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Volume 47 • Number 1 • January 2022

Editorial

Review

Vol. 47No. 1pp. 1–8
Artificial intelligence (AI) is a rapidly evolving area that offers unparalleled opportunities of progress and applications in many healthcare fields. In this review, we provide an overview of the main and latest applications of AI in nutrition research and identify gaps to address to potentialize this emerging field. AI algorithms may help better understand and predict the complex and non-linear interactions between nutrition-related data and health outcomes, particularly when large amounts of data need to be structured and integrated, such as in metabolomics. AI-based approaches, including image recognition, may also improve dietary assessment by maximizing efficiency and addressing systematic and random errors associated with self-reported measurements of dietary intakes. Finally, AI applications can extract, structure and analyze large amounts of data from social media platforms to better understand dietary behaviours and perceptions among the population. In summary, AI-based approaches will likely improve and advance nutrition research as well as help explore new applications. However, further research is needed to identify areas where AI does deliver added value compared with traditional approaches, and other areas where AI is simply not likely to advance the field. Novelty: Artificial intelligence offers unparalleled opportunities of progress and applications in nutrition. There remain gaps to address to potentialize this emerging field.

Articles

Vol. 47No. 1pp. 9–17
This pre-post study examined sex-differences in peak aerobic power (O2peak) and physical- and mental-health outcomes in adults with cardiovascular disease who completed high-intensity interval training (HIIT)-based cardiac rehabilitation. HIIT consisted of 25 minutes of alternating higher- (4×4 minutes 85–95% heart rate peak (HRpeak)) and lower- (3×3 minutes 60–70% HRpeak) intensity intervals twice weekly for 10 weeks. O2peak estimated from a graded exercise test using the American College of Sports Medicine equation, body mass index (BMI), waist circumference, blood pressure, blood biomarkers and anxiety and depression were assessed at baseline and follow-up. Linear mixed-effects models for repeated measures were performed to examine differences over time between sexes. Of 140 participants (mean ± standard deviation: 58 ± 9 years), 40 were female. Improvements in O2peak did not differ between sexes (interaction: p = 0.273, females: 28.4 ± 6.4 to 30.9 ± 7.6; males: 34.3 ± 6.3 to 37.4 ± 6.0 mL/kg/min). None of the time by sex interactions were significant. Significant main effects of time showed reductions in waist circumference, triglycerides, low-density lipoprotein (LDL), total cholesterol (TC)/high-density lipoprotein (HDL) and anxiety, and increases in O2peak and HDL from baseline to follow-up. Significant main effects of sex revealed smaller O2peak, BMI and waist circumference, and higher LDL, TC and HDL in females than males. HIIT led to similar improvements in estimated O2peak (females: 8.8%, males: 9.0%) and additional health outcomes between sexes. Novelty: HIIT-based cardiac rehabilitation led to similar improvements in estimated O2peak and other physical and mental health outcomes between sexes. The number of sessions attended was high (>70%) and did not differ by sex. Both sexes showed good compliance with the exercise protocol (HR target).
Vol. 47No. 1pp. 18–26
Spirulina supplementation has been reported to improve time to exhaustion and maximal oxygen consumption (O2max). However, there is limited information on its influence over the multiple intensities experienced by cyclists during training and competition. Fifteen trained males (age 40 ± 8 years, O2max 51.14 ± 6.43 mL/min/kg) ingested 6 g/day of spirulina or placebo for 21 days in a double-blinded randomised crossover design, with a 14-day washout period between trials. Participants completed a 1-hour submaximal endurance test at 55% external power output max and a 16.1-km time trial (day 1), followed by a lactate threshold test and repeated sprint performance tests (RSPTs) (day 2). Heart rate (bpm), respiratory exchange ratio, oxygen consumption (mL/min/kg), lactate and glucose (mmol/L), time (seconds), power output (W), and hemoglobin (g/L) were compared across conditions. Following spirulina supplementation, lactate and heart rate were significantly lower (P < 0.05) during submaximal endurance tests (2.05 ± 0.80 mmol/L vs 2.39 ± 0.89 mmol/L and 139 ± 11 bpm vs 144 ± 12 bpm), hemoglobin was significantly higher (152.6 ± 9.0 g/L) than placebo (143.2 ± 8.5 g/L), and peak and average power were significantly higher during RSPTs (968 ± 177 W vs 929 ± 149 W and 770 ± 117 W vs 738 ± 86 W). No differences existed between conditions for all oxygen consumption values, 16.1-km time trial measures, and lactate threshold tests (P > 0.05). Spirulina supplementation reduces homeostatic disturbances during submaximal exercise and augments power output during RSPTs. Novelty: Spirulina supplementation lowers heart rate and blood lactate during ∼1-hour submaximal cycling. Spirulina supplementation elicits significant augmentations in hemoglobin and power outputs during RSPTs.
