Kiran D.K. Ahuja

Acute effects of food on postprandial blood pressure and measures of arterial stiffness in healthy humans

BACKGROUND Recent research suggests that central pulse pressure may be a better indicator of cardiovascular disease outcomes than brachial pressure. Little information is available regarding the effect of food intake on postprandial central pressure and other measures of arterial stiffness when measured with a noninvasive pulse wave analysis (PWA) technique. OBJECTIVE The objective was to investigate the effects of water and food plus water intake on brachial and central blood pressure (BP) and measures of arterial stiffness, including augmentation pressure and augmentation index, by using the PWA technique. DESIGN Measurements of BP and PWA were made at fasting and for 2 h after the intake of water or breakfast (1300 kJ) in random order in 35 subjects. RESULTS Baseline fasting measures of BP and arterial stiffness were not significantly different before the 2 interventions. Consumption of food plus water, compared with water alone, led to a significantly lower (all P < 0.01) brachial diastolic pressure (difference: -3.8 mm Hg), central BP (difference: systolic, -6.1 mm Hg; diastolic, -3.8 mm Hg), central pulse pressure (difference: -2.4 mm Hg), mean arterial pressure (difference: -4.6 mm Hg), augmentation pressure (difference: -2.9 mm Hg), and augmentation index (difference: -5.3 mm Hg). CONCLUSIONS Markers of central hemodynamics are sensitive to feeding state and therefore should be measured at fasting to avoid variability due to recent (within 2-3 h) food intake. This is especially important when measurements are repeated over time to assess the effect of medication or lifestyle changes on cardiovascular disease risk factors.

Effects of a Controlled Diet Supplemented with Chickpeas on Serum Lipids, Glucose Tolerance, Satiety and Bowel Function

Objective: To compare the effect of a diet supplemented with chickpeas to a wheat-based diet of similar fibre content on serum lipids, glucose tolerance, satiety and bowel function. A third, lower-fibre wheat diet provided further information on dietary fibre quantity and bowel function and satiety. Method: Twenty-seven free-living adults followed two randomized, crossover dietary interventions each of five weeks duration. The chickpea diet included canned drained chickpeas, bread and shortbread biscuits containing 30% chickpea flour. The wheat diet included high-fibre wheat breakfast cereals and wholemeal bread. The diets were isoenergetic to the participants’ usual diet, matched for macronutrient content and controlled for dietary fibre. Following on from the second randomised intervention, a sub-group of 18 participants underwent a third, isoenergetic lower-fibre wheat diet that included low-fibre breakfast cereals and bread. Results: Repeated measures ANOVA revealed reductions in serum TC of 0.25 mmol/L (p < 0.01) and LDL-C of 0.20 mmol/L (p = 0.02) following the chickpea diet compared to the wheat. An unintended significant increase in PUFA and corresponding decrease in MUFA consumption occurred during the chickpea diet and statistical adjustment for this reduced but did not eliminate the effect on serum lipids. There was no significant difference in glucose tolerance. Perceived general bowel health improved significantly during the chickpea diet although there was considerable individual variation. Some participants reported greater satiety during the chickpea diet. Conclusions: The small but significant decrease in serum TC and LDL-C during the chickpea diet compared to the equivalent fibre wheat diet was partly due to unintentional changes in macronutrient intake occurring because of chickpea ingestion. If dietary energy and macronutrients were not controlled, chickpea consumption might result in greater benefits via influence on these factors.

Exploring the Popularity, Experiences, and Beliefs Surrounding Gluten-Free Diets in Nonceliac Athletes

Adherence to a gluten-free diet (GFD) for nonceliac athletes (NCA) has become increasingly popular despite a paucity of supportive medical or ergogenic evidence. This study aimed to quantify the demographics of NCA and determine associated experiences, perceptions, and sources of information related to GFD. Athletes (n = 910, female = 528, no gender selected = 5) completed a 17-question online survey. Forty-one percent of NCA respondents, including 18-world and/or Olympic medalists, follow a GFD 50-100% of the time (GFD > 50): only 13% for treatment of reported medical conditions with 57% self-diagnosing their gluten sensitivity. The GFD > 50 group characteristics included predominantly endurance sport athletes (70.0%) at the recreationally competitive level (32.3%), between 31 and 40 years of age (29.1%). Those who follow a GFD > 50 reported experiencing, abdominal/gastrointestinal (GI) symptoms alone (16.7%) or in conjunction with two (30.7%) or three (35.7%) additional symptoms (e.g., fatigue) believed to be triggered by gluten. Eighty-four percent of GFD > 50 indicated symptom improvement with gluten-removal. Symptom-based and non-symptom-based self-diagnosed gluten-sensitivity (56.7%) was the primary reason for adopting a GFD. Leading sources of GFD information were online (28.7%), trainer/coach (26.2%) and other athletes (17.4%). Although 5-10% of the general population is estimated to benefit clinically from a GFD a higher prevalence of GFD adherence was found in NCA (41.2%). Prescription of a GFD among many athletes does not result from evidence-based practice suggesting that adoption of a GFD in the majority of cases was not based on medical rationale and may be driven by perception that gluten removal provides health benefits and an ergogenic edge in NCA.

