Experts warn common mistakes can reduce iron supplement effectiveness

Experts have warned against common mistakes when taking iron supplements, stressing that the timing and accompanying foods or drinks can affect their absorption and effectiveness.

Iron supplements are used to treat anemia caused by iron deficiency, but they may cause side effects such as nausea, constipation, diarrhea, and stomach pain in some people.

Rachel Woods, associate professor of medical education at the Universities of Nottingham and Lincoln, explained that iron deficiency should be properly diagnosed and its causes identified before starting supplements, as it may result from blood loss or poor absorption due to intestinal issues.

Woods noted that certain drinks, such as coffee, significantly reduce iron absorption.

A study involving 34 women found that taking coffee with iron supplements reduced absorption by 54% compared to water, and absorption dropped by 66% when taken with breakfast.

Conversely, vitamin C increased iron absorption by 30% when 80 mg was consumed, while a 500 mg dose did not provide additional benefit.

The results also showed that iron absorption was 37% lower in the afternoon compared to the morning, though Woods clarified this is not a universal rule.

A randomized trial of 440 adults found that taking iron with vitamin C was no more effective than taking iron alone in improving hemoglobin levels and iron stores.

Calcium may also affect iron absorption when both are taken together in large amounts, but a review of studies found its long-term impact is limited.

Woods advises consulting a pharmacist about the timing of calcium and iron supplements.

The UK National Health Service recommends taking ferrous sulfate about 30 minutes before food or two hours after, but it can be taken with food if stomach upset occurs.

Woods emphasizes that consistency in taking supplements is more important than aiming for optimal absorption if it affects adherence to treatment.

She warned against taking supplements without a clear need or professional advice, noting that high doses of some vitamins can cause health problems, such as nerve damage from excess vitamin B12 and toxic levels of vitamin A.

Woods stressed the importance of identifying the cause of iron deficiency, following the recommended dosage, and being mindful of foods and drinks that may affect supplement absorption.