Ethnic differences in weight gain and diabetes risk: the Multiethnic Cohort Study.

AIM: To improve our understanding of excess body weight and risk for diabetes type 2, the study examined the influence of weight change in the Hawaii component, including 78,006 Caucasians, Japanese Americans and Native Hawaiians, of the Multiethnic Cohort Study. METHODS: Participants aged 58.5±9.2 years completed a questionnaire at cohort entry (Qx1), including weight at age 21, and a follow-up questionnaire 5 years later (Qx2). After 14 years of follow-up, 8892 incident diabetes cases were identified through self-reports or linkups with the major health plans in Hawaii. Cox regression analysis was applied, stratified by age and adjusted for confounders, to estimate hazard ratios (HRs). RESULTS: The mean weight gain from age 21 to Qx1 was 10.5±11.0 kg and, between Qx1 and Qx2, 0.8±5.6 kg. Diabetes risk showed a significant dose-response relationship with weight gain from age 21 (P<0.0001). The respective HRs for a weight gain of 5-10 kg and greater or equal to 25 kg were 1.8 (95% CI: 1.7-2.0) and 7.7 (95% CI: 7.1-8.4), while weight loss of greater than 5 kg significantly reduced diabetes risk (HR=0.7; 95% CI: 0.6-0.9). The interaction term of weight change since age 21 with ethnicity was also highly significant (P<0.0001). Compared with stable-weight Caucasians, the adverse effects of weight gain were more pronounced in those of Japanese and Native Hawaiian descent. Weight change between Qx1 and Qx2 conferred a smaller risk. CONCLUSION: These findings support the current public-health recommendations for weight control and particularly among ethnic groups at high risk for diabetes.

Meat consumption and risk of type 2 diabetes: the Multiethnic Cohort.

OBJECTIVE: To examine the association of meat consumption with diabetes risk in the Hawaii component of the Multiethnic Cohort and to assess effect modification by ethnicity. DESIGN: A prospective cohort study. Baseline information on diet and lifestyle was assessed by questionnaire. The cohort was followed up for incident cases of diabetes, which were identified through self-reports, medication questionnaires, or health plan linkages. Cox regression was used to calculate hazard ratios (HR) and 95% confidence intervals for diabetes associated with quintile of meat consumption. SETTING: Hawaii, USA. SUBJECTS: A total of 29,759 Caucasian, 35,244 Japanese-American and 10,509 Native Hawaiian men and women, aged 45-75 years at baseline. RESULTS: During a mean follow-up time of 14 years, 8587 incident diabetes cases were identified. Intake of red meat was positively associated with diabetes risk in men (fifth v. first quintile: HR=1.43; 95% CI 1.29, 1.59) and women (fifth v. first quintile: HR=1.30; 95% CI 1.17, 1.45) in adjusted models. The respective HR for processed red meat intake were 1.57 (95% CI 1.42, 1.75) and 1.45 (95% CI 1.30, 1.62). The association for processed poultry was weaker than for processed red meat, and fresh poultry intake was not associated with diabetes risk. For men only, we observed significant interactions of ethnicity with the red and processed red meat associations, with Caucasians experiencing slightly higher risks than Japanese-Americans. CONCLUSIONS: Our findings support the growing evidence that red and processed meat intake increase risk for diabetes irrespective of ethnicity and level of BMI.

Dietary adequacy of Inuit in the Canadian Arctic.

