Conventional dosing of iron supplements under challenge

A single dose of oral iron every second day may reduce side effects and improve iron absorption compared to traditional twice-daily dosing in iron-depleted patients, new research suggests.

A small but technologically sophisticated Swiss study used radiolabelling techniques to track the path of oral iron into erythrocytes. It compared once-daily dosing on consecutive versus alternate days, and once-daily versus twice daily dosing, in iron depleted women aged 18 to 40 (serum ferritin 25 μg/L or less).

The researchers also measured levels of serum hepcidin, a key regulator which reduces intestinal iron absorption in the presence of high levels of the element.

In the first part of the study, alternate-day dosing for 28 days led to greater iron absorption and lower hepcidin levels.

In the second part, once-daily and twice-daily dosing were equally effective in boosting total iron absorption, but twice-daily tablets led to higher hepcidin levels.

“Providing iron supplements on alternate days and in single doses optimises iron absorption and might be a preferable dosing regimen,” the research team concluded.

They said these findings in iron-depleted women needed to be confirmed in iron-deficient anaemic patients.

An editorial commented that the results were not surprising because hepcidin, increased by supplementation, is well known to decrease absorption of iron at the level of the intestinal epithelium.

“However, in no other prospective study has such a measurable benefit of a method of oral iron administration been shown,” it said.

Side effects such as nausea, abdominal pain and constipation were rare in the study, but the novel regimen was associated with a numerical reduction in their incidence.

“Oral iron is now considered frontline therapy for uncomplicated iron deficiency anaemia, except in those situations in which it is ineffective (eg, after bariatric surgery, heavy uterine bleeding, hereditary haemorrhagic telangiectasia, and active comorbidity) or even possibly harmful (inflammatory bowel disease),” the editorial stated.

“However, oral iron is rife with unpleasant side-effects, including constipation, gastric irritation, nausea and metallic taste. Although these symptoms are not devastating,

patients find them formidable and non-adherence is common.”

Supplementation in anaemia, using iron filings in cold wine, was first reported in 1832, it said.

“Iron deficiency soon became recognised as the most common micronutrient deficiency, and is now estimated to affect more than 35% of the world’s population and more than 50% of pregnant women, translating to a prevalence of more than two billion people worldwide.”

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