Validity and reliability of central blood pressure estimated by upper arm oscillometric cuff pressure

BACKGROUND Noninvasive central blood pressure (BP) independently predicts mortality, but current methods are operator-dependent, requiring skill to obtain quality recordings. The aims of this study were first, to determine the validity of an automatic, upper arm oscillometric cuff method for estimating central BP (O(CBP)) by comparison with the noninvasive reference standard of radial tonometry (T(CBP)). Second, we determined the intratest and intertest reliability of O(CBP). METHODS To assess validity, central BP was estimated by O(CBP) (Pulsecor R6.5B monitor) and compared with T(CBP) (SphygmoCor) in 47 participants free from cardiovascular disease (aged 57 ± 9 years) in supine, seated, and standing positions. Brachial mean arterial pressure (MAP) and diastolic BP (DBP) from the O(CBP) device were used to calibrate in both devices. Duplicate measures were recorded in each position on the same day to assess intratest reliability, and participants returned within 10 ± 7 days for repeat measurements to assess intertest reliability. RESULTS There was a strong intraclass correlation (ICC = 0.987, P < 0.001) and small mean difference (1.2 ± 2.2 mm Hg) for central systolic BP (SBP) determined by O(CBP) compared with T(CBP). Ninety-six percent of all comparisons (n = 495 acceptable recordings) were within 5 mm Hg. With respect to reliability, there were strong correlations but higher limits of agreement for the intratest (ICC = 0.975, P < 0.001, mean difference 0.6 ± 4.5 mm Hg) and intertest (ICC = 0.895, P < 0.001, mean difference 4.3 ± 8.0 mm Hg) comparisons. CONCLUSIONS Estimation of central SBP using cuff oscillometry is comparable to radial tonometry and has good reproducibility. As a noninvasive, relatively operator-independent method, O(CBP) may be as useful as T(CBP) for estimating central BP in clinical practice.

Effect of capsaicin and dihydrocapsaicin on in vitro blood coagulation and platelet aggregation

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in developed countries. The growing clinical and financial burden of CVD is, at least in part, being driven by aging populations, and thus represents a significant challenge to health care systemswith regard to diagnosis, prevention and treatment. Novel cost-effective approaches that slow or prevent the onset and/or reduce the incidence of CVD warrant investigation. Capsaicinoids, including capsaicin and dihydrocapsaicin, are the major pungent constituents of ‘hot chilli peppers’ of the Capsicum genus. These spice principles have been documented to increase carbohydrate metabolism [1,2], energy expenditure [3] and lipid metabolism [4–7], in rats and/or humans, and have been successfully used in the treatment of painful conditions such as rheumatoid arthritis, osteoarthritis and peripheral neuropathies [8]. Furthermore, we have recently shown that regular intake of chilli delays copperinduced oxidation of serum lipids in vitro [4] and lowers and improves post-prandial insulin and glucose profiles [9], actions that may help in reducing CVD risk. Their effect(s) however, on haemostasis have not been extensively investigated, and their potential “anti-haemostatic” properties may also reduce CVD risk. Limited reports have demonstrated that capsaicin inhibits platelet aggregation, although these studies investigated platelets from non-human species [10,11]. Furthermore, it was reported that capsaicin had no effect on blood coagulation [12], although the potential effects on individual clotting factors were not determined. The aim of this study was to therefore investigate and compare the effects of capsaicin and dihydrocapsaicin on markers of in vitro haemostasis, viz, blood coagulation and platelet aggregation. This studywas approved by the Human Research Ethics Committee (Tasmanian) Network (Ref No: H0009477). Informed consent was obtained from each subject in accordance with the Declaration of Helsinki of the World Medical Association. For blood coagulation experiments, normal reference plasma (NRP; Helena Laboratories, Beaumont, USA) was spiked with increasing concentrations (3.125100 μmol/L) of capsaicin (Sigma Chemical Company, St Louis, USA) or dihydrocapsaicin (Tocris Bioscience, Ellisville, USA). Each capsaicinoid was initially dissolved in 100% ethanol to make a stock solution of 1 mol/L and then diluted for further experiments in normal buffered saline, pH 7.1. After incubation for 30 minutes at 37 °C, prothrombin time (PT), activated partial thromboplastin time (aPTT) and the activities of clotting factors II, V, VII, VIII:C, IX, X, XI and XII were determined using a STarT4 coagulation analyzer (Diagnostica Stago, Parsippany, USA). For platelet aggregation experiments, venous whole blood was collected using 21 gauge syringes from six healthy subjects

