Eat Smart to Prevent Iron Deficiency

(Content revised 05/2024)

Key points for increasing iron absorption:

  • Have a balanced diet. Choose a variety of iron-rich foods.
  • Consuming meat helps absorb more iron from dark green vegetables and beans.
  • Smart food choices to boost iron intake:
    • Eat moderate amount of meat, fish and seafood
    • Choose more dark green vegetables, dried beans and nuts
    • Consume vitamin C-rich fruits and vegetables helps absorption of iron from plant sources
    • Avoid drinking tea and coffee with meals if you are anaemic or at risk of iron deficiency

What are the functions of iron?

  • Iron is essential for making haemoglobin, the substance in red blood cells that carries oxygen to cells in our bodies. In our cells, iron is also essential in chemical reactions for energy supply.
  • Iron deficiency may result in iron deficiency anaemia, paleness, dizziness, palpitations, fatigue, poor exercise tolerance and working capacity, weakened immunity, poor attention, etc. Iron deficiency may impair cognitive function and learning in children.
  • Pregnant women need more iron for the growing foetus and for making more red blood cells for themselves. Severe anaemia during pregnancy may lead to iron deficiency in infants and harm their brain development.

How much iron do we need?

  • The recommended amount of iron per day for different groups of people:
    Group Recommended daily intake
    Women aged 18 to 49 and pregnant women at 1st trimester 18 mg
    Pregnant women at 2nd trimester 25 mg
    Pregnant women at 3rd trimester 29 mg
    Lactating mothers 24 mg
    Women aged 50 or above (after menopause) 10 mg
    Adult men 12 mg

    Source: 2023 version of The Chinese Dietary Reference Intakes

  • Iron absorption in our gut is regulated by how much iron the body has. If the body lacks iron, more iron will be absorbed from food. Conversely, less iron is absorbed when the body store is sufficient.

Food Sources of Iron

Animal-based iron-rich foods

  • Meat, poultry, liver, fish and seafood contain haem iron which can be absorbed easily.
  • Red meat (beef, pork and lamb) is rich in haem iron. However, a high intake will increase colorectal cancer risk. World Cancer Research Fund recommends eating no more than 500g of cooked red meat a week (or 700 to 750g if uncooked), and avoid processed meat such as ham, bacon and sausage. It is best to consume a variety of iron rich foods to obtain a well-balanced nutrition.
  • For persons with iron deficiency or increased iron need, consuming red meat and eating liver occasionally help you improve iron status and recover from anaemia more quickly.
  • The following tables show the examples of iron content of animal based iron-rich foods (Source from Nutrient Information Inquiry System, Centre for Food Safety):
    1. The cooked weight and the iron content of meat, poultry & egg
      Food Cooked weight Iron content
      Lean cuts of beef 100g 1.7 to 3.7mg
      Lean cuts of pork 100g 0.6 to 1.9mg
      Lean cuts of lamb 100g 1.5 to 3.4 mg
      Lean cuts of duck 100g 2.6mg
      Chicken leg 100g 0.9 to 1.6mg
      Pork liver 100g 18.0mg
      Egg 1 egg (60g) 0.7 to 1.0mg
    2. The cooked weight and the iron content of fish and seafood.
      Food Cooked weight Iron content
      Oyster 100g 4.3 to 12.0mg
      Mussel 100g 6.7mg
      Clam 100g 28.0mg
      Shrimp 100g 0.4 to 3.1mg
      Salmon 100g 0.3 to 1.3mg
      Canned sardine 3 pieces (160g) 2.2 to 4.6mg

Plant-based iron-rich foods

  • Plant iron is non-haem iron. The gut absorption of plant iron is far less than iron in meat. It is affected by other foods and drinks in diet. Meat, fish and vitamin C help absorbing iron from plant foods. Tannic acid in coffee and tea, and phytates in vegetables, beans and grains reduce the absorption.
  •  Plant foods are significant sources of iron because a large proportion of what we eat is plant-based foods. You can get more iron by eating more dark green vegetables and beans, and choosing nuts and seeds as snack, etc.
  • The following tables show the examples and iron content of plant based iron-rich foods (Source from Nutrient Information Inquiry System, Centre for Food Safety):
    1. The weight and iron content of half a cup of cooked dried beans

      (Remark: 1 cup is equivalent to 240ml)

      Food Cooked weight Iron content
      Lentils 99g 1.6 to 2mg
      Kidney bean 89g 2 to 2.6mg
      Chickpeas 82g 1.1 to 2.4mg
      Soybean 86g 4.4mg
      Adzuki bean 115g 2.3mg
      Mung bean 101g 1.4mg
      Black bean 86g 1.8mg
    2. The weight and iron content of 1 bowl of cooked vegetables