BACKGROUND: Food intake amongst Canadian Inuit is currently in transition with a concurrent increase in diet-related chronic disease. There is a lack of current data on nutrient intake and dietary adequacy in this population. The present study aimed to assess dietary intake and adequacy amongst Inuit adults in a community in Nunavut, Canada. METHODS: Random sampling of 130 households in a remote Inuit community in the Kitikmeot region of Nunavut, Canada, was used for this cross-sectional study. Up to three 24-h dietary recalls were collected on nonconsecutive days, capturing weekday and weekend consumption. Data were analysed to estimate energy and nutrient intake, to determine dietary adequacy, and to summarise the most commonly reported foods and the top food contributors to selected nutrients. RESULTS: The response rate was 69%, with 75 Inuit adults participating (mean (standard deviation (SD)) age 44 (SD=17) years). Mean (SD) daily energy intake was 9.3 (4.4) MJ and 8.7 (3.5) MJ for men and women, respectively. Intakes of dietary fibre, calcium, total folate and vitamins A, D and E were below the Dietary Reference Intakes (Estimated Average Requirements where available) for 60-100% of all men and women. Traditional foods contributed substantially to protein and iron intake, whilst shop-bought foods were primary contributors to total fat, carbohydrate and sugar intake. CONCLUSIONS: The present study reports an in-depth assessment of total dietary quality amongst Inuit adults in Nunavut, Canada. The results obtained indicate inadequate intakes of several essential nutrients, as well as a reliance on a nontraditional diet. A nutrition intervention is needed to prevent a continued rise in diet-related chronic disease incidence.

Assessment of dietary adequacy in a remote Inuvialuit population.

BACKGROUND: Traditional foods are rich sources of essential nutrients, but Inuvialuit in the Northwest Territories (NWT), Canada, have been undergoing a nutrition transition, characterised by an increased consumption of non-nutrient-dense foods. The present study aimed to characterise energy, nutrient and food intakes amongst adult Inuvialuit. METHODS: The study collected up to three 24-h dietary recalls on nonconsecutive days for each participant in spring/summer of 2008 in one remote community in the NWT. Recall data were analysed for energy and nutrient intake, dietary adequacy, most commonly reported foods, and food contributors to energy and nutrients. RESULTS: Participants included 14 men and 50 women (response rate 79%). Median daily energy intake was 9.4 (interquartile range=5.7) MJ for men and 8.3 (3.6) MJ for women. The majority of adult Inuvialuit did not meet the recommendation for vitamins A [median intake=344.7 (246.3) µg-RAE in men, 248.9 (213.8) µg-RAE in women], B(6) [0.9 (0.8) mg in men, 1.0 (0.5) mg in women] and E [2.4 (2.1) mg in men, 1.8 (1.0) mg in women], dietary fibre [7.7 (5.7) g in men, 8.7 (4.4) g in women], calcium [779.6 (842.0) mg in men, 610.4 (431.5) mg in women] and total folate [222.6 (57.7) µg in men, 264.6 (127.5) µg in women]. Vitamin D intake was below the recommendation for most women [median intake=100.0 (119.2) IU]. Traditional foods contributed substantially to protein and iron intake. Juices were the main contributors to energy, carbohydrate and calcium. CONCLUSIONS: The present study revealed an inadequate consumption of essential nutrients in an Inuvialuit population. If these nutrient deficiencies continue, this population will face an increased burden of chronic diseases and malnutrition.

Prevalence and risk factors for self-reported chronic disease amongst Inuvialuit populations.

BACKGROUND: Chronic disease prevalence amongst Canadian Arctic populations is increasing, but the literature amongst Inuvialuit is limited. The present study aimed to provide baseline data that could be used to monitor changes in chronic disease risk factors and long-term health in the Arctic by determining prevalence and risk factors of self-reported chronic disease amongst adult Inuvialuit in remote communities. METHODS: Self-reported demographics and history of chronic disease (hypertension, heart disease, diabetes and cancer) were collected in three communities between July 2007 and July 2008 in the Northwest Territories. Food frequency questionnaires recorded dietary intake, International Physical Activity Questionnaires recorded physical activity and anthropometric measures of height and weight were obtained. RESULTS: Response rates ranged from 65-85%. More than 20% of the 228 participants aged 19-84 years reported having a chronic disease. Age-adjusted prevalence was 28, 9, 9 and 6 per 100 for hypertension, heart disease, diabetes and cancer, respectively. Compared with non-cases, participants reporting hypertension were more likely to have a higher body mass index and a lower level of education. Hypertension was more common amongst participants reporting heart disease and diabetes than Inuvialuit not reporting these morbidities. CONCLUSIONS: Inuvialuit participants in this study were most affected by hypertension and diabetes compared with heart disease or any cancer. Female participants had a higher prevalence of heart disease compared with the Canadian average. Primary preventive strategies are necessary to mitigate the increasing rates of chronic disease risk factors in this population. Further studies with a larger sample size and measured chronic disease are necessary to confirm the findings obtained in the present study.

