Associations between Aging and Vitamin D Status with Whole-Body Nitric Oxide Production and Markers of Endothelial Function.

BACKGROUND: Aging and vitamin D deficiency have been associated with reduced nitric oxide (NO) synthesis and impaired endothelial function (EF) but the evidence in humans remains weak. OBJECTIVES: Two independent cross-sectional studies were designed to evaluate the association between age, sex, and plasma vitamin D concentrations with physiological and biochemical biomarkers of NO synthesis and EF in young and older healthy participants (Study 1) and in overweight and obese postmenopausal females (Study 2). METHODS: In Study 1, 40 young (20-49 y) and older (50-75 y) males and females (10 participants per age and sex group) were included. Resting blood pressure and ear-to-finger peripheral pulse wave velocity (PWV) were measured. A stable-isotopic method was used to determine whole-body NO production. Plasma 25-hydroxyvitamin D (25(OH)D), nitrate, nitrite, and asymmetric dimethylarginine (ADMA) concentrations were determined. In Study 2, 80 older overweight and obese females (age 61.2 ± 6.2 y, body mass index 29.5 ± 4.4 kg/m2) were recruited. Postocclusion reactive hyperemia (PORH) and peripheral PWV were measured. Plasma concentrations of 25(OH)D, nitrate, cyclic guanosine monophosphate, 3-nitrotyrosine (3-NT), endothelin-1, vascular endothelial growth factor, and ADMA were determined. RESULTS: In Study 1, whole-body NO production was significantly greater in young compared with older participants (0.61 ± 0.30 µmol·h-1·kg-1 compared with 0.39 ± 0.10 µmol·h-1·kg-1, P = 0.01) but there was no evidence of a sex difference (P = 0.81). Plasma 25(OH)D concentration was not associated with PWV (r = 0.18, P = 0.28) or whole-body NO production (r = -0.20, P = 0.22). Plasma ADMA concentration was associated positively with age (r = 0.35, P = 0.03) and negatively with whole-body NO production (r = -0.33, P = 0.04). In Study 2, age was associated with lower PORH (r = -0.28, P = 0.02) and greater ADMA concentrations (r = 0.22, P = 0.04). Plasma 25(OH)D concentration was inversely associated with 3-NT concentrations (r = -0.31, P = 0.004). CONCLUSIONS: Older age was associated with lower whole-body NO production. Plasma vitamin D concentrations were not associated with NO production or markers of EF but showed a weak, significant correlation with oxidative stress in postmenopausal overweight females.

Effects of dietary nitrate supplementation on oral health and associated markers of systemic health: a systematic review.

Poor oral health can impact an individual's ability to eat and has been associated with an increased risk of non-communicable diseases. While the benefits of nitrate consumption on oral health were first proposed more than 20 years ago, no systematic review has been published examining effects of dietary nitrate on oral health. This systematic review investigated the effects of dietary nitrate on markers of oral health in vivo in randomized controlled trials (RCTs). Five databases (PubMed, The Cochrane Library, CINAHL, MEDLINE, and SPORTDiscus) were searched from inception until March 2023. Nine articles reporting data on 284 participants were included. Dietary nitrate was provided via beetroot juice in most studies. The duration of the interventions ranged from one day to six weeks. Dietary nitrate supplementation increased the relative abundance of several individual bacterial genera including Neisseria and Rothia. Dietary nitrate supplementation increased salivary pH and decreased salivary acidification following consumption of a sugar-sweetened beverage. Furthermore, dietary nitrate supplementation resulted in a decrease in the gingival inflammation index. The results of this systematic review suggest that dietary nitrate could represent a potential nutritional strategy to positively modify oral health by impacting the oral microbiome, altering salivary pH, and minimizing gingival inflammation.

The Mediterranean diet is not associated with neuroimaging or cognition in middle-aged adults: a cross-sectional analysis of the PREVENT dementia programme.

