Lynne Cobiac

Corrected Arm Muscle Area: An Independent Predictor of Long-Term Mortality in Community-Dwelling Older Adults?

OBJECTIVES: Older people are at risk of undernutrition because of a number of physiological conditions and lifestyle factors. The purpose of this study was to explore the predictive relationship of corrected arm muscle area (CAMA) with 8‐year mortality in a representative sample of older Australians.

Predicting Alzheimer disease with β-amyloid imaging: results from the Australian imaging, biomarkers, and lifestyle study of ageing

Biomarkers for Alzheimer disease (AD) can detect the disease pathology in asymptomatic subjects and individuals with mild cognitive impairment (MCI), but their cognitive prognosis remains uncertain. We aimed to determine the prognostic value of β‐amyloid imaging, alone and in combination with memory performance, hippocampal atrophy, and apolipoprotein E ε4 status in nondemented, older individuals.

Effects of high-amylose maize starch and butyrylated high-amylose maize starch on azoxymethane-induced intestinal cancer in rats

Colorectal cancer (CRC) is a major cause of death worldwide. Studies suggest that dietary fibre offers protection perhaps by increasing colonic fermentative production of butyrate. This study examined the importance of butyrate by investigating the effects of resistant starch (RS) and butyrylated-RS on azoxymethane (AOM)-induced CRC in rats. Four groups (n = 30 per group) of Sprague–Dawley rats were fed AIN-93G-based diets containing a standard low-RS maize starch (LAMS), LAMS + 3% tributyrin (LAMST), 10% high-amylose maize starch (HAMS) and 10% butyrylated HAMS (HAMSB) for 4 weeks. Rats were injected once weekly for 2 weeks with 15 mg/kg AOM, maintained on diets for 25 weeks and then killed. Butyrate concentrations in large bowel digesta were higher in rats fed HAMSB than other groups (P < 0.001); levels were similar in HAMS, LAMS and LAMST groups. The proportion of rats developing tumours were lower in HAMS and HAMSB than LAMS (P < 0.05), and the number of tumours per rat were lower in HAMSB than LAMS (P < 0.05). Caecal digesta butyrate pools and concentrations were negatively correlated with tumour size (P < 0.05). Hepatic portal plasma butyrate concentrations were higher (P < 0.001) in the HAMSB compared with other groups and negatively correlated with tumour number per rat (P < 0.009) and total tumour size for each rat (P = 0.05). HAMSB results in higher luminal butyrate than RS alone or tributyrin. This is associated with reduced tumour incidence, number and size in this rat model of CRC supporting the important protective role of butyrate. Interventional strategies designed to maximize luminal butyrate may be of protective benefit in humans.

A low-sodium diet supplemented with fish oil lowers blood pressure in the elderly.

Objective: To examine effects of dietary fish oil supplementation with sodium restriction on blood pressure in the elderly. Design: In a double-blind dietary intervention lasting 4 weeks, parallel comparisons of blood pressure were made in volunteers assigned to one of four treatment groups: fish oil and low sodium; fish oil and normal sodium; sunflower oil and low sodium; or sunflower oil and normal sodium. Setting: Subjects lived at home and attended our nutrition research clinic at fortnightly intervals for dietary counselling and blood pressure measurement. Participants: Health volunteers aged 60-80 years were sought by advertisement. A total of 114 men and women were enrolled in two cohorts; 106, with an initial mean blood pressure of 132/77 mmHg, satisfactorily completed the study. Intervention: All subjects adopted a low-sodium diet and dietary changes were effected by double-blind administration of slow-release sodium chloride or placebo tablets, along with capsules containing either fish or sunflower oil. Main outcome measure: The primary measure was the within-subject change in blood pressure after 4 weeks of intervention in each dietary treatment group. Results: Urinary sodium excretion in subjects on low-sodium diets decreased whilst potassium excretion was unaffected. Systolic blood pressure (SBP) fell in the group taking sunflower oil with low sodium, but there was only a transient fall in diastolic blood pressure (DBP). In those taking fish oil with normal sodium, the change in blood pressure was not significant, except after adjustment for initial blood pressure and weight changes. When fish oil was combined with low sodium, however, both SBP and DBP were substantially reduced; the reduction in DBP was significantly greater than in the other treatment groups. Conclusion: Dietary fish oil and sodium restriction can interact to lower DBP in the elderly.

Histone deacetylase inhibition in colorectal cancer cells reveals competing roles for members of the oncogenic miR-17-92 cluster.

