbed iron (3.6mg/100g), proteins (27.2mg/100g), vitamin B12 (3.8mcg/100g) and zinc (4.8mg/100g).
We have been told that red meat increase the risk of the cancer, diabetes and cardiovascular disease.
However, those hypothesis comes from non-controlled trials, but actually observational studies which many of them don't event differentiate red meat and processed red meat (the link only has been found in processed meat).
As long as your choosing unprocessed (preferably grass-fed) red meat, and avoiding burning the pieces, you should not worry too much, and when needed (low hemoglobine) enjoy your steak once in a while.
5. Iron-fortified cereals
Are the cereals your breakfast choice?
Are you vegetarian/vegan and you want to boost your hemoglobine level?
If so, you may study the ingredients list more carefully and choose the most nutritious products.
Manufactures enchance cereals with vitamins and minerals. Less than a cup (3/4) of fortified cereals can provide you 29mg of non heme iron (which is more than 100% of your RDA).
If you do so, make sure you do not consume coffee and tea with this meal, and having some fruits/veggies rich in vitamin C can increase iron's absorbtion.
The downsides of choosing fortified cereals is that the product is highly processed, with a high dose of simple carbohydrates which won't give you satiety and trigger the insulin response which is not what you want on your weight management program.
6. Pumpkin seeds
Did you know, instead of snacking another packet of crisps, you can replace it with pumpkin seeds and and at the same time boost you iron levels?
Pumpkin seeds kernels are rich in non-heme iron (8.82mg/100g).
Besides that they are rich in magnesium, zinc and phosporus.
They are good alternative to the unhealthy snacks, but remember they are quite calorific and rich in fat, 100g provides 541 calories, and 46g of fat.
You can easily enhance your meals with iron and other minerals by sprinkling your meals with an extra spoon of the pumpkin seeds.
Lentils are staples food, an essentials on a vegan/vegetarian diet, because of the nutritional value.
hey are rich in: iron (7.39mg/100g), proteins (25.8g/100g), dietary fibre (30.5g/100g) phospohorus (451 mg/100g), magnesium (122mg/100g), folates (479mcg/100g).
They provide 353 kcal/100g, mainly from carbohydrates (68%), but only 2g from simple sugars, which results in very low glycaemic index (GI 29) - make it suitable for people with diabetes.
The drawbacks of lentils are antinutritional factors such as trypsin inhibiton (aggrevate protein digestion), tannins and phytic acid.
he last two affects the iron biavailabilty, so it is essential to reduce their influence by thermically processing them (boliling, autoclaving, microwave cooking) and because they provide non-heme iron, also to increase vitamin C intake with the meal containing them.
8. Dried apricots
Dried apricots are a good snack or a sweet addition to your meals. They are rich in provitamin A (beta-carotene, 3604 IU/100g), potassium (1162mg/100g) and non-heme iron (6.31mg/100g).
The brighter color should not tempt you to buy them, because the more vivid they are the more preservative (sulfur dioxide – E220) they contains.
Some people are allergic to it, so when you can afford it try to buy those one with darker color and coarser texture (i.e. organic ones).
9. Soy beans
Soy beans are very good source of essential nutrients: proteins (36.5g/100g), carbohydrates (30.2g /100g), fats (19.9g/100g) and dietary fibre (9.3g/100g).
They also contain high amount on non-heme iron (15.7mg/100g), magnesium (280mg/100g) and phospohorus (704mg/100g).
Bear in mind that soy beans, similiary to lentils contains anti-nutrients which my decrease mineral absorbtion and also iron absorbtion, so fermentation and/or thermical processing are required.
Soy beans are popular in vegetarian and vegan diets, however they should not be a consumed more frequently by males, because it can affect fertility and sperm quantity and quality parameters [9,10].
10. Dried Spirulina
Dried spirulina is considered more of a supplement than normal food, however it can become a superfood addition, when your diet (i.e. vegetarian or vegan diet) requires a little iron/protein boost.
It contains high amount of proteins (~60%), which are complete, containing all aminoacids (with slightly lower amount of methionine , cysteine and lysine).
It can have some interactions with medications (especially anticoagulants and immunosupressants).
In 100g of dried spirulina you can high amount of an iron (28.5mg/100g) which is in the non-heme form, so addition of an extra vitamin C rich products is recommended.
