Total fermentable oligo-, di-, monosaccharides and polyols intake, carbohydrate malabsorption and gastrointestinal symptoms during a 56 km trail ultramarathon event

AIMS

To explore the relationship between nutritional intake, fermentable oligo-, di, monosaccharides and polyols, and carbohydrate malabsorption, with gastrointestinal symptoms during a 56 km trail ultramarathon event and identify differences in nutritional intake between runners with severe and non-severe gastrointestinal symptoms.

METHODS

Forty-four ultramarathoners recorded and self-reported dietary intake 3 days before, morning of, and during the ultramarathon with gastrointestinal symptoms obtained retrospectively and nutrient analysis via FoodWorks. Carbohydrate malabsorption was determined via breath hydrogen content pre- and post-race. Spearman's rank-order and Mann-Whitney U-tests were used to identify relationships and differences between groups.

RESULTS

Total fermentable oligo-, di, monosaccharides and polyols intake were not associated with gastrointestinal symptoms, but weak associations were observed for lower energy (rs = -0.302, p = 0.044) and fat intake (rs = -0.340, p = 0.024) 3 days before with upper gastrointestinal symptoms and higher caffeine intake 3 days before with overall gastrointestinal symptoms (rs = 0.314, p = 0.038). Total fermentable oligo-, di-, monosaccharides and polyols intake and breath hydrogen were not different between those with severe versus non-severe symptoms (p > 0.05). Although those with severe symptoms had higher caffeine (p = 0.032), and total polyols intake (p = 0.031) 3 days before, and higher % energy from fat (p = 0.043) and sorbitol intake (p = 0.026) during the race, and slower ultramarathon finish times (p = 0.042).

CONCLUSION

Total fermentable oligo-, di-, and monosaccharides intake and carbohydrate malabsorption were not associated with gastrointestinal symptoms. Additional research on the effect of fat, caffeine, and polyol intake on exercise-associated gastrointestinal symptoms is warranted and presents new nutritional areas for consideration when planning nutritional intake for ultramarathoners.

Auditing the Representation of Females Versus Males in Heat Adaptation Research

The aim of this audit was to quantify female representation in research on heat adaptation. Using a standardized audit tool, the PubMed database was searched for heat adaptation literature from inception to February 2023. Studies were included if they investigated heat adaptation among female and male adults (≥18-50 years) who were free from noncommunicable diseases, with heat adaptation the primary or secondary outcome of interest. The number and sex of participants, athletic caliber, menstrual status, research theme, journal impact factor, Altmetric score, Field-Weighted Citation Impact, and type of heat exposure were extracted. A total of 477 studies were identified in this audit, including 7,707 participants with ∼13% of these being female. Most studies investigated male-only cohorts (∼74%, n = 5,672 males), with ∼5% (n = 360 females) including female-only cohorts. Of the 126 studies that included females, only 10% provided some evidence of appropriate methodological control to account for ovarian hormone status, with no study meeting best-practice recommendations. Of the included female participants, 40% were able to be classified to an athletic caliber, with 67% of these being allocated to Tier 2 (i.e., trained/developmental) or below. Exercise heat acclimation was the dominant method of heat exposure (437 interventions), with 21 studies investigating sex differences in exercise heat acclimation interventions. We recommend that future research on heat adaptation in female participants use methodological approaches that consider the potential impact of sexual dimorphism on study outcomes to provide evidence-based guidelines for female athletes preparing for exercise or competition in hot conditions.

Omega-3 long chain polyunsaturated fatty acids as a potential treatment for reducing dysmenorrhoea pain: Systematic literature review and meta-analysis

AIM

This systematic literature review with meta-analysis aimed to determine the effect of omega-3 long chain polyunsaturated fatty acids on prostaglandin levels and pain severity in women with dysmenorrhoea and identify adverse side effects.

