Iron deficiency in women of reproductive age can have damaging effects on brain. A recent study examined the effects of consuming iron-biofortified beans for improving cognitive performance in iron-deficient women.
Iron deficiency is the most prevalent nutritional abnormality worldwide. The effects of iron deficiency have been extensively studied in systemic organs but very little is known about its effects on the brain. However, it is clear from animal studies that iron deficiency can affect the central nervous system’s structural components such as neurons, and its neurotransmitter metabolism and function. The most obvious systems affected are dopaminergic pathways that are a set of projection neurons in the brain that synthesize and release the neurotransmitter dopamine. Dopaminergic pathways are involved in many functions such as executive function, learning, motivation, and neuroendocrine control.
Iron deficiency, defined as a condition in which there is no mobilization of iron stores leading to a depleted state of iron in cells such as red blood cells, may cause reduced hemoglobin concentrations or anemia. As per a recent WHO report, anemia affects approximately 43% of the world’s children, 29% of non-pregnant women of reproductive age (WRA), and 38% of pregnant women. Based on past research, iron deficiency related changes in neural morphology and metabolism are possible well beyond infancy and childhood and can affect neural functioning across the lifespan of an individual.
Given the association of iron deficiency with cognitive functioning throughout the lifespan, it is important to understand its effect in educational settings where optimal cognitive function is essential. Furthermore, women of reproductive age are more vulnerable to iron deficiency and if they are attending higher education or are working professionals, it can impair their ability to compete and succeed.
In a recent study conducted on women attending the University of Rwanda, researchers tested if replenishing iron in the form of iron-biofortified beans would result in improvements in cognitive performance in women. This double-blinded randomized study published in The Journal of Nutrition recruited 150 healthy women between 18 to 27 years of age with depleted iron stores (ferritin less than 20mg/L). Researchers randomly assigned the women to consume either iron-biofortified beans or conventional beans for 18 weeks and undergo cognitive testing before and after consumption of iron-biofortified beans.
Measuring the Results
Laboratory analysis was conducted at the beginning of the study and after 18 weeks to test for complete blood count, and iron biomarkers such as serum ferritin (SF), serum transferrin receptor (TfR), C-reactive protein, and alpha-1-acid glycoprotein (AGP). The researchers used these measurements to calculate total body iron.
The participants went through a 60-90-minute cognitive testing at the start of the study and after 18 weeks. Five common measures of attentional and memory functioning were used- the simple reaction time task to estimate the simplest possible behavioral response to a visual stimulus, the go/no-go task to estimate the efficiency of sustained attention and speed of simple attention, the attentional network task to provide an estimate of the effectiveness of attention, the cued recognition task to estimate the speed, accuracy, and efficiency of recognition, and finally, the Sternberg memory search task to estimate speed and accuracy of visual memory.
Change in Iron Status and Cognitive Outcomes
The results of the study showed a positive association between consumption of iron-biofortified beans and cognitive improvements. The consumption of iron-biofortified beans resulted in a 17% larger improvement in the speed of spatial selective attention. They also found more than a seven-fold larger improvement in speed, a 68% greater improvement in the efficiency, and more than two-fold greater improvement in specificity of memory retrieval. Additionally, they found a more than two-fold and three-fold larger improvement in the speed and efficiency of memory search respectively. All these improvements were in relation to the results observed for women who consumed control beans.
Effects of the Intervention
The consumption of iron-biofortified beans significantly improved iron status in women of reproductive age leading to improved cognitive performance. The intervention was found to have a relatively larger impact on the memory tasks related to the efficiency of search and the speed of retrieval. The study results showed that performance on the task of attention and memory improved with improvements in ferritin levels.
This study has many strengths. It is a randomized, double-blind, controlled study with a long duration which allowed measurement of changes in iron biomarkers. Some other strengths include multiple measurement points and measurement of multiple iron biomarkers, a large sample size, and use of five different cognitive tests to assess cognitive function. The main limitation of the study is that the findings may not be generalized because of the homogenous nature of the sample.
These findings clearly indicate that the damaging effects of iron deficiency are not limited to the developing brain. Iron deficiency can affect women of reproductive age who are attending universities or workplace. The results suggest iron-biofortified beans that different domains of learning may be affected differently by iron deficiency. As noted earlier, cognitive performance is linked to iron status in women. Consumption of iron-biofortified beans leads to iron repletion and improves cognitive performance. The prevalence of iron deficiency is a significant public health issue warranting the need for further studies to understand the consequences of iron deficiency in young women worldwide.
Written by Preeti Paul, MS Biochemistry
Reference: Laura E Murray-Kolb, Michael J Wenger et al., Consumption of Iron-Biofortified Beans Positively Affects Cognitive Performance in 18- to 27-Year-Old Rwandan Female College Students in an 18-week Randomized Controlled Efficacy Trial, The Journal of Nutrition, Community and International Nutrition, September 27, 2017.