Combined Iron Deficiency and Low Aerobic Fitness Doubly Burden Academic Performance among Women Attending University

Aerobic fitness as a moderator of acute aerobic exercise effects on executive function

This study aimed to investigate the moderating role of aerobic fitness on the effect of acute exercise on improving executive function from both behavioral and cerebral aspects. Thirty-four young individuals with motor skills were divided into high- and low-fitness groups based on their maximal oxygen uptake. Both groups completed 30 min of moderate-intensity aerobic exercise on a power bike. Executive function tests (Flanker, N-back, More-odd-shifting) were performed before and after exercise and functional near-infrared spectroscopy was used to monitor prefrontal cerebral blood flow changes during the tasks. The results indicated significant differences between the two groups regarding executive function. Participants with lower aerobic fitness performed better than their higher fitness counterparts in inhibitory control and working memory, but not in cognitive flexibility. This finding suggests that the aerobic fitness may moderate the extent of cognitive benefits gained from acute aerobic exercise. Furthermore, the neuroimaging data indicated negative activation in the frontopolar area and dorsolateral prefrontal cortex in response to three complex tasks. These findings underscore the importance of considering individual aerobic fitness when assessing the cognitive benefits of exercise and could have significant implications for tailoring fitness programs to enhance cognitive performance.

Assessing the pattern electroretinogram as a proxy measure for dopamine in the context of iron deficiency

OBJECTIVES

Animal studies have suggested that dietary iron deficiency (ID) negatively affects dopamine (DA) synthesis and re-uptake, which in turn negatively affects memory and cognition. This study was intended to assess whether the pattern electroretinogram (pattern ERG) could be used as an indirect measure of DA in college-age women with and without ID by determining the extent to which features of the ERG were sensitive to iron status and were related to other indirect measures of DA.

METHODS

The pattern ERG was measured in 21 iron deficient non-anemic (IDNA) and 21 iron sufficient (IS) women, who also performed a contrast detection and probabilistic selection task, both with concurrent electroencephalography (EEG). Both spontaneous and task-related blink rates were also measured.

RESULTS

The implicit times of the A- and B-waves were significantly longer for the IDNA than for the IS women. Both the amplitudes and implicit times of the A- and B-waves were significantly correlated with levels of serum ferritin (sFt). Only the amplitude of the A-wave was correlated with spontaneous blink rate. It was possible to accurately identify a woman's iron status solely on the basis of the implicit time of the B-wave. Finally, the implicit times of the ERG features mediated the relationship between iron levels and accuracy in the probabilistic selection task.

CONCLUSIONS

Results suggest the utility of the pattern ERG in testing the hypothesis that iron deficiency affects DA levels in humans and that this may be one of the mechanisms by which iron deficiency negatively affects cognition.

Compliance compromises an interventional study on iron supplementation in female combatants

INTRODUCTION

Low iron levels are related to overuse injuries, poor physical performance and cognitive impairments in female recruits. The aim of this study was to evaluate iron supplement compliance in female combatants during basic training, and its effect on haemoglobin (Hgb), ferritin and injuries.

METHODS

329 female recruits to light infantry units filled induction questionnaires regarding smoking status, previous overuse injuries and iron deficiency. Blood was drawn for Hgb and ferritin. Subjects with ferritin levels below 20 ng/mL were considered iron depleted and were prescribed a ferrous fumarate supplement. After 4 months of basic training, the subjects completed a follow-up questionnaire regarding overuse injuries, reasons for failure to complete basic training and compliance with iron supplementation. Blood tests were repeated.

RESULTS

Mean ferritin levels declined during training (from 18.1±18.2 to 15.3±9.6, p=0.01). Compliance with iron supplementation was observed in 26 (26.3%) of the subjects. In compliant subjects, Hgb levels remained constant and ferritin levels increased by 2.9±5.4 (p=0.07). The main reasons for reported non-compliance were forgetfulness, 26 (35.6%), and gastrointestinal side effects, 17 (23.3%). Injuries during training were not found to be associated with iron status. Smokers had a significantly higher rate of reported injuries prior to training (p<0.01).