Diet‐derived butyrate, a histone deacetylase inhibitor (HDI), decreases proliferation and increases apoptosis in colorectal cancer (CRC) cells via epigenetic changes in gene expression. Other HDIs such as suberoylanilide hydroxamic acid (SAHA) and trichostatin A (TSA) have similar effects. This study examined the role of microRNAs (miRNAs) in mediating the chemo‐protective effects of HDIs, and explored functions of the oncogenic miR‐17‐92 cluster. The dysregulated miRNA expression observed in HT29 and HCT116 CRC cells could be epigenetically altered by butyrate, SAHA and TSA. These HDIs decreased expression of miR‐17‐92 cluster miRNAs (P < 0.05), with a corresponding increase in miR‐17‐92 target genes, including PTEN, BCL2L11, and CDKN1A (P < 0.05). The decrease in miR‐17‐92 expression may be partly responsible for the anti‐proliferative effects of HDIs, with introduction of miR‐17‐92 cluster miRNA mimics reversing this effect and decreasing levels of PTEN, BCL2L11, and CDKN1A (P < 0.05). The growth effects of HDIs may be mediated by changes in miRNA activity, with down‐regulation of the miR‐17‐92 cluster a plausible mechanism to explain some of the chemo‐protective effects of HDIs. Of the miR‐17‐92 cluster miRNAs, miR‐19a and miR‐19b were primarily responsible for promoting proliferation, while miR‐18a acted in opposition to other cluster members to decrease growth. NEDD9 and CDK19 were identified as novel miR‐18a targets and were shown to be pro‐proliferative genes, with RNA interference of their transcripts decreasing proliferation in CRC cells. This is the first study to identify competing roles for miR‐17‐92 cluster members, in the context of HDI‐induced changes in CRC cells.

Herbal medicine for dementia: A systematic review

This systematic review aimed to assess the effectiveness and safety of herbal medicines (HM) for treating dementia. Databases in English and Chinese were searched from their inceptions to February 2007. References in reviews and randomized controlled trials (RCTs) were screened by hand. Trials comparing orally administered HM with placebo, no intervention or other therapy were considered. Trials on Ginkgo biloba and its extracts were excluded to avoid duplication of existing reviews. Pairs of authors independently applied eligibility criteria, extracted data and assessed methodological quality using the Jadad Scale. Thirteen RCTs met the inclusion criteria of three or above on this scale. Six trials compared herbal medicine with placebo, one with no treatment, and the remainder with pharmaceutical intervention. Meta‐analyses were performed on common cognitive performance outcome measures. All studies reported HM had significant effects in improving symptoms. In studies that employed active controls, HM was at least as effective as the pharmaceutical intervention. Meta‐analyses found HM more effective than no treatment or placebo and at least equivalent to control interventions, although the overall effect was small. No severe adverse events were reported. These trials provide overall positive evidence for the effectiveness and safety of certain HMs for dementia management. Copyright

Butyrate delivered by butyrylated starch increases distal colonic epithelial apoptosis in carcinogen-treated rats.

Animal studies show that increasing large bowel butyrate concentration through ingestion of butyrylated or resistant starches opposes carcinogen-induced tumorigenesis, which is consistent with population data linking greater fiber consumption with lowered colorectal cancer (CRC) risk. Butyrate has been shown to regulate the apoptotic response to DNA damage. This study examined the impact of increasing large bowel butyrate concentration by dietary butyrylated starch on the colonic epithelium of rats treated with the genotoxic carcinogen azoxymethane (AOM). Four groups of 10 male rats were fed AIN-93G based-diets containing either low amylose maize starch (LAMS), LAMS with 3% tributyrin, 10% high amylose maize starch (HAMS) or 10% butyrylated HAMS (HAMSB). HAMS and HAMSB starches were cooked by heating in water. After 4 weeks, rats were injected once with AOM and killed 6 h later. Rates of apoptosis and proliferation were measured in colonic epithelium. Short-chain fatty acid concentrations in large bowel digesta and hepatic portal venous plasma were higher in HAMSB than all other groups. Apoptotic rates in the distal colon were increased by HAMSB and correlated with luminal butyrate concentrations but cellular proliferation rates were unaffected by diet. The increase in apoptosis was most marked in the base and proliferative zone of the crypt. Regulation of luminal butyrate using HAMSB increases the rates of apoptotic deletion of DNA-damaged colonocytes. We propose this pro-apoptotic function of butyrate plays a major role reducing tumour formation in the AOM-treated rat and that these data support a potential protective role of butyrate in CRC.

The relationship between breastfeeding and weight status in a national sample of Australian children and adolescents

BackgroundBreastfeeding has been shown consistently in observational studies to be protective of overweight and obesity in later life. This study aimed to investigate the association between breastfeeding duration and weight status in a national sample of Australian children and adolescents.MethodsA secondary analysis of the 2007 Australian National Childrens Nutrition and Physical Activity Survey data involving 2066, males and females aged 9 to 16 years from all Australian states and territories. The effect of breastfeeding duration on weight status was estimated using multivariate logistic regression analysis.ResultsCompared to those who were never breastfed, children breastfed for ≥6 months were significantly less likely to be overweight (adjusted odds ratio: 0.64, 95%CI: 0.45, 0.91) or obese (adjusted odds ratio: 0.51, 95%CI: 0.29, 0.90) in later childhood, after adjustment for maternal characteristics (age, education and ethnicity) and childrens age, gender, mean energy intake, level of moderate and vigorous physical activity, screen time and sleep duration.ConclusionsBreastfeeding for 6 or more months appears to be protective against later overweight and obesity in this population of Australian children. The beneficial short-term health outcomes of breastfeeding for the infant are well recognised and this study provides further observational evidence of a potential long-term health outcome and additional justification for the continued support and promotion of breastfeeding to six months and beyond.