METHODS

A literature search was conducted in Embase, Scopus, Web of Science, MEDLINE complete, CINAHL and AMED databases (PROSPERO CRD42022340371). Included studies provided omega-3 long chain polyunsaturated fatty acids compared to a control in women with dysmenorrhoea and reported pain and/or prostaglandin levels. A random effects meta-analysis with Cohen's d effect size (95% confidence interval) was performed in SPPS for studies that reported pain outcomes. Study quality was assessed using the Academy of Nutrition and Dietetics Quality Criteria Checklist.

RESULTS

Twelve studies (n = 881 dysmenorrhoeal women) of predominantly neutral quality (83%) were included that provided daily supplementation of 300-1800 mg omega-3 long chain polyunsaturated fatty acids over 2 or 3 months. Meta-analysis (n = 8 studies) showed a large effect of omega-3 long chain polyunsaturated fatty acids (d = -1.020, 95% confidence interval -1.53 to -0.51) at reducing dysmenorrhoea pain. No studies measured prostaglandin levels, 86% of studies measuring analgesic use showed a reduction with omega-3 long chain polyunsaturated fatty acids and few studies reported mild adverse side effects in individual participants.

CONCLUSIONS

Findings suggest that daily supplementation of 300-1800 mg omega-3 long chain polyunsaturated fatty acids over 2-3 months are generally well tolerated and reduces pain and analgesic use in women with dysmenorrhoea. However, the neutral quality of research is limited by methodological issues and the mechanism of action remains to be determined.

Plasma measurements of the dual sugar test reveal carbohydrate immediately alleviates intestinal permeability caused by exertional heat stress

The aim of this set of randomised cross-over studies was to determine the impact of progressive heat exposure and carbohydrate or protein feeding during exertional stress on small intestine permeability using a dual sugar test. In our previous work, and typically in the field, recovery of lactulose and l-rhamnose is measured cumulatively in urine. This follow-up study exploits our novel high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) protocol to accurately quantify the sugars in plasma. Endurance-trained participants completed experimental trial A (ET-A; n = 8), consisting of 2 h running at 60%V ̇ O 2 max ${\dot V_{{{\mathrm{O}}_{\mathrm{2}}}{\mathrm{max}}}}$ in temperate, warm and hot ambient conditions, and/or experimental trial B (ET-B; n = 9), consisting of 2 h running at 60%V ̇ O 2 max ${\dot V_{{{\mathrm{O}}_{\mathrm{2}}}{\mathrm{max}}}}$ in the heat while consuming water, carbohydrate or protein. Blood samples were collected and plasma lactulose (L) and l-rhamnose (R) appearance, after dual sugar solution ingestion at 90 min of exercise, was quantified by HPAEC-PAD to measure plasma L/R and reveal new information about intestinal permeability immediately post-exercise and during recovery. In ET-A, plasma L/R increased immediately post-exercise in hot compared with temperate and warm conditions, while, in ET-B, carbohydrate alleviated this, and this information was otherwise missed when measuring urine L/R. Consuming carbohydrate or protein before and during exercise attenuated small intestine permeability throughout recovery from exertional heat stress. We recommend using the dual sugar test with quantification of plasma sugars by HPAEC-PAD at intervals to maximise intestinal permeability data collection in exercise gastroenterology research, as this gives additional information compared to urinary measurements. KEY POINTS: Intestinal permeability is typically assessed using a dual sugar test, by administering a drink containing non-metabolisable sugars (e.g. lactulose (L) and l-rhamnose (R)) that can enter the circulation by paracellular translocation when the epithelium is compromised, and are subsequently measured in urine. We demonstrate that our recently developed ion chromatography protocol can be used to accurately quantify the L/R ratio in plasma, and that measuring L/R in plasma collected at intervals during the post-exercise recovery period reveals novel acute response information compared to measuring 5-h cumulative urine L/R. We confirm that exercising in hot ambient conditions increases intestinal epithelial permeability immediately after exercise, while consuming carbohydrate or protein immediately before and during exercise attenuates this. We recommend using our dual sugar absorption test protocol to maximise intestinal epithelial permeability data collection in exercise gastroenterology research and beyond.