Table 2 Iron-rich food comparison :
|Number||Product||Iron content /100g||Serving||Iron content / serving||Iron form||Vegetarian||Vegan||Comments|
|1||Chicken liver (cooked, panfried)||12.9 mg||44g - 1 liver||5.67 mg||Heme iron||No||No||The best form of the iron. Should not be consumed by pregnant women, because of high vitamin A content. As a detoxifying organ can contains heavy metals and aflatoxins, should not be consumed more frequently than twice a week|
|2||Black pudding (blood sausage)||6.4 mg||100g 4 slices||6.40 mg||Heme iron||No||No||The best form of the iron|
|3||Oysters (mollusks, cooked)||7.8 mg||85g 3 oz||6.6 mg||Heme iron||No||No||The best form of the iron|
|4||Beef, tenderloin steak, boneless, separable lean only, trimmed to 0% fat, cooked, grilled||3.6 mg||85g 3 oz||3.05 mg||Birth||No||No||The best form of the iron|
|5||Iron-fortified cereals||62 mg||29g 0.75 cup||18 mg||Non-heme iron||Yes||Yes||Highly processed food, artifically added vitamins and minerals|
|6||Pumpkin seeds and sqash seed kernels (dried)||8.82 mg||129g 1 cup||11.38 mg||Non-heme iron||Yes||Yes|
|7||Lentils (pink or red, raw)||7.39 mg||192g 1 cup||14.19 mg||Non-heme iron||Yes||Yes||It contains a lot of a dietary fibre, which decreases iron absorbtion|
|8||Apricots, dried||6.31 mg||119g 1 cup||7.51 mg||Non-heme iron||Yes||Yes||It may contains sulfur dioxide used as anti-oxidant by a manufacture which can cause allergies|
|9||Soy beans (mature seed, raw)||15.7 mg||186g 1 cup||29.20 mg||Non-heme iron||Yes||Yes||Should not me eaten by male, contains phytoestrogenes whic can affect their fertility|
|10||Spirulina seaweed, dried||28.5 mg||112g 1 cup||31.92 mg||Non-heme iron||Yes||Yes||High intake can cause diarrhoea. It should be introduced slowly in low doses|
Take away notes
There are two forms of an iron: heme (which you can find in meat, poultry, fish and shellfish) and non-heme (grains, beans, vegetables, fruits and others).
When you have been diagnosed with iron-deficiency anemia and you have to boost your iron levels, you might want to consider iron-rich food as an alternative to supplements which may have some side effects i.e. constipation or stomach upset.
If you are not vegetarian or vegan, you may start introducing heme-iron-rich-products such as chicken liver, black pudding,oysters and different kind of meats (i.e. beef). In this case you should not worry to much about iron absorbtion.
However if you cannot eat meat-related products for various reasons, you can introduce plant-based products which contains higher amount of non-heme iron. In this case you have to remember that certain things can decrease absorbtion such as phytic acids (lentils, beans) or tannins (tea, coffee).
You can try and reduce their influence by fermenting and boiling your legumes and avoiding tea and coffee around your mealtimes.
If you want to boost a non-heme iron absorbtion you may consume more products rich in vitamin C (i.e. red pepper, kiwi etc.) combined with iron-rich product (only apply to to non-heme form of iron).
- Ciborowska H., Rudnicka A., Dietetyka, żywienie zdrowego i chorego człowieka. PZWL 2007
- https://en.wikipedia.org/wiki/Anemia as seen on 19/06/2016
- Janz T.G., Johanson R.L., Rubenstein S.D., Anemia in emergency department: evaluation and treatement. Emergency medicine practice 2013, 15(11): 1-15
- Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc : a Report of the Panel on Micronutrients. Washington, DC: National Academy Press; 2001
- USDA National Nutrient Database for Standard ReferenceRelease 28 Nutrients: Iron, Fe (mg) Food Subset: All Foods Ordered by: Nutrient Content Measured by: Household Report Run at: October 22, 2015 11:13 EDT https://ods.od.nih.gov/pubs/usdandb/Iron-Content.pdf
- Nasser M., Ei-Salam A., Ahmad S., Basir A., Rais A.K., Bibi A., Ullah R., Muhammad Z., Hussain I., Distribution of Heavy Metals in the Liver, Kidneys, Pancreas and Meat of Cow, buffalo, Goat, Sheep and Chicken from Kohat market Pakistan. Life Sciences Journal 2013; 10
- Herzallah S.M., Aflatoxin B1 residues in eggs and flesh of laying hens fed aflatoxin B1 contaminated diet. American Journal of Agricultural and Biological Sciences 2013 8(2): 151-161
- Hefnawy T.H., Effect of processing methods on nutritional composition and anti-nutritional factors in lentils (Lens culinaris), Annals of Agricultural Sciences, 2011, vol 56, issue 2, 57-61
- Chavarro J.E. Toth T.L., Sadio S.M., Hauser R., Soy food and isoflavone intake in relation to semen quality parameters among men from an infertility clinic.Reproduction 2008, 23(11)
- . Giahi L., Mohammadomoradi S., Javidan A., Sadeghi M.R., Nutritional modificationsin male infertility: a systematic review covering 2 decades. Nutri Rev. 2016 Feb; 74(2):118-30