Torukiri I. Ibiebele

Diabetes mellitus and serum carotenoids: findings of a population-based study in Queensland, Australia

BACKGROUND Epidemiologic evidence suggests that serum carotenoids are potent antioxidants and may play a protective role in the development of chronic diseases including cancers, cardiovascular disease, and inflammatory diseases. The role of these antioxidants in the pathogenesis of diabetes mellitus remains unclear. OBJECTIVE This study examined data from a cross-sectional survey to investigate the association between serum carotenoids and type 2 diabetes. DESIGN Study participants were adults aged > or = 25 y (n = 1597) from 6 randomly selected cities and towns in Queensland, Australia. Study examinations conducted between October and December 2000 included fasting plasma glucose, an oral-glucose-tolerance test, and measurement of the serum concentrations of 5 carotenoid compounds. RESULTS Mean 2-h postload plasma glucose and fasting insulin concentrations decreased significantly with increasing quintiles of the 5 serum carotenoids--alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein/zeaxanthin, and lycopene. Geometric mean concentrations for all serum carotenoids decreased (all decreases were significant except that of lycopene) with declining glucose tolerance status. Beta-carotene had the greatest decrease, to geometric means of 0.59, 0.50, and 0.42 micromol/L in persons with normal glucose tolerance, impaired glucose metabolism, and type 2 diabetes, respectively (P < 0.01 for linear trend), after control for potential confounders. CONCLUSIONS Serum carotenoids are inversely associated with type 2 diabetes and impaired glucose metabolism. Randomized trials of diets high in carotenoid-rich vegetables and fruit are needed to confirm these results and those from other observational studies. Such evidence would have very important implications for the prevention of diabetes.

Evaluation of brief dietary questions to estimate vegetable and fruit consumption - using serum carotenoids and red-cell folate

OBJECTIVE To evaluate responses to self-administered brief questions regarding consumption of vegetables and fruit by comparison with blood levels of serum carotenoids and red-cell folate. DESIGN A cross-sectional study in which participants reported their usual intake of fruit and vegetables in servings per day, and serum levels of five carotenoids (alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein/zeaxanthin and lycopene) and red-cell folate were measured. Serum carotenoid levels were determined by high-performance liquid chromatography, and red-cell folate by an automated immunoassay system. SETTINGS AND SUBJECTS Between October and December 2000, a sample of 1598 adults aged 25 years and over, from six randomly selected urban centres in Queensland, Australia, were examined as part of a national study conducted to determine the prevalence of diabetes and associated cardiovascular risk factors. RESULTS Statistically significant (P<0.01) associations with vegetable and fruit intake (categorised into groups: </=1 serving, 2-3 servings and >/=4 servings per day) were observed for alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein/zeaxanthin and red-cell folate. The mean level of these carotenoids and of red-cell folate increased with increasing frequency of reported servings of vegetables and fruit, both before and after adjusting for potential confounding factors. A significant association with lycopene was observed only for vegetable intake before adjusting for confounders. CONCLUSIONS These data indicate that brief questions may be a simple and valuable tool for monitoring vegetable and fruit intake in this population.

High Intake of Folate from Food Sources Is Associated with Reduced Risk of Esophageal Cancer in an Australian Population

Folate plays a key role in DNA synthesis and methylation. Limited evidence suggests high intake may reduce risks of esophageal cancer overall; however, associations with esophageal cancer subtypes and Barretts esophagus (BE), a precancerous lesion, remain unexplored. We evaluated the relation between intake of folate, B vitamins, and methyl-group donors (methionine, choline, betaine) from foods and supplements, polymorphisms in key folate-metabolizing genes, and risk of BE, esophageal adenocarcinoma (EAC), and esophageal squamous cell carcinoma (ESCC) in 2 population-based case-control studies in Australia. BE patients without (n = 266) or with (n = 101) dysplasia were compared with population controls (n = 577); similarly, EAC (n = 636) or ESCC (n = 245) patients were compared with population controls (n = 1507) using multivariable adjusted logistic regression. Increasing intake of folate from foods was associated with reduced EAC risk (P-trend = 0.01) and mitigated the increased risks of ESCC associated with smoking and alcohol consumption. In contrast, high intake of folic acid from supplements was associated with a significantly elevated risk of BE with dysplasia. High intakes of riboflavin and methionine from food were associated with increased EAC risk, whereas increasing betaine intake was associated with reduced risks of BE without (P-trend = 0.004) or with dysplasia (P-trend = 0.02). Supplemental thiamin, riboflavin, niacin, and vitamin B-12 were associated with increased EAC risk. There were no consistent associations between genetic polymorphisms studied and BE or EAC risk. High intake of folate-containing foods may reduce risk of EAC, but our data raise the possibility that folic acid supplementation may increase risks of BE with dysplasia and EAC.