The increase in core body temperature in response to exertional-heat stress can predict exercise-induced gastrointestinal syndrome

Utilizing metadata from existing exertional and exertional-heat stress studies, the study aimed to determine if the exercise-associated increase in core body temperature can predict the change in exercise-induced gastrointestinal syndrome (EIGS) biomarkers and exercise-associated gastrointestinal symptoms (Ex-GIS). Endurance-trained individuals completed 2 h of running exercise in temperate (21.2-30.0°C) to hot (35.0-37.2°C) ambient conditions (n = 132 trials). Blood samples were collected pre- and post-exercise to determine the change in gastrointestinal integrity biomarkers and systemic inflammatory cytokines. Physiological and thermoregulatory strain variables were assessed every 10-15 min during exercise. The strength of the linear relationship between maximal (M-Tre) and change (Δ Tre) in rectal temperature and EIGS variables was determined via Spearman's rank correlation coefficients. While the strength of prediction was determined via simple and multiple linear regression analyses dependent on screened EIGS and Ex-GIS confounding factors. Significant positive correlations between Tre maximum (M-Tre) and change (Δ Tre) with I-FABP (rs = 0.434, p < 0.001; and rs = 0.305, p < 0.001; respectively), sCD14 (rs = 0.358, p < 0.001; and rs = 0.362, p < 0.001), systemic inflammatory response profile (SIR-Profile) (p < 0.001), and total Ex-GIS (p < 0.05) were observed. M-Tre and Δ Tre significantly predicted (adjusted R2) magnitude of change in I-FABP (R2(2,123)=0.164, p < 0.001; and R2(2,119)=0.058, p = 0.011; respectively), sCD14 (R2(2,81)=0.249, p < 0.001; and R2(2,77)=0.214, p < 0.001), SIR-Profile (p < 0.001), and total Ex-GIS (p < 0.05). Strong to weak correlations were observed between M-Tre and Δ Tre with plasma concentrations of I-FABP, sCD14, SIR-Profile, and Ex-GIS in response to exercise. M-Tre and Δ Tre can predict the magnitude of these EIGS variables and Ex-GIS in response to exercise.

Sex differences among endurance athletes in the pre-race relationships between sleep, and perceived stress and recovery

This study examined sex differences among endurance athletes in pre-race relationships between sleep, and perceived stress and recovery. Thirty-six athletes completed the Short Recovery and Stress Scale, and had sleep monitored via actigraphy, over four consecutive days prior to an ultra-marathon. Overall, compared with males, females had shorter wake after sleep onset (mean ± SD, 50 ± 23 vs 65 ± 23 min, p = .04) and lower emotional balance (3.9 ± 1.1 vs 4.8 ± 1.1 arbitrary units, p = .001). The day before the race, females scored higher for all stress-related items (p < 0.05). Among females, higher scores for emotional balance (β = -31 min, p = .01) and negative emotional state (β = -21 min, p < .001) were associated with reduced sleep duration. Among males, higher scores for overall stress were associated with increased sleep duration (β = 22 min, p = .01). Across all athletes, longer sleep duration was associated with improved overall recovery (β = 0.003 arbitrary units, p = .02). Females experienced greater pre-race stress than males, and their sleep duration was associated with emotional factors. The SRSS may help identify female athletes at risk of sleep difficulties prior to competition.

Farmed Mussels: A Nutritive Protein Source, Rich in Omega-3 Fatty Acids, with a Low Environmental Footprint

The world’s ever-growing population presents a major challenge in providing sustainable food options and in reducing pressures on the Earth’s agricultural land and freshwater resources. Current estimates suggest that agriculture contributes ~30% of global greenhouse gas (GHG) emissions. Additionally, there is an increased demand for animal protein, the production of which is particularly polluting. Therefore, the climate-disrupting potential of feeding the planet is likely to substantially worsen in the future. Due to the nutritional value of animal-based protein, it is not a simple solution to recommend a wholesale reduction in production/consumption of animal proteins. Rather, employing strategies which result in the production of low carbon animal protein may be part of the solution to reduce the GHGs associated with our diets without compromising diet quality. We suggest that farmed mussels may present a partial solution to this dilemma. Mussel production has a relatively low GHG production and does not put undue pressure on land or fresh water supplies. By drawing comparisons to other protein sources using the Australian Food and Nutrient Database and other published data, we demonstrate that they are a sustainable source of high-quality protein, long-chain omega-3 fatty acids, phytosterols, and other key micronutrients such as B-12 and iron. The aim of this review is to summarise the current knowledge on the health benefits and potential risks of increasing the consumption of farmed mussels.

