Quick Summary
Iron supplements can cause constipation, nausea, and other digestive discomfort, particularly at higher doses. The type and amount of iron may affect how well a supplement is tolerated.
Some forms, including iron amino-acid chelates and carbonyl iron, may be associated with fewer gastrointestinal side effects than certain traditional iron salts. However, individual responses vary.
Choosing an appropriate iron form, following the recommended serving, and considering how you take your supplement can help you make a more informed choice.
Why Do Iron Supplements Cause Constipation?
Iron supplements can cause digestive side effects such as constipation, nausea, abdominal discomfort, or changes in bowel habits. These effects may be more common with higher amounts of supplemental iron.
The form of iron may also affect tolerability. According to the NIH Office of Dietary Supplements, some forms of iron, including iron amino-acid chelates and carbonyl iron, might cause fewer gastrointestinal side effects than some ferrous or ferric iron salts.
This does not mean that a particular form will prevent constipation for everyone. Individual tolerance can vary.
For more information about digestive comfort and everyday dietary habits, read our guide to constipation, bloating, and the US diet.
Iron Form Matters: What Is Chelated Iron?
Iron supplements are available in several forms, including ferrous salts, carbonyl iron, and iron amino-acid chelates.
Iron bisglycinate is a type of iron amino-acid chelate in which iron is bound to amino acids. Research has examined iron bisglycinate as an alternative form of supplemental iron, including its absorption and tolerability.
The NIH notes that some alternative forms of supplemental iron, including iron amino-acid chelates and carbonyl iron, might cause fewer gastrointestinal side effects than ferrous or ferric salts.
When choosing an iron supplement, consider the form of iron, amount of elemental iron, serving size, and your individual nutritional needs.
If you are unsure which type of supplement is appropriate for you, our guide on finding the right dietary supplements for your body provides additional information to consider.
Does Vitamin C Help Iron Absorption?
Yes. Vitamin C can improve the absorption of nonheme iron, the type of iron found in plant foods and many dietary supplements.
According to the NIH Office of Dietary Supplements, consuming Vitamin C alongside nonheme iron can increase the amount of iron absorbed by the body.
This is why Vitamin C is commonly included in iron supplements.
WeightWorld's Iron with Vitamin C Tablets provide 65 mg of carbonyl iron and 125 mg of Vitamin C per tablet.
Always check the current Supplement Facts panel and serving instructions before use.
Who May Need an Iron Supplement?
Iron is an essential mineral involved in several normal functions in the body. It is a component of hemoglobin, which helps red blood cells carry oxygen, and is also involved in energy metabolism and other physiological processes.
Some people have higher iron requirements or may be more likely to have inadequate iron intake, including:
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Women who menstruate
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Pregnant women
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Vegetarians and vegans
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Certain athletes
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People with inadequate dietary iron intake
However, iron supplementation is not appropriate for everyone. If you are concerned about your iron intake or iron status, speak with a healthcare professional. Blood tests may be used to assess iron status.
5 Everyday Habits That May Affect Iron Absorption
How you take an iron supplement can influence your absorption and tolerability.
|
Habit |
What to Consider |
|
Coffee and tea around your dose |
Certain compounds in coffee and tea can reduce nonheme iron absorption. Follow the timing guidance provided by your healthcare professional or product label. |
|
Calcium at the same time |
Calcium may interfere with iron absorption. Consider taking separate calcium and iron supplements at different times if advised by your healthcare professional. |
|
Taking iron on an empty stomach |
Iron is often absorbed well on an empty stomach, but this may increase digestive discomfort for some people. Taking it with food may improve tolerability, although food can also affect absorption. |
|
Pairing iron with Vitamin C |
Vitamin C can improve the absorption of nonheme iron. Vitamin C-rich foods or an iron supplement containing Vitamin C can be options. |
|
Inconsistent use |
If you have been advised to take an iron supplement, follow the recommended serving consistently. Do not exceed the recommended amount unless advised by a healthcare professional. |
Can You Take Iron Without Getting Constipated?
Not necessarily. Some people experience constipation or other digestive symptoms when taking iron, while others do not.
The amount and form of iron can influence tolerability. Some alternative forms, such as iron amino-acid chelates and carbonyl iron, may cause fewer gastrointestinal side effects for some people.
If constipation or other digestive discomfort continues, speak with a healthcare professional about the appropriate iron form and amount for you.
Final Thoughts
Constipation and digestive discomfort can occur with iron supplementation, but individual responses vary.
When choosing an iron supplement, consider the form of iron, elemental iron amount, serving size, and whether Vitamin C is included. Following the recommended serving and product directions can also help you use the supplement appropriately.
If you are unsure whether you need an iron supplement, speak with a healthcare professional before starting one.
For a broader look at choosing supplements based on your individual needs, read how to find the right dietary supplements for your body.
Important: Excessive iron intake can be harmful. Iron supplements may also interact with certain medications. Keep iron supplements away from children and follow the product's recommended serving.