CONCLUSIONS

Ferritin levels decline during training. Compliance with iron supplementation is low. Iron supplementation has a significant effect on ferritin levels, even in the non-compliance group. Injuries were not related to iron status in this group. Further research is needed in order to clarify the most appropriate iron supplementation method.

Iron Deficiency among School-Aged Adolescents in Hong Kong: Prevalence, Predictors, and Effects on Health-Related Quality of Life

Iron deficiency (ID) is a prevalent nutritional deficiency affecting children/adolescents worldwide. We reported (1) the prevalence of ID and ID with anemia (IDA) among Chinese school-aged adolescents, (2) clinical and dietary predictors of iron status, and (3) its impact on health-related qualities of life (HRQoL). This cross-sectional study recruited 183 boys and 340 girls (mean age = 17.55) from 16 schools in Hong Kong. ID is defined as serum ferritin <15 μg/L. The participants reported their dietary habits, menstrual patterns (girls), and HRQoL using structured questionnaires. The overall prevalence of ID was 11.1%. None of the boys had ID or IDA. Among girls, the rate of ID was 17.1% and IDA was 10.9%. One-third (36.3%) reported a regular habit of skipping ≥1 meal/day. Lower ferritin was found in adolescents who skipped meals (Est = -35.1, p = 0.017). Lower ferritin is correlated with poorer school functioning (Est = 0.81, p = 0.045) and fatigue (Est = 0.92, p = 0.016). Skipping meals is associated with poorer physical (p = 0.0017) and school functioning (p = 0.027). To conclude, 1 in 10 school-aged adolescents in Hong Kong are iron-deficient. The ID rate in girls (17.1%) is similar to that in other industrialized countries (5.2-16.6%). Future work should promote awareness on the potential health consequences of poor dietary habits on ID and the well-being of adolescents.

Modeling relationships between iron status, behavior, and brain electrophysiology: evidence from a randomized study involving a biofortified grain in Indian adolescents

Background

Iron deficiency (ID) and iron deficiency anemia (IDA) are highly-prevalent nutrient deficiencies and have been shown to have a range of negative effects on cognition and brain function. Human intervention studies including measures at three levels—blood, brain, and behavior—are rare and our objective was to model the relationships among measures at these three levels in school-going Indian adolescents.

Methods

Male and female adolescents in rural India were screened for ID/IDA. Subjects consumed 2 meals/day for 6 months; half were randomly assigned to consume meals made from a standard grain (pearl millet) and half consumed meals made from an iron biofortified pearl millet (BPM). Prior to and then at the conclusion of the feeding trial, they completed a set of cognitive tests with concurrent electroencephalography (EEG).

Results

Overall, serum ferritin (sFt) levels improved over the course of the study. Ten of 21 possible measures of cognition showed improvements from baseline (BL) to endline (EL) that were larger for those consuming BPM than for those consuming the comparison pearl millet (CPM). Critically, the best model for the relationship between change in iron status and change in cognition had change in brain measures as a mediating factor, with both change in serum ferritin as a primary predictor and change in hemoglobin as a moderator.

Conclusions

A dietary intervention involving a biofortified staple grain was shown to be efficacious in improving blood iron biomarkers, behavioral measures of cognition, and EEG measures of brain function. Modeling the relationships among these variables strongly suggests multiple mechanisms by which blood iron level affects brain function and cognition.

Trial registration

Registered at ClinicalTrials.gov, NCT02152150, 02 June 2014.

Supplementary Information

The online version contains supplementary material available at (10.1186/s12889-022-13612-z).

Independent and combined associations between multiple lifestyle behaviours and academic grades of inner urban and peri-urban high school students: a cross-sectional study in Chongqing, China

OBJECTIVES

This study aims to assess the independent and combined associations between multiple lifestyle behaviours and academic grades of inner urban high school students (IUHSSs) and peri-urban high school students (PUHSSs).

DESIGN

A cross-sectional study was conducted.

PARTICIPANTS

There are 1481 high school students (49.9% boys) in this study, who were enrolled from one inner urban and two peri-urban schools in Chongqing, China.

OUTCOME MEASURES

Academic grades were assessed based on the students' self-reported grade ranking in the last cumulative examination.

