Linda Malan

Effects of iron and n−3 fatty acid supplementation, alone and in combination, on cognition in school children: a randomized, double-blind, placebo-controlled intervention in South Africa

BACKGROUND Little is known about the combined effects of iron and n-3 (omega-3) fatty acid (FA) supplementation on cognitive performance. The provision of either DHA/EPA or iron alone in rats with combined iron and n-3 FA deficiency has been reported to exacerbate cognitive deficits associated with deficiency. OBJECTIVE We investigated the effects of iron and DHA/EPA supplementation, alone and in combination, in children with poor iron and n-3 FA status. DESIGN In a 2-by-2 factorial trial, children with iron deficiency (ID) (n = 321; aged 6-11 y) were allocated to receive 1) iron (50 mg) plus DHA/EPA (420/80 mg), 2) iron plus placebo, 3) placebo plus a mixture of DHA and EPA (DHA/EPA), or 4) placebo plus placebo as oral supplements (4/wk) for 8.5 mo. Cognition was assessed at baseline and endpoint by using the Hopkins Verbal Learning Test (HVLT) and subscales of the Kaufman Assessment Battery for Children. RESULTS Both iron and DHA/EPA significantly increased weight-for-age z scores. Iron increased the number of words recalled at HVLT recall 2 (intervention effect: 0.90; 95% CI: 0.18, 1.62), and in anemic children, iron increased scores in the Atlantis Delayed test (1.51; 95% CI: 0.03, 2.99) and HVLT recall 2 (2.02; 95% CI: 0.55, 3.49). DHA/EPA showed no benefit in any of the cognitive tests but decreased Atlantis test scores (-2.48; 95% CI: -3.99, -0.96) in children who were anemic at baseline and decreased Atlantis delayed scores (-0.9; 95% CI: -1.45, -0.36) in girls with ID, whereas boys tended to perform better. CONCLUSIONS In children with poor iron and n-3 FA status, iron supplementation improved verbal and nonverbal learning and memory, particularly in children with anemia. In contrast, DHA/EPA supplementation had no benefits on cognition and impaired working memory in anemic children and long-term memory and retrieval in girls with ID.

Overweight impairs efficacy of iron supplementation in iron-deficient South African children: a randomized controlled intervention

Background:Many countries in the nutrition transition have high rates of iron deficiency (ID) and overweight (OW). ID is more common in OW children; this may be due to adiposity-related inflammation reducing iron absorption.Objective:We investigated whether weight status predicts response to oral iron supplementation in ID South African children.Design:A placebo-controlled trial of oral iron supplementation (50 mg, 4 × weeks for 8.5 months) was done in ID 6- to 11-year-old children (n=321); 28% were OW or obese. BMI-for-age z-scores (BAZ), hepcidin (in a sub-sample), hemoglobin, serum ferritin (SF), transferrin receptor (TfR), zinc protoporphyrin (ZnPP) and C-reactive protein (CRP) were measured; body iron was calculated from the SF to TfR ratio.Results:At baseline, BAZ correlated with CRP (r=0.201, P<0.001) and CRP correlated with hepcidin (r=0.384, P<0.001). Normal weight children supplemented with iron had significantly lower TfR concentrations at endpoint than the OW children supplemented with iron and the children receiving placebo. Higher BAZ predicted higher TfR (β=0.232, P<0.001) and lower body iron (β=−0.090, P=0.016) at endpoint, and increased the odds ratio (OR) for remaining ID at endpoint in both the iron and placebo groups (iron: OR 2.31, 95% CI: 1.13, 4.73; placebo: OR 1.78, 95% CI: 1.09, 2.91). In the children supplemented with iron, baseline hepcidin and BAZ were significant predictors of endpoint TfR, with a trend towards a hepcidin × BAZ interaction (P=0.058).Conclusion:South African children with high BAZ have a two-fold higher risk of remaining ID after iron supplementation. This may be due to their higher hepcidin concentrations reducing iron absorption. Thus, the current surge in OW in rapidly developing countries may undercut efforts to control anemia in vulnerable groups. The trial is registered at clinicaltrials.gov as NCT01092377.

Combined Deficiency of Iron and (n-3) Fatty Acids in Male Rats Disrupts Brain Monoamine Metabolism and Produces Greater Memory Deficits Than Iron Deficiency or (n-3) Fatty Acid Deficiency Alone

