How to choose an iron supplement

Start with the form of iron and the amount of elemental iron per daily dose. Then look at any additional nutrients in the formula and how well the supplement is likely to suit your routine.

If iron supplements have upset your stomach in the past, you may want to consider forms such as iron bisglycinate or microencapsulated iron, which are often chosen for better digestive tolerability. Some formulas also combine iron with vitamin C, folate, or vitamin B12.

What are the different forms of iron in supplements?

Common options include ferrous sulfate, ferrous fumarate, ferrous gluconate, iron bisglycinate, and microencapsulated iron. Ferrous sulfate, fumarate, and gluconate are widely used iron salts, but they can be harder on the digestive system for some people.

Iron bisglycinate is a chelated form in which iron is bound to the amino acid glycine. Microencapsulation uses a protective coating around the iron particles and is another approach used to improve tolerability.

So when comparing iron supplements, don't just look at the milligrams - check which form of iron the product contains as well.

Is a higher dose of iron always better?

No. More iron does not automatically mean a better supplement. The right amount depends on your individual needs, and higher doses can also be harder on the digestive system.

If you are taking iron because a deficiency has been confirmed, the dose should ideally be based on your blood test results and advice from a healthcare professional.

Why do iron supplements often contain vitamin C?

Vitamin C increases iron absorption, particularly the absorption of non-heme iron. This is why it is often included in iron supplements and why vitamin C-rich foods are commonly recommended alongside plant-based sources of iron.

Can iron supplements upset your stomach?

Yes. Iron supplements can cause nausea, stomach discomfort, a heavy feeling, or constipation in some people. How well you tolerate them can depend on the dose, the form of iron, and your individual sensitivity.

If standard iron salts are difficult for you to take, options such as iron bisglycinate or microencapsulated iron may be better tolerated.

When is the best time to take iron supplements?

Iron is generally absorbed best on an empty stomach. However, taking it without food can cause nausea or stomach discomfort for some people.

If that happens, taking your iron supplement with food may make it easier to tolerate, although absorption can be slightly lower. Always check the directions for your specific product, as recommendations may vary depending on the form and formulation.

Can I take iron supplements with coffee or tea?

It is best not to take iron at the same time as coffee or tea. The polyphenols they contain can reduce the absorption of non-heme iron, so try to leave at least 1-2 hours between your iron supplement and coffee or tea.

It is also a good idea to take iron separately from calcium supplements or high-calcium foods, as calcium can interfere with iron absorption.