Can probiotic yogurt prevent diarrhoea in children on antibiotics? A double-blind, randomised, placebo-controlled study

Objective To estimate the efficacy of a probiotic yogurt compared to a pasteurised yogurt for the prevention of antibiotic-associated diarrhoea in children. Design and setting This was a multisite, randomised, double-blind, placebo-controlled clinical trial conducted between September 2009 and 2012. The study was conducted through general practices and pharmacies in Launceston, Tasmania, Australia. Participants and interventions Children (aged 1–12 years) prescribed antibiotics, were randomised to receive 200 g/day of either yogurt (probiotic) containing Lactobacillus rhamnosus GG (LGG), Bifidobacterium lactis (Bb-12) and Lactobacillus acidophilus (La-5) or a pasteurised yogurt (placebo) for the same duration as their antibiotic treatment. Outcomes Stool frequency and consistency were recorded for the duration of treatment plus 1 week. Primary outcome was stool frequency and consistency, classified at different levels of diarrhoea severity. Due to the small number of cases of diarrhoea, comparisons between groups were made using Fishers exact analysis. Results 72 children commenced and 70 children (36 placebo and 34 probiotic) completed the trial. There were no incidents of severe diarrhoea (stool consistency ≥6, ≥3 stools/day for ≥2 consecutive days) in the probiotic group and six in the placebo group (Fishers exact p=0.025). There was also only one episode of minor diarrhoea (stool consistency ≥5, ≥2 stools/day for ≥2 days in the probiotic group compared to 21 in the placebo group (Fishers exact p<0.001). The probiotic group reported fewer adverse events (1 had abdominal pain, 1 vomited and 1 had headache) than the placebo group (6 had abdominal pain, 4 had loss of appetite and 1 had nausea). Conclusions A yogurt combination of LGG, La-5 and Bb-12 is an effective method for reducing the incidence of antibiotic-associated diarrhoea in children. Trial registration number Australian New Zealand Clinical Trials Registry ACTRN12609000281291

Glutathione peroxidase, superoxide dismutase and catalase genotypes and activities and the progression of chronic kidney disease

BACKGROUND Oxidative stress has been linked to the progression of disease, including chronic kidney disease (CKD). The aim of the present study was to determine the association between single-nucleotide polymorphisms (SNPs) of the antioxidant enzymes, superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase and their activities and the progression of CKD. METHODS This is a prospective cohort study of 185 CKD patients (Stages 2-4), followed for up to 12 months. All patients were genotyped for SNPs of SOD (SOD Ala16Val), GPx (GPx Pro197Leu) and catalase (C-262T). The rate of change over the study period of estimated glomerular filtration rate (eGFR), plasma and red blood cell (RBC) GPx, RBC SOD and RBC catalase activities were determined. RESULTS CKD patients with the SOD Ala/Val and Val/Val genotypes had a significantly greater eGFR decline compared to those with the Ala/Ala genotype (Ala/Val compared with Ala/Ala odds ratio (OR) 0.35, 95% CI 0.19 to 0.64, P = 0.001; Val/Val compared with Ala/Ala OR 0.25, 95% CI 0.10 to 0.65, P = 0.005). The progression of CKD was not associated with SNPs of the GPx or catalase genes studied but there was a direct relationship between the rate of change of plasma GPx activity and the rate of change of eGFR over 12 months (P = 0.025). CONCLUSION CKD patients with the SOD Ala/Val and Val/Val genotypes have a greater decline in kidney function than those with the Ala/Ala genotype.

Make vitamin D while the sun shines, take supplements when it doesn't: a longitudinal, observational study of older adults in Tasmania, Australia.

Low vitamin D status has been associated with a number of chronic conditions, particularly in older adults. The aim of this study was to identify how best to maintain optimum vitamin D status throughout the year in this high-risk population. The main objectives of the study were to assess seasonal vitamin D status; identify the main determinants of vitamin D status; determine if taking part in the study led to alterations in participant behaviour and vitamin D status. A longitudinal design across four consecutive seasons observed ninety-one 60–85 year old community-dwelling adults in Tasmania (41π S) over 13 consecutive months, with a follow-up assessment at next winters end. Associations between solar UVB exposure, sun protection behaviours, dietary and supplemental vitamin D with serum 25(OH)D concentrations were assessed. Variation in serum 25(OH)D demonstrated an identical pattern to solar UVB, lagging 8–10 weeks. Serum 25(OH)D was positively associated with summer UVB (mean 15.9 nmol/L; 95%CI 11.8–19.9 nmol/L, p<0.001) and vitamin D supplementation (100–600 IU/day: 95%CI 10.2 nmol/L; 0.8–19.6 nmol/L; p = 0.03; 800 IU/day: 21.0 nmol/L; 95%CI 8.1–34.0 nmol/L; p = 0.001). Seasonal variation in serum 25(OH)D was greatly diminished in supplement users. The most common alteration in participant behaviour after the study was ingesting vitamin D supplements. Post-study vitamin D supplementation ℘800 IU/day was seven times more likely than during the study resulting in mean difference in serum 25(OH)D between supplement and non-supplement users of 30.1 nmol/L (95%CI 19.4–40.8 nmol/L; p<0.001). The main limitation was homogeneity of participant ethnicity. Solar exposure in summer and ingestion of vitamin D supplements in other seasons are the most effective ways of achieving and maintaining year-round vitamin D sufficiency in older adults in the Southern hemisphere. Vitamin D supplementation has greatest effect on vitamin D status if ingested during and after winter, i.e. between the autumn and spring equinoxes.