Deficiencies of iron (Fe) (ID) and (n-3) fatty acids (FA) [(n-3)FAD] may impair brain development and function through shared mechanisms. However, little is known about the potential interactions between these 2 common deficiencies. We studied the effects of ID and (n-3)FAD, alone and in combination, on brain monoamine pathways (by measuring monoamines and related gene expression) and spatial working and reference memory (by Morris water maze testing). Using a 2 × 2 design, male rats were fed an ID, (n-3)FAD, ID+(n-3)FAD, or control diet for 5 wk postweaning (postnatal d 21-56) after (n-3)FAD had been induced over 2 generations. The (n-3)FAD and ID diets decreased brain (n-3) FA by 70-76% and Fe by 20-32%, respectively. ID and (n-3)FAD significantly increased dopamine (DA) concentrations in the olfactory bulb (OB) and striatum, with an additive 1- to 2-fold increase in ID+(n-3)FAD rats compared with controls (P < 0.05). ID decreased serotonin (5-HT) levels in OB, with a significant decrease in ID+(n-3)FAD rats. Furthermore, norepinephrine concentrations were increased 2-fold in the frontal cortex (FC) of (n-3)FAD rats (P < 0.05). Dopa decarboxylase was downregulated in the hippocampus of ID and ID+(n-3)FAD rats (fold-change = -1.33; P < 0.05). ID and (n-3)FAD significantly impaired working memory performance and the impairment positively correlated with DA concentrations in FC (r = 0.39; P = 0.026). Reference memory was impaired in the ID+(n-3)FAD rats (P < 0.05) and was negatively associated with 5-HT in FC (r = -0.42; P = 0.018). These results suggest that the combined deficiencies of Fe and (n-3) FA disrupt brain monoamine metabolism and produce greater deficits in reference memory than ID or (n-3)FAD alone.

In Male Rats with Concurrent Iron and (n-3) Fatty Acid Deficiency, Provision of Either Iron or (n-3) Fatty Acids Alone Alters Monoamine Metabolism and Exacerbates the Cognitive Deficits Associated with Combined Deficiency

Concurrent deficiencies of iron (Fe) (ID) and (n-3) fatty acids [(n-3)FAD)] in rats can alter brain monoamine pathways and impair learning and memory. We examined whether repletion with Fe and DHA/EPA, alone and in combination, corrects the deficits in brain monoamine activity (by measuring monoamines and related gene expression) and spatial working and reference memory [by Morris water maze (MWM) testing] associated with deficiency. Using a 2 × 2 design, male rats with concurrent ID and (n-3)FAD [ID+(n-3)FAD] were fed an Fe+DHA/EPA, Fe+(n-3)FAD, ID+DHA/EPA, or ID+(n-3)FAD diet for 5 wk [postnatal d 56-91]. Biochemical measures and MWM performance after repletion were compared to age-matched control rats. The provision of Fe in combination with DHA/EPA synergistically increased Fe concentrations in the olfactory bulb (OB) (Fe x DHA/EPA interaction). Similarly, provision of DHA/EPA in combination with Fe resulted in higher brain DHA concentrations than provision of DHA alone in the frontal cortex (FC) and OB (P < 0.05). Dopamine (DA) receptor D1 was upregulated in the hippocampus of Fe+DHA/EPA rats (fold-change = 1.25; P < 0.05) and there were significant Fe x DHA/EPA interactions on serotonin (5-HT) in the OB and on the DA metabolite dihydroxyphenylacetic acid in the FC and striatum. Working memory performance was impaired in ID+DHA/EPA rats compared with controls (P < 0.05). In the reference memory task, Fe+DHA/EPA improved learning behavior, but Fe or DHA/EPA alone did not. These findings suggest that feeding either Fe or DHA/EPA alone to adult rats with both ID and (n-3)FAD affects the DA and 5-HT pathways differently than combined repletion and exacerbates the cognitive deficits associated with combined deficiency.

n–3 Long-chain PUFAs reduce respiratory morbidity caused by iron supplementation in iron-deficient South African schoolchildren: a randomized, double-blind, placebo-controlled intervention

BACKGROUND Although iron supplementation in malaria-free areas mostly reduces infectious morbidity, it can sometimes increase morbidity from infections as a result of the dependence of pathogenic microorganisms on iron. Supplementation with n-3 (ω-3) long-chain polyunsaturated fatty acids (LCPUFAs) improved morbidity in several human studies. However, information on the combined effect of iron and n-3 LCPUFA supplementation on infectious morbidity is limited. OBJECTIVE We determined whether n-3 LCPUFAs and iron supplementation, alone or in combination, affected absenteeism and illness in iron-deficient schoolchildren with low fish intake. DESIGN A total of 321 South African children (aged 6-11 y) with iron deficiency (ID) were randomly divided into 4 groups to receive 1) iron plus placebo, 2) a mixture of docosahexaenoic acid and eicosapentaenoic acid (DHA/EPA) plus placebo, 3) iron plus DHA/EPA, or 4) placebo plus placebo as oral supplements 4 times/wk for 8.5 mo. Morbidity was recorded, and iron-status indexes were measured. The total phospholipid fatty acid composition of peripheral blood mononuclear cell membranes was analyzed in a subsample (n = 130). RESULTS Iron supplementation increased the number of days with illness when all symptoms were considered (B: 0.87; 95% CI: 0.71, 1.03) as well as illness that was specifically caused by respiratory symptoms (B: 1.45; 95% CI: 1.21, 1.70), whereas DHA/EPA reduced the number of days with illness at school (B: -0.96; 95% CI: -1.33, -0.59). The increases caused by iron were reduced to the levels seen in the placebo plus placebo group when iron was provided in combination with DHA/EPA as indicated by significant iron × DHA/EPA interactions (both P < 0.001). CONCLUSION Iron supplementation increased morbidity (mostly respiratory) in iron-deficient South African schoolchildren with low DHA/EPA intake, but when iron was given in combination with DHA/EPA, this effect was prevented.