Beverage intake and obesity in Australian children

BackgroundThere have been increases in the obesity and overweight rates in Australian children over the past 25 years and it has been suggested that sugar sweetened beverages (SSB) have played a role in this increase.ObjectiveThe objectives of this study were to: (1) examine SSB intakes in the 2007 Australian Childrens Nutrition and Physical Activity Survey (2) relate SSB intake to rates of overweight and obesity, socio-economic status (SES), TV viewing time, and activity levels and (3) compare 2007 SSB intakes with data from the 1995 National Nutrition Survey.DesignA computer assisted 24 h dietary recall in 4,400 children aged 2-16 years was performed.ResultsIn the 2007 survey 47% of all children reported drinking SSBs with 25% consuming sugar sweetened soft drinks on the day of the survey. The mean consumption of soft drink was 436 g/d/consumer. Activity levels were unrelated to SSB consumption. Television viewing was positively related to soft drink consumption with a difference of 55 g/day from bottom to top tertile of time spent TV viewing (p = 0.015) in children aged 9-16 years. 55% of SSB consumption occurred at home and 10% occurred at school. Lower SES status was associated with a greater prevalence of SSB consumption- 30% for the lowest SES quartile vs 19% in the highest quartile. The proportion of overweight who consumed SSBs (which excludes 100% fruit) was not different from the non-overweight children although the proportion of SSB consumers in the 6% of children who were obese was significant compared with the non-overweight children (59% vs 47%, p < 0.05). In the 2007 survey 23% of children were overweight (17%) or obese (6%) while in the 1995 survey this figure was 21%. The proportion of children consuming SSBs in 1995 and 2007 for selected age groups were: 2-3 years - 25.8% and 12.8% respectively and 4-7 years - 33.6% and 20.5% respectively (p < 0.001 for both).ConclusionsThis cross-sectional data set provides evidence that SSB consumption for Australian children is still high despite the decrease since 1995 in some age groups. It provides little support to conclude that overweight in children is currently being driven by excessive SSB consumption although it may be factor in some obese children. Conclusions are limited by the cross sectional nature of the study.

Butyrate esterified to starch is released in the human gastrointestinal tract

BACKGROUND Short-chain fatty acids (SCFAs) maintain human colonic function and may help prevent colonic disease. A study with ileostomists showed that starches acylated with specific SCFAs largely survive passage through the small intestine, but the percentage released in the colon has not been established. OBJECTIVE The objective was to determine the percentage of ingested esterified butyrate released in the human gastrointestinal tract. DESIGN The study was a randomized, crossover, controlled trial consisting of baseline and four 2-wk periods during which 16 volunteers consumed diets low in resistant starch plus 20 and 40 g cooked high-amylose maize starch (HAMS: HAMS20 or HAMS40) or butyrylated HAMS (HAMSB20 or HAMSB40) daily. HAMSB20 contained 31.8 mmol esterified butyrate. Complete 48-h fecal collections were made on days 2-3 and 12-13 of each period. RESULTS Free fecal butyrate concentrations were higher after HAMSB40 than after HAMSB20 (P < 0.005) and HAMS (P < 0.0001) and higher than baseline data (P < 0.0001). Fecal esterified butyrate concentrations were highest in the HAMSB40 (days 12-13; P < 0.0001) group, and concentrations in the HAMSB40 (days 2-3) and HAMSB20 groups were higher than those in the HAMS groups and those at baseline (P < 0.0001). Ingestion of HAMSB20 and HAMSB40 resulted in the release of 26.8 ± 1.0 and 50.2 ± 2.4 mmol butyrate/d (days 12-13) (84.2 ± 3.0% and 79.0 ± 3.1% of total ingested esterified butyrate), respectively, in the gastrointestinal tract. By calculation, ∼57.2% of ingested esterified butyrate was released in the colon. Microbial analysis showed that this release was probably facilitated mainly by Parabacteroides distasonis, which increased in abundance with HAMSB40 (days 12-13) (P < 0.001). CONCLUSIONS This study shows that cooked butyrylated starch delivers esterified butyrate to the human colon effectively and has the potential to improve human bowel health. This trial is registered in the Australian Clinical Trials Registry as ACTRN012606000398505.