Evaluating the effect of a 12-month youth advisory group on adolescent's leadership skills and perceptions related to chronic disease prevention research: a mixed-methods study.

BACKGROUND: Youth Advisory Groups (YAGs) represent a promising method to engage adolescents in research of relevance to them and their peers. However, YAGs are rarely implemented or evaluated in chronic disease prevention research. The aims of this study were firstly, to evaluate the effect of participation in a 12-month YAG on adolescents' leadership skills and perceptions related to chronic disease prevention research and secondly, to evaluate the process of establishing and facilitating a 12-month YAG and identify barriers and enablers to establishment and facilitation. METHODS: This study was a 12-month pre-post study. Eligible participants were adolescents (13-18-years) and current members of an established YAG. Data collection involved online surveys and semi-structured interviews at baseline, six-months and 12-months follow-up. Participatory outcomes such as self-efficacy, leadership skills, and collective participation were derived from Youth Participatory Action Research Principles (YPAR), and the Lansdown-UNICEF conceptual framework for measuring outcomes of adolescent participation. Process evaluation data were captured via meeting minutes, Slack metrics and researcher logs. Quantitative data was analysed using descriptive statistics and qualitative data was thematically analysed using a reflexive thematic analysis approach. RESULTS: Thirteen (13/16) YAG youth advisors consented to participate in the evaluation study (mean age 16.0 years, SD 1.3; 62% (8/13) identified as female). Survey data assessing participatory outcomes found an increase in leadership and life skills scores over 12-months (+ 8.90 points). Semi-structured interview data collected over the 12-month term revealed three key themes namely: influence, empowerment, and contribution. Comparison of pre-post themes determined a positive trend at follow-ups, demonstrating improved participatory outcomes. Process indicators revealed that at 12-month follow-up the YAG was implemented as planned. Semi-structured interview data determined barriers to YAG facilitation included time and limited face-to-face components, while enablers to YAG facilitation included flexibility, accessible delivery methods, and a supportive adult facilitator. CONCLUSION: This study found that a YAG fostered positive participatory outcomes and unique opportunities for youth participants. A successful YAG based on YPAR principles requires researchers to ensure YAG establishment and facilitation is an iterative process. Taking into consideration important barriers and enablers to YAG facilitation ensures adolescent engagement in a YAG is both meaningful and impactful.

The tempo of puberty and its relationship to adolescent health and well-being: A systematic review.

AIM: Emerging evidence suggests that pubertal tempo, that is rate of passage through puberty, has relevance to adolescent mood and behaviour. However, its wider health and developmental significance remain unclear. This systematic review sought to clarify the relationship of pubertal tempo to indicators of health and development, and to document tempo definitions and pubertal durations reported in the literature. METHODS: Eight electronic databases were searched from earliest record to July 2018. Study eligibility: healthy participants; age 8-21 years; ≥2 longitudinal measures of puberty; analysis of tempo against a health or developmental indicator. RESULTS: Thirty-eight studies met eligibility, and these reported on diverse tempo definitions and seven health- and development-related domains. Data sets with varying tempo definitions converged on an association of rapid pubertal progression to: (a) higher adiposity during childhood and adolescence in both sexes; and (b) lower psychosocial well-being in adolescent males. Later thelarche unanimously predicted faster progression to menarche in females, but this compensation was largely undetected when alternate definitions of pubertal timing and/or tempo were used. Duration of puberty ranged from 2.5-4.1 years. CONCLUSION: Pubertal tempo may be clinically relevant when considering trajectories of adiposity and psychosocial well-being among adolescents, especially males. Consensus on the definition of tempo would facilitate between-study comparisons.

New insights into the association of mid-childhood macronutrient intake to pubertal development in adolescence using nutritional geometry.