      (Remark: 1 bowl is equivalent to 250 to 300ml)

      Food Cooked weight Iron content
      Spinach 160g 3.2 to 5.8mg
      Chinese kale 160g 1mg
      Bok choi 160g 1.6 to 3.2mg
      Broccoli 160g 0.9 to 1.1mg
      Green peas 160g 1.8 to 2.6mg
      Edamame 160g 3.6mg
      Wood ear fungus (by soaking of 10g of dried wood ear fungus) about 80g 4.4mg
    3. The weight and iron content of 1 tablespoon of nuts and seeds

      (Remark: 1 tablespoon is equivalent to 15ml)

      Food Weight Iron content
      Black sesame 9g 2.0mg
      White sesame 9g 1.3mg
      Pumpkin seed 10g 0.2 to 0.9mg
      Cashew nuts 15g 0.9mg
      Almond 15g 0.7mg

Iron-fortified food

Iron-fortified breakfast cereals are also good source of iron. Look for the amount of iron the product contains by reading the nutrition label on the food packaging.

Vitamin C-rich fruits and vegetables

  • Consume vitamin C-rich fruits or vegetables with meal, or within 1 to 2 hours after meal can increase the absorption of iron from plant source.
  •  Examples are kiwifruit, citrus fruits (e.g. orange, grapefruit, tangerine, etc.), papaya, pineapple, guava, cantaloupe, strawberries, bell peppers, honey pea, cauliflower, broccoli, tomato, bitter melon, etc.
  • Vitamin C is water soluble. It is easily destroyed by heat. Therefore avoid soaking the vegetables for long time. To reduce the loss of vitamin C from cooking, steam or cook these vegetables quickly with a small amount of water, or stir-frying with small amount of oil.

How to get more iron from your diet?

  • Have iron-rich vegetables along with meat, fish or seafood. Consume vitamin C-rich fruits after a meal. This helps the absorption of iron.
    • Example: Stir-fry meat with broccoli served with red rice, clam and udon in soup served with edamame
  • Add iron-rich and vitamin C-rich ingredients in dishes:
    • Example 1: Stir-fry chicken with honey peas and wood ear fungus
      • Include iron-rich fungus, sesame or nuts, etc.
      • Use vitamin C-rich vegetables e.g. honey peas or cauliflowers, etc.
    • Example 2: Bell pepper and chickpeas with fusilli
      • Add bell peppers to enhance the taste and vitamin C in the meal
      • Use tomato and tomato paste as the sauce to enrich vitamin C content
  • Include these ingredients when you buy or prepare salad:
    • Iron-rich vegetables such as baby spinach, butter lettuce, broccoli, edamame, green peas, beetroots, etc.
    • Vitamin C-rich fruits and vegetables such as tomato, bell peppers, pineapple, oranges, etc.
    • Iron-rich ingredients such as chicken, salmon, egg, lentils, kidney bean, chickpeas, almond, pumpkin seeds, etc.
    • Replace salad cream with vitamin C-rich lemon juice or lime juice, or iron-rich hummus
    • Example: baby spinach with grilled chicken and beans (with lemon juice)

Tips for choosing beverages

  • Plain water, water with added lemon, etc. are better choices
  • It is best to enjoy your coffee or tea at least an hour before or after a meal to avoid their effect on the iron absorption

Persons at risk of iron deficiency

  • People at risk of iron deficiency are those with higher iron needs, such as infants and toddlers, adolescent girls and women with heavy menstrual periods, pregnant women and women after childbirth, frequent blood donors, persons with gastrointestinal conditions, etc. People who are on restrictive diet are also at a higher risk.
  • Pregnant women, apart from consuming more iron-rich foods, can take a prenatal multivitamin/multimineral supplement containing iron.

Notes on taking iron supplement

  • Too much iron can be harmful. You should follow your doctor's advice when taking an iron supplement.
  • Iron or iron-containing supplements is better absorbed if it is taken on an empty stomach, 1 hour before or 2 hours after meal. However, it can cause stomachache, nausea, diarrhea in some people. Taking the supplements with meal may avoid these problems.
  • Calcium may interfere with iron absorption. Avoid taking iron supplement with a calcium supplement or calcium-rich foods at the same time.

Other nutrients that you need for preventing anemia

  • Apart from iron, you also need folate and vitamin B12 to produce red blood cell.
  • Green leafy vegetables, beans, orange, papaya, etc. are good source of folate.
  • Vitamin B12 is found in meat, fish, egg and milk. Strict vegetarians can get vitamin B12 from vitamin B12-fortified food products, or take supplement under instruction of healthcare professionals.
  • Having a balanced diet is essential to obtain all nutrients needed to prevent anemia.