Protein Requirements of Pre-Menopausal Female Athletes: Systematic Literature Review

This systematic literature review aimed to determine the protein requirements of pre-menopausal (e.g., 18-45 years) female athletes and identify if the menstrual cycle phase and/or hormonal contraceptive use influence protein requirements. Four databases were searched for original research containing pre-menopausal female athletes that ingested protein alongside exercise. The Academy of Nutrition and Dietetics Quality Criteria Checklist was used to determine study quality. Fourteen studies, which included 204 recreationally active or competitive females, met the eligibility criteria for inclusion in this review, and all were assessed as positive quality. The estimated average requirement (EAR) for protein intake of pre-menopausal recreational and/or competitive female athletes is similar for those undertaking aerobic endurance (1.28-1.63 g/kg/day), resistance (1.49 g/kg/day) and intermittent exercise (1.41 g/kg/day) of ~60-90 min duration. The optimal acute protein intake and influence of menstrual cycle phase or hormonal contraceptive use on protein requirements could not be determined. However, pre- and post-exercise protein intakes of 0.32-0.38 g/kg have demonstrated beneficial physiological responses in recreational and competitive female athletes completing resistance and intermittent exercise. The protein requirements outlined in this review can be used for planning and assessing protein intakes of recreational and competitive pre-menopausal female athletes.

Is the gut microbiota bacterial abundance and composition associated with intestinal epithelial injury, systemic inflammatory profile, and gastrointestinal symptoms in response to exertional-heat stress?

OBJECTIVES

The study aimed to examine if the α-diversity and relative abundance of the gastrointestinal bacterial taxa is associated with the response magnitude of markers characteristic of exercise-induced gastrointestinal syndrome in response to exertional-heat stress.

DESIGN

Cross-sectional.

METHODS

Twenty-two endurance-trained athletes completed 2h running at 60% V.O_2max in hot ambient conditions (35.2°C, 25% relative humidity). Faecal samples were collected pre-exercise to determine bacterial taxonomy by 16S rRNA amplicon sequencing (Illumina MiSeq platform). Data were processed using the QIIME2 pipeline (v2019.1) establishing taxonomic classification with >95% confidence using SILVA. Pre- and post-exercise blood samples were used to determine plasma I-FABP and cortisol concentrations, and systemic inflammatory response profile. Markers of physiological and thermoregulatory strain, and gastrointestinal symptoms were measured every 10min during exercise. Associations were determined by partial correlation controlled for body mass variables.

RESULTS

Positive associations between Tenericutes (r₍₁₈₎=0.446, p=0.049) and Verrucomicrobia (r₍₁₈₎=0.450, p=0.046) phylum, Akkermansiaceae (r₍₁₈₎=0.486, p=0.030) and Ruminococcaceae (r₍₁₈₎=0.449, p=0.047) family and aligned genus groups with I-FABP were observed. Whilst, associations between Faecalibacterium (r₍₁₂₎=0.668, p=0.009) and Ruminoclostridium-9 (r₍₁₂₎=-0.577, p=0.031) genus with systemic inflammatory profile were observed. Association between bacterial phyla, family, and genus groups were also observed for gastrointestinal symptoms and markers of thermoregulatory strain (r₍₁₈₎ >0.400, p<0.05).

CONCLUSIONS

The relative abundance of several commensal bacterial groups showed modest favourable (i.e., low perturbations) or detrimental associations with the magnitude of gastrointestinal integrity perturbations and symptoms, and potentially influences body temperature change, in response to exertional-heat stress.