Socioeconomic indicators and frequency of traditional food, junk food, and fruit and vegetable consumption amongst Inuit adults in the Canadian Arctic.

BACKGROUND: Increasing consumption of non-nutrient-dense foods (NNDF), decreasing consumption of traditional foods (TF) and low consumption of fruit and vegetables (FV) may contribute to increasing chronic disease rates amongst Inuit. The present study aimed to assess the daily frequency and socioeconomic and demographic factors influencing consumption of TF, FV and NNDF amongst Inuit adults in Nunavut, Canada. METHODS: Using a cross-sectional study design and random household sampling in three communities in Nunavut, a food frequency questionnaire developed for the population was used to assess frequency of NNDF, TF and FV consumption amongst Inuit adults. Socioeconomic status (SES) was assessed by education level, ownership of items in working condition, and whether or not people in the household were employed or on income support. Mean frequencies of daily consumption were compared across gender and age groups, and associations with socioeconomic indicators were analysed using logistic regression. RESULTS: Two hundred and eleven participants (36 men, 175 women; mean (standard deviation) ages 42.1 (15.0) and 42.2 (13.2) years, respectively; response rate 69-93%) completed the study. Mean frequencies of consumption for NNDF, TF and FV were 6.3, 1.9 and 1.6 times per day, respectively. On average, participants ≤50 years consumed NNDF (P=0.003) and FV (P=0.01) more frequently and TF (P=0.01) less frequently than participants >50 years. Education was positively associated with FV consumption and negatively associated with TF consumption. Households on income support were more likely to consume TF and NNDF. CONCLUSIONS: These results support the hypothesis that the nutrition transition taking place amongst Inuit in Nunavut results in elevated consumption of NNDF compared with TF and FV.

Food patterns and socioeconomic indicators of food consumption amongst Inuvialuit in the Canadian Arctic.

BACKGROUND: Inuvialuit in the Canadian Arctic have been experiencing a nutrition transition resulting in a decrease in nutrient-dense food consumption, which may, in part, explain this population's increasing chronic disease rates. Because the available literature is limited, the present study aimed to document the extent of this transition by examining current dietary patterns and socioeconomic factors affecting food group consumption. METHODS: This cross-sectional study was conducted in three Inuvialuit communities in the Northwest Territories between 2007 and 2008. A validated food frequency questionnaire determined intake frequency of fruit and vegetables (FV), traditional foods (TF) and non-nutrient-dense foods (NNDF). Socioeconomic status (SES) was assessed by questions on education, ownership of items in working condition used to create a Material Style of Life (MSL) scale and residents in household employed/on income support. Daily intake frequencies were compared by gender and age group using Wilcoxon rank sum test. SES association with food group intake was determined using logistic regression. RESULTS: The response rate was 65-85%. One hundred and seventy-five participants were female and 55 were male, aged 19-84 years [mean (SD) 44 (14)]. Mean frequencies of FV and TF consumption were 1.6 (1.5) and 1.6 (1.7) times per day, respectively. NNDF were reported 9.2 (3.0) times per day. The highest MSL score (>12) was significantly associated with higher fruit (≥0.7 times per day) and higher TF intake (≥1.1 times per day) compared with the lowest score (≤7). An intermediate MSL score (8-12) was related to higher vegetable consumption (≥0.4 times per day). CONCLUSIONS: NNDF were consumed approximately seven times more frequently than TF in the present study, indicating that the dietary transition is well underway amongst Inuvialuit. Participants with higher SES were more likely to consume nutrient-dense foods, suggesting possible cost barriers.

High levels of physical activity and obesity co-exist amongst Inuit adults in Arctic Canada.

