Hoi Lun Cheng

The relationship between obesity and hypoferraemia in adults: a systematic review

A growing number of studies suggest a potential link between obesity and altered iron metabolism. The purpose of this systematic review was to examine existing literature on iron status in obese populations. A comprehensive literature search was conducted. Included studies recruited participants ≥ 18 years with a body mass index ≥ 30 kg m−2 and provided descriptive statistics for haemoglobin or ferritin at a minimum. There were 25 studies meeting all eligibility criteria, of these 10 examined iron status in free‐living obese individuals and 15 reported baseline iron biomarkers from bariatric surgery candidates. Non‐obese comparison groups were used by 10 (40%) articles. In these, seven obese groups reported higher mean haemoglobin concentration; six reported significantly higher ferritin concentration; and four significantly lower transferrin saturation. Due to insufficient data, it was not possible to make conclusions regarding mean differences for soluble transferrin receptor (sTfR), hepcidin or C‐reactive protein. Existing evidence suggests a tendency for higher haemoglobin and ferritin concentration and lower transferrin saturation in obesity. Alternation of iron biomarkers in obese populations may be a result of obesity‐related inflammation and/or related comorbidities. Further research incorporating measurement of inflammatory cytokines, sTfR and hepcidin is required to confirm the impact of obesity on iron status.

Relationship between physical activity and cognitive function in apparently healthy young to middle-aged adults: A systematic review

OBJECTIVES There is increasing evidence that physical activity (PA) positively affects cognitive function (CF). Existing research has focussed on this association in children and the elderly, with less research available in young to middle-aged adults who constitute a substantial proportion of the population. DESIGN A systematic review investigating the relationship between habitual PA (≥12 months) and CF in young to middle-aged adults (18-50 years). METHODS A search was conducted using AMED, CINAHL, MEDLINE, PsychINFO, AUSPORT MED and SPORTDiscus databases. Eligible studies had to report descriptive statistics for CF and PA levels in healthy participants 18-50 years. Effect sizes (ES) (Hedges g) were calculated where possible. RESULTS The initial search netted 26,988 potentially relevant manuscripts, with four more identified through hand searching. Fourteen were included for review. A range of validated platforms assessed CF across three domains: executive function (12 studies), memory (four studies) and processing speed (seven studies). Habitual PA was assessed via questionnaire/self-report methods (n=13, 8 validated) or accelerometers (n=1). In studies of executive function, five found a significant ES in favour of higher PA, ranging from small to large. Although three of four studies in the memory domain reported a significant benefit of higher PA, there was only one significant ES, which favoured low PA. Only one study examining processing speed had a significant ES, favouring higher PA. CONCLUSIONS A limited body of evidence supports a positive effect of PA on CF in young to middle-aged adults. Further research into this relationship at this age stage is warranted.

Iron, hepcidin and inflammatory status of young healthy overweight and obese women in Australia

Background and Aims Evidence suggests obesity-related inflammation alters iron metabolism potentially increasing the risk of iron deficiency. This cross-sectional study aimed to investigate iron, hepcidin and inflammatory status in young, healthy overweight and obese women. Methods 114 young (18–25 years), healthy comorbidity-free women with a body mass index (BMI) ≥27.5 kg/m2 were recruited. Biochemical data were analysed using mean ± standard deviation or median (interquartile range) and multivariate modelling. Biochemical markers were also stratified according to varying degrees of overweight and obesity. Results Anaemia (haemoglobin <120 g/l) and iron deficiency (serum ferritin <15.0 µg/l) were prevalent in 10% and 17% of participants respectively. Mean/median soluble transferrin receptor was 1.61±0.44 mg/l; hepcidin 6.40 (7.85) ng/ml and C-reactive protein (CRP) 3.58 (5.81) mg/l. Multivariate modelling showed that BMI was a significant predictor of serum iron (coefficient = -0.379; standard error = 0.139; p = 0.008), transferrin saturation (coefficient = -0.588; standard error = 0.222; p = 0.009) and CRP (coefficient = 0.127; standard error = 0.024; p<0.001). Stratification of participants according to BMI showed those with ≥35.0 kg/m2 had significantly higher CRP (p<0.001) than those in lower BMI categories. Conclusions Increasing obesity was associated with minor disturbances in iron metabolism. However, overall outcomes indicated simple iron deficiency (hypoferritinaemia) was the primary iron-related abnormality with no apparent contribution of inflammation or hepcidin, even in those with BMI >35.0 kg/m2. This indicates that obesity alone may not be sufficient to induce clinically significant disturbances to iron metabolism as previously described. This may be attributed to the lack of comorbidity in this cohort.