RESULTS

In IUHSSs and PUHSSs, high frequency of sugar-sweetened beverage consumption was unlikely to obtain high academic grades (OR 0.56, 95% CI 0.32 to 0.99 and 0.63, 95% CI 0.42 to 0.96), respectively). Among IUHSSs, meeting the recommendations for weekday screen time and egg consumption (OR 1.57, 95% CI 1.06 to 2.34 and 1.60, 95% CI 1.04 to 2.47, respectively) and high frequency of fruit consumption (1.67, 95% CI 1.11 to 2.50) were significantly associated with high academic grades; meeting the recommendation for weekday sleep duration was unlikely to obtain high academic grades (0.46, 95% CI 0.21 to 0.98). Among PUHSSs, meeting the recommendations for weekend sleep duration (1.40, 95% CI 1.02 to 1.93) and eating dinner regularly (1.55, 95% CI 1.01 to 2.37) had significant associations with high academic grades. No significant associations were found between physical activity and academic grades in both IUHSSs and PUHSSs (p>0.05). Moreover, IUHSSs with 9-13 healthy lifestyle behaviours were 3.25 times more likely to achieve high academic grades than IUHSSs with 1-6 healthy lifestyle behaviours (3.25, 95% CI 1.96 to 5.40). No significant associations were found in the combined associations between multiple lifestyle behaviours and academic grades among PUHSSs (p>0.05).

CONCLUSIONS

Correlations were observed between lifestyle behaviours and academic grades among high school students, and cumulative associations between multiple healthy lifestyle behaviours and academic outcomes appear to be stronger than the independent associations. These findings are particularly applicable to IUHSSs.

Clinically diagnosed iron and iodine deficiencies and disorders in the entire population of US military service members from 1997 to 2015

OBJECTIVE

Iron and/or iodine deficiencies can have multiple serious adverse health outcomes, but examination of incidence rates of these deficiencies has rarely been conducted in any large population. This study examined incidence rates, temporal trends and demographic factors associated with medically diagnosed iron and iodine deficiencies/disorders in US military service members (SM).

DESIGN

The Defense Medical Epidemiological Database (DMED) was queried for medical visits of active duty SM to obtain specific International Classification of Diseases, Version 9, codes involving clinically diagnosed iron and iodine deficiencies/disorders.

SETTING

Analysis of existing database (DMED).

PARTICIPANTS

Entire population of US military SM from 1997 to 2015 (average n per year = 1 382 266, 15 % women).

RESULTS

Overall incidence rates for iron and iodine were 104 and 36 cases/100 000 person-years, respectively. Over the 19-year period, rates for iron disorders increased steadily (108 % for men, 177 % for women). Rates for iodine disorders also increased steadily for men (91 %), but, for women, there was an initial rise followed by a later decline. Overall, women's rates were 12 and 10 times higher than men's for iron and iodine, respectively. Compared with whites, blacks and those of other races had higher rates of deficiencies of both minerals. Incidence rates for iodine deficiency increased substantially with age.

CONCLUSIONS

The overall incidence of clinically diagnosed iron and iodine deficiency among SM was low, but increased over the 19 years examined, and certain demographic groups were at significantly greater risk. Given the unexpected increases in incidence of these mineral disorders, increased surveillance may be appropriate.Clinical Trial Registration No. ISRCTN58987177 (http//:www.isrctn.com/ISRCTN58987177).

Nutrition Knowledge of Collegiate Athletes in the United States and the Impact of Sports Dietitians on Related Outcomes: A Narrative Review

In the last decade, the number of full-time registered dietitians (RDs) serving intercollegiate athletes in the United States has more than quadrupled. However, many student athletes may be at increased risk of nutrition-related problems that impact physical and academic performance, which include inadequate macronutrients, inadequate micronutrients, and excessive macronutrients. This narrative review reports the current literature to date on nutrition-related knowledge in collegiate athletes and the impact of sports RDs on student athletes’ nutrition knowledge and behaviors. To date, only observational and quasi-experimental studies have been published with regard to changes in nutrition knowledge and behaviors in NCAA athletes. While these studies report benefits of the RD as a member of the interdisciplinary student athlete support team, more well-designed randomized control trials are warranted to determine benefits related to health outcomes and sport-specific performance outcomes.