BACKGROUND: Existing evidence indicates that Inuit in Arctic Canada are undergoing a lifestyle transition leading to decreased physical activity (PA) and increased body mass index (BMI). Data specific to PA and BMI amongst Inuit in Nunavut, Canada, are currently limited. The present study aimed to characterise current PA and BMI levels in a sample of Inuit adults. METHODS: Inuit adults randomly selected from a cross-sectional survey of three communities in Nunavut, Canada, completed an adapted International Physical Activity Questionnaire (IPAQ) and an anthropometric survey. Data were analysed by gender and age group using standardised IPAQ protocol. RESULTS: Response rates ranged from 69-93%. Two hundred and eighteen Inuit adults [180 women, 38 men; mean (standard deviation (SD)) ages 42.3 (13.0) and 42.4 (14.8) years respectively; age range 19-89 years] completed the IPAQ. All men and 97% of women allowed height and weight measurements; the remainder were self-reported. Mean (SD) BMI was 27.7 (6.3) kg/m(2) for males and 30.3 (8.0) kg/m(2) for females. The largest proportion of women and participants in both age groups had a BMI in the obese category; males were evenly split between the normal and obese categories. Self-reported PA was high, with most men, women and participants ≤50 years in the high category of PA. Participants >50 years were evenly split across the medium and high categories. Most participants (72%) were classified as being overweight or obese, yet reported medium or high levels of PA (89%). CONCLUSIONS: The findings obtained in the present study indicate the co-existence of high BMI and high self-reported PA amongst Inuit adults.

Inuvialuit adults in the Canadian Arctic have a high body mass index and self-reported physical activity.

BACKGROUND: Inuvialuit in Arctic Canada are undergoing nutrition and lifestyle transitions that encourage decreased physical activity (PA) and increased body mass index (BMI), although data specific to PA and BMI within this unique population are not currently available. The present study aimed to characterise current PA and BMI levels in a sample of Inuvialuit adults. METHODS: Inuvialuit adults randomly selected from a cross-sectional survey of three communities in the Northwest Territories, Canada, completed an adapted International Physical Activity Questionnaire (IPAQ) and an anthropometric questionnaire to obtain height and weight. Data were analysed using the standardised IPAQ protocol, and the results are presented by gender and age group (≤50 and >50 years). RESULTS: One hundred and ninety-six Inuvialuit adults [148 women, 48 men; mean (standard deviation (SD)) ages 45 (14) and 41 (14) years, respectively; age range 19-84 years] completed the IPAQ (response rates 65-85%). Seventy-one percent of men and 74% of women allowed height measurements, whilst 81% and 84% allowed weight measurements, respectively; the remainder provided self-reported anthropometrics. Mean (SD) BMIs were 28.6 (7.7) kg/m(2) for males and 30.5 (8.8) kg/m(2) for females. The greatest percentage of participants in both gender and age groups fell into the obese BMI category. Self-reported PA was high, with means for men and participants ≤50 years in the high category of PA and means for women and participants >50 years in the medium category. Almost two-thirds (65%) of participants were classified as being overweight or obese, although 89% reported medium or high levels of PA. CONCLUSIONS: The results obtained in the present study indicate widespread overweight/obesity accompanying high levels of self-reported PA.

Effects of insulin, glucagon and triiodothyronine on DNA synthesis in rat hepatocyte primary cultures induced by liver tumour promoters and EGF.