Anthropometric characteristics of Australian junior representative rugby league players

OBJECTIVES To comprehensively describe anthropometric characteristics of Australian junior elite rugby league players and assess potential anthropometric dissimilarities between players of varying positional groups, ethnicity (Polynesian vs. non-Polynesian) and playing level (junior vs. professional; using published data from Australian professional players). DESIGN Cross-sectional study. METHODS Height, body mass, eight skinfolds, five girths and two bone breadths were measured with body fat (BF%) and somatotype calculated using population-appropriate equations. DATA mean ± SD. RESULTS This study recruited 116 junior players. Mean age, mass and BF% were 17 ± 1 y, 87.0 ± 11.6 kg and 14.0 ± 4.6% respectively. Compared to backs, forwards had greater mass (92.6 ± 12.2 vs. 80.9 ± 7.1 kg), skinfolds, girths, femur breadth, BF% (16.1 ± 4.8% vs. 11.8 ± 3.2%) (all p<0.01), and were more endo- and mesomorphic, but less ectomorphic (all p<0.001). Compared to other positional groups, props had greater mass, adiposity, calf girth and endomorphy, while adjustables (fullbacks, five-eighths, halfbacks, hookers) had the shortest stature (all p<0.01). Polynesians exhibited greater height (181.0 ± 5.7 vs. 178.7 ± 6.3 cm), mass (90.6 ± 11.7 vs. 84.7 ± 11.1 kg), arm and calf girths, bone breadths and mesomorphy (7.6 ± 1.2 vs. 6.7 ± 1.1) than non-Polynesians (all p<0.05). Juniors had lower height, mass, waist and smaller sum of skinfolds than professional players (all p<0.05). CONCLUSIONS Greater mass, mesomorphy, adiposity and bone size in forwards is desirable for tackling and attacking and may protect against high impact forces sustained in this position. Advantageous anthropometric attributes exhibited in Polynesian players may influence selection into junior elite rugby league teams. Anthropometric data from this study may assist other junior players and coaches with training, dietary modification and position allocation.

Higher protein diet for weight management in young overweight women: a 12-month randomized controlled trial

Clinical research on weight management in young women is limited. This randomized controlled trial compared the efficacy of two iso‐energetically restricted (5600 kJ) diets [higher protein (HP): 32% protein, 41% carbohydrate, 25% fat or higher carbohydrate (HC): 20, 58, 21%, respectively] in 71 (HP: n = 36; HC: n = 35) young healthy women (18–25 years; body mass index ≥ 27.5 kg/m2) for weight (kg; percent weight loss), body composition, metabolic and iron changes assessed at baseline, 6 and 12 months. Data: mean (95% CI). In HP completers at 6 months, percent weight loss was higher [HP: 9.3 (5.6–13.1); HC: 5.1 (2.3–7.9)%; p = 0.06]; although, this did not reach statistical significance. Absolute weight [HP: 8.9 (5.3–12.5); HC: 4.6 (2.2–7.0) kg; p = 0.034] and fat loss [HP: 8.0 (4.4–11.5); HC: 3.4 (1.3–5.6) kg; p = 0.022] were significantly greater. No significant between‐diet differences were observed at 12 months. Biochemistry remained within normal ranges with HP showing superior preservation of ferritin at 6 months [HP: 53 (40–66); HC: 46 (30–61) µg/l; p = 0.029]. Both diets supported clinically meaningful weight loss with HP tending to be more effective in the medium‐term.