BACKGROUND AND PURPOSE: The Mediterranean diet (MedDiet) has been associated with reduced dementia incidence in several studies. It is important to understand if diet is associated with brain health in midlife, when Alzheimer's disease and related dementias are known to begin. METHODS: This study used data from the PREVENT dementia programme. Three MedDiet scores were created (the Pyramid, Mediterranean Diet Adherence Screener [MEDAS] and MEDAS continuous) from a self-reported food frequency questionnaire. Primary outcomes were hippocampal volume and cube-transformed white matter hyperintensity volume. Secondary outcomes included cornu ammonis 1 and subiculum hippocampal subfield volumes, cortical thickness and measures of cognition. Sex-stratified analyses were run to explore differential associations between diet and brain health by sex. An exploratory path analysis was conducted to study if any associations between diet and brain health were mediated by cardiovascular risk factors for dementia. RESULTS: In all, 504 participants were included in this analysis, with a mean Pyramid score of 8.10 (SD 1.56). There were no significant associations between any MedDiet scoring method and any of the primary or secondary outcomes. There were no differences by sex in any analyses and no significant mediation between the Pyramid score and global cognition by cardiovascular risk factors. CONCLUSIONS: Overall, this study did not find evidence for an association between the MedDiet and either neuroimaging or cognition in a midlife population study. Future work should investigate associations between the MedDiet and Alzheimer's disease and related dementias biomarkers as well as functional neuroimaging in a midlife population.

Higher plant-derived nitrate intake is associated with lower odds of frailty in a cross-sectional study of community-dwelling older women.

PURPOSE: Dietary nitrate intake is inversely related to numerous contributors towards frailty, including cardiovascular disease and poor physical function. Whether these findings extend to frailty remain unknown. We investigated if habitual nitrate intake, derived from plants or animal-based foods, was cross-sectionally associated with frailty in women. METHODS: Community-dwelling older Australian women (n = 1390, mean age 75.1 ± 2.7 years) completed a validated semi-quantitative food frequency questionnaire (FFQ). Nitrate concentrations in food were obtained from international nitrate databases. We adopted the Rockwood frailty index (FI) of cumulative deficits comprising 33 variables across multiple health domains (scored 0 to 1), which predicts increased hospitalisation and mortality risk. A FI ≥ 0.25 indicated frailty. Cross-sectional associations between nitrate intake (total plant and animal nitrate, separately) and frailty were analysed using multivariable-adjusted logistic regression models (including lifestyle factors), as part of restricted cubic splines. RESULTS: A non-linear inverse relationship was observed between total plant nitrate intake and frailty. Compared to women with the lowest plant nitrate intake (Quartile [Q]1), women with greater intakes in Q2 (OR 0.69 95%CI 0.56-0.84), Q3 (OR 0.67 95%CI 0.50-0.90) and Q4 (OR 0.66 95%CI 0.45-0.98) had lower odds for frailty. A nadir in the inverse association was observed once intakes reached ~ 64 mg/d (median Q2). No relationship was observed between total animal nitrate and frailty. CONCLUSION: Community-dwelling older women consuming low amounts of plant-derived nitrate were more likely to present with frailty. Consuming at least one daily serving (~ 75 g) of nitrate-rich green leafy vegetables may be beneficial in preventing frailty.

Nutrition for dementia prevention: a state of the art update for clinicians.

BACKGROUND AND OBJECTIVES: Dementia prevalence continues to rise. It is therefore essential to provide feasible and effective recommendations to encourage healthy brain ageing and reduce dementia risk across the population. Appropriate nutrition represents a potential strategy to mitigate dementia risk and could be recommended by clinicians as part of mid-life health checks and other health initiatives to reduce dementia prevalence. The purpose of this review is to provide a clinician-focused update on the current state of the knowledge on nutrition and dementia prevention. METHODS: Narrative review. RESULTS: Strong evidence exists to support the consumption of healthy, plant-based dietary patterns (e.g. Mediterranean, MIND or Nordic diet) for maintaining cognitive function and reducing dementia risk in later life and is supported by dementia prevention guideline from leading public health bodies (e.g. World Health Organization). Emerging evidence suggests potential cognitive benefits of consuming specific nutrients/foods (e.g. n-3 fatty acids or fish, flavonols and B-vitamins) and multi-nutrient compounds (e.g. Fortasyn Connect). Challenges and opportunities for integrating nutritional/dietary interventions for dementia prevention into clinical practice are explored in this review. CONCLUSIONS: Appropriate nutrition represents an important factor to help facilitate healthy cognitive ageing and allay dementia risk. The information provided in this article can help clinicians provide informed opinions on appropriate nutritional strategies as part of mid-life Health Checks and other risk reduction initiatives.