Vol. 47No. 1pp. 27–33
It is unclear whether neuromuscular electrical stimulation (NMES) has meaningful metabolic effects when users have the opportunity to self-select the intensity to one that can be comfortably tolerated. Nine healthy men aged 28 ± 9 y (mean ± SD) with a body mass index 22.3 ± 2.3 kg/m2 completed 3 trials involving a 2-h oral glucose tolerance test whilst, in a randomised counterbalanced order, (1) sitting motionless (SIT), (2) standing motionless (STAND); and (3) sitting motionless with NMES of quadriceps and calves at a self-selected tolerable intensity. The mean (95% confidence interval [CI]) total energy expenditure was greater in the NMES trial (221 [180–262] kcal/2 h) and STAND trial (178 [164–191] kcal/2 h) than during SIT (159 [150–167] kcal/2 h) (both, p < 0.05). This was primarily driven by an increase in carbohydrate oxidation in the NMES and STAND trials compared with the SIT trial (p < 0.05). Postprandial insulin iAUC was lower in both NMES and STAND compared with SIT (16.4 [7.7–25.1], 17 [7–27] and 22.6 [10.8–34.4] nmol·120 min/L, respectively; both, p < 0.05). Compared with sitting, both NMES and STAND increased energy expenditure and whole-body carbohydrate oxidation and reduced postprandial insulin concentrations in healthy men, with more pronounced effects seen with NMES. Self-selected NMES is a potential strategy for improving metabolic health. This trial is registered at ClinicalTrials.gov (ID: NCT04389736). Novelty: NMES at a comfortable intensity enhances energy expenditure and carbohydrate oxidation, and reduces postprandial insulinemia. Thus, self-selected NMES represents a potential strategy to improve metabolic health.
OPEN ACCESSEditor's choice
Vol. 47No. 1pp. 34–40
In January 2019, Health Canada released a revised Canada’s Food Guide (CFG). This study aimed to understand the perceptions of the 2019 CFG among Canadian parents with children aged 2–12 years. From October 2019–January 2020, 8 focus groups with parents from Southwestern Ontario were conducted using a semi-structured interview script focused on understanding perceptions of the 2019 CFG. A hybrid thematic approach with inductive and deductive analyses was used. Forty parents (72.5% mothers, 77.5% white) with diverse levels of education and income participated. Most parents were aware of the 2019 CFG. Positive perceptions of the 2019 CFG were that the guide was visually appealing and less biased from the food industry compared with previous guides. Parents also reported that the focus on eating behaviours could support healthy eating among their families. Negative perceptions included insufficient information about plant-based proteins, removal of milk and alternatives food group, and lack of representation of various cultures in the guide. Challenges to following the CFG recommendations, including time constraints and limited knowledge regarding how to identify and prepare plant-based proteins, were discussed. Parent perceptions of the CFG can help inform public health policies and behavioural-change strategies designed to support adherence to the 2019 CFG recommendations. Novelty: Awareness of the 2019 Canada’s Food Guide (CFG) was high. Parents identified that the 2019 CFG was visually appealing and less biased from the food industry. Concerns about the recommendations of plant-based proteins, “exclusion” of dairies, and lack of cultural representation.
