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Can Iron Supplements Cause Constipation?

author image Cassie Yanker
Cassie Yanker is a Registered Dietitian who began writing professionally in 2011. She holds a Bachelor of Science degree in both nutrition and community health from the University of Northern Colorado. Cassie completed the dietetic internship program through Bowling Green State University in Ohio and received a Master's Certificate.
Can Iron Supplements Cause Constipation?
A young woman is laying on her couch with stomach pains. Photo Credit: conejota/iStock/Getty Images

Iron is vital for your body throughout life. It is a part of the red blood cells, and it carries oxygen to all parts of the body. Iron from some food sources, such as meat, is readily absorbed into the body. When iron supplements are used, the iron is not readily absorbed and can result in constipation. Increasing the amount of vitamin C in your diet can enhance the absorption of iron in your body.

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Iron in the Body

Getting enough iron is hard enough for people who eat a mixed diet; it can be especially challenging if you are not eating a variety of healthy foods. The body only needs small amounts of iron. Taking an iron supplement can help you get more iron in your body. Some side affects of iron can be constipation or upset stomach. Talk with your doctor before taking an iron supplement.

Facts about Iron Supplements

Iron supplements are helpful if you are unable to get enough iron in your diet. Foods such as red meat, dried beans, fortified cereals and molasses have high amounts of iron. Multivitamins generally provide 30 mg iron daily, while some iron supplements can provide 60 mg or more. The U.S. Food and Drug Administration recommends getting 45 mg iron or less every day. Iron supplements come in two different forms, ferrous and ferric. The ferrous iron supplement is usually absorbed better. Iron supplements can cause stomach problems such as nausea, abdominal cramping or constipation.

Iron and Constipation

The amount of iron in the supplement can affect whether or not constipation occurs. Your body may not need the additional iron that you are taking, or there may be too much in the supplement. This means that if you are taking large amounts of iron, you are more likely to get side affects such as constipation. Most multivitamins contain 30 mg of iron, while actual iron supplements contain as much as 180 mg.

Tips for Avoiding Constipation

Constipation can usually be decreased by drinking a large glass of water with the supplement. Increasing your vitamin C intake has been linked with better iron absorption, depending on the type of iron supplement you are taking as well as the amount. You can also cut the dosage by half for a few days to relieve your constipation.

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