Written by Slawomir (“Swavak”) Gromadzki, MPH
FUNCTIONS OF IRON
The trace mineral, iron, performs a large number of roles in our bodies. In our red blood cells iron is required to form haemoglobin which transports oxygen to every cell in our body increasing energy levels. Iron, therefore, contributes to the reduction of tiredness and fatigue. It also helps metabolize proteins, boosts our immunity, and helps maintain brain and endocrine (hormonal) function.
It’s thought millions of the UK population suffer from mild anaemia, most often caused by an inadequate intake of nutrients such as iron, folate or vitamin B12. Iron deficiency leads to anaemia and it is regarded as the most common nutritional deficiency in the U.S., where about 10 percent of all women are considered iron deficient. There are an estimated 2 billion iron deficient people worldwide.+
Iron deficiency is the result of unhealthy refined diet, avoiding high in iron plant foods, use of stimulants, and other factors including poor absorption and heavy menstruation. Also regular consumption of soda, cow’s milk, and chocolate contribute to iron deficiency.
It is a very well established fact that both black and green tea as well as coffee (especially when ingested during meals and up to 2 hours after meals) lead to iron deficiency. In England alone people manage to get through an amazing 235 million cups coffee and tea every day. Both tea and coffee contain tannins which are also present in wine, beer and some other foods. These tannins adversely affect iron availability, which could lead to iron deficiency anaemia. One study has shown that tea consumption may reduce iron absorption by as much as 60% and coffee reduces its uptake by 50%! Another study showed just 100 mg of tannins inhibited absorption by almost 90%, whereas additional research concluded we would have to drink 3 strong cups of tea or coffee a day to have this effect.
Unfortunately, also green tea has the same effect as coffee and black tea due to high content of tannins. There many examples of individuals who developed iron deficiency due to regular green tea drinking, here is one of them: “I have been drinking green teas every day for the past few years. Two years ago I was diagnosed with an iron deficiency and to date I have had several blood transfusions and numerous treatments of ferrit through IV. I have had numerous medical tests, bone marrow, colonoscopy, capsule endoscopy etc. And have not found the cause. Yesterday a friend who had similar problems told me she had been admitted to the Mayo Clinic some months ago and the team their discovered her problem was excessive drinking of green tea.”
Symptoms of iron deficiency anaemia may include the following: fatigue, weakness, pale skin, tingling sensation in the legs, poor memory, dizziness, hair loss, tongue swelling or soreness, depression, anxiety, and breathlessness. Chronic lack of iron may also contribute to the following: Fibromyalgia, inflammatory bowel disease, hypothyroidism, attention deficit hyperactivity disorder, Parkinson’s disease, neurodegenerative conditions, celiac disease, restless leg syndrome, muscle weakness, and decline in motor skills.
BEST DIETARY SOURCES OF IRON
It is true that animal foods contain heme iron, which is more absorbable than non-heme iron found in plant foods, but it is also true that it is easy to overdose iron as a result of consuming animal foods and that unlike non-heme iron from plants the heme iron from animal foods increases risk of various health conditions (listed below). In addition, no animal product can be recommended today as a healthy source of any nutrient due to possible risk factors such as cholesterol, dioxins, viruses, toxins, lack of fibre, prions, etc. that can be found in meat, dairy, fish and other animal sources. Fortunately, there is no necessity to consume animal foods in order to supply our body with sufficient amounts of iron as there are plant products that are also very high or high in natural iron. The following are regarded as the most iron-dense plant foods:
– Wheatgrass is a gluten-free food made from the young shoots of the wheat plant. Though it is best-known for its incredible concentration of the potent blood cleanser and builder chlorophyll, wheatgrass is also rich in iron. Specifically, one ounce of wheatgrass contains 64 milligrams of iron, or 350 percent of our RDI!
– Chlorella is one of the most nutrient-dense foods in the world. A one ounce (about 2 tablespoons) serving of this single-celled green algae supplies us with a whopping 37 milligrams of iron, or 200 percent of our recommended daily intake!
– Spirulina contains a considerably lower 8 milligrams of iron than chlorella, but it exceeds chlorella in other areas. For this reason, many experts recommended consuming chlorella and spirulina together to maximize nutrient intake and remove practically any possible nutrient deficiency.
– Some sources maintain moringa leaf to be up to 25 times higher in iron than spinach.
– Barley grass is known to contain 5 times the iron in spinach.
– Goji berries – a mere quarter-cup of these red, tangy berries provide us with all the iron we need for the day.
– Blackstrap molasses derived from the sugar cane plant, whose roots tap into the deepest (and most mineral-rich) parts of the soil. Two tablespoons of blackstrap contain 15 percent of our RDI for iron.