Vol. 47No. 1pp. 41–50
Type 2 diabetes occurs as a result of insulin resistance and dysfunction in insulin signaling. Controlling hyperglycemia and activation of insulin signaling are important in the management of type 2 diabetes. This study aimed to evaluate the effect of genistein and Momordica charantia L. fruit (MCF) on oxidative stress, markers of inflammation, and their role in proglucagon and insulin receptor messenger RNA (mRNA) expression by real-time PCR in diabetic rats. Thirty-five albino rats were divided into 7 groups (n = 5). Group I (non-diabetic) and group II (diabetic control) were treated with distilled water, and groups III and IV received 250 mg/kg and 500 mg/kg lyophilized MCF, respectively. Groups V and VI received 10 mg/kg and 20 mg/kg genistein, respectively, while group VII received 500 mg/kg metformin. The administration lasted for 28 days. MCF and genistein significantly reduced interleukin (IL)-1β and tumor necrosis factor alpha (TNF-α) levels, which were elevated in the serum of diabetic rats. Treatment with MCF and genistein significantly increased the expression of proglucagon mRNA in the small intestine and insulin receptor mRNA in the liver of diabetic rats. In conclusion, MCF and genistein ameliorate type 2 diabetes complications by preventing the loss of insulin-positive cells, inhibiting IL-1β and TNF-α, and upregulating proglucagon and insulin receptor mRNA expression. Novelty: MCF and genistein have an inhibitory effect on diabetic induced IL-1β and TNF-α production. MCF and genistein upregulate proglucagon and insulin receptor mRNA expression.
Vol. 47No. 1pp. 51–59
Heart rate variability (HRV) measurement provides non-invasive assessment of autonomic stability and cardiometabolic disease risk. Insufficient physical activity in early childhood may contribute to negative cardiometabolic health. The Active Early Learning (AEL) study was a 6-month randomised controlled trial investigating the effects of a physical activity-based program incorporating movement within the daily curriculum of preschool children. The current study assessed the effects of the AEL intervention on HRV as a measure of cardiac vagal control. Children aged between 3–5 years and enrolled in a preschool with an attendance of ≥15 children were eligible. Physical activity was recorded using an Actigraph wGT3x accelerometer worn at the waist of participants over 3 consecutive days. A Polar H10 chest strap measured HRV with the HF-band and RMSSD representing cardiac vagal control. After 6 months of the AEL trial, linear mixed model analyses revealed a significant intervention effect for increased HF (p = 0.044). The control group did not demonstrate changes in cardiac vagal control after the intervention ceased. Independent of age, sex, physical activity and BMI, the AEL study elicited significant improvements in the cardiac vagal control of participants who received the intervention. Findings highlight the importance of investigating HRV for assessing the cardiometabolic health in young children. ANZCTR trial registration number: ACTRN12619000638134. Novelty: The AEL curriculum improved child HRV independent of age, sex, physical activity and BMI. Heart rate and RR intervals did not demonstrate changes for the intervention and control groups. Multivariate programs for developing physical competence, confidence, knowledge and motivation may improve child health.
Vol. 47No. 1pp. 60–68
The purpose of the present study was to investigate changes in the energy cost of locomotion during walking (Cw) related to changes in body mass (BM, kg) and body composition in adolescents with obesity. Twenty-six (12 boys and 14 girls) obese adolescents (mean: body mass index, 33.6 ± 3.7 kg·m–2; 42.7 ± 4.5% fat mass (FM)) followed a 9-month multidisciplinary inpatient weight-reduction program consisting of lifestyle education, moderate energy restriction, and regular physical activity in a specialised institution. At baseline (M0), the end of the 9-month program (M9), and after the 4-month follow-up (M13), oxygen consumption and carbon dioxide production of the standardised activity program were assessed by whole-body indirect calorimetry over 24 hours, and body composition was assessed by dual-energy X-ray absorptiometry. At M9, adolescents showed an 18% reduction in BM (p < 0.001) and 40% in total FM, while fat-free mass (kg) remained stable in boys but decreased by ∼6% in girls (p = 0.001). Similarly, the mean Cw decreased by 20% (p < 0.001). At M13, BM, FM, and Cw were slightly higher compared with at M9. In conclusion, moderate energy restriction and regular moderate physical activities improved walking economy, improved exercise tolerance, and induced beneficial changes in the body composition of adolescents with obesity. Novelty: Reduction of FM in the trunk region, and consequently reducing the work carried out by respiratory muscles, contributes to reducing Cw in adolescents with obesity. A lower walking cost can be effective in improving exercise tolerance and quality of life in obese adolescents.