Mediterranean diet adherence is associated with lower dementia risk, independent of genetic predisposition: findings from the UK Biobank prospective cohort study.

BACKGROUND: The identification of effective dementia prevention strategies is a major public health priority, due to the enormous and growing societal cost of this condition. Consumption of a Mediterranean diet (MedDiet) has been proposed to reduce dementia risk. However, current evidence is inconclusive and is typically derived from small cohorts with limited dementia cases. Additionally, few studies have explored the interaction between diet and genetic risk of dementia. METHODS: We used Cox proportional hazard regression models to explore the associations between MedDiet adherence, defined using two different scores (Mediterranean Diet Adherence Screener [MEDAS] continuous and Mediterranean diet Pyramid [PYRAMID] scores), and incident all-cause dementia risk in 60,298 participants from UK Biobank, followed for an average 9.1 years. The interaction between diet and polygenic risk for dementia was also tested. RESULTS: Higher MedDiet adherence was associated with lower dementia risk (MEDAS continuous: HR = 0.77, 95% CI = 0.65-0.91; PYRAMID: HR = 0.86, 95% CI = 0.73-1.02 for highest versus lowest tertiles). There was no significant interaction between MedDiet adherence defined by the MEDAS continuous and PYRAMID scores and polygenic risk for dementia. CONCLUSIONS: Higher adherence to a MedDiet was associated with lower dementia risk, independent of genetic risk, underlining the importance of diet in dementia prevention interventions.

Effects of a mediterranean diet on the gut microbiota and microbial metabolites: A systematic review of randomized controlled trials and observational studies.

Consumption of the Mediterranean dietary pattern (MedDiet) is associated with reduced risk of numerous non-communicable diseases. Modulation of the composition and metabolism of the gut microbiota represents a potential mechanism through which the MedDiet elicits these effects. We conducted a systematic literature search (Prospero registration: CRD42020168977) using PubMed, The Cochrane Library, MEDLINE, SPORTDiscuss, Scopus and CINAHL databases for randomized controlled trials (RCTs) and observational studies exploring the impact of a MedDiet on gut microbiota composition (i.e., relative abundance of bacteria or diversity metrics) and metabolites (e.g., short chain fatty acids). Seventeen RCTs and 17 observational studies were eligible for inclusion in this review. Risk of bias across the studies was mixed but mainly identified as low and unclear. Overall, RCTs and observational studies provided no clear evidence of a consistent effect of a MedDiet on composition or metabolism of the gut microbiota. These findings may be related to the diverse methods across studies (e.g., MedDiet classification and analytical techniques), cohort characteristics, and variable quality of studies. Further, well-designed studies are warranted to advance understanding of the potential effects of the MedDiet using more detailed examination of microbiota and microbial metabolites with reference to emerging characteristics of a healthy gut microbiome.

Moderate doses of dietary nitrate elicit greater effects on blood pressure and endothelial function than a high dose: A 13-week pilot study.

BACKGROUND & AIMS: Few studies have explored the prolonged effects of dietary nitrate on vascular health. This pilot study tested the effects of prolonged consumption (13 weeks) of a range of doses of dietary nitrate (NO3-), provided as beetroot juice (BJ), on blood pressure (BP) and endothelial function in overweight and obese older participants. METHODS AND RESULTS: Sixty-two overweight or obese older participants (60-75 years) were randomized to the following interventions: (1) high NO3- (2) medium NO3-, (3) low NO3-, or (4) placebo. Resting clinic and home BP were measured pre- and post-intervention. Laser Doppler iontophoresis was used to quantify changes in endothelial-dependent and independent microvascular blood flow. RESULTS: This pilot study showed that medium and low doses of NO3- were more effective in lowering resting-clinic SBP (P = 0.04 and, P = 0.03, respectively) than was PL. The lower doses of NO3- also resulted in significant increases in microvascular perfusion (medium, P = 0.02; low, P = 0.002) relative to baseline values. CONCLUSION: These findings indicate that supplementation with medium and low, but not high, doses of NO3- for 13 weeks had positive effects on BP and endothelial function in older overweight and obese adults. These findings require confirmation in larger studies.

