Low iron

If you don’t get enough iron from the food you eat, your body’s iron stores become depleted. This can lead to low iron levels, also known as iron deficiency.

Key points about iron deficiency 

  1. Iron is an important mineral needed by every cell in your body to maintain healthy functioning.
  2. Lack of iron is the most common nutrient deficiency worldwide.
  3. Common causes include poor diet or low iron intake, high blood loss, poor iron absorption or increased need for iron at certain life stages.
  4. If you are severely iron depleted, this can lead to iron deficiency anaemia.
  5. Symptoms of iron deficiency include shortness of breath, tiredness and fatigue, reduced exercise tolerance and poor concentration.
  6. Treatment includes iron supplements and eating more iron-rich foods, such as red meat, leafy greens, fruits such as figs or prunes, and iron-fortified cereals.

What is iron?

Iron is an important dietary mineral that is found in every cell of your body. It is stored in your liver, spleen and bone marrow as ferritin.

Iron is needed by your body for many roles, including:

  • producing red blood cells to carry oxygen around your body
  • producing proteins to carry oxygen to your muscles
  • a healthy immune system to fight infections
  • normal child growth and intellectual development
  • normal production and functioning of cells and hormones
  • healthy hair, skin and nails
  • healthy brain development.

What are the causes of iron deficiency?

There are many causes of low iron including the following:

  • Not eating enough iron-rich foods – especially if you don't get enough iron from your food over time or are in a group that needs it most (see below).
  • Too much blood loss – red blood cells contain iron, so you lose iron if you bleed a lot, eg, with heavy periods, nosebleeds, a stomach ulcer (you lose blood in your gut), bowel cancer (which can cause hidden bleeding from your gut) or from medicines such as NSAIDs and aspirin.
  • Poor absorption of iron – this can happen when you have gut conditions such as coeliac disease, after gastric surgery or taking certain medicines.
  • Increased need for iron in certain stages of life – such as during rapid childhood growth, adolescence, pregnancy, breastfeeding or when exercising a lot.

In New Zealand, the groups most at risk of low iron are those who are having periods (menstruating), pregnant or breastfeeding, as well as young children, teenagers, athletes, vegetarians and vegans.

Having periods (menstruating) and being pregnant

If you are having periods, you need more iron because of the blood loss. If you get pregnant, you also need more than double the usual amount of iron during pregnancy.

Young children

Iron deficiency in preschool children in New Zealand is a cause for concern, with up to 14% of those under 2 years of age having low iron. Low iron levels can have a permanent impact on brain development, making these children less able to learn.

They may also not gain enough weight, have problems with feeding and digestion, get tired easily and be more prone to infection and illness. Children between 6 and 24 months are at greatest risk, especially those from low-income families.

Teenagers and athletes

Teenagers need extra nutrients to fuel growth spurts, but they are also more likely to have a poor diet. Iron can be lost through excessive sweating in athletes. Some athletes who need to be a certain weight for their sport have unbalanced diets.

Vegetarians and vegans

Iron in plant-based foods is not as easily absorbed as iron found in meat, so vegetarians and vegans may get too little iron in their diet. Tell your doctor if you are a vegetarian or vegan so they can give you some advice about what to eat or refer you to a dietitian.

Restrictive diets

If you follow a restrictive or fad diet, eg, a diet that can cause you to lose weight rapidly, you can become iron deficient.

What are the symptoms of iron deficiency?

Mild iron deficiency may cause no symptoms, or you may have symptoms such as lack of energy, difficulty concentrating or learning, headaches, irritability or be prone to infections. You may also find your nails break more easily or notice your hair is dryer or falling out.

If you are severely iron deficient, this can cause iron deficiency anaemia (low red blood count).

Symptoms of iron deficiency include:

  • tiredness and fatigue
  • lack of energy
  • racing heart rate (palpitations)
  • pale face or mouth
  • being short of breath when you exert yourself 
  • poor concentration
  • angina or chest pain getting worse.

How is iron deficiency diagnosed?

You may only find out you have low iron levels through a routine blood test. But if you have any of the symptoms above, talk to your doctor so they can work out whether you have low iron and, if so, diagnose the cause. 