Nutritional geometry (NG) is a novel dietary analysis approach that considers nutrient balance, rather than single nutrient effects, on health and behaviour. Through NG, recent animal experiments have found that lifespan and reproduction are differentially altered by dietary macronutrient distribution. Epidemiological research using NG reports similar findings for human ageing. Yet, the relation of macronutrient balance to human reproduction, especially reproductive maturation, remains undefined. We studied the impact of childhood macronutrient intake on pubertal maturation, by applying NG to an Australian longitudinal adolescent dataset. Food records, collected at age 8 years from 142 pre-pubertal children (females, 92; males, 50), were analysed for absolute energy, percentage energy and energy-adjusted residuals from protein, carbohydrate and fat. Pubertal stage change (assessed at 8, 13 and 15 years) was modelled to obtain individual mathematical estimates of pubertal timing and tempo. Timing of menarche was recorded. The association of macronutrients to pubertal timing/tempo was assessed via NG, involving generalised additive models and heat maps to aid interpretation. Results showed lower dietary protein (relative to carbohydrate and fat) in girls consistently predicted earlier pubertal timing and menarche, and was related to faster pubertal tempo (all P < 0·05). No significant associations were identified in boys for both timing and tempo. Results suggest a role of non-protein macronutrients in facilitating female maturation; corroborating feeding and reproductive behaviour patterns observed in earlier NG studies of primates. Application of NG to other adolescent datasets is required to confirm the present findings. Such work would advance understanding of how nutrient balance shapes human development and health.

Omega-3 polyunsaturated fatty acids status and cognitive function in young women.

BACKGROUND: Research indicates that low omega-3 polyunsaturated fatty acid (n-3 PUFA) may be associated with decreased cognitive function. This study examined the association between n-3 PUFA status and cognitive function in young Australian women. METHODS: This was a secondary outcome analysis of a cross-sectional study that recruited 300 healthy women (18-35 y) of normal weight (NW: BMI 18.5-24.9 kg/m2) or obese weight (OB: BMI ≥30.0 kg/m2). Participants completed a computer-based cognition testing battery (IntegNeuro™) evaluating the domains of impulsivity, attention, information processing, memory and executive function. The Omega-3 Index (O3I) was used to determine n-3 PUFA status (percentage of EPA (20:5n-3) plus DHA (22:6n3) in the red cell membrane) and the participants were divided into O3I tertile groups: T1 < 5.47%, T2 = 5.47-6.75%, T3 > 6.75%. Potential confounding factors of BMI, inflammatory status (C-reactive Protein), physical activity (total MET-min/wk), alpha1-acid glycoprotein, serum ferritin and hemoglobin, were assessed. Data reported as z-scores (mean ± SD), analyses via ANOVA and ANCOVA. RESULTS: Two hundred ninety-nine women (26.9 ± 5.4 y) completed the study (O3I data, n = 288). The ANOVA showed no overall group differences but a significant group × cognition domain interaction (p < 0.01). Post hoc tests showed that participants in the low O3I tertile group scored significantly lower on attention than the middle group (p = 0.01; ES = 0.45 [0.15-0.74]), while the difference with the high group was borderline significant (p = 0.052; ES = 0.38 [0.09-0.68]). After confounder adjustments, the low group had lower attention scores than both the middle (p = 0.01) and high (p = 0.048) groups. These findings were supported by univariate analyses which found significant group differences for the attention domain only (p = 0.004). CONCLUSIONS: Cognitive function in the attention domain was lower in women with lower O3I, but still within normal range. This reduced but normal level of cognition potentially provides a lower baseline from which cognition would decline with age. Further investigation of individuals with low n-3 PUFA status is warranted.

New insights in professional horse racing; "in-race" heart rate data, elevated fracture risk, hydration, nutritional and lifestyle analysis of elite professional jockeys.

Weight-making practices have been shown to impair musculoskeletal and physiological function of jockeys. This study investigated the "in-race" heart rate (HR) responses and hydration status during competitive racing, as well as selected physiological and lifestyle parameters of professional jockeys based in Hong Kong. "In-race" HR responses and early morning hydration status of 20 male jockeys were examined in hot and moderate climactic occasions. Additionally, bone mineral density (BMD), dietary intake and lifestyle choices were assessed. Osteopenia was observed in the calcanei of jockeys (left: 0.51 ± 0.06; right: 0.46 ± 0.12 g · cm-2). Energy and protein intake were significantly lower on a race day compared to a non-race day (P < 0.05). "In-race" HRmax values were similar to those from VO2max laboratory tests (186 ± 14 vs. 185 ± 8 bpm). Hypohydration was observed on both racing days. (USG: 1.0247 ± 0.006 and 1.0256 ± 0.0258 mg · L-1 for hot and moderate conditions, respectively). Sauna usage (25.5%) and food restriction (20.4%) were the most common weight-making practices. Current lifestyle choices of jockeys result in suboptimal bone health, hydration status and nutritional intake, which can significantly enhance the fracture risk. Further research should develop exercise and nutrition guidelines for optimising their skeletal health.