Dietary nitrate, aging and brain health: the latest evidence.

PURPOSE OF REVIEW: With an increasing population age, cognitive decline and age-associated neurodegenerative diseases are becoming increasingly prevalent and burdensome in society. Dietary supplementation with inorganic nitrate, which serves as a nitric oxide precursor, has been suggested as a potential nutritional strategy to improve brain health in older adults. In this review, we discuss recent findings in this area. RECENT FINDINGS: A number of studies have emerged in the past 12-18 months exploring the effects of dietary nitrate supplementation on cognitive function, with typically (although not exclusively) null findings emerging. This research is characterized by small, acute/short-term studies, although observational studies and longer-duration randomised controlled trials are beginning to emerge. From the limited research reporting benefits of nitrate supplementation on cognitive function, one important discovery has been the identification of a potential pathway through which nitrate could impact cognitive health, involving modulation of the oral microbiome, which warrants further investigation. SUMMARY: Despite some promising early findings, there is currently insufficient evidence to recommend increased dietary nitrate intake for the purpose of improving brain health. However, longer-term, larger-scale trials in potentially responsive groups are warranted to provide definitive evidence in this area.

Nitric oxide, aging and aerobic exercise: Sedentary individuals to Master's athletes.

Aging is associated with a decline in physiological function and exercise performance. These effects are mediated, at least in part, by an age-related decrease in the bioavailability of nitric oxide (NO), a ubiquitous gasotransmitter and regulator of myriad physiological processes. The decrease in NO bioavailability with aging is especially apparent in sedentary individuals, whereas older, physically active individuals maintain higher levels of NO with advancing age. Strategies which enhance NO bioavailability (including nutritional supplementation) have been proposed as a potential means of reducing the age-related decrease in physiological function and enhancing exercise performance and may be of interest to a range of older individuals including those taking part in competitive sport. In this brief review we discuss the effects of aging on physiological function and endurance exercise performance, and the potential role of changes in NO bioavailability in these processes. We also provide a summary of current evidence for dietary supplementation with substrates for NO production - including inorganic nitrate and nitrite, l-arginine and l-citrulline - for improving exercise capacity/performance in older adults. Additionally, we discuss the (limited) evidence on the effects of (poly)phenols and other dietary antioxidants on NO bioavailability in older individuals. Finally, we provide suggestions for future research.

Independent and interactive associations of dietary nitrate and salt intake with blood pressure and cognitive function: a cross-sectional analysis in the InCHIANTI study.

Blood pressure (BP) control is a key target for interventions to reduce cognitive decline. This cross-sectional study explored associations between objective (24-hour urine excretion) and subjective (food frequency questionnaire [FFQ]) measures of dietary sodium and nitrate intakes with cognitive function and resting BP in the InCHIANTI cohort. Baseline data from 989 participants aged >50 years were included. In fully adjusted models, participants with concurrent high nitrate and low sodium (Odds Ratio (OR)=0.49, 95%CI 0.32-0.76, p = 0.001) and high nitrate and high sodium (OR = 0.49, 95%CI 0.32-0.77, p = 0.002) 24-hour urinary concentrations had lower odds of high BP than participants with low nitrate and high sodium concentrations. We found no significant associations between sodium and nitrate intakes (24-hour urinary concentrations and FFQ) and poor cognitive performance. Urinary nitrate excretion was associated with lower BP and results appeared to be independent of sodium intake. Further analyses in longitudinal studies are required to substantiate these findings.