Iron and a mixture of DHA and EPA supplementation, alone and in combination, affect bioactive lipid signalling and morbidity of iron deficient South African school children in a two-by-two randomised controlled trial

We recently reported that iron supplementation increased respiratory morbidity in iron deficient South African children. This increase, however, was attenuated when iron was provided in combination with a mixture of DHA/EPA. To explore potential underlying mechanisms, we examined the effects of iron and DHA/EPA, alone and in combination, on plasma lipid-derived immune modulator concentrations and related gene expression in peripheral blood mononuclear cells (PBMC). DHA/EPA decreased inflammatory 12-hydroxyeicosatetraenoic acid and tended to increase anti-inflammatory and pro-resolving 17-hydroxydocosahexaenoic acid (17-HDHA), while iron decreased 17-HDHA. However, in combination with iron, the anti-inflammatory effect of DHA/EPA was maintained. These biochemical changes may explain the prevention of iron-induced respiratory morbidity that we observed when iron was supplemented in combination with DHA/EPA during the 8.5 month randomised controlled trial and might lead to a safer approach of delivering iron supplementation. The study was registered at clinicaltrials.gov as NCT01092377.

Sensitivity of fatty acid desaturation and elongation to plasma zinc concentration: a randomised controlled trial in Beninese children

Zn status may affect fatty acid (FA) metabolism because it acts as a cofactor in FA desaturase and elongase enzymes. Zn supplementation affects the FA desaturases of Zn-deficient rats, but whether this occurs in humans is unclear. We evaluated the associations between baseline plasma Zn (PZn) concentration and plasma total phospholipid FA composition, as well as the effect of daily consumption of Zn-fortified water on FA status in Beninese children. A 20-week, double-blind randomised controlled trial was conducted in 186 school age children. The children were randomly assigned to receive a daily portion of Zn-fortified, filtered water delivering on average 2·8 mg Zn/d or non-fortified filtered water. Plasma total phospholipid FA composition was determined using capillary GLC and PZn concentrations by atomic absorption spectrometry. At baseline, PZn correlated positively with dihomo-γ-linolenic acid (DGLA, r 0·182; P=0·024) and the DGLA:linoleic acid (LA) ratio (r 0·293; P<0·000), and negatively with LA (r -0·211; P=0·009) and the arachidonic acid:DGLA ratio (r -0·170; P=0·036). With the intervention, Zn fortification increased nervonic acid (B: 0·109; 95 % CI 0·001, 0·218) in all children (n 186) and more so in children who were Zn-deficient (n 60) at baseline (B: 0·230; 95 % CI 0·023, 0·488). In conclusion, in this study, Zn-fortified filtered water prevented the reduction of nervonic acid composition in the plasma total phospholipids of children, and this effect was stronger in Zn-deficient children. Thus, Zn status may play an important role in FA desaturation and/or elongation.

Perspectives on the use of seed oils in the South African diet

The debate and the evidence in the literature on the importance of the type of fat in the diet continues to elicit interest, and hopefully better understanding. Opperman et al 1 addressed the suggestion made in The Real Meal Revolution 2 that seed oils are toxic, high in trans fat and genetically modified in this issue of the SAJCN. The authors concluded in their findings that South African seed oils, i.e. sunflower oil, olive oil and canola oil are of good quality and safe for human consumption, based on their fatty acid composition, i.e. trans-fatty acid content, peroxide and conjugated diene levels. They further concluded that oil crops are not genetically modified. 1

Low immune cell ARA and high plasma 12-HETE and 17-HDHA in iron-deficient South African school children with allergy

Allergy has been associated with altered fatty acid and inflammatory status. In this cross-sectional study of 321 rural iron deficient (ID) South African children (aged 6-11 years), a subsample (n=111) of children with parent-reported allergy data were divided into an allergic (n=30) and non-allergic (n=81) group and compared. PBMC arachidonic acid (ARA; P=0.010) and the PBMC ARA to dihomo-gamma-linolenic acid (DGLA) ratio (P=0.035) were lower in the allergic children. Plasma 12-hydroxyeicosatetraenoic acid and 17-hydroxydocosahexaenoic acid (17-HDHA) were higher (P=0.040 and 0.020, respectively) in the allergic group. Thus, a fatty acid composition and lipid mediator levels indicative of increased release of ARA from PBMC membranes, increased inflammation as well as the resolving thereof, were associated with parent-reported allergy symptoms. This study used baseline data of an intervention study which was registered at clinicaltrials.gov as NCT01092377.