Impact of Diet and Weight Loss on Iron and Zinc Status in Overweight and Obese Young Women

Young overweight women are at risk of iron and zinc deficiency. This study assessed iron, zinc and inflammatory status during a 12-month weight loss trial in young women (18-25 y; BMI >=27.5 kg/m2) randomised to a higher-protein (HP: 32% protein; 12.2 mg/day iron; 11.7 mg/day zinc) or lower-protein (LP: 20%; 9.9 mg/day; 7.6 mg/day respectively) diet with contrasting haem iron and zinc content. In completers (HP: n=21; LP: n=15), HP participants showed higher median ferritin (52.0 vs 39.0 μg/L; p=0.021) and lower median soluble transferrin receptor-ferritin index (sTfR-F; 0.89 vs 1.05; p=0.024) although concentrations remained within normal range for both diets. Median C-reactive protein (CRP; HP: 3.54; LP: 4.63 mg/L) and hepcidin (HP: 5.70; LP: 8.25 ng/mL) were not elevated at baseline, and no longitudinal between-diet differences were observed for zinc and CRP. Compared to those with <5% weight loss, HP participants losing >=10% weight showed lower median sTfR-F (0.76 vs 1.03; p=0.019) at six months. Impact of >=10% weight loss on iron was more apparent in LP participants who exhibited greater mean serum iron (20.0 vs 13.5 μmol/L; p=0.002), transferrin saturation (29.8% vs 19.4%; p=0.001) and lower sTfR (1.24 vs 1.92 mg/L; p=0.034) at 12 months. Results show normal iron and zinc status can be maintained during 12 months of energy restriction. In the absence of elevated baseline inflammation and hepcidin, a more favourable iron profile in those with >=10% weight loss may reflect stronger compliance or the potential influence of iron regulatory mechanisms unrelated to inflammatory hepcidin reduction.

Relationship between Obesity and Cognitive Function in Young Women: The Food, Mood and Mind Study

Limited research addresses links between obesity and cognitive function in young adults. Objective. To investigate the relationship between obesity and cognitive function in young women. Methods. This cross-sectional study recruited healthy, young (18–35 y) women of normal (NW: BMI = 18.5–24.9 kg·m−2) or obese (OB: BMI ≥ 30.0 kg·m−2) weight. Participants completed a validated, computer-based cognitive testing battery evaluating impulsivity, attention, information processing, memory, and executive function. Questionnaires on depression and physical activity and a fasting blood sample for C-reactive protein and the Omega-3 Index were also collected. Cognition data are presented as z-scores (mean ± SD), and group comparisons were assessed via ANOVA. Potential confounding from questionnaire and blood variables were evaluated using ANCOVA. Results. 299 women (NW: n = 157; OB: n = 142) aged 25.8 ± 5.1 y were enrolled. Cognition scores were within normal range (±1 z-score), but OB had lower attention (NW: 0.31 ± 1.38; OB: −0.25 ± 1.39; ES: 0.41, CI: 0.17–0.64; p < 0.001) and higher impulsivity (NW: 0.36 ± 1.14; OB: −0.07 ± 1.07; ES: 0.39, CI: 0.15–0.62; p=0.033). Confounder adjustment had minimal impact on results. Conclusion. The OB group had normal but significantly lower performance on attention and were more impulsive compared to NW participants. This may indicate early cognitive decline, but longitudinal research confirming these findings is warranted.