Mediterranean Diet Increases Endothelial Function in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

BACKGROUND: The endothelium plays a key role in the maintenance of vascular health and represents a potential physiological target for dietary and other lifestyle interventions designed to reduce the risk of cardiovascular diseases (CVD) including stroke or coronary heart disease. OBJECTIVE: To conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) investigating the effects of the Mediterranean dietary pattern (MedDiet) on endothelial function. METHODS: Medline, Embase, and Scopus databases were searched from inception until January 2019 for studies that met the following criteria: 1) RCTs including adult participants, 2) interventions promoting the MedDiet, 3) inclusion of a control group, and 4) measurements of endothelial function. A random-effects meta-analysis was conducted. Metaregression and subgroup analyses were performed to identify whether effects were modified by health status (i.e., healthy participants versus participants with existing comorbidities), type of intervention (i.e., MedDiet alone or with a cointervention), study duration, study design (i.e., parallel or crossover), BMI, and age of participants. RESULTS: Fourteen articles reporting data for 1930 participants were included in the meta-analysis. Study duration ranged from 4 wk to 2.3 y. We observed a beneficial effect of the MedDiet on endothelial function [standardized mean difference (SMD): 0.35; 95% CI: 0.17, 0.53; P <0.001; I2 = 73.68%]. MedDiet interventions improved flow-mediated dilation (FMD)-the reference method for noninvasive, clinical measurement of endothelial function-by 1.66% (absolute change; 95% CI: 1.15, 2.17; P <0.001; I2 = 0%). Effects of the MedDiet on endothelial function were not modified by health status, type of intervention, study duration, study design, BMI, or age of participants (P >0.05). CONCLUSIONS: MedDiet interventions improve endothelial function in adults, suggesting that the protective effects of the MedDiet are evident at early stages of the atherosclerotic process with important implications for the early prevention of CVD. This study has the PROSPERO registration number: CRD42018106188.

Appetite and energy intake responses to breakfast consumption and carbohydrate supplementation in hypoxia.

PURPOSE: The purpose of experiment one was to determine the appetite, acylated ghrelin and energy intake response to breakfast consumption and omission in hypoxia and normoxia. Experiment two aimed to determine the appetite, acylated ghrelin and energy intake response to carbohydrate supplementation after both breakfast consumption and omission in hypoxia. METHODS: In experiment one, twelve participants rested and exercised once after breakfast consumption and once after omission in normobaric hypoxia (4300 m: FiO2 ~11.7%) and normoxia. In experiment two, eleven participants rested and exercised in normobaric hypoxia (4300 m: FiO2 ~11.7%), twice after consuming a high carbohydrate breakfast and twice after breakfast omission. Participants consumed both a carbohydrate (1.2g·min-1 glucose) and a placebo beverage after breakfast consumption and omission. Measures of appetite perceptions and acylated ghrelin were taken at regular intervals throughout both experiments and an ad-libitum meal was provided post-exercise to quantify energy intake. RESULTS: Breakfast consumption had no significant effect on post exercise energy intake or acylated ghrelin concentrations, despite reductions in appetite perceptions. As such, breakfast consumption increased total trial energy intake compared with breakfast omission in hypoxia (7136 ± 2047 kJ vs. 5412 ± 1652 kJ; p = 0.02) and normoxia (9276 ± 3058 vs. 6654 ± 2091 kJ; p < 0.01). Carbohydrate supplementation had no effect on appetite perceptions or acylated ghrelin concentrations after breakfast consumption or omission. As such, carbohydrate supplementation increased total energy intake after breakfast consumption (10222 ± 2831 kJ vs. 7695 ± 1970 kJ p < 0.01) and omission (8058 ± 2574 kJ vs. 6174 ± 2222 kJ p = 0.02). CONCLUSION: Both breakfast consumption and carbohydrate supplementation provide beneficial dietary interventions for increasing energy intake in hypoxic conditions.

Validity and reliability of test strips for the measurement of salivary nitrite concentration with and without the use of mouthwash in healthy adults.

