Pregnancy Nutrition: The Importance of Iron
Iron is a mineral found in red blood cells and, to a lesser extent, in muscle cells. It has the important function of transporting oxygen to cells so that they can function properly.
In recent years there has been debate on whether or not pregnant women should be routinely advised to take iron supplements during pregnancy. Many feel that it is unnatural: Women have been having children for centuries without additional iron, so why can’t we?
Let’s look at the facts:
What are the dietary sources of iron?
There are two main types of dietary iron. The first is haem iron, which is found in red meat and the brown meat of chicken and in some fish. The other source is non-haem iron, which is found in whole grain cereals, dark green vegetables, pulses, eggs, dried fruit and fortified breakfast cereals. The absorption of non-haem iron by the body is influenced by many factors.
Did you know?
- The body adapts to absorb more iron from the diet if the body’s iron stores are low.
- Fruits, vegetables and juices greatly improve the absorption of iron when eaten with a non-haem iron source. Try a glass of orange juice with fortified breakfast cereal, tomato with brown bread and dried fruit mixed with fresh fruit.
- There are compounds called phytates found mostly in high fibre cereals, such as bran. They can strongly bind non-haem iron in the gut and prevent it from being absorbed. The good news is that vitamin C can counteract this to some extent.
- Tea, coffee, and cola can also reduce iron absorption, so it is advisable not to consume these drinks with meals.
How much iron do I need?
During pregnancy extra iron is needed to increase the mother’s volume of red blood cells so that she can transport oxygen to the growing baby. Additional iron is also required to create iron stores in the baby’s liver, which should support the baby for the first six months of life.
The body has many ways of adapting to these extra demands. The first being that women absorb more iron from their food when they are pregnant than they would usually. This is more apparent in the second half of pregnancy. The body also saves iron, as pregnant women don’t menstruate.
Even with these methods of improving iron status, the pregnant woman still depends heavily on her own iron stores, to provide the extra iron needed.
Unfortunately, many women do not have adequate iron stores and in reality a large proportion of women have no stores at all. Eating a balanced diet in pregnancy goes a long way.
Who is at risk of having low iron stores?
- Vegetarians during pregnancy
- Women who have poor dietary habits
- Teenage mothers
- Women who have very heavy or prolonged periods
- Women who have had previous pregnancies in the recent past
What are the risks of having low iron stores?
Recent Irish research has shown that mothers who have low iron stores in early pregnancy are at increased risk of having premature babies, or having full-term babies who have a low birth weight. These babies in turn are at increased risk of becoming anaemic in infancy.
What about supplements?
It is difficult to diagnose iron deficiency during pregnancy because of all the physiological changes going on during this time. Haemoglobin is routinely measured during pregnancy, but in many situations this can be an unreliable marker of iron status.
Women whose stores are adequate and who have been eating a well balanced diet both before and during pregnancy are unlikely to require supplements. For those at risk of having low iron stores, an iron supplement can greatly improve the pregnancy for both the mother and the baby.
Are there side effects of iron supplements?
Everybody knows that iron supplements can cause constipation during pregnancy and sometimes nausea. To improve this, women taking supplements are advised to drink at least 6-8 glasses of liquid daily, eat high fibre foods such as brown bread, whole grain cereals, fruit and vegetables, and also take daily light exercise.
Some mothers feel that iron taken in the ferrous gluconate form does not have the side effect of constipation to the same extent as other iron salts.
Side effects vary from one woman to another and finding the right supplement is often a matter of trying a few until you find one that suits you.