Enhanced cell proliferation may favour DNA-damaging processes (tumour initiation) as well as the expansion of clones of altered cells (tumour promotion). The latter process appears to be responsible for carcinogenesis by non-genotoxic compounds. We previously have established rat hepatocyte primary cultures under serum-free conditions and studied the effect of the rat liver tumour promoter cyproterone acetate (CPA) on DNA synthesis. It was found that glucocorticoid concentration of 100 nm dexamethasone was necessary for the induction of DNA synthesis. In the present study the growth supporting effect of insulin, glucagon and triiodothyronine (T3) were examined. Pretested concentrations of CPA, pregnenolone-16alpha-carbonitrile (PCN), alpha-hexachlorocyclohexane (HCH), nafenopin (NAF) and phenobarbital (PB) were added for stimulation of DNA synthesis. EGF served as a reference stimulator. Beginning with standard medium concentrations of insulin (7 nM), glucagon (0.4 nM) and triiodothyronine (100 nM) dose-response studies were obtained by leaving all but one of the hormone concentrations constant. DNA synthesis was measured by incorporation of [(3)H]thymidine into DNA. In solvent-treated dimethyl sulfoxide (DMSO) cultures insulin at 6 nM and higher induced a 2.5-fold induction of DNA synthesis. Insulin also enhanced DNA synthesis induced by CPA, HCH, NAF, PCN and EGF but not by phenobarbital (EC(50), 2-3 nm). The effect of glucagon (0.016nm-16nm) appeared to be much less prominent and was observed only at superphysiological concentrations with CPA, PCN, HCH and EGF. DNA synthesis induced by NAF was slightly suppressed at 1.6nm glucagon. T3 did not induce DNA synthesis by itself, nor was there modulation of DNA synthesis induced by rat liver tumour promoters. Thus the so-called hepatotrophic hormones differentially modulate the induction of DNA synthesis by rat liver tumour promoters in primary rat hepatocyte cultures.

Effect of transforming growth factor beta on cell death of cultured rat hepatocytes.

We investigate mechanisms of regression of liver hyperplasia which occurs after induction of growth by hepatomitogens and their subsequent withdrawal. We hypothesized that transforming growth factor beta 1 (TGF-beta 1) might be involved in the control of regression. Therefore we studied the effect of this agent on DNA synthesis and death of hepatocytes cultured in vitro. Both the low basal rate of DNA synthesis of untreated cells and its increase by epidermal growth factor (10 ng/ml) were suppressed by TGF-beta 1 at concentrations higher than 0.01-0.1 ng/ml. At the same range of concentrations of TGF-beta 1, the DNA content of the cultures declined significantly and numerous dead cells could be seen in the monolayer. Time course studies showed that TGF-beta 1 (1 ng/ml) decreased DNA content in the cultures linearly to 41 +/- 7% of controls during a period of 48 h. A similar decrease occurred with vital hepatocytes in hematoxylin and eosin stained monolayers. These changes were accompanied by an extensive release of lactate dehydrogenase which began at 20 h and was 70% of the total lactate dehydrogenase content of the cultures at 40-48 h. Little formation of guanidine hydrochloride resistant bodies and no fragmentation of DNA, indicators of apoptotic cell death, were detected after TGF-beta 1 (1 ng/ml) treatment. Time lapse cinematography revealed an active detachment of the cells from the underlying collagen gel. These studies show that inhibition of DNA synthesis by TGF-beta 1 is associated with enhanced cell death in cultured hepatocytes.

Testing for induction of DNA synthesis in human hepatocyte primary cultures by rat liver tumor promoters.

Parenchymal liver cells were isolated from human liver pieces of surgical waste as well as from rat livers. DNA synthetic activity was measured after different times in primary culture by [3H]thymidine incorporation and autoradiography. Labeling of control cultures of human hepatocytes at densities between 8,000 and 15,000 cells/cm2 was very low (0.4 to 1.3%). Human recombinant epidermal growth factor increased labeling 2- to 4-fold (P less than 0.01). Treatment with known inducers of liver growth in rats, namely, cyproterone acetate, alpha-hexachlorocyclohexane, nafenopin, phenobarbital, and rifampicin did not increase the number of labeled human liver cells. In some of the experiments, a 24-h exposure to the chemicals of rat or human hepatocytes was followed by a 24-h treatment with epidermal growth factor (EGF). In rat hepatocytes, incorporation rates were significantly increased. Cyproterone acetate and EGF acted in an additive manner, alpha-hexachlorocyclohexane and EGF were clearly overadditive, and phenobarbital had little effect. In human hepatocytes, little alteration in labeling indices was found; in some cases labeling was, rather, found to be lower than in cultures treated with EGF alone. These results show that human hepatocytes cultured in vitro are sensitive to stimulation of DNA synthesis by EGF; they differ from rat hepatocytes in their response to some drugs which show liver growth-promoting activity in rodents.