The nitrate (NO3-)-nitrite (NO2-)-nitric oxide (NO) pathway has received considerable interest in recent years as a potential target for nutritional interventions designed to increase NO production, and elicit therapeutic effects in humans. In particular, studies have evaluated the effects of supplemental dietary NO3-, which serves as a 'substrate' for this pathway, on numerous different health outcomes. One challenge has been to evaluate compliance with the NO3- interventions. A recent advance in this field has been the development of a non-invasive, simple and rapid method to measure nitrite concentrations in saliva using small test salivary strips. In the present study, ten healthy adults were recruited to a randomised, crossover study and received an acute dose of NO3--rich beetroot juice (BJ) after rinsing their mouth with either water or commercially available antibacterial mouthwash. Salivary NO3- and NO2- concentrations were measured at baseline and up to 5 h after BJ consumption using the gold-standard chemiluminescence and a colorimetric Griess assay. In addition, two salivary test strips (Berkeley Test strips, CA, USA) were used to measure NO2-concentrations at the same time points. Five observers read the strips and inter- and intra-observer reliability was measured. The Bland-Altman method was used to provide a visual representation of the agreement between the methods used to evaluate salivary NO3-/NO2-concentration. Sialin concentrations were measured at baseline and up to 5 h after BJ consumption. BJ elevated salivary NO3- and NO2- concentrations when the mouth was rinsed with water (both P < 0.01), as assessed via both chemiluminescence and Griess methods. Rinsing the mouth with antibacterial mouthwash attenuated markedly the increase in NO2- (P < 0.001), while NO3-concentrations were unaffected (P > 0.05). The Intra-Class Coefficients of Correlation (ICC) showed a high inter- and intra-observer reliability (r > 0.8). A significant positive correlation was found between absolute salivary NO2- concentrations measured by strips and Griess and chemiluminescence methods (rho = 0.83 and 0.77, respectively) and also when expressed as changes in salivary NO2- concentrations (rho = 0.80 and 0.79, respectively). Bland Altman analysis indicated a poor agreement for absolute NO2- concentrations between salivary strips and the chemiluminescence and Griess methods. A small significant negative correlation was found between changes in salivary sialin and salivary NO2- concentrations (r = -0.20, P = 0.04). A non-significant positive correlation was observed between the change in salivary sialin and salivary NO3- concentrations (r = 0.18, P = 0.06). This study suggests that commercially available salivary NO2- test strips provide a reasonable surrogate marker for monitoring changes in salivary NO2- concentrations in humans. However, the strips do not provide accurate estimates of absolute NO2- concentrations.

Effects of inorganic nitrate and nitrite consumption on cognitive function and cerebral blood flow: A systematic review and meta-analysis of randomized clinical trials.

We conducted a systematic review and meta-analysis of randomized clinical trials examining the effect of inorganic nitrate or nitrite supplementation on cognitive function (CF) and cerebral blood flow (CBF). Two databases (PubMed, Embase) were searched for articles from inception until May 2017. Inclusion criteria were: randomized clinical trials; participants >18 years old; trials comparing a nitrate/nitrite intervention with a control. Thirteen and nine trials were included in the meta-analysis to assess CF and CBF, respectively. Random-effects models were used and the effect size described as standardized mean differences (SMDs). A total of 297 participants (median of 23 per trial) were included for CF; 163 participants (median of 16 per trial) were included for CBF. Nitrate/nitrite supplementation did not influence CF (SMD +0.06, 95% CI: -0.06, 0.18, P = 0.32) or CBF under resting (SMD +0.14, 95% CI: -0.13, 0.41, P = 0.31), or stimulated conditions (SMD + 0.23, 95% CI: -0.11, 0.56, P = 0.19). The meta-regression showed an inverse association between duration of the intervention and CBF (P = 0.02) but no influence of age, BMI or dose (P < 0.05). Nitrate and nitrite supplementation did not modify CBF or CF. Further trials employing larger samples sizes and interventions with longer duration are warranted.

A single day of mixed-macronutrient overfeeding does not elicit compensatory appetite or energy intake responses but exaggerates postprandial lipaemia during the next day in healthy young men.