Reproducibility of food and nutrient intake estimates using a semi-quantitative FFQ in Australian adults

OBJECTIVE To assess the reproducibility of a 135-item self-administered semi-quantitative FFQ. DESIGN Control subjects who had previously completed an FFQ relating to usual dietary intake in a nationwide case-control study of cancer between November 2003 and April 2004 were randomly selected, re-contacted, and invited to complete the same FFQ a second time approximately one year later (between January and April 2005). Agreement between the two FFQ was compared using weighted kappa statistics and intraclass correlation coefficients (ICC) for food groups and nutrients. Summary questions, included in the FFQ, were used to assess overall intakes of vegetables, fruits and meat. SETTING General community in Australia. SUBJECTS One hundred men and women aged 22-79 years, randomly selected from the previous control population. RESULTS The weighted kappa and ICC measures of agreement for food groups were moderate to substantial for seventeen of the eighteen food groups. For nutrients, weighted kappa ranged from 0.44 for starch to 0.83 for alcohol while ICC ranged from 0.51 to 0.91 for the same nutrients. Estimates of meat, fruit and vegetable intake using summary questions were similar for both survey periods, but were significantly lower than estimates from summed individual food items. CONCLUSIONS The FFQ produced reproducible results and is reasonable in assessing the usual intake of various foods and nutrients among an Australian adult population.

Metabolic syndrome and serum carotenoids: findings of a cross-sectional study in Queensland, Australia.

Several components of the metabolic syndrome, particularly diabetes and CVD, are known to be oxidative stress-related conditions and there is research to suggest that antioxidant nutrients may play a protective role in these conditions. Carotenoids are compounds derived primarily from plants and several have been shown to be potent antioxidant nutrients. The aim of the present study was to examine the associations between metabolic syndrome status and major serum carotenoids in adult Australians. Data on the presence of the metabolic syndrome, based on International Diabetes Federation 2005 criteria, were collected from 1523 adults aged 25 years and over in six randomly selected urban centres in Queensland, Australia, using a cross-sectional study design. Weight, height, BMI, waist circumference, blood pressure, fasting and 2 h blood glucose and lipids were determined, as well as five serum carotenoids. Mean serum alpha-, beta-carotenes and the sum of the five carotenoid concentrations were significantly lower (P < 0.05) in persons with the metabolic syndrome (after adjusting for age, sex, education, BMI status, alcohol intake, smoking, physical activity status and vitamin/mineral use) than persons without the syndrome. alpha-, beta- and total carotenoids also decreased significantly (P < 0.05) with increased number of components of the metabolic syndrome, after adjusting for these confounders. These differences were significant among former smokers and non-smokers, but not in present smokers. Low concentrations of serum alpha-, beta-carotenes and the sum of five carotenoids appear to be associated with metabolic syndrome status. Additional research, particularly longitudinal studies, may help to determine whether these associations are causally related to the metabolic syndrome, or are a result of the pathologies of the syndrome.

Dietary antioxidants and risk of Barrett's esophagus and adenocarcinoma of the esophagus in an Australian population.

While dietary antioxidants are emerging as potentially modifiable risk factors for esophageal adenocarcinoma (EAC), studies on dietary antioxidants and its precursor Barretts esophagus (BE) are limited. The present study extends previous work on BE by investigating risks of nondysplastic BE, dysplastic BE and EAC associated with intake of antioxidants such as vitamin C, vitamin E, β‐carotene, and selenium. Age and sex matched control subjects (n=577 for BE; n=1,507 for EAC) were sampled from an Australian population register. Information on demography, and well established EAC risk factors were obtained using self‐administered questionnaires. Intake of antioxidants for patients newly diagnosed with nondysplastic BE (n=266), dysplastic BE (n=101), or EAC (n=299), aged 18–79 years, were obtained using a food frequency questionnaire. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using multivariable adjusted logistic regression models. High intake of β‐carotene from food and supplement sources combined was inversely associated with risk of dysplastic BE (OR Q4 vs. Q1=0.45; 95%CI: 0.20–1.00). High intake of vitamin E from food sources (OR Q4 vs. Q1=0.43; 95%CI: 0.28–0.67), from food and supplements combined (OR Q4 vs. Q1=0.64; 95%CI: 0.43–0.96), and a high antioxidant index score were inversely associated with risk of EAC. We found no significant trends between intake of β–carotene, vitamin C, vitamin E, and selenium and risk of nondysplastic or dysplastic BE. However, our data suggest that a high intake of β‐carotene may be associated with decreased risk of dysplastic BE.