Cardiovascular and metabolic effects of community based resistance training in an older population

Ageing is associated with decreases in strength and cardiovascular fitness, and increased cardiovascular risk factors. The aim of the current study was to determine the effectiveness of 16 weeks of community based resistance compared to flexibility training on strength, cardiovascular fitness and cardiovascular and metabolic parameters in a group of previously sedentary, healthy older men and women. A randomised controlled crossover intervention study. Forty nine healthy sedentary participants (23 males; age 66.7 ± 4.3 years; weight 78.6 ± 15.4 kg; mean ± SD) completed 16 weeks of supervised community-based resistance training and 16 weeks of flexibility training in a randomised order. Prior to and following each intervention, participants were assessed for muscle strength, cardiovascular fitness (VO(2 peak)), fasted blood lipids and blood glucose, insulin and insulin resistance. Resistance training resulted in significant increases in knee extension (+25.7 Nm; p < 0.001) and knee flexion strength (+8.9 Nm; p = 0.048) and decreases in fasting total cholesterol (-0.51 mmol L(-1); p = 0.001), HDL cholesterol (-0.12 mmol L(-1); p = 0.035), LDL cholesterol (-0.35 mmol L(-1); p = 0.022), glucose (-0.42 mmol L(-1); p < 0.001), insulin (-1.28 μU/mL; p = 0.049) and insulin resistance (-0.50 μU/mL; p = 0.004) compared to the flexibility protocol. No significant changes between the treatments were observed in VO(2peak) (+2.04 mL kg(-1)min(-1); p = 0.12). Community based resistance training is suitable for improving strength and reducing cardiovascular and metabolic risk factors in healthy older individuals.

No Effects of a Short-Term Gluten-free Diet on Performance in Nonceliac Athletes.

PURPOSE Implementation of gluten-free diets among nonceliac athletes has rapidly increased in recent years because of perceived ergogenic and health benefits. The aim of this study was to investigate the effects of a gluten-free diet (GFD) on exercise performance, gastrointestinal (GI) symptoms, perceived well-being, intestinal injury, and inflammatory responses in nonceliac athletes. METHODS Thirteen competitive endurance cyclists (8 males, 5 females) with no positive clinical screening for celiac disease or history of irritable bowel syndrome (mean ± SD; age, 32 ± 7 yr; weight, 71.1 ± 13.4 kg; height, 177.0 ± 11.8 cm, VO2max 59.1 ± 8.0 mL·kg⁻¹·min⁻¹) were allocated to a 7-d gluten-containing diet (GCD) or GFD separated by a 10-d washout in a controlled, randomized, double-blind, crossover study. Cyclists ate a GFD alongside either gluten-containing or gluten-free food bars (16 g wheat gluten per day) while habitual training and nutrition behaviors were controlled. During each diet, cyclists completed the Daily Analysis of Life Demand for Athletes (DALDA) and GI questionnaires (postexercise and daily). On day 7, cyclists completed a submaximal steady-state (SS) 45-min ride at 70% Wmax followed by a 15-min time trial (TT). Blood samples were taken preexercise, post-SS, and post-TT to determine intestinal fatty acid binding protein (IFABP) and inflammatory markers (cytokine responses: interleukin [IL] 1β, IL-6, IL-8, IL-10, IL-15, tumor necrosis factor α). Mixed effects logistic regression was used to analyze data. RESULTS TT performance was not significantly different (P = 0.37) between the GCD (245.4 ± 53.4 kJ) and GFD (245.0 ± 54.6 kJ). GI symptoms during exercise, daily, and DALDA responses were similar for each diet (P > 0.11). There were no significant differences in IFABP (P = 0.69) or cytokine (P > 0.13) responses. CONCLUSIONS A short-term GFD had no overall effect on performance, GI symptoms, well-being, and a select indicator of intestinal injury or inflammatory markers in nonceliac endurance athletes.