Iron Nutrition: What exactly is iron and why is it important to get our iron nutrition levels correct?
We require iron for many bodily functions including oxygen transport and storage, enzyme function and efficient immune defenses.
Iron is a mineral and one of its most important functions is transport of oxygen. Red blood cells contain a protein called haemoglobin. Haemoglobin is responsible for transferring the oxygen molecules we breathe in from our lungs to our cells. The component in haemoglobin that picks up, or binds with, the oxygen molecules is iron. Around two thirds of the iron in our body can be found in our haemoglobin. The red color of blood is due to its iron content.
Iron is also an important component of myoglobin. Myoglobin is a protein responsible for assisting with the storage of oxygen in our muscle cells. Our muscles are also red courtesy of their iron content. There are a lot of enzymes in our body that have iron. Many of these enzymes are responsible for assisting in the production of the energy that keeps our bodies functioning. Our immune system too requires enough iron to function correctly.
Correct Iron Nutrition
A deficiency in iron causes a condition called anemia. The most common symptoms of anemia include:
- Low energy levels and tiredness
- Dizziness and weakness
- Difficulty in concentrating
- Higher risk of picking up infections
- Headache
- Paler than normal skin
It’s been calculated that as much as one-third of the global population is iron deficient to some degree.
Conversely, too much iron is also not good for us. Our bodies can store iron very effectively, and are not particularly efficient at removing it. Therefore excess iron intake can quickly lead to toxicity. Iron toxicity causes a condition called haemochromatosis and ironically some of the symptoms are similar to those caused by too little iron! Generally though haemochromatosis can cause damage to internal organs, notably the heart (leading to increased risk of heart disease), pancreas and liver. It may also cause joint pain, extreme tiredness and weakness, loss of weight and also body hair loss. Haemochromatosis is also believed to contribute to an increased risk of certain types of cancer, notably colorectal cancer.
Inadequate Iron Nutrition – High Risk Categories
Some of the groups most at risk of developing an iron deficiency are:
- Pre-menopausal women
- Pregnant women
- Lactating women
- Young children and infants being fed a lot of cow’s milk
- Vegetarians
- Vegans
- People who donate blood frequently
- Women with menorrhagia
- People suffering from colon cancer (likely due to blood loss)
- People with some gastrointestinal disorders like ulcerative colitis, Crohn’s disease and celiac disease
- People who have undergone gastrointestinal surgery
Types Of Dietary Iron
There are 2 main types of dietary iron. Haem iron is found in animal proteins ie meat, fish, chicken and is the form of iron that has the highest level of bioavailability for humans. Non-haem iron is also found in animal proteins but by and large we obtain most of our non-haem iron from plant foods like whole grains, nuts and vegetables. Non-haem iron is not as bioavailable to humans.
Our ability to absorb non-haem iron is also more readily affected by other things we eat, as there are a number of other minerals, phytates, polyphenols and vegetable proteins that bind to non-haem iron and remove it before we can absorb it. Excess iron intake conversely can also be detrimental to our absorption of zinc and calcium.
Ensuring Adequate Iron Nutrition
But it isn’t all bad news for iron absorption! Vitamin C and ascorbic acid significantly increase our uptake of non-haeme iron when eaten as part of a diet high in those sources of iron. Eating foods high in haeme iron also assists with the absorption of non-haeme iron. Many cooked vegetables also yield more iron than they do when eaten raw. For instance, we can absorb up to a third of the iron in cooked broccoli vs just 6% from raw broccoli.
Vitamin A aids in the release of stored iron so a diet that contains insufficient amounts of this vitamin could also lead to an iron deficiency.
Using Supplements To Help Maintain Correct Iron Nutrition
A normal healthy adult male should be absorbing about 1 milligram of iron daily whilst a woman of child-bearing age requires about 1.5 milligrams. Whilst eating a balanced diet is obviously the preferred way to obtain enough iron, the pressures of modern life unfortunately can make this hard to do.
We also absorb less than one-fifth of the iron we consume and as previously mentioned, this can be affected by a range of other dietary considerations. If we already have enough iron in our bodies, we will absorb less from our food. Other things we eat and drink can affect how much iron we absorb too. Calcium, phosphorus, zinc, phytates, polyphenols and vegetable proteins for instance will inhibit non-haem iron absorption. Phytates also inhibit absorption of manganese, zinc and calcium. Tannin (found in tea, coffee and wine) binds to iron and removes it from the body.
Therefore, in order to actually absorb the amount of iron we require, we need to consume a lot more of it, which is not always possible. That’s why many people turn to iron supplements to assist with getting adequate iron nutrition. Fortunately iron is one of those minerals that is widely available in many different supplemental forms. The forms of iron – ferrous and ferric iron salts (ferrous gluconate, ferrous sulfate and ferric citrate), found in dietary supplements are generally much more bio-available than those from natural sources, meaning a little goes a long way.
Many multi-vitamin / mineral supplements for women will often contain the complete daily recommended intake of iron. Those for men and postmenopausal women on the other hand generally contain much less iron and some have none at all.
Conversely, iron only supplements often supply more than 3 times the daily requirements. If you’re considering using one of these, be aware that excess iron supplementation (considered to be more than 45 mg a day) can cause gastrointestinal upsets like constipation and nausea.
The best way to guarantee adequate levels of iron nutrition is to eat a balanced diet of meat, fruit, vegetables and cereals. This provides the best all-round guarantee of absorbing enough iron to meet our nutritional needs.
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