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"Kevin D. Croft"
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Flavonoid intake is associated with lower mortality in the Danish Diet Cancer and Health Cohort
2019
Flavonoids, plant-derived polyphenolic compounds, have been linked with health benefits. However, evidence from observational studies is incomplete; studies on cancer mortality are scarce and moderating effects of lifestyle risk factors for early mortality are unknown. In this prospective cohort study including 56,048 participants of the Danish Diet, Cancer, and Health cohort crosslinked with Danish nationwide registries and followed for 23 years, there are 14,083 deaths. A moderate habitual intake of flavonoids is inversely associated with all-cause, cardiovascular- and cancer-related mortality. This strong association plateaus at intakes of approximately 500 mg/day. Furthermore, the inverse associations between total flavonoid intake and mortality outcomes are stronger and more linear in smokers than in non-smokers, as well as in heavy (>20 g/d) vs. low-moderate (<20 g/d) alcohol consumers. These findings highlight the potential to reduce mortality through recommendations to increase intakes of flavonoid-rich foods, particularly in smokers and high alcohol consumers.
The studies showing health benefits of flavonoids and their impact on cancer mortality are incomplete. Here, the authors perform a prospective cohort study in Danish participants and demonstrate an inverse association between regular flavonoid intake and both cardiovascular and cancer related mortality.
Journal Article
Resolvins D1, D2, and Other Mediators of Self-Limited Resolution of Inflammation in Human Blood following n-3 Fatty Acid Supplementation
by
Mori, Trevor A
,
Croft, Kevin D
,
Zahra, Paul
in
Aged
,
Analytical, structural and metabolic biochemistry
,
Biological and medical sciences
2012
Resolvins and protectins are families of local lipid mediators generated from the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) during self-limited resolution of inflammation. We aimed to develop a liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay to measure these lipid mediators in human blood following n-3 fatty acid supplementation and to determine whether the blood collection method affects their measured concentration.
Blood samples from 20 healthy volunteers enrolled in an n-3 fatty acid supplementation trial were collected in EDTA, heparin, or citrate, or prepared as serum after volunteers had undergone 3 weeks of supplementation. Plasma or serum was purified by solid-phase chromatography and analyzed with LC-MS/MS.
The assay identified 18R/S-hydroxy-5Z,8Z,11Z,14Z,16E-eicosapentaenoic acid (18R/S-HEPE); 17S-hydroxy-4Z,7Z,10Z,13Z,15E,19Z-docosahexaenoic acid (17R/S-HDHA); 7S,8R,17S-trihydroxy-4Z,9E,11E,13Z,15E,19Z-docosahexaenoic acid (RvD1); 7S,8R,17R-trihydroxy-4Z,9E,11E,13Z,15E19Z-docosahexaenoicacid (17R-RvD1); 7S,16R,17S-trihydroxy-4Z,8E,10Z,12E,14E,19Z-docosahexaenoic acid (RvD2); 10S,17S-dihydroxy-4Z,7Z,11E,13Z,15E,19Z-docosahexaenoicacid (10S,17S-DiHDHA); and 10R,17S-dihydroxy-4Z,7Z,11E,13E,15Z,19Z-docosahexaenoic acid (protectin D1, PD1). The limits of detection and quantification were 3 pg and 6 pg on-column, respectively. The pathway precursors 18R/S-HEPE and 17R/S-HDHA, but not the resolvins, were lower in serum compared with plasma. After n-3 fatty acid supplementation, mean (SD) EDTA plasma concentrations were: 18R/S-HEPE 386 (56) pg/mL, 17R/S-HDHA 365 (65) pg/mL, RvD2 26 (4) pg/mL, RvD1 31 (5) pg/mL, and 17R-RvD 161 (7) pg/mL. 10S,17S-DiHDHA and PD1 concentrations were below the limit of quantification.
