| Iron | ||||||||
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- Why iron is good for you
- Important iron facts
- Groups at risk of iron deficiency
- Symptoms of iron deficiency
- Iron and health
- Iron in foods
- Iron recommended daily intake (RDI)
- Iron works best with
- Overdosage, toxicity and cautions for iron
Iron is required to carry oxygen in the blood. Every one of the red blood cells in the body contains a protein called haemoglobin (four atoms of iron are attached to every atom of haemoglobin molecule). In the lungs, oxygen molecules attach to the iron atoms and are carried to the blood cells. When the oxygen reaches its destination, it is swapped for the waste carbon monoxide and carried back to the lungs where it is removed by exhalation.
- Iron comes in two categories: haeme iron, found in meat and non-haeme iron, found in plant foods.
- Haeme iron is much more easily absorbed from foods than non-haeme iron
- The iron content of vegetable foods can be increased by using cast-iron cookware
- Non-haeme iron absorbed can be increased by eating even a small amount of food that has haeme iron in it
- Eating foods with vitamin C helps the body absorb more of the non-haeme iron
- Copper is vital for iron metabolism
- The amount of oxygen in the body determines how much oxygen gets to the rest of the body. Not enough iron and less and less red blood cells are made. Not enough red blood cells anaemia occurs – weak, tired, pale and short of breath
Groups at risk of iron deficiency
Iron deficiency is common – about 25% of the population may be at risk of iron deficiency.
- Women – need extra iron in general to make up for the blood lost each month due to menstruation
- Teenage girls – need extra iron for their growth and development
- Babies and toddlers – need plenty of iron because they are growing up so fast and if they do not get it, they may fall behind in their mental development.
- Pregnant and nursing women – need a lot of iron as they are passing a lot of their iron to their babies
- Athletes – need extra iron because they are using more of it when exercising
People in these groups at risk of deficiency should talk to a medical professional about iron supplements BEFORE taking them.
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General symptoms of iron deficiency are:
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- Anaemia - iron helps anaemia by increasing the number of red blood cells that are circulating in the blood and also in the stores of red blood cells. Iron can only help if the anaemia is caused by iron deficiency
- Menstrual problems - iron helps to replace the iron and blood lost when a woman has her periods, especially if she loses a lot of blood each menstrual cycle
People who wish to take an iron supplement should talk to a medical professional BEFORE taking it.
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| FOOD | AMOUNT | iron (mg) |
|---|---|---|
| Liver, chicken | 85g | 7.3 |
| White beans | 1 cup | 6.6 |
| Liver, beef | 85g | 5.8 |
| Oysters, raw | 6 medium | 5.6 |
| Black beans | 1 cup | 3.6 |
| Molasses, blackstrap | 1 Tbsp | 3.5 |
| Chickpeas | 1 cup | 3.2 |
| Kidney beans | 1 cup | 3.2 |
| Spinach, cooked | ½ cup | 3.2 |
| Prune Juice | 2/3 cup | 3.0 |
| Potato, baked | 85g | 2.7 |
| Barley | 1 cup | 2.1 |
| Raisins, seedless | 2/3 cup | 2.1 |
| Beef, mince | 85g | 1.8 |
| Lima beans | ½ cup | 1.8 |
| Wheatgerm | ¼ cup | 1.8 |
| Almonds, dry roasted | 30g | 1.1 |
| Chicken | 85g | 1.1 |
| Tomato juice | 1 cup | 1.1 |
| Bread, whole wheat | 1 slice | 0.9 |
| Brussels sprouts | ½ cup | 0.9 |
| Walnuts | 30g | 0.7 |
| Broccoli, cooked | ½ cup | 0.6 |
| Kale | ½ cup | 0.6 |
| Pecans | 30g | 0.6 |
| Strawberries | 1 cup | 0.6 |
| Peanut butter | 2 Tbsp | 0.5 |
| Tomato | 1 medium | 0.5 |
Iron recommended daily intake (RDI)
| RDA | lifestage | age | amount |
|---|---|---|---|
| INFANTS | 0-6mths 7-12mths |
0.27mg 1.1mg |
|
| CHILDREN | 1-3yrs 4-8yrs |
7mg 10mg |
|
| CHILDREN | 9-13yrs male: 14-18yrs female: 14-18yrs |
8mg 11mg 15mg |
|
| ADULTS | male: 19-50yrs female: 19-50yrs |
8mg 18mg |
|
| SENIORS | 51+yrs |
8mg | |
| PREGNANT | all ages | 27mg | |
| LACTATING | <18yrs 19-50yrs |
10mg 9mg |
|
| TOLERABLE UPPER LIMIT | lifestage | age | AMOUNT |
| INFANTS | 0-12mths | 40mg | |
| CHILDREN | 1-8yrs | 40mg | |
| CHILDREN | 9-13yrs 14-18yrs |
40mg 45mg |
|
| ADULTS | 19-50yrs | 45mg | |
| SENIORS | 51+yrs |
45mg | |
| PREGNANT | all ages | 45mg | |
| LACTATING | all ages | 45mg | |
| TOXIC LEVEL | >100mg | ||
The tolerable upper limits should only be taken for short periods and only under medical supervision.
Overdosage, toxicity and cautions for iron
Too much iron (>100mg) can be very toxic and in fact, lethal.
Iron supplements may be fatal for adults when taken in doses of 200-250 mg/kg per body weight.
Chronic symptoms of overdosage - arthritis, aggressive behaviour, anorexia, fatigue, gut damage, increased oxidative stress, cancer and heart disease, increased blood levels of serotonin and histamine, hostility, hyperactivity, headaches, liver damage, metabolic acidosis, Parkinson’s disease, weight loss.
To reduce iron toxicity and its symptoms, supplemention with the following is recommended: vitamin B3 (niacin), tryptophan, zinc, manganese, lipoic acid and quercetin.
references
- USDA National Nutrient Database - provides nutrient values for foods (accessed 5 January 2005)
- Osiecki, H. The Nutrient Bible. Bio-Concepts Publishing QLD, 2002
- Whitney EN, Cataldo DB, Rolfes SR. Understanding Normal and Clinical Nutrition, 6th Edition. Wadsworth/Thomson Learning, 2002