Discrete episodes of overconsumption may induce a positive energy balance and impair metabolic control. However, the effects of an ecologically relevant, single day of balanced macronutrient overfeeding are unknown. Twelve healthy men (of age 22 (sd 2) years, BMI 26·1 (sd 4·2) kg/m2) completed two 28 h, single-blind experimental trials. In a counterbalanced repeated measures design, participants either consumed their calculated daily energy requirements (energy balance trial (EB): 10 755 (sd 593) kJ) or were overfed by 50 % (overfeed trial (OF): 16 132 (sd 889) kJ) under laboratory supervision. Participants returned to the laboratory the next day, after an overnight fast, to complete a mixed-meal tolerance test (MTT). Appetite was not different between trials during day 1 (P>0·211) or during the MTT in the fasted or postprandial state (P>0·507). Accordingly, plasma acylated ghrelin, total glucagon-like peptide-1 and total peptide YY concentrations did not differ between trials during the MTT (all P>0·335). Ad libitum energy intake, assessed upon completion of the MTT, did not differ between trials (EB 6081 (sd 2260) kJ; OF 6182 (sd 1960) kJ; P=0·781). Plasma glucose and insulin concentrations were not different between trials (P>0·715). Fasted NEFA concentrations were lower in OF compared with EB (P=0·005), and TAG concentrations increased to a greater extent on OF than on EB during the MTT (P=0·009). The absence of compensatory changes in appetite-related variables after 1 d of mixed macronutrient overfeeding highlights the limited physiological response to defend against excess energy intake. This supports the concept that repeated discrete episodes of overconsumption may promote weight gain, while elevations in postprandial lipaemia may increase CVD risk.

Substrate oxidation and the influence of breakfast in normobaric hypoxia and normoxia.

PURPOSE: Previous research has reported inconsistent effects of hypoxia on substrate oxidation, which may be due to differences in methodological design, such as pre-exercise nutritional status and exercise intensity. This study investigated the effect of breakfast consumption on substrate oxidation at varying exercise intensities in normobaric hypoxia compared with normoxia. METHODS: Twelve participants rested and exercised once after breakfast consumption and once after omission in normobaric hypoxia (4300 m: FiO2 ~ 11.7%) and normoxia. Exercise consisted of walking for 20 min at 40%, 50% and 60% of altitude-specific [Formula: see text]O2max at 10-15% gradient with a 10 kg backpack. Indirect calorimetry was used to calculate carbohydrate and fat oxidation. RESULTS: The relative contribution of carbohydrate oxidation to energy expenditure was significantly reduced in hypoxia compared with normoxia during exercise after breakfast omission at 40% (22.4 ± 17.5% vs. 38.5 ± 15.5%, p = 0.03) and 60% [Formula: see text]O2max (35.4 ± 12.4 vs. 50.1 ± 17.6%, p = 0.03), with a trend observed at 50% [Formula: see text]O2max (23.6 ± 17.9% vs. 38.1 ± 17.0%, p = 0.07). The relative contribution of carbohydrate oxidation to energy expenditure was not significantly different in hypoxia compared with normoxia during exercise after breakfast consumption at 40% (42.4 ± 15.7% vs. 48.5 ± 13.3%, p = 0.99), 50% (43.1 ± 11.7% vs. 47.1 ± 14.0%, p = 0.99) and 60% [Formula: see text]O2max (54.6 ± 17.8% vs. 55.1 ± 15.0%, p = 0.99). CONCLUSIONS: Relative carbohydrate oxidation was significantly reduced in hypoxia compared with normoxia during exercise after breakfast omission but not during exercise after breakfast consumption. This response remained consistent with increasing exercise intensities. These findings may explain some of the disparity in the literature.

Nutritional Intake in Elite Cross-Country Skiers During Two Days of Training and Competition.