This is the first study reporting 17R/S-HDHA, RvD1, and RvD2 concentrations measured in human blood following oral n-3 fatty acid supplementation. The concentrations of the antiinflammatory lipid mediators RvD1 and RvD2 were within the biological range known to have antiinflammatory and proresolving activities in isolated human leukocytes and in in vivo studies in mice.
Journal Article
Antibacterial Mouthwash Blunts Oral Nitrate Reduction and Increases Blood Pressure in Treated Hypertensive Men and Women
by
Puddey, Ian B.
,
Croft, Kevin D.
,
Woodman, Richard J.
in
Aged
,
Anti-Bacterial Agents - adverse effects
,
Blood Pressure - drug effects
2015
BACKGROUND
Endothelial nitric oxide (NO) is fundamental to cardiovascular health. Dietary nitrate and nitrate from endothelial derived NO metabolism provides a significant contribution to the circulating NO pool through the nitrate–nitrite–NO pathway. A critical step in this pathway is the reduction of nitrate to nitrite by the oral microbiota. We aimed to assess the effects of antibacterial mouthwash use on markers of nitrate–nitrite–NO metabolism and blood pressure in treated hypertensive men and women.
METHODS
Fifteen treated hypertensive men and women (mean age 65 years) were recruited to a randomized controlled cross-over trial. The effects of 3-day use of antibacterial mouthwash on oral nitrate to nitrite reduction, salivary and plasma nitrate and nitrite, plasma cyclic guanosine monophosphate (cGMP) and systolic and diastolic blood pressure were compared to control (water).
RESULTS
Relative to control, 3-day antibacterial mouthwash use resulted in decreased oral nitrate to nitrite reduction (P = 0.02), decreased salivary nitrite (P = 0.01) and increased salivary nitrate (P < 0.001), and there was a trend toward a decrease in plasma nitrite concentration (P = 0.09). Use of antibacterial mouthwash over 3 days also resulted in higher systolic blood pressure (2.3mm Hg; 95% CI: 0.5, 4.0; P = 0.01), but not diastolic blood pressure (P = 0.4) or plasma cGMP (P = 0.7), relative to control.
CONCLUSIONS
Interruption of the nitrate–nitrite–NO pathway through the use of antibacterial mouthwash was paralleled by a small elevation of systolic blood pressure in treated hypertensive men and women.
Journal Article
Isoquercetin and inulin synergistically modulate the gut microbiome to prevent development of the metabolic syndrome in mice fed a high fat diet
2018
Dietary fibre positively influences gut microbiome composition, enhancing the metabolism of dietary flavonoids to produce bioactive metabolites. These synergistic activities facilitate the beneficial effects of dietary flavonoids on cardiometabolic health parameters. The aims of this study were to investigate whether isoquercetin (a major dietary flavonoid) and inulin (soluble fibre), either alone or in combination could improve features of the metabolic syndrome. Following a 1 week acclimatization, male C57BL6 mice (6–8 weeks) were randomly assigned to; (i) normal chow diet (n = 10), (ii) high fat (HF) diet (n = 10), (iii) HF diet + 0.05% isoquercetin (n = 10), (iv) HF diet + 5% inulin, or (v) HF diet + 0.05% isoquercetin + 5% inulin (n = 10). Body weight and food intake were measured weekly. At 12 weeks, glucose and insulin tolerance tests were performed, and blood, faecal samples, liver, skeletal muscle and adipose tissue were collected. At 12 weeks, mice on the HF diet had significantly elevated body weights as well as impaired glucose tolerance and insulin sensitivity compared to the normal chow mice. Supplementation with either isoquercetin or inulin had no effect, however mice receiving the combination had attenuated weight gain, improved glucose tolerance and insulin sensitivity, reduced hepatic lipid accumulation, adipocyte hypertrophy, circulating leptin and adipose FGF21 levels, compared to mice receiving the HF diet. Additionally, mice on the combination diet had improvements in the composition and functionality of their gut microbiome as well as production of short chain fatty acids. In conclusion, long-term supplementation with the dietary flavonoid isoquercetin and the soluble fibre inulin can attenuate development of the metabolic syndrome in mice fed a high fat diet. This protective effect appears to be mediated, in part, through beneficial changes to the microbiome.