Combined caffeine and carbohydrate ingestion: effects on nocturnal sleep and exercise performance in athletes.

PURPOSE: In athletes, caffeine use is common although its effects on sleep have not been widely studied. This randomised, double-blind, placebo-controlled crossover trial investigated the effects of late-afternoon caffeine and carbohydrate-electrolyte (CEB) co-ingestion on cycling performance and nocturnal sleep. METHODS: Six male cyclists/triathletes (age 27.5 ± 6.9 years) completed an afternoon training session (TS; cycling 80 min; 65% VO2max) followed by a 5 kJ kg(-1) cycling time trial (TT). Caffeine (split dose 2 × 3 mg kg(-1)) or placebo was administered 1 h prior and 40 min into the TS. A 7.4% CEB (3 ml kg(-1) every 15 min) was administered during the TS, followed 30 min after by a standardised evening meal. Participants retired at their usual bedtime and indices of sleep duration and quality were monitored via polysomnography. DATA: mean ± SD. RESULTS: All participants performed better in the caffeine TT (caffeine 19.7 ± 3.3; placebo 20.5 ± 3.5 min; p = 0.006), while ratings of perceived exertion (caffeine 12.0 ± 0.6; placebo 12.9 ± 0.7; p = 0.004) and heart rate (caffeine 175 ± 6; placebo 167 ± 11 bpm; p = 0.085) were lower in the caffeine TS. Caffeine intake induced significant disruptions to a number of sleep indices including increased sleep onset latency (caffeine 51.1 ± 34.7; placebo 10.2 ± 4.2 min; p = 0.028) and decreased sleep efficiency (caffeine 76.1 ± 19.6; placebo 91.5 ± 4.2%; p = 0.028), rapid eye movement sleep (caffeine 62.1 ± 19.6; placebo 85.8 ± 24.7 min; p = 0.028) and total sleep time (caffeine 391 ± 97; placebo 464 ± 49 min; p = 0.028). CONCLUSIONS: This study supports a performance-enhancing effect of caffeine, although athletes (especially those using caffeine for late-afternoon/evening training and competition) should consider its deleterious effects on sleep.

Influence of dietary macronutrient composition on eating behaviour and self-perception in young women undergoing weight management.

The control of eating behaviours such as hunger and disinhibition is problematic for women during weight management. Higher-protein (HP) diets have been shown to promote greater weight reduction than higher-carbohydrate (HC) diets, but their impact on eating behaviours is relatively unexplored. This study compared two iso-energetically restricted (5,600 kJ/day) diets differing in protein (HP: 32%, HC: 20%) and carbohydrate (HP: 41%, HC: 58%) on appetite ratings, restraint, disinhibition, perceived hunger and binge eating in 36 (HP: n = 21, HC: n = 15) young (18-25 years), healthy women with BMI ≥27.5 kg/m(2) who completed a 12-month clinical weight management trial. Dietary compliance and self-worth were also assessed. Results showed that both diets induced improvements in restraint and disinhibition from baseline (p < 0.01), with HP participants losing a non-significantly greater amount of weight than HC participants (HP: 9.6 ± 2.6, HC: 4.1 ± 1.4 kg, p = 0.07). Despite reasonable compliance, no significant appetite and eating behaviour differences were observed between the diets. Reduction in disinhibition (regardless of diet) significantly predicted weight loss (ß = 0.574, p < 0.001) and self-worth improvement (ß = -0.463, p = 0.002), while HP intake predicted greater self-worth change (ß = -0.371, p = 0.011). This study demonstrates that young women can improve restraint and disinhibition on a weight management programme, with the reduction in disinhibition shown to be a key predictor of weight loss. HP intake may offer some advantage for increasing self-worth but not eating behaviours. As HP diets are popular, these findings warrant confirmation in a larger sample.

Menstrual Dysfunction in Adolescents with Chronic Illness: A Systematic Review.