Incidence and characteristics of injuries in elite Australian junior rugby league players

OBJECTIVES Rugby league (RL) is a physically demanding collision sport, yet few studies describe injuries at the junior level despite their potential impact on career pathways and long-term health. With the absence of an injury surveillance paradigm in junior competition, this study aimed to investigate injury incidence in an Australian setting. DESIGN Prospective cohort study. METHODS A set of injury surveillance forms were developed and used to record injury characteristics, mechanism, severity and follow-up throughout one season. RESULTS Junior RL players (n=368, age: 15.8±1.0 years) from 15 clubs provided baseline information. Of these, approximately six clubs (n=122) provided longitudinal injury data. A total of 109 injuries (90% match-related) were recorded, with the tackle accounting for 61%. Injury incidence (37.1 injuries per 1000 match hours) was consistent with previous literature. Most injuries did not result in missed matches. The ankle and head/face were most frequently injured (both 13%), with ankle injuries leading to the highest losses of match-play. Contusions were common (38%), although ligament injuries caused the greatest match-play losses. Injury site significantly differed between forwards and backs (p=0.003), with forwards sustaining more head/face and sternum injuries, and backs more ankle injuries. Injury type (p=0.25) and severity (p=0.09) were similar between positions. CONCLUSIONS Given the ongoing biological maturation in adolescent players and the injury risks related to RL, playing intensity, training regimes and injury incidence warrant rigorous documentation and monitoring. This study argues for functional but low-burden injury surveillance systems (e.g. electronic platforms) to be developed and implemented in junior RL.

Association between Haem and Non-Haem Iron Intake and Serum Ferritin in Healthy Young Women

Iron is an essential micronutrient for human health and inadequate intake may result in iron deficiency (ID) or iron deficiency anaemia (IDA). Unlike other recent studies investigating iron status in young women, this cross-sectional study analysed dietary intake and biochemical data from healthy young (18–35 years) women (n = 299) to determine the association between both haem iron (HI) and non-haem iron (NHI) intakes and serum ferritin (SF). Dietary restraint and possible inflammation secondary to obesity were also measured and accounted for, and energy intake was adjusted for using the residuals method. Independent samples t-tests and chi-squared tests were performed, and factors found to be significantly different between iron replete (IR) and ID/IDA participants were analysed using general linear modelling. ID/IDA participants consumed significantly lower total energy than iron replete (IR) (p = 0.003). Lower energy intake was also associated with higher levels of dietary restraint (p = 0.001). Both HI and NHI were positively associated with SF with HI was found to be a stronger predictor (β = 0.128, p = 0.009) than NHI (β = 0.037, p = 0.028). The study demonstrates that intake of both HI and NHI, as well as adequate dietary energy, are associated with normal iron status levels in young women, and that restrained eaters may be at greater risk of low iron status.

Ghrelin and Peptide YY Change During Puberty: Relationships with Adolescent Growth, Development and Obesity.

Context Pubertal adolescents show strong appetites. How this is mediated is unclear, but ghrelin and peptide YY (PYY) play potentially important roles. Objective To measure ghrelin and PYY change in relation to pubertal growth. Design Three-year prospective cohort study. Setting Australian regional community. Participants Eighty healthy adolescents (26 girls; 54 boys) recruited at 10 to 13 years. Main Outcome Measures Fasting circulating total ghrelin, total PYY, IGF-1, insulin, leptin (via radioimmunoassay), estradiol and testosterone (via mass spectrometry), anthropometry, and body composition (via bioelectrical impedance). Results Adolescents exhibited normal developmental change. Mixed models revealed positive associations for ghrelin to age2 (both sexes: P < 0.05), indicating a U-shaped trend over time. Ghrelin was also inversely associated with IGF-1 (both sexes: P < 0.05), leptin in girls (P < 0.01), and insulin in boys (P < 0.05) and negatively correlated with annual height and weight velocity (both sexes: P ≤ 0.01). PYY showed no age-related change in either sex. Neither ghrelin nor PYY were associated with Tanner stage. Weight subgroup analyses showed significant ghrelin associations with age2 in healthy-weight but not overweight and obese adolescents (7 girls; 18 boys). Conclusions Adolescents showed a U-shaped change in ghrelin corresponding to physical and biochemical markers of growth, and no change in PYY. The overweight and obesity subgroup exhibited an apparent loss of the U-shaped ghrelin trend, but this finding may be attributed to greater maturity and its clinical significance is unclear. Further research on weight-related ghrelin and PYY trends at puberty is needed to understand how these peptides influence growth and long-term metabolic risk.