Journal Article
Statin therapy causes gut dysbiosis in mice through a PXR-dependent mechanism
2017
Background
Statins are a class of therapeutics used to regulate serum cholesterol and reduce the risk of heart disease. Although statins are highly effective in removing cholesterol from the blood, their consumption has been linked to potential adverse effects in some individuals. The most common events associated with statin intolerance are myopathy and increased risk of developing type 2 diabetes mellitus. However, the pathological mechanism through which statins cause these adverse effects is not well understood.
Results
Using a murine model, we describe for the first time profound changes in the microbial composition of the gut following statin treatment. This remodelling affected the diversity and metabolic profile of the gut microbiota and was associated with reduced production of butyrate. Statins altered both the size and composition of the bile acid pool in the intestine, tentatively explaining the observed gut dysbiosis. As also observed in patients, statin-treated mice trended towards increased fasting blood glucose levels and weight gain compared to controls. Statin treatment affected the hepatic expression of genes involved in lipid and glucose metabolism. Using gene knockout mice, we demonstrated that the observed effects were mediated through pregnane X receptor (PXR).
Conclusion
This study demonstrates that statin therapy drives a profound remodelling of the gut microbiota, hepatic gene deregulation and metabolic alterations in mice through a PXR-dependent mechanism. Since the demonstrated importance of the intestinal microbial community in host health, this work provides new perspectives to help prevent the statin-associated unintended metabolic effects.
Journal Article
Overfeeding Reduces Insulin Sensitivity and Increases Oxidative Stress, without Altering Markers of Mitochondrial Content and Function in Humans
2012
Mitochondrial dysfunction and increased oxidative stress are associated with obesity and type 2 diabetes. High fat feeding induces insulin resistance and increases skeletal muscle oxidative stress in rodents, but there is controversy as to whether skeletal muscle mitochondrial biogenesis and function is altered.
Forty (37 ± 2 y) non-obese (25.6 ± 0.6 kg/m(2)) sedentary men (n = 20) and women (n = 20) were overfed (+1040 ± 100 kcal/day, 46 ± 1% of energy from fat) for 28 days. Hyperinsulinemic-euglycemic clamps were performed at baseline and day 28 of overfeeding and skeletal muscle biopsies taken at baseline, day 3 and day 28 of overfeeding in a sub cohort of 26 individuals (13 men and 13 women) that consented to having all 3 biopsies performed. Weight increased on average in the whole cohort by 0.6 ± 0.1 and 2.7 ± 0.3 kg at days 3 and 28, respectively (P<0.0001, without a significant difference in the response between men and women (P = 0.4). Glucose infusion rate during the hyperinsulinemic-euglycemic clamp decreased from 54.8 ± 2.8 at baseline to 50.3 ± 2.5 µmol/min/kg FFM at day 28 of overfeeding (P = 0.03) without a significant difference between men and women (P = 0.4). Skeletal muscle protein carbonyls and urinary F2-isoprostanes increased with overfeeding (P<0.05). Protein levels of muscle peroxisome proliferator-activated receptor gamma coactivator-1α (PGC1α) and subunits from complex I, II and V of the electron transport chain were increased at day 3 (all P<0.05) and returned to basal levels at day 28. No changes were detected in muscle citrate synthase activity or ex vivo CO(2) production at either time point.
Peripheral insulin resistance was induced by overfeeding, without reducing any of the markers of mitochondrial content that were examined. Oxidative stress was however increased, and may have contributed to the reduction in insulin sensitivity observed.