This study investigated the energy, macronutrient, and fluid intakes, as well as hydration status (urine specific gravity), in elite cross-country skiers during a typical day of training (Day 1) and a sprint skiing competition the following day (Day 2). A total of 31 (18 males and 13 females) national team skiers recorded their food and fluid intakes and urine specific gravity was measured on Days 1 and 2. In addition, the females completed the Low Energy Availability in Females Questionnaire to assess their risk of long-term energy deficiency. Energy intake for males was 65 ± 9 kcal/kg on Day 1 versus 58 ± 9 kcal/kg on Day 2 (p = .002) and for females was 57 ± 10 on Day 1 versus 55 ± 5 kcal/kg on Day 2 (p = .445). Carbohydrate intake recommendations of 10-12 g·kg-1·day-1 were not met by 89% of males and 92% of females. All males and females had a protein intake above the recommended 1.2-2.0 g/kg on both days and a postexercise protein intake above the recommended 0.3 g/kg. Of the females, 31% were classified as being at risk of long-term energy deficiency. In the morning of Day 1, 50% of males and 46% of females were dehydrated; on Day 2, this was the case for 56% of males and 38% of females. In conclusion, these data suggest that elite cross-country skiers ingested more protein and less carbohydrate than recommended and one third of the females were considered at risk of long-term energy deficiency. Furthermore, many of the athletes were dehydrated prior to training and competition.

The Effect of a Dietary Nitrate Supplementation in the Form of a Single Shot of Beetroot Juice on Static and Dynamic Apnea Performance.

INTRODUCTION: The purpose of the present study was to assess the effects of acute nitrate ([Formula: see text])-rich beetroot juice (BRJ) supplementation on peripheral oxygen saturation (SpO2), heart rate (HR), and pulmonary gas exchange during submaximal static and dynamic apnea. METHODS: Nine (six males and three females) trained apneists (age: 39.6 ± 8.2 years, stature: 170.4 ± 11.5 cm, and body mass: 72.0 ± 11.5 kg) performed three submaximal static apneas at 60%, 70%, and 80% of the participant's current reported personal best time, followed by three submaximal (∼75% or personal best distance) dynamic apneas following the consumption of either a 70-ml concentrated BRJ (7.7 mmol [Formula: see text]) or a [Formula: see text]-depleted placebo (PLA; 0.1 mmol [Formula: see text]) in double-blind randomized manner. HR and SpO2 were measured via fingertip pulse oximetry at the nadir, and online gas analysis was used to assess pulmonary oxygen uptake ([Formula: see text]) during recovery following breath-holds. RESULTS: There were no differences (p < .05) among conditions for HR (PLA = 59 ± 11 bpm and BRJ = 61 ± 12 bpm), SpO2 (PLA = 83% ± 14% and BRJ = 84% ±9%), or [Formula: see text] (PLA = 1.00 ± 0.22 L/min and BRJ = 0.97 ± 0.27 L/min). CONCLUSION: The consumption of 7.7 mmol of beetroot juice supplementation prior to a series of submaximal static and dynamic apneas did not induce a significant change in SpO2, HR, and [Formula: see text] when compared with placebo. Therefore, there is no apparent physiological response that may benefit free divers as a result of the supplementation.

Associations between anxiety, depression, and weight status during and after pregnancy: A systematic review and meta-analysis.

Previous work has found adverse mental health symptomology in women living with obesity, compared with those of healthy weight, around the time of pregnancy. This meta-analysis aimed to explore the association between anxiety, depression, and weight status in women living with obesity before, during, and after pregnancy. Bibliographic databases were systematically searched, and 14 studies were included, which aimed to assess the association between excess weight and anxiety or depression outcomes in women before, during, or after pregnancy. Data were analyzed via narrative synthesis and random effects multi-level meta-analyses. Scores on mental health indices were significantly greater (indicative of worse anxiety/depression) in women with obesity compared to women of a healthy weight, around the time of pregnancy (SMD = 0.21 [95% CI: 0.11-0.31; 95% prediction intervals: 0.13-0.56], I2  = 73%, p < 0.01). Depressive symptoms were greater during and after pregnancy (SMD = 0.23 [95% CI: 0.13-0.34; 95% prediction intervals: -0.12 to 0.59], I2  = 75.0%, p < 0.01), and trait anxiety symptoms were greater during pregnancy (SMD = 0.24 [95% CI: 0.01-0.47; 95% prediction intervals: -0.25 to 0.72], I2  = 83.7%, p = 0.039) in women living with obesity, compared to those of healthy weight. Narrative evidence suggests that socioeconomic status and ethnicity may modify the relationship between obesity and mental health symptomology. The findings indicate that maternal obesity is associated with greater anxiety and depression symptoms. These findings may inform the design of maternal weight management interventions.