– Spinach, Swiss chard, kale and broccoli are the most iron-rich greens. A cup of cooked or raw spinach may contain 6-7 mg of iron.
– Just one cup of cooked organic soybeans contains 9 mg of natural organic iron! Remember that unlike GMO organic soya beans and soya product should be regarded as perfectly safe and one of the most healthy and nutrient-dense foods. One cup of cooked white beans or lentils contains 6.5 milligrams of iron, kidney beans: 5.2 milligrams; chickpeas: 4.7 mg.
– In contrast, 3 ounces of a duck contain 3.5 milligrams of iron, a can of sardines: 2.7 milligrams, 3 ounces of grass-fed beef: 2 mg, and 3 ounces of lamb (19): 1 milligrams. Even liver doesn’t seem to be a higher source of iron as 3.5-ounce (100-gram) serving of beef liver contains 6.5 mg of iron.
– Whole milk contains less iron than any other type of milk, with just .07 mg per 1-cup serving. Organic unsweetened soya milk is much better source of iron.
Contrary to the popular view, animal foods do not seem to be higher in iron than mentioned above plant sources. In addition, plant foods usually contain significant concentrations of vitamin C which doubles the absorption of iron. Vitamin C is not found in useful amounts in cooked animal foods. Another important fact is that, unlike heme iron found in animal foods, non-heme iron in plant sources does not increase risk of cancer, diabetes, stroke, inflammation and heart disease (see quote by Dr. Greger below).
Other valuable plant sources of iron are whole grains, split peas, dried fruits, nuts, and seeds.
UNLIKE NON-HEME IRON FROM PLANTS THE HEME IRON FOUND IN ANIMAL FOODS INCREASES RISK OF HEART ATTACK, STROKE, CANCER & DIABETES
According to Dr. Michael Greger M.D. “It is commonly thought that those who eat plant-based diets may be more prone to iron deficiency, but it turns out that they’re no more likely to suffer from iron deficiency anemia than anybody else. This may be because not only do those eating meat-free diets tend to get more fiber, magnesium, and vitamins like A, C, and E, but they also get more iron. The iron found predominantly in plants is non-heme iron, which isn’t absorbed as well as the heme iron found in blood and muscle, but this may be a good thing. Avoidance of heme iron may be one of the key elements of plant-based protection against metabolic syndrome, and may also be beneficial in lowering the risk from other chronic diseases such as heart disease. The data linking coronary heart disease and the intake of iron, in general, has been mixed. This inconsistency of evidence may be because of where the iron comes from. The majority of total dietary iron is non-heme iron, coming mostly from plants. So, total iron intake is associated with lower heart disease risk, but iron intake from meat is associated with significantly higher risk for heart disease. This is thought to be because iron can act as a pro-oxidant, contributing to the development of atherosclerosis by oxidizing cholesterol with free radicals. The risk has been quantified as a 27% increase in coronary heart disease risk for every 1 milligram of heme iron consumed daily. The same has been found for stroke risk. The studies on iron intake and stroke have had conflicting results, but that may be because they had never separated out heme iron from non-heme iron… until now. Researchers found that the intake of meat (heme) iron, but not plant (non-heme) iron, was associated with an increased risk of stroke. The researchers also found that higher intake of heme iron—but not total or plant (non-heme) iron—was significantly associated with greater risk for type 2 diabetes. There may be a 16% increase in risk for type 2 diabetes for every 1 milligram of heme iron consumed daily. The same has also been found for cancer, with up to 12% increased risk for every milligram of daily heme iron exposure. In fact, we can actually tell how much meat someone is eating by looking at their tumors. To characterize the mechanisms underlying meat-related lung cancer development, researchers asked lung cancer patients how much meat they ate and examined the gene expression patterns in their tumors. They identified a signature pattern of heme-related gene expression. Although they looked specifically at lung cancer, they expect these meat-related gene expression changes may occur in other cancers as well.” (source >)
HEME VS NON-HEME FORMS OF IRON
There are two forms of dietary iron, heme iron and non-heme iron. Heme iron is bound to haemoglobin (the oxygen transporting protein in red blood cells) whereas the non-heme iron is not bound to haemoglobin.
Plants and iron-fortified foods contain only non-heme iron, whereas meat, seafood, and poultry contain both heme and non-heme iron.
Heme iron is more efficiently absorbed form of iron. It is estimated that around 15 to 35 % of heme iron is absorbed, compared to 5 to 20 % of non-heme iron.
Unfortunately, although it is true that heme iron, the type found predominantly in blood and muscle, is absorbed better than the non-heme iron present in plants, yet the heme iron may increase the risk of cancer, stroke, heart disease, and metabolic syndrome (see quote below by Dr. Greger).