Exertional-heat stress-associated gastrointestinal perturbations during Olympic sports: Management strategies for athletes preparing and competing in the 2020 Tokyo Olympic Games

Exercise-induced gastrointestinal syndrome (EIGS) is a common characteristic of exercise. The causes appear to be multifactorial in origin, but stem primarily from splanchnic hypoperfusion and increased sympathetic drive. These primary causes can lead to secondary outcomes that include increased intestinal epithelial injury and gastrointestinal hyperpermeability, systemic endotoxemia, and responsive cytokinemia, and impaired gastrointestinal function (i.e. transit, digestion, and absorption). Impaired gastrointestinal integrity and functional responses may predispose individuals, engaged in strenuous exercise, to gastrointestinal symptoms (GIS), and health complications of clinical significance, both of which may have exercise performance implications. There is a growing body of evidence indicating heat exposure during exercise (i.e. exertional-heat stress) can substantially exacerbate these gastrointestinal perturbations, proportionally to the magnitude of exertional-heat stress, which is of major concern for athletes preparing for and competing in the upcoming 2020 Tokyo Olympic Games. To date, various hydration and nutritional strategies have been explored to prevent or ameliorate exertional-heat stress associated gastrointestinal perturbations. The aims of the current review are to comprehensively explore the impact of exertional-heat stress on markers of EIGS, examine the evidence for the prevention and (or) management of EIGS in relation to exertional-heat stress, and establish best-practice nutritional recommendations for counteracting EIGS and associated GIS in athletes preparing for and competing in Tokyo 2020.

Impact of exercise-induced hypohydration on gastrointestinal integrity, function, symptoms, and systemic endotoxin and inflammatory profile

It is commonly believed that gastrointestinal issues during exercise are exacerbated by hypohydration. This study aimed to determine the effect of exercise-induced hypohydration on gastrointestinal integrity, function, symptoms, and systemic endotoxin and inflammatory profiles. In a randomized crossover design, male endurance runners ( n = 11) performed 2 h of running at 70% of maximum oxygen uptake in 25°C ambient temperature with water provision [euhydration (EuH)] and total water restriction [hypohydration (HypoH)] during running, which accounted for 0.6 ± 0.6% and 3.1 ± 0.7% body mass loss, respectively. Blood and fecal samples were collected before and after exercise. Breath samples (H2 determination) were collected and gastrointestinal symptoms (GIS) recorded before, during, and after exercise. HypoH resulted in a higher, yet insignificant, ∆ preexercise to postexercise plasma cortisol concentration (+286 nmol/l vs. +176 nmol/l; P = 0.098) but significantly higher intestinal fatty acid-binding protein (I-FABP) (+539 pg/ml vs. +371 pg/ml; P = 0.047) concentration compared with EuH. A greater breath H2 response ( P = 0.026) was observed on HypoH (1,188 ppm/3 h, peak +12 ppm) vs. EuH (579 ppm/3 h, peak +6 ppm). Despite greater GIS incidence on HypoH (82%) vs. EuH (64%), GIS severity scores were not significant between trials. Exercise-induced leukocytosis (overall pre- to postexercise: 5.9 × 109/l to 12.1 × 109/l) was similar on both trials. Depressed in vitro neutrophil function was observed during recovery on HypoH (−36%) but not on EUH (+6%). A pre- to postexercise increase ( P < 0.05) was observed for circulating cytokine concentrations but not endotoxin values. Hypohydration during 2 h of running modestly perturbs gastrointestinal integrity and function and increases GIS incidence but does not affect systemic endotoxemia and cytokinemia.

NEW & NOTEWORTHY Despite anecdotal beliefs that exercise-induced hypohydration exacerbates perturbations to gastrointestinal status, the present study reports only modest perturbations in gastrointestinal integrity, function, and symptoms compared with euhydration maintenance. Exercise-induced hypohydration does not exacerbate systemic endotoxemia and cytokinemia compared with euhydration maintenance. Programmed water intake to maintain euhydration results in gastrointestinal symptom severity similar to exercise-induced hypohydration. Maintaining euhydration during exertional stress prevents the exercise-associated depression in bacterially stimulated neutrophil function.