Vol. 47No. 1pp. 69–74
Polycystic ovary syndrome (PCOS) is the most common endocrine disorder among women of reproductive age and is affected by various dietary factors. Therefore, this study aimed to investigate the relationship between dietary diversity score (DDS) and the risk of PCOS. Our case-control study was conducted in the summer and autumn of 2019 in Taleghani and Arash hospitals in Tehran, Iran. A total of 494 participants (203 cases and 291 controls) were included in the study. Thereafter, their demographic information, dietary intake, and anthropometric and physical activity assessments were gathered. A validated semi-quantitative food frequency questionnaire was then used to calculate the DDS by scoring 5 food groups. To evaluate the risk of PCOS in association with DDS, the subjects were categorized based on the quartile cut-off points of the DDS. The mean ± SD age of the participants in both the case and control groups was 28.98 ± 5.43 and 30.15 ± 6.21 years, while mean ± SD body mass index was 25.74 ± 5.44 and 23.65 ± 3.90 kg/m2, respectively. The comparison between the case and control groups indicated that total DDS was 5.19 ± 1.19 for the cases and 5.51 ± 1.19 for the controls. The comparison of DDS in the highest versus the lowest quartiles showed a decreased risk of PCOS (p < 0.05). We demonstrated an inverse association between DDS and PCOS compared with the control group. Furthermore, a higher DDS was significantly associated with a lower risk of PCOS (odds ratio = 0.40). Novelty: This is the first investigation on the relationship between DDS and PCOS. Results depicted an inverse relationship between DDS and PCOS.
Vol. 47No. 1pp. 75–82
Blood donation entails acute reductions of cardiorespiratory fitness in healthy men. Whether these effects can be extrapolated to blood donor populations comprising women remains uncertain. The purpose of this study was to comprehensively assess the acute impact of blood withdrawal on cardiac function, central hemodynamics and aerobic capacity in women throughout the mature adult lifespan. Transthoracic echocardiography and O2 uptake were assessed at rest and throughout incremental exercise (cycle ergometry) in healthy women (n = 30, age: 47–77 yr). Left ventricular end-diastolic volume (LVEDV), stroke volume (SV), cardiac output () and peak O2 uptake (O2peak), and blood volume (BV) were determined with established methods. Measurements were repeated following a 10% reduction of BV within a week period. Individuals were non-smokers, non-obese and moderately fit (O2peak = 31.4 ± 7.3 mL·min–1·kg–1). Hematocrit and BV ranged from 38.0 to 44.8% and from 3.8 to 6.6 L, respectively. The standard 10% reduction in BV resulted in 0.5 ± 0.1 L withdrawal of blood, which did not alter hematocrit (P = 0.953). Blood withdrawal substantially reduced cardiac LVEDV and SV at rest as well as during incremental exercise (≥10% decrements, P ≤ 0.009). Peak was proportionally decreased after blood withdrawal (P < 0.001). Blood withdrawal induced a 10% decrement in O2peak (P < 0.001). In conclusion, blood withdrawal impairs cardiac filling, and aerobic capacity in proportion to the magnitude of hypovolemia in healthy mature women. Novelty: The filling of the heart and therefore cardiac output are impaired by blood withdrawal in women. Oxygen delivery and aerobic capacity are reduced in proportion to blood withdrawal.
Vol. 47No. 1pp. 83–90
The terms drinking to thirst and ad libitum drinking are used interchangeably, but should they? We investigated the differences in how athletes consumed fluids during exercise when instructed to drink according to thirst or ad libitum. Using a randomized, crossover, and counterbalanced design, 10 males (27 ± 4 y) cycled 120 km (48 ± 4% of peak power, 33 °C, 40% relative humidity) on 2 occasions, while drinking water according to thirst or ad libitum. Participants covered the cycling trials in 222 ± 11 min (p = 0.29). Although the body mass loss at the end of exercise and total volume of water consumed were similar between trials, thirst perception before each sip and the volume consumed per sip were significantly higher with thirst than ad libitum drinking, whereas the total number of sips was significantly lower with thirst than ad libitum drinking. Perceived exertion, rectal temperature, and heart rate were all significantly higher with thirst than ad libitum drinking, but the difference was trivial. In conclusion, thirst and ad libitum drinking are associated with different drinking patterns, but equally maintain fluid balance during prolonged exercise. The terms drinking to thirst and ad libitum drinking can be used interchangeably to guide fluid intake during prolonged exercise. Novelty: Both strategies are associated with different patterns of fluid ingestion during prolonged exercise, but are equally effective in maintaining fluid balance. Perceived exertion, rectal temperature, and heart rate are regulated dissimilarly by thirst and ad libitum drinking, but the difference is trivial.