STUDY OBJECTIVE: Menstrual dysfunction can impact both the physical and emotional health of young people.1 Multiple chronic diseases have been associated with menstrual dysfunction in adults2; however, there is little research in adolescents, despite nonadherence and suboptimal illness control in this group. We aimed to identify the impact of chronic illness on the age of menarche and the menstrual cycle in adolescents. METHODS: Studies were extracted of female adolescents aged 10-19 who had a chronic physical illness. Data included outcomes on age of menarche and/or menstrual cycle quality. Exclusion criteria aimed to exclude diseases where menstrual dysfunction was a known part of the disease pathophysiology (ie, polycystic ovarian syndrome)3 or in which medications were used that directly impacted gonadal function.4 A literature search (to January 2022) was performed on the EMBASE, PubMed, and Cochrane library databases. Two widely used modified quality analysis tools were used. RESULTS: Our initial search netted 1451 articles, of which 95 full texts were examined and 43 met the inclusion criteria. Twenty-seven papers focused on type 1 diabetes (T1D), with 8 papers examining adolescents with cystic fibrosis and the remaining studying inflammatory bowel disease, juvenile idiopathic arthritis, coeliac disease, and chronic renal disease. Metanalysis of 933 patients with T1D vs 5244 controls demonstrated a significantly later age of menarche in T1D (by 0.42 years; P ≤ .00001). There was also a significant association between higher HbA1c and insulin dose (IU/kg) and later age of menarche. Eighteen papers reviewed other aspects of menstruation, including dysmenorrhea, oligomenorrhoea, amenorrhea, and ovulatory function, with variable findings. CONCLUSION: Most studies were small and in single populations. Despite this, there was evidence of delayed menarche and some evidence of irregular menses in those with cystic fibrosis and T1D. Further structured studies are needed to evaluate menstrual dysfunction in adolescents and how it relates to their chronic illness.

How are adolescents engaged in obesity and chronic disease prevention policy and guideline development? A scoping review.

BACKGROUND: Adolescent consumer engagement is widely accepted, with global calls to meaningfully involve adolescents for effective and tailored policy and guideline development. However, it is still unclear if and how adolescents are engaged. The aim of this review was to determine if and how adolescents meaningfully participate in policy and guideline development for obesity and chronic disease prevention. METHODS: A scoping review was conducted guided by the Arksey and O'Malley six stage framework. Official government websites for Australia, Canada, United Kingdom, and United States including intergovernmental organizations (World Health Organisation and United Nations) were examined. Universal databases Tripdatabase and Google advanced search were also searched. Current and published international and national obesity or chronic disease prevention policies, guidelines, strategies, or frameworks that engaged adolescents aged 10-24 years in meaningful decision-making during the development process were included. The Lansdown-UNICEF conceptual framework was used to define mode of participation. RESULTS: Nine policies and guidelines (n = 5 national, n = 4 international) engaged adolescents in a meaningful capacity, all focused on improving 'health and well-being'. Demographic characteristics were poorly reported, still most ensured representation from disadvantaged groups. Adolescents were primarily engaged in consultative modes (n = 6), via focus groups and consultation exercises. Predominantly in formative phases e.g., scoping the topic or identifying needs (n = 8) and to a lesser extent in the final stage of policy and guideline development e.g., implementation or dissemination (n = 4). No policy or guideline engaged adolescents in all stages of the policy and guideline development process. CONCLUSION: Overall, adolescent engagement in obesity and chronic disease prevention policy and guideline development is consultative and rarely extends throughout the entire development and implementation process.

Impact of growth, gonadal hormones, adiposity and the sodium-to-potassium ratio on longitudinal adolescent measures of blood pressure at puberty.

Blood pressure (BP) rises rapidly at puberty. While this is partly due to normal development, factors like excess adiposity and a high intake of dietary sodium relative to potassium may contribute to a true increase in hypertension risk. This study aimed to assess the relative impact of growth, gonadal hormones, adiposity and the sodium-to-potassium ratio (Na:K) on longitudinal BP measures at puberty. This study analysed data from a three-year longitudinal cohort study of pubertal adolescents. Anthropometry, body composition (bio-electrical impedance), serum testosterone and oestradiol (mass spectrometry) were measured annually. Na:K was measured from three-monthly urine samples. These variables were used to predict annual BP measures using mixed modelling and ordinal regression. Data from 325 adolescents (11.7 ± 1.0 y; 55% male) were analysed, showing typical growth patterns at puberty. Systolic BP increased over time in both sexes (p < 0.01), with boys exhibiting a significantly steeper rise compared to girls. Adiposity variables (BMI z-score, percent body fat, fat mass, waist-to-height ratio) strongly and consistently predicted systolic and diastolic BP in both sexes (all p < 0.05). Systolic BP was also significantly and positively related to height (p < 0.05). No associations with BP were identified in either sex for gonadal hormones or Na:K. Similar results were obtained when BP was classified into hypertension categories. Relative to other developmental and diet-related variables tested, adiposity was found to be the strongest most consistent predictor of BP in pubertal adolescents. Findings highlight the importance of dedicated youth obesity management interventions and policy measures for reducing long-term hypertension and cardiovascular disease risks.Australian New Zealand Clinical Trials Registry ACTRN12617000964314.

