Fatigue is one of the first signs of a suboptimal iron intake due to the oxygen-carrying capacity of iron in the body. When energy is low it is one of the first nutrients to be considered. Other signs of insufficient iron include pale or yellowing of the skin, shortness of breath, muscle weakness, sleeplessness, hormone imbalance and trouble concentrating or learning new information — to name just a few.
This is because a lack of iron affects most systems in the body including the central nervous system, immune system, cardio respiratory system, vascular system, endocrine and gastrointestinal systems.
While anaemia, the most severe deficiency of iron, is rare, even mild iron deficiency can negatively impact on health in the long term. That’s why it is concerning that in New Zealand there is a significant proportion of the population who have low iron status or an inadequate dietary intake of iron. Up to 30 per cent of infants under 3 years have low iron status, and iron deficiency has more than doubled in young females aged 15-19.
Women of childbearing age are at particular risk given the losses that occur during menstruation. This is compounded with over one third in this age group reporting an inadequate iron intake. This is more pronounced in Maori and Pacific women of the same age. People following a vegan or vegetarian diet are more likely to have low iron stores and finally pregnant or lactating women are at greater risk given the additional stress that pregnancy places on the body.
Where does iron in the diet come from?
Iron is available in two forms, the majority of iron being non-haem iron, which is present in most foods such as cereals, green vegetables and legumes (chickpeas, red kidney beans and lentils, as examples). Iron that is present in haem form is found in animal protein, the richest sources in the diet coming from mussels, oysters, beef, lamb and liver.
Eggs are another useful source of haem iron. The iron in haem form is most bioavailable, making it easier for the body to use, however we actually absorb very little iron from food relative to the amount present, with up to 35 per cent of haem iron being absorbed, compared to just 5 per cent of non haem iron.
The reduced absorption of non-haem iron is due to constituents in the food that bind the mineral and block its absorption. There are other factors that influence our ability to absorb iron, both dietary and factors relating to the individual.
Coffee, tea, polyphenols (found in plants) and calcium can inhibit the absorption of up to 50 per cent of available non-haem iron, whereas vitamin C-containing foods (most vegetables), citric and acetic acid (found in most vinegars) and vitamin A can enhance its absorption.
Though iron is less available in a vegetarian diet, the absorption is enhanced in those with low iron stores. Of course, ideally, people wouldn’t be in a compromised iron state to begin with.
The role iron plays
Iron plays an important role in the development and functioning of the brain, including the production and breakdown of neurotransmitters — chemical messengers that communicate messages from your brain to your body. A disruption to these processes can affect mood and behaviour.
A cross sectional study of children and adolescents with iron deficiency anaemia found an increased prevalence of mood disorders, autism spectrum disorder, attention deficit hyperactivity disorder, and developmental disorders compared to children with adequate iron status.
Research has also found the stress of pregnancy on the body can deplete reserves of nutrients, including vitamin B12, zinc and iron, and a lack of these may increase a women’s risk of depression. In addition, animal studies have found an increase in anxiety symptoms in mice bred to remove the ability for iron to be taken up in the brain.
A deficiency of iron in the brain impacts on sleep patterns. Research has found an association between short sleep and low levels of iron from the diet. People with restless leg syndrome have also been found to have low levels of iron in the brain and, when supplemented, their symptoms have resolved.
Iron deficiency is an oft found co-morbidity in heart failure patients, highlighting the important role that iron plays in cardiac function. Iron is essential for a resilient and robust immune system. Seventy percent of our immune system is housed in the gut, and compromised gut function that affects iron absorption or uptake can lower immune function and compromise the immune system’s ability to fight infection.
Iron deficiency anaemia is the most common complication of inflammatory bowel disease, with between 20-30 per cent prevalence in ulcerative colitis and Crohn’s disease, with women being particularly vulnerable. This can be due to inflammation of intestinal mucosal cells, either resulting in chronic blood loss or an inability to absorb dietary iron. The absorption can also be impaired from infections such as H. pylori or intake may be reduced due to gut discomfort.
This relationship between iron status and gut function makes it critical to work to strengthen the gut cell lining and allow the immune system to function well. Strategies include removing inflammatory foods (common ones being gluten-containing grains, dairy, nightshade vegetables, alcohol and caffeine) for a period to allow for inflammation to settle down.
This is combined with a focus on nutrients to support gut healing, such as cuts of meat that include the gelatinous part of the animal (or a preservative-free gelatin supplement) and fermented foods, along with supplements such as a good probiotic, aloe vera and l-glutamine.
A strategy to increase iron status when deficient should include supplementation along with dietary strategies, so a focus on increasing red meat intake, organ meat (such as liver, or a pate), eggs and plenty of green vegetables alongside. These do not contain the haem iron that is most bioavailable, however the absorption of the non-haem iron they docontain is enhanced in the presence of haem iron.
Too much iron
It is worth noting that too much iron causes cellular damage, increasing oxidation of musculoskeletal tissue and leading to tissue breakdown. This is as harmful as low iron status. Therefore, if you think you are deficient in iron, please get your levels checked before beginning supplementation.
Take a look at Bite's iron rich recipes collection for ways to incorporate both haem and non-haem iron in your diet.
Through her nutrition consultation and subscription service of meal plans, nutritionist Mikki Williden helps people manage their diets in an interesting way, at a low cost. Find out more at mikkiwilliden.com