Why is anemia linked to constipation

Cochrane

Why is?

Globally, around every third non-pregnant woman of reproductive age suffers from anemia, i.e. she has fewer red blood cells or less hemoglobin in each red blood cell than normal (hemoglobin is a red substance that combines with oxygen and transports it around the body). Although there are several causes of anemia, very often it is due to prolonged iron deficiency. The common practice for preventing or treating anemia in women is to take iron supplements (sometimes in combination with folic acid and other vitamins and minerals) daily for three months. However, ingestion is often associated with side effects such as nausea or constipation. Intermittent supplementation (i.e. taking supplements one, two, or three times a week on non-consecutive days) has been suggested as an effective and safe alternative to daily supplementation.

Why is that important?

Women with anemia may have less energy to work out and may be more prone to infection. Globally, most women already have anemia by the time they become pregnant, which puts them at greater risk for low birth weight infants and other complications during childbirth.

Some scientists believe that taking iron a few times a week (instead of every day) can help women with anemia feel better and increase their hemoglobin levels without causing as many side effects. When women experience fewer side effects, they are more likely to take the iron supplements more often and for a longer period of time.

What evidence did we find?

We reviewed the evidence in February 2018. We included 25 randomized controlled trials (a type of experiment in which participants are randomly assigned to one or more treatment groups) that were conducted on 10,996 women. We included studies that compared iron supplements given on non-consecutive days (intermittent supplementation) with no intervention, placebos (dummy pills), or the same supplements given daily. Most of the studies were carried out in school facilities and funded mainly by international organizations, universities and health ministries in the respective countries. About a third of the included studies did not provide any information on funding sources.

The results show that women who received intermittent supplementation with iron only or in combination with folic acid or other nutrients were less likely to be anemic than women who received no iron supplement or a placebo. They also had higher levels of hemoglobin and ferritin (a protein that stores iron). Intermittent supplementation also reduced the risk of iron deficiency. The results suggest that intermittent supplementation was just as effective as daily supplementation in reducing the prevalence of anemia and increasing hemoglobin levels - but with fewer side effects. It had no influence on the increase in the ferritin concentration.

We found sparse evidence for the effect of intermittent supplementation versus placebo or daily supplementation on iron deficiency anemia, morbidity, disease outcome, adherence to therapy, economic productivity, and job performance.

What does that mean?

Compared to no treatment, placebo, or daily supplementation, intermittent iron supplementation in menstruating women can be an effective measure for reducing anemia and improving hemoglobin levels. Intermittent supplementation may have fewer side effects than daily supplementation. The results were not influenced by whether the dietary supplements were administered once or twice a week, for less or more than three months, with less or more than 60 mg elemental iron per week, or to population groups with different degrees of anemia at the start of the study (starting point for comparisons) were. The overall evidence base was of low quality.