Journal Article
Changes in Oxidative Damage, Inflammation and NAD(H) with Age in Cerebrospinal Fluid
2014
An extensive body of evidence indicates that oxidative stress and inflammation play a central role in the degenerative changes of systemic tissues in aging. However a comparatively limited amount of data is available to verify whether these processes also contribute to normal aging within the brain. High levels of oxidative damage results in key cellular changes including a reduction in available nicotinamide adenine dinucleotide (NAD(+)), an essential molecule required for a number of vital cellular processes including DNA repair, immune signaling and epigenetic processing. In this study we quantified changes in [NAD(H)] and markers of inflammation and oxidative damage (F2-isoprostanes, 8-OHdG, total antioxidant capacity) in the cerebrospinal fluid (CSF) of healthy humans across a wide age range (24-91 years). CSF was collected from consenting patients who required a spinal tap for the administration of anesthetic. CSF of participants aged >45 years was found to contain increased levels of lipid peroxidation (F2-isoprostanes) (p = 0.04) and inflammation (IL-6) (p = 0.00) and decreased levels of both total antioxidant capacity (p = 0.00) and NAD(H) (p = 0.05), compared to their younger counterparts. A positive association was also observed between plasma [NAD(H)] and CSF NAD(H) levels (p = 0.03). Further analysis of the data identified a relationship between alcohol intake and CSF [NAD(H)] and markers of inflammation. The CSF of participants who consumed >1 standard drink of alcohol per day contained lower levels of NAD(H) compared to those who consumed no alcohol (p<0.05). An increase in CSF IL-6 was observed in participants who reported drinking >0-1 (p<0.05) and >1 (p<0.05) standard alcoholic drinks per day compared to those who did not drink alcohol. Taken together these data suggest a progressive age associated increase in oxidative damage, inflammation and reduced [NAD(H)] in the brain which may be exacerbated by alcohol intake.
Journal Article
Dietary Iron Enhances Colonic Inflammation and IL-6/IL-11-Stat3 Signaling Promoting Colonic Tumor Development in Mice
2013
Chronic intestinal inflammation and high dietary iron are associated with colorectal cancer development. The role of Stat3 activation in iron-induced colonic inflammation and tumorigenesis was investigated in a mouse model of inflammation-associated colorectal cancer. Mice, fed either an iron-supplemented or control diet, were treated with azoxymethane and dextran sodium sulfate (DSS). Intestinal inflammation and tumor development were assessed by endoscopy and histology, gene expression by real-time PCR, Stat3 phosphorylation by immunoblot, cytokines by ELISA and apoptosis by TUNEL assay. Colonic inflammation was more severe in mice fed an iron-supplemented compared with a control diet one week post-DSS treatment, with enhanced colonic IL-6 and IL-11 release and Stat3 phosphorylation. Both IL-6 and ferritin, the iron storage protein, co-localized with macrophages suggesting iron may act directly on IL-6 producing-macrophages. Iron increased DSS-induced colonic epithelial cell proliferation and apoptosis consistent with enhanced mucosal damage. DSS-treated mice developed anemia that was not alleviated by dietary iron supplementation. Six weeks post-DSS treatment, iron-supplemented mice developed more and larger colonic tumors compared with control mice. Intratumoral IL-6 and IL-11 expression increased in DSS-treated mice and IL-6, and possibly IL-11, were enhanced by dietary iron. Gene expression of iron importers, divalent metal transporter 1 and transferrin receptor 1, increased and iron exporter, ferroportin, decreased in colonic tumors suggesting increased iron uptake. Dietary iron and colonic inflammation synergistically activated colonic IL-6/IL-11-Stat3 signaling promoting tumorigenesis. Oral iron therapy may be detrimental in inflammatory bowel disease since it may exacerbate colonic inflammation and increase colorectal cancer risk.
Journal Article
Cruciferous vegetables lower blood pressure in adults with mildly elevated blood pressure in a randomized, controlled, crossover trial: the VEgetableS for vaScular hEaLth (VESSEL) study
2024
Background
Higher cruciferous vegetable intake is associated with lower cardiovascular disease risk in observational studies. The pathways involved remain uncertain. We aimed to determine whether cruciferous vegetable intake (active) lowers 24-h brachial systolic blood pressure (SBP; primary outcome) compared to root and squash vegetables (control) in Australian adults with mildly elevated BP (SBP 120–160 mmHg inclusive).
