| A healthy diet,physical activity,and weight management represent the cornerstone of diabetes prevention.More than 50% of persons with diabetes in the word reside in Asia,but how dietary behaviors may affect diabetes development has been less clear in Asian than in Western populations.Under the support of the China Scholarship Council,the author was trained as a joint Ph D student at the National University of Singapore.During the period,we investigated dietary contributors to type 2 diabetes(T2D)using the Singapore Chinese Health Study,one of the largest population-based prospective cohort studies in Asia.In Part I,we investigated several dietary patterns formulated based on research evidence from Western countries in relation to T2 D risk in this Asian population,and we further evaluated the independent associations between components of these dietary patterns and T2 D risk.In part II,we examined several vegetables commonly consumed in Asians,including light green vegetables,dark green leafy vegetables and cruciferous vegetables,in relation to risk of T2 D in this population.Part ?ObjectiveTo investigate the prospective relationships between five predefined dietary patterns,including the alternate Mediterranean diet(a MED),alternative Healthy Eating Index(AHEI)-2010,Dietary Approaches to Stop Hypertension(DASH)diet,an overall plant-based diet index(PDI),and a healthful plant-based diet index(h PDI),and risk of T2 D in an Asian population.We further evaluated the associations between individual components of these dietary patterns and risk of T2 D.Subjects and MethodsA total of 63,257 Chinese aged 45 to 74 years were enrolled between 1993 and 1998.Participants belonged to one of the major dialect groups(Hokkien or Cantonese)of Chinese in Singapore.Baseline information on habitual dietary intake over the past year was collected using a 165-item,semi-quantitative food frequency questionnaire(FFQ)that was administered by a trained interviewer.Other information were also collected at recruitment through in-person interviews,including subjects' demographics,height and weight,tobacco use,physical activity,female menstrual and reproductive history,and medical history.The first and second follow-up interviews were conducted by telephone calls during 1999 to 2004 and 2006 to 2010.The present analysis excluded those participants who had known baseline diabetes,cancer,stroke or heart disease;had unrealistic daily energy intake;were lost to follow-up or died before diabetes diagnosis,left 45,411 eligible subjects.According to predetermined criteria,dietary pattern scores(a higher score indicates better adherence)were calculated for the above-mentioned five dietary patterns.Cox proportional hazards regression was used to estimate hazard ratio(HR)and 95% confidence interval(CI)of T2 D risk associated with quintiles of the dietary pattern scores,with the lowest quintiles as reference groups.The main analyses were further stratified by age,sex,body mass index(BMI),presence of hypertension,and smoking status of the participants.Various sensitivity analyses were also performed to test robustness of the findings.ResultsDuring a median 11.2 years(494,741 person-years)of follow-up,5207 incident cases of T2 D occurred.After the adjustment for multiple potential confounders including BMI,all the five dietary pattern scores were significantly and inversely associated with risk of T2D(all P-trend<0.001),with the strongest association observed for a higher DASH score.The adjusted HRs comparing the highest with the lowest quintiles of the dietary pattern scores were 0.84(95% CI: 0.77-0.92)for a MED,0.79(95% CI: 0.73-0.87)for AHEI-2010,0.71(95% CI: 0.65-0.79)for DASH,0.83(95% CI: 0.76-0.92)for PDI,and 0.81(95% CI: 0.75-0.89)for h PDI.These inverse associations did not differ substantially in subgroup populations according to baseline age,sex,BMI or presence of hypertension,but were limited to non-smokers,and the interaction with smoking status was significant for a MED and AHEI-2010 indices(P for interaction with smoking<0.001 for a MED and 0.03 for AHEI-2010).Further sensitivity analysis confirmed the robustness of these results.Among the individual components of the evaluated dietary patterns,high consumption of red meat and processed meat(HR for 1 serving/day increment=1.29,95% CI:1.11-1.50;P-trend<0.001)and sugar-sweetened beverages(HR for 1 glass/day increment=1.11(95% CI: 1.04-1.19;P-trend<0.001)and low consumption of whole grains(HR for 1 serving/day increment=0.93,95% CI: 0.90-0.97;P-trend=0.01)and coffee(HR for 2 cups/day increment=0.94,95% CI: 0.90-0.99;P-trend=0.004)were significantly associated with a higher risk of T2 D.ConclusionsOur study showed that adherence to several predefined dietary patterns formulated based on research evidence from Western countries was similarly associated with a lower risk of type 2 diabetes in an Asian population,and these inverse associations were largely independent of multiple conventional risk factors for type 2 diabetes.High consumption of whole grain and coffee and low consumption of red meat and processed meat and sugar-sweetened beverages were significant contributors to the observed inverse associations between these dietary patterns and risk of type 2 diabetes.Our findings support that dietary pattern approaches should be among the most important primary prevention strategies for type 2 diabetes.Part ?ObjectiveIn this part,we investigated the prospective associations between consumption of light green vegetables,dark green vegetables(all were leafy)and cruciferous vegetables and risk of T2 D in an Asian population.Subjects and MethodsAs was described in the Part I,we included in the present analysis 45,411 participants(age range: 45-74 years)of the Singapore Chinese Health Study free of diabetes,cancer or cardiovascular disease at baseline(1993-1998).Dietary information was collected using an interview-based,validated FFQ.Physician-diagnosed incident T2 D were reported at follow-up I(1999-2004)and II(2006-2010)interviews.Owing to the moderate correlations between vegetables and dietary energy,consumption of each vegetable group was divided by dietary energy and expressed as g/2000 kcal.We used the Cox proportional hazards regression to estimate HR and 95%CI of T2 D risk associated with quintiles of energy-adjusted vegetable consumption,with the lowest quintiles as reference groups.We also conducted stratified analyses and tested interactions of vegetable consumption by sex,BMI,presence of hypertension,and smoking status of the participants.ResultsA total of 5207 incident T2 D cases occurred during the follow-up.After adjustment for potential confounders including BMI,none of the three vegetable groups were substantially associated with risk of T2D(P-trend?0.21).The fully adjusted HRs comparing the highest with the lowest quintiles of the consumption were 0.95(95% CI: 0.87-1.04)for light green vegetables,1.05(95% CI: 0.96-1.15)for dark green leafy vegetables,and 0.97(95% CI: 0.88-1.06)for cruciferous vegetables.The lack of associations between the three vegetable groups and risk of T2 D were generally consistent in the analyses stratified by sex,BMI,and presence of.When stratifying the analyses by smoking status of the participants,light green vegetable intake was associated with a significant 21% reduction in T2 D risk(HR=0.79,95% CI: 0.66-0.95;P-trend=0.04),and cruciferous vegetable intake was associated with a borderline significant 16% reduction in T2 D risk(HR=0.84,95% CI: 0.70-1.01;P-trend=0.05)lower risk of T2 D in ever smokers(current or past smokers),but no significant interaction with smoking status was observed(P-interaction = 0.11 and 0.22,respectively).ConclusionsOverall,consumption of green vegetables(either light green vegetable or dark green leafy vegetables)or cruciferous vegetable was not substantially associated with risk of T2 D in an Asian population.The suggestive reductions in T2 D risk associated higher consumption of light green vegetables and cruciferous vegetables warrant further investigations in other Asian population. |
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