The Impact of Mild Heat Stress During Prolonged Running On Gastrointestinal Integrity, Gastrointestinal Symptoms, Systemic Endotoxin and Cytokine Profiles

The study aimed to determine the effects of mild exertional heat stress on intestinal injury, permeability, gastrointestinal symptoms, and systemic endotoxin and cytokine responses. Ten endurance runners completed 2 h of running at 60% V̇O2max in warm (WARM: 30°C) and temperate (TEMP: 22°C) ambient conditions. Rectal temperature (Tre) and gastrointestinal symptoms were recorded every 10 min during exercise. Blood samples were collected pre- and post-exercise, and during recovery to determine plasma intestinal fatty acid-binding protein (I-FABP) and cortisol concentrations, and systemic endotoxin and inflammatory cytokine profiles. Urinary lactulose:L-rhamnose ratio (L/R) was used to measure small intestine permeability. Compared with TEMP, WARM significantly increased Tre from 50 min onwards (38.1±0.3°C vs. 38.4±0.5°C, respectively; p<0.01), gastrointestinal symptoms (p=0.017), post-exercise plasma cortisol (26% vs. 59%, respectively; p<0.001) and I-FABP (127% vs. 184%, respectively; p<0.001) concentrations. Circulatory anti-endotoxin antibodies increased post-exercise (p<0.001) on WARM (20%) and TEMP (28%). No differences were observed for plasma endotoxin concentration (6% vs. 5% increase, respectively) or small intestine permeability (L/R 0.026±0.010 and 0.025±0.015, respectively). Both pro- and anti-inflammatory cytokines increased post-exercise, with inflammatory response cytokines TNF-α (p=0.015) and IL-8 (p=0.044), and compensatory anti-inflammatory cytokines IL-10 (p=0.065), and IL-1ra higher on WARM than TEMP. Findings suggest that exposure to warm ambient conditions during prolonged submaximal running induces transient intestinal epithelial injury, increases gastrointestinal symptoms, and promotes greater perturbations to the systemic cytokine profile compared to running in temperate conditions.

Systematic review: exercise-induced gastrointestinal syndrome-implications for health and intestinal disease

BACKGROUND

"Exercise-induced gastrointestinal syndrome" refers to disturbances of gastrointestinal integrity and function that are common features of strenuous exercise.

AIM

To systematically review the literature to establish the impact of acute exercise on markers of gastrointestinal integrity and function in healthy populations and those with chronic gastrointestinal conditions.

METHODS

Search literature using five databases (PubMed, EBSCO, Web of Science, SPORTSdiscus, and Ovid Medline) to review publications that focused on the impact of acute exercise on markers of gastrointestinal injury, permeability, endotoxaemia, motility and malabsorption in healthy populations and populations with gastrointestinal diseases/disorders.

RESULTS

As exercise intensity and duration increases, there is considerable evidence for increases in indices of intestinal injury, permeability and endotoxaemia, together with impairment of gastric emptying, slowing of small intestinal transit and malabsorption. The addition of heat stress and running mode appears to exacerbate these markers of gastrointestinal disturbance. Exercise stress of ≥2 hours at 60% VO_2max appears to be the threshold whereby significant gastrointestinal perturbations manifest, irrespective of fitness status. Gastrointestinal symptoms, referable to upper- and lower-gastrointestinal tract, are common and a limiting factor in prolonged strenuous exercise. While there is evidence for health benefits of moderate exercise in patients with inflammatory bowel disease or functional gastrointestinal disorders, the safety of more strenuous exercise has not been established.

CONCLUSIONS

Strenuous exercise has a major reversible impact on gastrointestinal integrity and function of healthy populations. The safety and health implications of prolonged strenuous exercise in patients with chronic gastrointestinal diseases/disorders, while hypothetically worrying, has not been elucidated and requires further investigation.