As far as supplemental iron is concerned the absorption rate of non-heme iron supplements, such as ferrous sulfate and ferrous fumarate, is 3% on an empty stomach and 1% with food. This is much less than the absorption rate of heme iron, as found in liver, which is as high as 35%. However, I do not recommend consuming liver nor any other animal sources of iron due to various dangerous risk factors associated with them. Below there is a list of safe plant sources which are higher in iron than even liver.
Non-heme iron salts are the most popular iron supplements. One reason is that even though heme iron is better absorbed, it is easy to take higher quantities of non-heme iron salts so that the net amount of iron absorbed is about equal. For instance, if you take 5 mg of heme iron and 50 mg of non-heme iron, the net absorption for each will be about the same.
FERROUS VS FERRIC FORMS OF IRON
There are ferrous and ferric iron forms.
Common ferrous preparations include ferrous succinate, ferrous bisglycinate, ferrous fumarate, ferrous sulfate, ferrous gluconate, and ferrous lactate.
Among the ferric preparations ferric citrate and ferric sulfate are most commonly used.
Because of its higher solubility, ferrous iron in dietary supplements is more bioavailable than ferric iron.
Iron supplements contain different amounts of elemental iron, which is the amount of iron that is actually absorbed, depending on which form of iron is used in the supplement. For example, ferrous gluconate contains only 12 % elemental iron, ferrous sulfate contains 20 % elemental iron while ferrous fumarate, ferrous succinate, and ferrous bisglycinate contain over 30 % of elemental iron.
Elemental iron is listed in the supplement label, so consumers do not need to calculate the amount of iron supplied by various forms of iron supplements.
TYPES OF FERROUS IRON
– Ferrous succinate is 35% elemental iron. Regarded by some sources as the most bioavailable among ferrous irons.
– Iron bisglycinate (ferrous form of iron called ferrous bisglycinate) is 33% elemental iron. It is regarded as the best iron form due to high bioavailability and because it shouldn’t cause gastric problems (including constipation). Iron bisglycinate is a chelated form of non-haem iron (consists of ferrous iron combined with an amino acid) that passes through the stomach and small intestine without breaking apart. It has been shown to be more effectively absorbed than other types of iron chelate. Iron bisglycinate should be combined with glycine and vitamin C for optimal absorption, to prevent the gastrointestinal side effects. According to the research, iron absorption was higher from ferrous bisglycinate than from ferrous sulfate or ferric trisglycinate and ferrous bisglycinate was an effective and safe source of iron. Ferrous bisglycinate 25 mg iron is as bioavailable as ferrous sulfate 50 mg according to a study.
– Ferrous fumarate is 33% elemental iron, ferrous fumarate is an inexpensive form of iron with tolerable adverse effects and it increases iron stores significantly. Ferrous bisglycinate and carbonyl iron show equal efficacy as ferrous fumarate in increasing Hb and produced less adverse effects than ferrous fumarate, but cost more. Thus ferrous fumarate still can be considered as best cost effective choice with tolerable adverse effects for treatment as well as prevention of iron deficiency anaemia in pregnancy. Ferrous Fumarate is found, for example, in Haemovit Plus which contains 47mg of highly absorbable Ferrous Fumarate per capsule. Haemovit Plus, however, might be too high in iron for an average person and should be recommended rather for individuals with already diagnosed iron deficiency or women with heavy menstruation as too much iron in the body leads to overproduction of free radicals and other side effects. As far as bioavailability and tolerability is concerned ferrous fumarate is superior to ferric forms as they have few times lower bioavailability.
– Ferrous sulfate monohydrate is 33% elemental iron while ferrous sulfate heptahydrate is 20% elemental iron. Ferrous sulphate preparations present good bioavailability (between 10 and 15%), while bioavailability of iron ferric preparations is 3 to 4 times lower than that of FS. This is due to the extremely poor solubility of ferric iron in alkaline media and the fact that ferric iron needs to be transformed into ferrous iron before being absorbed. Ferrous sulfate, can cause gastrointestinal side effects – including nausea, vomiting, constipation, and diarrhoea because these forms of iron are poorly absorbed.
– Ferrous gluconate is 12% elemental iron. Ferrous gluconate is found in Iron Formula (HealthAid) which contains 17mg per 3 tablets). Ferrous gluconate has lower bioavailability than fumarate.
TYPES OF FERRIC IRON
– Iron Citrate (ferric citrate) has lower bioavailability than the ferrous forms but it is the best option among 3 different ferric irons as it doesn’t cause toxicity. Ferric Ammonium Citrate (Iron citrate) is found in Haemovit Gold (HealthAid).