Eating disorders in weight-related therapy (EDIT): Protocol for a systematic review with individual participant data meta-analysis of eating disorder risk in behavioural weight management.

The Eating Disorders In weight-related Therapy (EDIT) Collaboration brings together data from randomised controlled trials of behavioural weight management interventions to identify individual participant risk factors and intervention strategies that contribute to eating disorder risk. We present a protocol for a systematic review and individual participant data (IPD) meta-analysis which aims to identify participants at risk of developing eating disorders, or related symptoms, during or after weight management interventions conducted in adolescents or adults with overweight or obesity. We systematically searched four databases up to March 2022 and clinical trials registries to May 2022 to identify randomised controlled trials of weight management interventions conducted in adolescents or adults with overweight or obesity that measured eating disorder risk at pre- and post-intervention or follow-up. Authors from eligible trials have been invited to share their deidentified IPD. Two IPD meta-analyses will be conducted. The first IPD meta-analysis aims to examine participant level factors associated with a change in eating disorder scores during and following a weight management intervention. To do this we will examine baseline variables that predict change in eating disorder risk within intervention arms. The second IPD meta-analysis aims to assess whether there are participant level factors that predict whether participation in an intervention is more or less likely than no intervention to lead to a change in eating disorder risk. To do this, we will examine if there are differences in predictors of eating disorder risk between intervention and no-treatment control arms. The primary outcome will be a standardised mean difference in global eating disorder score from baseline to immediately post-intervention and at 6- and 12- months follow-up. Identifying participant level risk factors predicting eating disorder risk will inform screening and monitoring protocols to allow early identification and intervention for those at risk.

Adolescence and young adulthood: an untapped window of opportunity for obesity prevention.

Adolescence and young adulthood (AYA) are formative life stages, second only to the first 1000 days. Yet young people have historically been 'forgotten' in our health system. Major health risk factors, like adolescent obesity, have largely been left untreated, resulting in significant chronic disease burdens and health costs later in life. In Australia, strategies to address obesity have primarily been implemented disjointedly by different jurisdictions of government, which has meant that obesity responses across the country have been piecemeal. Current state-based interventions show modest effects on improving weight-related behaviours. Major fiscal and regulatory measures have yet to be implemented despite demonstrable public health benefits and public support. The new National obesity strategy 2022-2032, which recognises the importance of engaging with youth, is a welcomed approach to coordinating obesity prevention Australia-wide. The challenge remains to ensure that meaningful AYA engagement is followed through with future interventions. The digitalisation of society poses future health challenges for AYA because of the likelihood of greater physical inactivity and ease of access to junk foods.

Shifting From Tokenism to Meaningful Adolescent Participation in Research for Obesity Prevention: A Systematic Scoping Review.

Background: Traditionally, adolescent participation in research has been tokenistic. Adolescents are rarely afforded the opportunity to influence decision-making in research designed to prevent obesity. Engaging adolescents in meaningful decision-making may enhance research translation. This review aimed to analyze the current modes and nature of adolescent participation in obesity prevention research decision-making. Methods: A systematic scoping review was conducted using Arksey and O'Malley's six-stage framework. Six major databases were searched for peer-reviewed primary research studies with adolescent participation related to obesity, physical activity, and diet. Modes of adolescent participation were categorized based on the Lansdown-UNICEF conceptual framework for measuring outcomes of adolescent participation. The framework outlines three modes of meaningful participation: (i) consultative, which involves taking opinions and needs into consideration; (ii) collaborative, where adolescents are partners in the decision-making process; and (iii) adolescent-led participation where adolescents have the capacity to influence the process and outcomes. The degree of involvement in research cycles was classified based on the National Health and Medical Research Council consumer engagement framework. Five stages of the research cycle were determined: identify, design and develop, conduct, analyze and disseminate. Results: In total, 126 papers describing 71 unique studies were identified. Of these, 69% (49/71) took place in the USA, and 85% (52/61) were conducted in minority or underserved communities, while males were more likely to be under-represented. In 49% (35/71) of studies, participation was consultative and 9% (6/71) of studies involved an adolescent-led approach. Furthermore, 87% (62/71) of studies incorporated adolescent participation in one or more of the research cycle's formative phases, which involve eliciting views, opinions and idea generation. Only 11% of studies engaged adolescents in all five stages of the research cycle where adolescents could have more influence over the research process. Conclusion: Meaningful adolescent participation in the obesity prevention research cycle is limited. Empowering and mobilizing equal partnership with adolescents should be at the forefront of all adolescent-related obesity prevention research.