Demographic, nutritional, social and environmental predictors of learning skills and depression in 20,000 Indian adolescents: Findings from the UDAYA survey

OBJECTIVES

Adolescent wellbeing is critical to breaking the intergenerational cycle of poverty and one in five of the world's adolescents live in India. We explored predictors of learning skills and depression in Indian adolescents.

METHODS

Data on adolescents aged 10-19y (three groups: 5,840 unmarried males, 8,953 unmarried females, 4,933 married females) were available from the state-representative Understanding the Lives of Adolescents and Young Adults survey in Uttar Pradesh and Bihar. Multivariable logistic regression models adjusted for cluster sampling design and state fixed effects were used to examine factors (demographic, health/nutrition, social, and environmental) associated with three outcomes: reading proficiency, math proficiency, and depressive symptoms.

FINDINGS

Learning skills were poor (28-61% lacked basic reading and math skills depending on adolescent group and outcome) and depression was common (8-26%). Better learning skills were predicted by greater household wealth (AOR 1.72-2.55 depending on group) and household head education (AOR 1.03-1.07 per year), being in school (AOR 4.19-18.65), parental support (AOR 1.11-1.39), having gender equal attitudes (AOR 1.56-2.67), number of food groups consumed at least weekly (unmarried females: AOR 1.11), and having an improved latrine (AOR 1.33-1.51). Poorer learning skills were predicted by family substance use (AOR 0.68-0.74), underweight (males: AOR 0.74), witnessing parental violence (AOR 0.66-0.78). Depressive symptoms were predicted by witnessing parental violence (AOR 1.51-1.92) and experiencing sexual abuse (AOR 2.30-6.16).

CONCLUSION

Factors across multiple life dimensions are associated with learning skills and depression in Indian adolescents. Adolescent-focused policies and programs should consider health/nutrition, social, and environmental aspects of life in vulnerable individuals.

Executive functions mediate the relationship between cardiorespiratory fitness and academic achievement in Spanish schoolchildren aged 8 to 11 years

OBJECTIVES

Previous research has studied the influence of physical fitness on academic achievement through executive functions. However, the nature of this relationship remains unclear. This study aimed to analyze how cardiorespiratory fitness (CRF) and executive functions are associated with academic achievement and to examine whether the relationship between CRF and academic achievement is mediated by executive functions in schoolchildren.

METHODS

This was a cross-sectional study including 570 schoolchildren, aged 8 to 11 years, from Cuenca, Spain. Data were collected from September to October 2017. Sociodemographic variables, family socioeconomic status, pubertal status, academic achievement, CRF (20-meter shuttle run test) and executive functions (inhibition, cognitive flexibility and working memory, NIH Toolbox battery in Spanish, v 1.8; iPad Pro, Apple, Inc.) were measured.

RESULTS

Overall, ANCOVA models controlling for age, gender and mother educational level showed higher scores in language and mathematics in children in higher categories of CRF, inhibition, cognitive flexibility and working memory than in children in lower categories. The effect sizes were moderate (p < 0.05, partial eta squared: from 0.05 to 0.12). Moreover, the mediation analysis showed that inhibition partially mediated the relationship between CRF and language (c' = 0.058; IC = [0.005; 0.028]) and mathematics (c' = 0.064; IC = [0.005; 0.030]) grades. Similarly, cognitive flexibility mediated CRF's relationship with language (c' = 0.059; IC = [0.003; 0.028]) and with mathematics (c' = 0.066; IC = [0.003; 0.029]); however, a significant relationship remained. For working memory, mediation analysis showed no significant results (c' = 0.92; IC = [-0.002;0.025] P > 0.05 in language; c' = 0.103; IC = [-0.002;0.029] P > 0.05 in mathematics). Mediation ranged from 13.38% to 36%.

CONCLUSIONS

Children in higher categories of both CRF and executive function showed higher grades in mathematics and language. The findings indicated that a significant proportion of the positive influence of CRF on academic achievement was mediated by improvements in inhibition and cognitive flexibility. Thus, this study supports the hypothesis that improvements in CRF may contribute to increasing academic achievement not only through a direct mechanism but also through improvements in executive functions.