Your doctor will ask you questions about your symptoms, what you eat, the medicines you take and your family medical history. They may also examine your stomach or do a digital rectal exam. This involves inserting a finger into your rectum to check for blood loss.

If your doctor thinks you may have low iron, they will order blood tests to check your iron levels and red blood count and to find out if you are bleeding somewhere in your body.

Further testing may be needed if the cause of your low iron is unclear, including:

  • a urine (pee) test to find out whether there are red blood cells in it
  • endoscopy – a flexible tube with a camera in inserted into your gut either from your mouth or from your rectum to look for any hidden sources of bleeding
  • a blood test and an endoscopy to screen for coeliac disease.

How is iron deficiency treated?

Treatment depends on the cause of your low iron. As well as treating the cause, your need to improve your iron levels. These can be done in the following ways:

  • Increasing how much iron you get from the food you eat (see below).
  • An iron tablet – you may need vitamin C along with the tablet to help absorb the iron. Iron tablets need to be prescribed by your doctor. Read more about oral iron supplements.
  • An iron injection – you may need this if you have severe iron deficiency and you need a lot of iron replaced. Read more about iron injection.

Your blood count may have to be checked regularly to make sure the problem has not returned. 

A small number of people are at risk of storing too much iron, so iron supplementation should only be done under the supervision of a doctor and reviewed from time to time. Read more about iron overload (haemochromatosis).

How can I care for myself with iron deficiency?

Your body absorbs only a small amount of iron at any one time, so you need to eat a lot of iron-rich foods every day. 

Iron-rich foods for your diet include:

  • meat and fish –  beef, lamb (especially kidneys and liver), veal, pork, poultry, mussels, oysters, sardines and tuna
  • fruits – dried fruits such as prunes, figs, raisins, currants or peaches, and prune or blackberry juice
  • vegetables – greens (eg, spinach, silverbeet, lettuce. bok choy, puha), beans and peas, pumpkin and sweet potatoes
  • grains – oats, iron-fortified breakfast cereals and wholegrain breads.

To get the most out of iron-rich foods:

  • eat foods rich in vitamin C (citrus fruits, leafy green vegetables) to help iron absorption
  • don't drink milk with meals or when you take your iron tablets as the calcium in it can interfere with iron absorption
  • don't drink tea or coffee with meals as this also reduces iron uptake.

Talk to your doctor if you need a referral to a dietitian for dietary advice.

The iron in meat, fish and chicken is called haem iron. There is more of it and and it is more easily absorbed than the iron in vegetables, which is called non-haem iron. It is best to get iron from a variety of sources – protein in meat also helps your gut absorb non-haem iron.

The table below shows iron content in 100g of different foods:

Haem iron
Lamb kidneys 12mg
Lean beef steak 4.3mg
Chicken breast 1.9mg
Non-haem iron (harder to absorb)
Tofu 5.4mg
Baked beans 1.9mg
Spinach 1.3mg

Read more about iron

Infants and young children

Breast milk contains enough iron for babies until 6 months of age. Meat or iron-fortified cereals should be introduced by 6–8 months. Bottle-fed or weaned babies should have iron-fortified formula until 12 months of age.

  • Cow’s milk should not be given in the first year of life. It is not a good source of iron and can cause stomach upsets with some bleeding in the gut and further iron loss.
  • Tea should not be given to preschoolers as it prevents iron absorption.

Make sure your child’s diet is well balanced and contains a wide variety of the iron-rich foods mentioned above. Refer to Plunket guidelines on when to introduce different foods. A liquid iron supplement may be necessary if your child has iron deficiency.

Learn more

The following links provide further information about iron deficiency. Be aware that websites from other countries may have information that differs from New Zealand recommendations.   

What's your number: could you be short on iron? Beef + Lamb NZ
 Gastro Info NZ
Low iron & iron deficiency anaemia HealthInfo Canterbury, NZ
Iron deficiency anaemia NHS, UK
Iron deficiency DermNet NZ
Iron Nutrition Foundation, NZ


  1. Iron deficiency Auckland Regional HealthPathways, NZ, 2020
  2. Iron deficiency Starship Clinical Guidelines, NZ, 2016
  3. Iron-deficiency anaemia Patient Info, UK
Credits: Health Navigator Editorial Team.