Adolescent Participation in Research, Policies and Guidelines for Chronic Disease Prevention: A Scoping Review Protocol.

Adolescents (10-24 years old) account for 23% of the global population. Physical inactivity, suboptimal dietary intake, overweight, and obesity during adolescence are risk factors associated with chronic disease development into adulthood. Research, policies, and guidelines that seek to prevent chronic disease risk factor development rarely engage adolescents in planning and decision-making processes. The aims of this review are to investigate (i) how adolescents currently participate in research, policy, and guidelines for reduction of chronic disease risk factors, and (ii) provide recommendations to optimize adolescent participation in future research, policy, and guideline decision making for chronic disease prevention. A systematic scoping review of the health peer-review research, policy, and guidelines, using Arksey and O'Malley's six-stage framework, will be conducted. Participatory outcomes will be assessed based on the Lansdown-UNICEF conceptual framework for measuring adolescent participation. Classified as consultative, collaborative, or adolescent-led according to the degree of influence and power adolescents possess in the decision- making processes. Consultation with adolescents via digital surveys and focus groups will provide further information, perspective, and insight. Qualitative data will be analyzed by descriptive numerical summary and qualitative content analytical techniques. The title of this protocol is registered with Joanna Briggs Institute and Open Science Framework, doi:10.17605/OSF.IO/E3S64.

Bumpy and Smoother Pathways of Puberty Hormone Change: A Novel Way to Define Gonadal Hormone Trajectories in Adolescents.

CONTEXT: The study of gonadal hormone effects on adolescent wellbeing has been limited by logistical challenges. Urine hormone profiling offers new opportunities to understand the health and behavioral implications of puberty hormones. OBJECTIVE: To characterize pubertal change in urinary testosterone and estradiol among male and female adolescents, respectively. DESIGN: Three-year prospective cohort study. SETTING: Australian regional community. PARTICIPANTS: 282 (163 male) normally developing adolescents aged 11.8 ± 1.0 years at baseline. MAIN OUTCOME MEASURE: Quarterly urine measurements of testosterone and estradiol (mass spectrometry); annual anthropometric assessment and Tanner stage (TS) self-report. RESULTS: Two-class sigmoidal and quadratic growth mixture models (centered on age at TS3) were identified as best-fit for describing testosterone (male) and estradiol (female) change. Classes 1 (male: 63%; female: 82%) and 2 (male: 37%; female: 18%) were respectively named the "stable" and "unstable" trajectories, characterized by different standard deviation of quarterly hormone change and magnitude of hormone peaks and troughs (all P < 0.001). Compared with class 1 (stable), class 2 males were taller at baseline (154 vs 151 cm), reported earlier and faster TS progression (P < 0.01), and showed higher serum testosterone levels at baseline and 3 years (P ≤ 0.01). Class 2 females exhibited smaller height and weight gains over the 3 years and had higher baseline serum estradiol (249 vs 98 pmol/L; P = 0.002) than class 1. CONCLUSIONS: Adolescents showed 2 distinct urinary gonadal hormone trajectories, characterized by stability of change over time, which were not associated with consistent anthropometric differences. Results provide a methodology for studying gonadal hormone impacts on other aspects of biopsychosocial wellbeing. Identification of potential "at-risk" hormone groups would be important for planning supportive interventions.

Association between Obesity and Omega-3 Status in Healthy Young Women.