Tracking Changes of Chinese Pre-Service Teachers' Aerobic Fitness, Body Mass Index, and Grade Point Average Over 4-years of College

Although increasing attention has been given to student academic achievement, usually measured by grade point average (GPA), and fitness in children and adolescents, much fewer studies have been conducted in higher education settings, especially in China. This study investigated the longitudinal associations of aerobic fitness (AF), body mass index (BMI), and GPA in Chinese pre-service teachers at a university. A longitudinal research design was employed to track changes in AF, BMI, and GPA, for a total of 1980 students for four years. Multi-level growth models were used to examine the interactive changes of the above three variables. It was found that GPA and BMI increased each year, while AF declined dramatically at the fourth year. The three-way interaction among GPA, gender, and BMI was significant, suggesting females who were overweight/obese had lower GPA. The data from the current study suggested that AF did not impact students' GPA. Class standing (i.e., the fourth year) and gender (i.e., females) need to be taken into consideration when designing interventions to improve student overall fitness and academic performance in Chinese pre-service teacher populations.

Cognitive Performance in Indian School-Going Adolescents Is Positively Affected by Consumption of Iron-Biofortified Pearl Millet: A 6-Month Randomized Controlled Efficacy Trial

BACKGROUND

Iron deficiency remains the most prevalent micronutrient deficiency globally, but few studies have examined how iron status relates to cognition in adolescents. Iron biofortification of staple food crops is being scaled up, yet it is unknown whether consuming biofortified crops can benefit cognition.

Objective

Our objective was to determine the efficacy of iron-biofortified pearl millet in improving attention and memory in Indian school-going adolescents.

Methods

A double-blind, randomized, intervention study was conducted in 140 Indian boys and girls, aged 12-16 y, who were assigned to consume iron-biofortified [Fe = 86 parts per million (ppm)] or conventional (Fe = 21-52 ppm) pearl millet. Hemoglobin, ferritin, and transferrin receptor (TfR) were measured and body iron (BI) was calculated at baseline and after 4 and 6 mo. Five measures of cognitive function were obtained at baseline and 6 mo: simple reaction time (SRT), Go/No-Go (GNG) task, Attentional Network Task (ANT), Composite Face Effect (CFE) task, and Cued Recognition Task (CRT). Intention-to-treat analysis was used.

Results

Daily iron intake from pearl millet was higher in those consuming biofortified compared with conventional pearl millet (19.6 compared with 4.8 mg/d). Effects on ferritin, TfR, and BI at 4 mo, and on TfR at 6 mo (all P < 0.05), indicated efficacy of biofortified pearl millet over conventional pearl millet in improving iron status. Compared with conventional pearl millet, the consumption of biofortified pearl millet resulted in greater improvement in attention (SRT, GNG, and ANT) and memory (CFE and CRT). Reaction time decreased twice as much from 0 to 6 mo in those consuming biofortified compared with conventional pearl millet on attention tasks (SRT: -123 compared with -63 ms; GNG: -67 compared with -30 ms; ANT double cue: -74 compared with -32 ms; all P < 0.01).

Conclusion

Consuming iron-biofortified pearl millet improves iron status and some measures of cognitive performance in Indian adolescents. This trial was registered at http://www.clinicaltrials.gov as NCT02152150.

Consumption of a Double-Fortified Salt Affects Perceptual, Attentional, and Mnemonic Functioning in Women in a Randomized Controlled Trial in India

