You are here: > Thyroid NZ Home > Healthy thyroids, healthy people > RDIs and Food Sources – Iron
Iron is a building block of a number of proteins – including haemoglobin, a protein present in red blood cells that carries oxygen from the lungs to different tissues and organs in the body – and enzymes. One of those enzymes is the thyroid peroxidase enzyme, which plays an important role in the synthesis of the thyroid hormones T4 and T3 by the thyroid gland. Another enzyme is iodothyronine deiodinase, which plays a role in the conversion of the thyroid hormone T4 into the more active hormone T3.
Low iron levels can interfere with the activity of these proteins and enzymes, and can also significantly increase the presence of thyroid autoantibodies. As a result, low iron levels can lead to thyroid disease, particularly hypothyroidism (especially in pregnant women) and thyroid autoimmunity.
It is therefore important to make sure that our diet contains sufficient iron. This page gives a brief overview of how much iron a healthy person needs to consume daily in their diet and from which food sources.
Babies, children and teenagers need more iron because they are growing rapidly.
People who menstruate require extra iron due to monthly blood loss.
Pregnant women need sufficient iron for both themselves and their developing baby, particularly during the later stages of pregnancy when the baby grows quickly.
Athletes, especially endurance runners, may also require additional iron.
There are two types of iron found in food: haem iron and non-haem iron.
Haem iron is absorbed efficiently by the body, whereas non-haem iron is absorbed less effectively. Meat, poultry and seafood contain both haem and non-haem iron. Plant-based foods such as vegetables, cereals, beans and lentils contain only non-haem iron, meaning the body absorbs the iron from these foods less easily.
Beef and lamb (the redder the meat, the higher the iron content)
Venison
Kidney and liver
Shellfish, such as mussels and oysters
Chicken, fish and seafood, such as paua and mussels
Grains: porridge, oats, iron-fortified breakfast cereals (e.g. Weet-Bix) and wholegrain bread
Vegetables: leafy greens (spinach, silverbeet, lettuce), beans and peas, pumpkin and sweet potatoes
Eggs
Chickpeas, beans and lentils
Some nuts and seeds
Lean red meat is one of the best sources of easily absorbed haem iron, so aim to include it in meals three to four times per week. Other meats, such as chicken and pork, as well as fish, are also good sources of iron.
To improve the absorption of non-haem iron, eat vitamin C-rich foods – such as kiwifruit, citrus fruits, oranges and capsicums – at the same time. For example, adding kiwifruit to your breakfast cereal can increase the amount of iron absorbed.
Combining haem iron foods with non-haem iron foods also improves iron absorption. For example, adding lean meat to a salad sandwich helps the body absorb more iron from the bread and salad.
If you do not eat meat or seafood, include non-haem iron-rich foods such as tofu, iron-fortified breakfast cereals, beans and lentils in your diet every day.
Tea can reduce the amount of iron absorbed by the body. It is best consumed between meals or at least 30–60 minutes after eating.
Low iron levels can result from:
Not eating enough iron-rich foods
Increased iron requirements, for example during pregnancy
Blood loss through conditions affecting the digestive tract, such as peptic ulcers, tumours or ulcerative colitis
Although less common, it is also possible to have excessively high iron levels. This may result from taking iron supplements unnecessarily, excessive alcohol consumption, hepatitis or haemochromatosis – a condition in which the body absorbs too much iron.
If you are concerned about your iron levels – for example, if you experience heavy periods, fatigue, weakness, dizziness or paleness – speak to your GP or healthcare professional about having a blood test.
Iron supplements should only be taken under medical supervision, as inappropriate use may reduce the absorption of other important nutrients such as zinc and calcium. They can also interfere the absorption of thyroid hormone replacement drugs, such as levothyroxine.
References
Nutrient Reference Values for Australia and New Zealand – Iron (National Health and Medical Research Council and Ministry of Health, 2014)
Healthify – Iron (Health Navigator Charitable Trust, last reviewed: 25 Jul 2025)
Garofalo V., Condorelli, R. A., et al. (2023). Relationship between Iron Deficiency and Thyroid Function: A Systematic Review and Meta-Analysis. Nutrients, 15(22), 4790.