Cancers in Australia in 2010 attributable to modifiable factors: summary and conclusions.

Objective: To estimate the numbers and proportions of cancers occurring in Australia in 2010 attributable to modifiable causal factors.

Carbohydrate intake, glycemic load, glycemic index, and risk of ovarian cancer

BACKGROUND Our objective was to determine the relationship between dietary glycemic load (GL), glycemic index (GI), carbohydrate intake, and ovarian cancer risk in a population-based case-control study. PATIENTS AND METHODS A self-administered questionnaire was used to collect data on demographic and lifestyle factors, and a food frequency questionnaire was used to collect dietary information from 1366 women with ovarian cancer and 1414 population controls. RESULTS GL was positively associated with ovarian cancer. The adjusted odds ratio (OR) for the highest versus the lowest quartile of intake was 1.24 [95% confidence interval (CI) 1.00-1.55, P for trend = 0.03]. Fiber intake was inversely associated with risk. The OR comparing women in the highest fiber-intake group with those in the lowest was 0.78 (95% CI 0.62-0.98, P for trend = 0.11). We found no association between GI, carbohydrate intake, and ovarian cancer. In analyses stratified by body mass index, the risk estimates for GL, carbohydrate, and sugar were higher among overweight/obese women; however, the interaction term was only significant for sugar (P for interaction = 0.004). CONCLUSIONS Our results suggest that diets with a high GL may increase the risk of ovarian cancer, particularly among overweight/obese women, and a high intake of fiber may provide modest protection.

Development and validity assessment of a diet quality index for Australians

Existing Australian diet quality indices have assumed links to health outcomes but their validity for this has not been reported. We extend the features of existing indices for Australian adults by constructing a new diet quality index (Aussie-DQI) using the national dietary guidelines linked to the Australia National Health Priority Areas. Construct validity was assessed using 24 hour dietary recalls from the 1995 National Nutrition Survey (n=10,851 adults aged 19 years and older). Construct and criterion validity were assessed using food frequency questionnaire data from the Nambour Skin Cancer study (n=1355), a community-based longitudinal study with 16 year follow-up and cause-specific mortality outcomes. Generalised linear regression was used to assess associations between Aussie-DQI scores and socio-economic, demographic, health-behaviour characteristics, and food and nutrient intakes, while Cox proportional-hazards modeling was used to assess associations with cancer and allcause mortality. A high Aussie-DQI score was associated with being female, being older, non-smoking status, and BMI in the normal range in both study populations; and Aussie-DQI scores were inversely associated with cancer mortality among men in multivariable-adjusted analyses (hazard ratio = 0.30, 95% CI: 0.11, 0.83; p for trends = 0.06). In conclusion, Aussie-DQI successfully discriminated diet quality and showed that men, younger adults, current smokers and those overweight/obese were less likely to consume foods that meet dietary recommendations; and that a high diet quality is associated with decreased risk of cancer mortality among men. This study adds further evidence to clarify the role of diet quality in decreasing mortality from chronic diseases.

Alcohol intake and risk of skin cancer: A prospective study

Objective:To investigate the association between total alcohol intake and intake of different types of alcoholic beverages in relation to the risk of basal cell (BCC) and squamous cell (SCC) carcinoma of the skin.Design:Prospective cohort study.Setting:Follow-up data from a community-based skin cancer study in Australia.Subjects:Randomly selected sample of 1360 adult residents of the township of Nambour who completed a food frequency questionnaire in 1992 and were monitored for BCC and SCC until 31 December 2002.Results:No significant association was found between overall BCC or SCC risk and total alcohol intake, or intake of beer, white wine, red wine or sherry and port. However, among those with a prior skin cancer history, there was a significant doubling of risk of SCC for above-median consumption of sherry and port (multivariable adjusted relative risk 2.46, 95% confidence interval 1.06–5.72) compared with abstainers.Conclusions:There are no associations between first occurrence of skin cancers and alcoholic beverage consumption. People with a history of skin cancer who consume above-average quantities of sherry or port may be at a raised risk of SCC, although replication of these findings in different study populations is needed to confirm this possible role of specific alcoholic beverages in secondary keratinocytic skin cancer risk.