Methods
In this randomized, controlled, crossover trial, participants completed two 2-week dietary interventions separated by a 2-week washout. Cruciferous vegetables were compared to root and squash vegetables (~ 300 g/day) consumed with lunch and dinner meals. Participants were blinded to which interventions were the active and control. Adherence was assessed using food diaries and biomarkers (S-methyl cysteine sulfoxide (SMCSO, active) and carotenoids (control)). Twenty-four-hour brachial ambulatory SBP and secondary outcomes were assessed pre- and post each intervention. Differences were tested using linear mixed effects regression.
Results
Eighteen participants were recruited (median (IQR) age: 68 (66–70); female:
n
= 16/18; mean ± SD clinic SBP: 135.9 ± 10.0 mmHg). For both interventions, 72% participants had 100% adherence (IQR: 96.4–100%). SMCSO and carotenoids were significantly different between interventions (mean difference active vs. control SMCSO: 22.93 mg/mL, 95%CI 15.62, 30.23,
P
< 0.0001; carotenoids: − 0.974 mg/mL, 95%CI − 1.525, − 0.423,
P
= 0.001). Twenty-four-hour brachial SBP was significantly reduced following the active vs. control (mean difference − 2.5 mmHg, 95%CI − 4.2, − 0.9,
P
= 0.002; active pre: 126.8 ± 12.6 mmHg, post: 124.4 ± 11.8 mmHg; control pre: 125.5 ± 12.1 mmHg, post: 124.8 ± 13.1 mmHg,
n
= 17), driven by daytime SBP (mean difference − 3.6 mmHg, 95%CI − 5.4, − 1.7,
P
< 0.001). Serum triglycerides were significantly lower following the active vs. control (mean difference − 0.2 mmol/L, 95%CI − 0.4, − 0.0,
P
= 0.047).
Conclusions
Increased intake of cruciferous vegetables resulted in reduced SBP compared to root and squash vegetables. Future research is needed to determine whether targeted recommendations for increasing cruciferous vegetable intake benefits population health.
Trial registration
Clinical trial registry ACTRN12619001294145.
https://www.anzctr.org.au
Journal Article
Effect of dietary nitrate supplementation on thermoregulatory and cardiovascular responses to submaximal cycling in the heat
by
Smith, Kurt J
,
Cox, Gregory R
,
Burke, Louise M
in
Blood flow
,
Blood pressure
,
Cardiovascular system
2018
PurposeThis study investigated whether reported improvements in blood flow distribution, and the possible related effects on thermoregulation during exercise following supplementation with beetroot juice (BR), a rich source of dietary nitrate (NO3−), are mitigated in the heat.Methods12 male endurance-trained cyclists (age 27 ± 6 years, VO2peak 68.6 ± 8.1 ml kg−1 min−1) completed two 60 min submaximal cycling trials at 60% of VO2peak power output. Trials were performed in hot environmental conditions (33.3 ± 0.4 °C, 48.8 ± 3.0% RH) following 3 days of supplementation with either NO3−-rich BR (6.5 mmol NO3− for 2 days and 13 mmol NO3− on the final day) or NO3−-depleted placebo (PLA). Salivary NO3− and nitrite (NO2−) were measured before and after the supplementation period. During exercise, cutaneous blood flow, blood pressure (MAP), core temperature (Tc), mean skin temperature (Tsk), indices of muscle oxygenation and oxygen (O2) consumption were measured.ResultsSalivary NO3− and NO2− increased significantly following BR by 680 and 890%, respectively. There were no significant differences observed for cutaneous blood flow, MAP, Tc, Tsk, muscle oxygenation, or O2 consumption between BR and PLA.ConclusionThis investigation shows that the ergogenic effects and health benefits of BR supplementation, such as augmented cutaneous blood flow, reduced MAP, increased muscle oxygenation, and improved aerobic efficiency may be attenuated when exercise is performed in hot conditions.
Journal Article