OTHER FORMS OF SUPPLEMENTAL IRON
Other forms of supplemental iron, such as heme iron polypeptides, carbonyl iron, iron amino-acid chelates, and polysaccharide-iron complexes, might have fewer gastrointestinal side effects than ferrous or ferric salts.
Preparations with iron III hydroxide polymaltose generally display poorer bioavailability and their clinical efficacy is yet to be established.
RECOMMENDED DAILY INTAKE OF IRON
0 to 3 months: 2 mg
4 to 6 months: 4 mg
7 to 12 months: 8mg
Children 1 to 3 years: 9 mg
Children 4 to 8 years: 9 mg
Children 9 to 13: 8 mg
Women 19 to 50: 17 mg
Pregnant women: 27 mg
Lactating women: 10 mg
Women over 50: 10 mg
Men 19 to 60: 10 mg
Younger children need more iron than older children because iron is required for proper growth and cognitive development. It can be hard for them to get enough iron from their diet alone. Iron deficiency is seen most often between six months and three years of age due to rapid growth and inadequate intake of dietary iron. Infants and children are at a heightened risk for iron deficiency if they’re born prematurely, are given cow’s milk before their first year of life, and if they are formula-fed instead of breastfed.
Heavy menstruating women and women who are pregnant need more iron. Also those who lost blood due to a recent surgery need iron supplements.
OVERDOSING & TOXICITY OF IRON
High doses of supplemental iron (45 mg/day or more) may cause gastrointestinal side effects, such as nausea, diarrhoea, vomiting, upset stomach and constipation. Iron supplements could be a double-edged sword. If we don’t get enough, we risk fatigue and other symptoms of iron anaemia; but if we ingest too much, we may increase risk of brain degeneration (such as Alzheimer’s), cancer, heart disease, stroke, diabetes, and a number of inflammatory conditions. Chronic excessive intake of iron may also contribute to the following: Premature aging, anorexia, Grave’s disease, heart arrhythmia, liver damage and liver disease, or hemochromatosis.
Too much iron in the body can lead to the mentioned above problems because the human body doesn’t seem to have a mechanism to rid itself of excess iron. In excess iron works as a pro-oxidant, and therefore it can significantly increase the harmful free-radical activity.
For this reason, take only good quality iron supplements and make sure you don’t overdose it or try getting iron from mentioned above plant-based sources, over which our body has some control.
Slowly working up to the full dose can limit these side effects, as can taking iron with food. However, taking iron with some foods and beverages limits the absorption of the iron, especially if you take it along with dairy products, tea, or coffee.
While ferrous sulfate is the most commonly used type of iron supplement, switching to a different form of iron (such as bisglycinate) and lowering the daily dose may help prevent side effects.
In addition, if you want to prevent oxidative or radical effect of excess iron take 600mg of Alpha lipoic acid (ALA) twice a day. According to the 2008 human study, “Lipoic acid and acetyl-carnitine reverse iron-induced oxidative stress.” ALA is regarded as one of the most effective detoxification aids as it can reduce chemical toxicity in tissues and counteract subsequent oxidative stress changes. This benefit of ALA has been shown with regards to cyanate poisoning, ifosfamide (chemotherapy drug), and toxic mushroom poisoning. ALA works as a chelator or remover of toxic minerals and heavy metals (such as lead or mercury) from our body. It is also able to chelate excess iron in our body. Iron can be also catalysed into a harmful activity by the certain drugs such as antibiotic gentamicin. Combination of gentamicin and iron leads to the formation of dangerous free radicals. It means that Alpha lipoic acid has also the ability to disarm the harmful iron! Find out more fascinating facts about ALA >
Calcium might interfere with the absorption of iron. For this reason, some experts suggest that people take individual calcium and iron supplements at different times of the day.
Vitamin C strongly enhances the absorption of non-heme iron by reducing dietary ferric iron to ferrous iron and forming an absorbable, iron-ascorbic acid complex.
Organic acids such as citric, malic, tartaric, and lactic acid have some enhancing effects on non-heme iron absorption.
Do not take any kind of iron supplement if you have hemochromatosis and hemosiderosis.
It is also suggested to avoid iron supplements in haemolytic anaemia such as sickle cell anaemia. Anaemia caused by sickle cell disease is not the same as the common iron deficiency anaemia. The problem isn’t the amount of iron, but the shape of the cells themselves. You don’t want to increase your haemoglobin too much, and create more of a chance of a crisis. Therefore, in case of sickle cell anaemia you shouldn’t take iron supplements without seeking professional advice as they could be dangerous as because extra iron build up in the body can lead to liver damage and other problems mentioned above. Read how to cope with Sickle Cell Anaemia >
Fairweather-Tait SJ, Wawer A, Gillings R, et al. Iron status in the elderly. Mech Ageing Dev 2014;136-137(100):22-28
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