Background: Iron deficiency and iron deficiency anemia have been shown to have negative effects on aspects of perception, attention, and memory.Objective: The purpose of this investigation was to assess the extent to which increases in dietary iron consumption are related to improvements in behavioral measures of perceptual, attentional, and mnemonic function.Methods: Women were selected from a randomized, double-blind, controlled food-fortification trial involving ad libitum consumption of either a double-fortified salt (DFS) containing 47 mg potassium iodate/kg and 3.3 mg microencapsulated ferrous fumarate/g (1.1 mg elemental Fe/g) or a control iodized salt. Participants' blood iron status (primary outcomes) and cognitive functioning (secondary outcomes) were assessed at baseline and after 10 mo at endline. The study was performed on a tea plantation in the Darjeeling district of India. Participants (n = 126; 66% iron deficient and 49% anemic at baseline) were otherwise healthy women of reproductive age, 18-55 y.Results: Significant improvements were documented for iron status and for perceptual, attentional, and mnemonic function in the DFS group (percentage of variance accounted for: 16.5%) compared with the control group. In addition, the amount of change in perceptual and cognitive performance was significantly (P < 0.05) related to the amount of change in blood iron markers (mean percentage of variance accounted for: 16.0%) and baseline concentrations of blood iron markers (mean percentage of variance accounted for: 25.0%). Overall, there was evidence that the strongest effects of change in iron status were obtained for perceptual and low-level attentional function.Conclusion: DFS produced measurable and significant improvements in the perceptual, attentional, and mnemonic performance of Indian female tea pickers of reproductive age. This trial was registered at clinicaltrials.gov as NCT01032005.

Iron Deficiency Anemia, Not Iron Deficiency, Is Associated with Reduced Attention in Healthy Young Women

Women of reproductive age are at increased risk for iron deficiency (ID) and iron deficiency anemia (IDA), with both implicated in decreased cognitive function (CF). Obesity may complicate this association via inflammatory-mediated ferritin elevation. This cross-sectional study examined the association between hematological iron status (iron replete (IR), ID or IDA) and CF in healthy, young (18-35 years) women of normal-weight (NW: BMI 18.5-24.9 kg/m²) or obese-weight (OB: BMI >30 kg/m²). Participants completed a validated, computer-based cognition assessment evaluating impulsivity, attention, information processing, memory and executive function; CF reported as z-scores (mean ± SD). Iron status and CF were compared between groups via ANOVA, with adjustment for potential confounders (BMI, physical activity, C-reactive protein) via ANCOVA. A total of 157 NW and 142 OB women (25.8 ± 5.1 years) participated. Prevalence of ID and IDA were 14% and 6% respectively, with no significant difference between NW and OB groups. Women with IDA scored significantly lower on attention (although within normal range; ±1 z-score), compared to ID (IDA: -0.75 ± 1.89; ID: 0.53 ± 1.37; p = 0.004) but not IR (0.03 ± 1.33, p = 0.21) groups; there were no significant differences between ID and IR groups (p = 0.34). Adjustment for confounders did not significantly alter these results. In conclusion, women with IDA showed significantly reduced attention compared to women with ID.

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

Background: Evidence shows that iron deficiency in adulthood may affect cognitive performance, possibly by disrupting neurotransmitter regulation or brain energy metabolism. Women of reproductive age (WRA) are among those who are most vulnerable to iron deficiency; however, they have been largely ignored in the literature relating iron status to cognition.Objective: Our aim was to determine the efficacy of iron-biofortified beans in improving cognition in WRA compared with control beans.Methods: A double-blind, randomized intervention study was conducted in 150 women aged 18-27 y with low iron status (ferritin <20 μg/L). Women were randomly assigned to consume iron-biofortified beans (86.1 ppm iron) or control beans (50.1 ppm iron) daily for 18 wk. Iron status was assessed based on hemoglobin, ferritin, transferrin receptor, and body iron values and on cognitive performance on 5 computerized tasks at baseline and endline.Results: Groups did not differ on any variables at baseline. Per protocol analyses revealed that consumption of the biofortified beans resulted in a 17% larger improvement in the speed of spatial selective attention; a nearly 7-fold larger improvement in the speed, a 68% greater improvement in the efficiency, and a >2-fold greater improvement in the specificity of memory retrieval; and a >2-fold larger improvement in the speed and a >3-fold larger improvement in the efficiency of memory search-all of which are relative to consumption of the control beans (P < 0.01 for all comparisons).Conclusions: Cognitive performance is sensitive to iron status, and consumption of iron-biofortified beans for 18 wk improved cognitive performance, especially the efficiency of search and the speed of retrieval on memory tasks, in young adult women. This trial was registered at clinicaltrials.gov as NCT01594359.