The effect of sex, menstrual cycle phase and oral contraceptive use on intestinal permeability and ex-vivo monocyte TNFα release following treatment with lipopolysaccharide and hyperthermia.

PURPOSE: Investigate the impact of sex, menstrual cycle phase and oral contraceptive use on intestinal permeability and ex-vivo tumour necrosis factor alpha (TNFα) release following treatment with lipopolysaccharide (LPS) and hyperthermia. METHODS: Twenty-seven participants (9 men, 9 eumenorrheic women (MC) and 9 women taking an oral contraceptive pill (OC)) completed three trials. Men were tested on 3 occasions over 6 weeks; MC during early-follicular, ovulation, and mid-luteal phases; OC during the pill and pill-free phase. Intestinal permeability was assessed following a 4-hour dual sugar absorption test (lactulose: rhamnose). Venous blood was collected each trial and stimulated with 100 µg·mL-1 LPS before incubation at 37 °C and 40 °C and analysed for TNFα via ELISA. RESULTS: L:R ratio was higher in OC than MC (+0.003, p = 0.061) and men (+0.005, p = 0.007). Men had higher TNFα responses than both MC (+53 %, p = 0.004) and OC (+61 %, p = 0.003). TNFα release was greater at 40 °C than 37 °C (+23 %, p < 0.001). CONCLUSIONS: Men present with lower resting intestinal barrier permeability relative to women regardless of OC use and displayed greater monocyte TNFα release following whole blood treatment with LPS and hyperthermia. Oral contraceptive users had highest intestinal permeability however, neither permeability or TNFα release were impacted by the pill cycle. Although no statistical effect was seen in the menstrual cycle, intestinal permeability and TNFα release were more variable across the phases.

Anthocyanin-Rich Blackcurrant Extract Preserves Gastrointestinal Barrier Permeability and Reduces Enterocyte Damage but Has No Effect on Microbial Translocation and Inflammation After Exertional Heat Stress.

This study investigated the effects of 7 days of 600 mg/day anthocyanin-rich blackcurrant extract intake on small intestinal permeability, enterocyte damage, microbial translocation, and inflammation following exertional heat stress. Twelve recreationally active men (maximal aerobic capacity = 55.6 ± 6.0 ml·kg-1·min-1) ran (70% VO2max) for 60 min in an environmental chamber (34 °C, 40% relative humidity) on two occasions (placebo/blackcurrant, randomized double-blind crossover). Permeability was assessed from a 4-hr urinary excretion of lactulose and rhamnose and expressed as a ratio of lactulose/rhamnose. Venous blood samples were taken at rest and 20, 60, and 240 min after exercise to measure enterocyte damage (intestinal fatty acid-binding protein); microbial translocation (soluble CD14, lipopolysaccharide-binding protein); and interleukins 6, interleukins 10, and interleukins 1 receptor antagonist. Exercise increased rectal temperature (by ∼2.8 °C) and heart rate (by ∼123 beats/min) in each condition. Blackcurrant supplementation led to a ∼12% reduction in lactulose/rhamnose ratio (p < .0034) and enterocyte damage (∼40% reduction in intestinal fatty acid-binding protein area under the curve; p < .0001) relative to placebo. No between-condition differences were observed immediately after exercise for lipopolysaccharide-binding protein (mean, 95% confidence interval [CI]; +80%, 95% CI [+61%, +99%]); soluble CD14 (+37%, 95% CI [+22%, +51%]); interleukins 6 (+494%, 95% CI [+394%, +690%]); interleukins 10 (+288%, 95% CI [+105%, +470%]); or interleukins 1 receptor antagonist (+47%, 95% CI [+13%, +80%]; all time main effects). No between-condition differences for these markers were observed after 60 or 240 min of recovery. Blackcurrant extract preserves the GI barrier; however, at subclinical levels, this had no effect on microbial translocation and downstream inflammatory processes.

Addition of pectin-alginate to a carbohydrate beverage does not maintain gastrointestinal barrier function during exercise in hot-humid conditions better than carbohydrate ingestion alone.

The objective of this study was to compare the effects of consuming a 16% maltodextrin+fructose+pectin-alginate (MAL+FRU+PEC+ALG) drink against a nutrient-matched maltodextrin+fructose (MAL+FRU) drink on enterocyte damage and gastrointestinal permeability after cycling in hot and humid conditions. Fourteen recreational cyclists (7 men) completed 3 experimental trials in a randomized placebo-controlled design. Participants cycled for 90 min (45% maximal aerobic capacity) and completed a 15-min time-trial in hot (32 °C) humid (70% relative humidity) conditions. Every 15 min, cyclists consumed 143 mL of either (i) water; (ii) MAL+FRU+PEC+ALG (90 g·h-1 CHO/16% w/v); or (iii) a ratio-matched MAL+FRU drink (90 g·h-1 CHO/16% w/v). Blood was sampled before and after exercise and gastrointestinal (GI) permeability, which was determined by serum measurements of intestinal fatty acid binding protein (I-FABP) and the percent ratio of lactulose (5 g) to rhamnose (2 g) recovered in postexercise urine. Compared with water, I-FABP decreased by 349 ± 67pg·mL-1 with MAL+FRU+PEC+ALG (p = 0.007) and by 427 ± 56 pg·mL-1 with MAL+FRU (p = 0.02). GI permeability was reduced in both the MAL+FRU+PEC+ALG (by 0.019 ± 0.01, p = 0.0003) and MAL+FRU (by 0.014 ± 0.01, p = 0.002) conditions relative to water. In conclusion, both CHO beverages attenuated GI barrier damage to a similar extent relative to water. No metabolic, cardiovascular, thermoregulatory, or performance differences were observed between the CHO beverages. Novelty Consumption of multiple-transportable CHO, with or without hydrogel properties, preserves GI barrier integrity and reduces enterocyte damage during prolonged cycling in hot-humid conditions.

Dietary supplementation with New Zealand blackcurrant extract enhances fat oxidation during submaximal exercise in the heat.

OBJECTIVES: This study investigated the effect of 7 days' supplementation with New Zealand blackcurrant extract on thermoregulation and substrate metabolism during running in the heat. DESIGN: Randomized, double-blind, cross-over study. METHODS: Twelve men and six women (mean±SD: Age 27±6 years, height 1.76±0.10m, mass 74±12kg, V̇O2max 53.4±7.0mLkg-1min-1) completed one assessment of maximal aerobic capacity and one familiarisation trial (18°C, 40% relative humidity, RH), before ingesting 2×300mgday-1 capsules of CurraNZ™ (each containing 105mg anthocyanin) or a visually matched placebo (2×300mg microcrystalline cellulose M102) for 7 days (washout 14 days). On day 7 of each supplementation period, participants completed 60min of fasted running at 65% V̇O2max in hot ambient conditions (34°C and 40% relative humidity). RESULTS: Carbohydrate oxidation was decreased in the NZBC trial [by 0.24gmin-1 (95% CI: 0.21-0.27gmin-1)] compared to placebo (p= 0.014, d=0.46), and fat oxidation was increased in the NZBC trial [by 0.12gmin-1 (95% CI: 0.10 to 0.15gmin-1)], compared to placebo (p=0.008, d=0.57). NZBC did not influence heart rate (p=0.963), rectal temperature (p=0.380), skin temperature (p=0.955), body temperature (p=0.214) or physiological strain index (p=0.705) during exercise. CONCLUSIONS: Seven-days intake of 600mg NZBC extract increased fat oxidation without influencing cardiorespiratory or thermoregulatory variables during prolonged moderate intensity running in hot conditions.