Omega-3 polyunsaturated fatty acids (n-3 PUFAs) are essential for healthy development and protect against metabolic disease. However, individuals with obesity may be pre-disposed to experiencing lower n-3 PUFA status than normal-weight individuals. This cross-sectional study examined the relationship between the omega-3 index (O3I), body mass index (BMI) and dietary intake in healthy young women (n = 300; age = 18-35 y), a group not previously focused on. Intake was adjusted for energy using the residuals method, and associations were explored using independent t-tests and Pearson's correlations. Participants with obesity were found to have significantly lower O3I than normal-weight participants (p < 0.0001); however, no significant differences were observed in mean n-3 PUFA intakes. Even so, energy-adjusted intakes of n-3 PUFAs, with the exception of alpha-linolenic acid, were significantly correlated with O3I. This study demonstrates that O3I is influenced by both BMI and diet in young women; however the relationship between these two variables may be complex. Current intakes of n-3 PUFA observed in young women may not be effective in achieving target O3I levels in those with obesity, and further research is needed to find effective ways of improving n-3 PUFA status in a group already at increased risk of metabolic disease.

Foot Length Growth as a Novel Marker of Early Puberty.

Foot growth is part of overall pubertal growth but its relation to other anthropometric and hormonal changes is unclear. Our objective was to determine how foot length changes relate to changes in other growth parameters (height and weight), Tanner stage, and serum hormones. Adolescents (n = 342) were recruited to a 3-year longitudinal cohort study, underwent annual anthropometric assessments (height, weight, and foot length), and provided self-rated Tanner staging. They also provided blood samples that were analyzed using liquid chromatography-tandem mass spectrometry for serum testosterone and estradiol and classified as pre-pubertal or pubertal based on circulating hormone levels. Average annual percent increase in foot length was greater for pre-pubertal adolescents compared with pubertal. Increased foot length was associated with increases in height, weight, Tanner stage, and serum hormones in males and pre-menarcheal females but not post-menarcheal females. Foot length offers a novel, noninvasive, cost-effective, and easily demonstrable marker of early pubertal changes.

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.

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 (ß = 0.128, p = 0.009) than NHI (ß = 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.

Effect of Glycemic Index of a Pre-exercise Meal on Endurance Exercise Performance: A Systematic Review and Meta-analysis.

BACKGROUND: Low glycemic index (GI) pre-exercise meals may enhance endurance performance by maintaining euglycemia and altering fuel utilization. However, evidence for performance benefits is equivocal. OBJECTIVE: To evaluate the effect of a low GI (LGI) versus a high GI (HGI) pre-exercise meal on endurance performance using meta-analyses. METHODS: Data sources included MEDLINE, SPORTDiscus, AUSPORT, AusportMed, Web of Science, and Scopus. Eligibility criteria were randomized, crossover trials with an endurance exercise (≥60 min) component, e.g., time trial (TT), time to exhaustion (TTE) test, or submaximal bout followed by TT or TTE. Participants were healthy, active individuals aged ≥16 years. Interventions included a LGI (≤55) and HGI (≥70) meal ingested 30-240 min before exercise. Study quality was assessed using an adapted version of the validated Downs and Black tool. Effect size (ES) and 95 % confidence interval were calculated for each study and pooled according to performance test type and whether exogenous carbohydrate (CHO) was given during exercise. Potential effect modifiers including exercise duration, pre-exercise meal timing, glycemic load (GL), and fitness were assessed using meta-regression. RESULTS: The search netted 3431 citations with 19 studies eligible for inclusion (totaling 188 participants; 91 % male; VO2max: >50 ml/kg/min). Meals with 0.18-2 g CHO/kg body mass, and a mean GI and glycemic load of 82 (GL: 72) and 35 (GL: 32) for HGI and LGI, respectively, were given between 30 and 210 min before exercise. All test types without CHO ingestion during exercise showed slightly improved performance with LGI, but no significant pooled effects were observed (ES: -0.17 to -0.36; p > 0.05). Studies where exogenous CHO was ingested during exercise showed conflicting results (ES: -0.67 to 0.11; p = 0.04 to 0.94). No significant relationship was observed with any of the effect modifiers (p > 0.05). No consistent metabolic responses (glucose, insulin, lactate, respiratory exchange ratio) during exercise were observed with either meal type. LIMITATIONS: There were small numbers of studies within each exercise testing protocol and limited statistical power within studies. Pre-exercise meal timing, GL, meal composition and participant fitness varied across studies, limiting the capacity to assess the influence of these factors on study outcomes. CONCLUSION: There was no clear benefit of consuming a LGI pre-exercise meal for endurance performance regardless of carbohydrate ingestion during exercise.