OPEN ACCESS
Vol. 47No. 1pp. 91–98
Vitamin D status, measured in a Vitamin D Standardization Program certified laboratory, was assessed among children of South Asian and European ethnicity living in the national capital region of Canada to explore factors that may account for inadequate status. Demographic information, dietary and supplemental vitamin D over 30 d prior to measurement of serum 25-hydroxyvitamin D (25OHD), and anthropometry were measured (age 6.0–18.9 y; n = 58/group; February–March 2015). No group related differences in age, height and body mass index (BMI) Z-scores or in food vitamin D intakes were observed. Standardized serum 25OHD was lower in South Asian children (mean ± SD: 39.0 ± 16.8 nmol/L vs. European: 58.4 ± 15.8 nmol/L). A greater proportion of South Asian children had serum 25OHD <40 nmol/L (56.9 vs. 8.6%, P < 0.0001) and fewer took supplements (31 vs. 50%, P = 0.0389). In a multi-factorial model (r2 = 0.54), lower vitamin D status was associated with overweight/obese BMI and older age (14–18 y); no interaction with ethnicity was observed. Lower vitamin D status was associated with lower total vitamin D intake only in South Asian children. This study reinforces the importance of public health actions towards meeting vitamin D intake recommendations among those of high-risk deficiency. Novelty: A higher proportion of South Asian vs. European children had inadequate vitamin D status. Lower vitamin D status was associated with a BMI in the overweight/obese range. Lower vitamin D status was associated with lower total vitamin D intake in South Asian but not European children.
Vol. 47No. 1pp. 99–105
The increase in blood pressure (BP) during somatic growth might have direct determinants but also mediating factors. We investigated whether uric acid (UA) and other metabolic factors would mediate the association between body composition components and BP. A cross-sectional study was conducted in 928 children and adolescents (aged 6–18 years), in which body composition and blood biochemistry were evaluated. Structural equation modeling was performed to test the direct and indirect pathways between systolic blood pressure (SBP) and body composition parameters. Muscle mass (MM) showed a strong direct effect on BP, regardless of sex. In girls, a mediating pathway through UA was not significant, but the association between fat mass (FM) and MM with SBP was mediated by the cluster of metabolic factors. In boys, both MM and FM were associated with SBP through a mediating pathway via UA, but not via the cluster of metabolic factors. The association between body composition and BP in children and adolescents has a complex design and also has a sex-specific mediating component. The increase in the UA levels may affect BP levels early in boys. Also, metabolic changes elicited by FM contribute to the increase in BP at an early age in girls. Novelty: MM showed a strong direct effect on BP, regardless of sex. In girls, the association between FM and MM with SBP was mediated by the cluster of metabolic factors. In boys, both MM and FM were associated with SBP through a mediating pathway via UA.

Brief communications

Vol. 47No. 1pp. 106–109
This study examined if acute dietary nitrate supplementation (140 mL beetroot juice, BRJ) would reduce oxygen consumption (O2) during cycling at power outputs of 50 and 70% maximal oxygen consumption in 14 well-trained female Canadian University Ringette League athletes. BRJ had no effect on O2 or heart rate but significantly reduced ratings of perceived exertion (RPE) at both intensities. Individually, 4 participants responded to BRJ supplementation with a ≥3% reduction in O2 at the higher power output. Novelty: Acute BRJ supplementation did not improve exercise economy in well-trained females, but significantly reduced RPE. However, 4/14 subjects did respond with a ≥3% O2 reduction.
Vol. 47No. 1pp. 110–113
During uncompensable occupational heat stress, heat-mitigation controls are required to prevent core temperature exceeding recommended limits (≥38 °C). However, the initial stay time before employing controls remained unknown. We estimated these times for moderate-intensity work at 26, 28, 30, and 32 °C wet-bulb globe temperatures (WBGT) in 50 young (18–30 years) and older (50–70 years), non-heat acclimatized men. Initial stay time was 111 min at 26 °C WBGT and declined exponentially to 44 min at 32 °C WBGT. Novelty: We provide estimates of the moderate-intensity work duration before heat-mitigation is required in wet-bulb globe temperatures between 26–32 °C for young and older, non-heat acclimatized men.
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2025
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