Flavonoid Intake And The Risk Of Age-related Cataract

Background/Objectives Epidemiological evidence suggests that diets rich in fruits and vegetables may reduce the risk of developing age-related cataract(ARC).Flavonoids are widely distributed in fruits and vegetables and can protect the lens epithelial cells from oxidative damage,increase the activity of antioxidant enzymes and delay of the lens opacity,closely related with the incidence of age-related cataract in vitro research.We speculated that dietary flavonoids may be inversely associated with age-related cataract.The objective of this study was to design the food-frequency questionnaire(FFQ)suited for the age-related cataract to evaluate retrospectively the association between the intakes of the total five flavonoids,the five flavonoid subclasses and the risk of age-related cataract.The primary analysis was for flavonoids,anthocyanidins,flavan-3-ols,flavanones,flavones and flavonols;secondary analyses were carried out for apigenin,luteolin,kaempferol,myricetin,quercetin and isorhamnetin separately.Subjects/Methods The flavonoids intake and correlation of age-related cataract study is a population-based case-control study.Age-related cataract patients randomly selected from Heilongjiang province as the case group,normal people as control group.Heilongjiang province is located in the northeast of China,the winter time is long and the economy is relatively backward,and the types and availability of fresh vegetables and fruits are less than in the south of China,therefore it was an appropriate research object to explore the relationship between the flavonoids intake and age-related cataract.We optimize the food-frequency questionnaire of the study based on the FFQ with good reliabity and validity,which have been used before.Six food groups which totaled 139 items were included in the FFQ.Between March 2012 and November 2012,40 ARC patients aged between 50 and 70 years were randomly selected in the Ophthalmic Hospital of Harbin Medical University to complete the FFQ of the study.3-consecutive 24-hour-dietary record was submitted 4 weeks later.Meanwhile the same FFQ was completed again.3-consecutive 24-hour-dietary record and FFQ twice was evaluated the validity and reliabity of the FFQ in the study.According to the epidemiological characteristics of age-related cataract and the conditions of the residents in Heilongjiang province,design the natural condition questionnaire.Between November 2012 and October 2013,249 ARC patients aged between 50 and 70 years were randomly selected in the Ophthalmic Hospital of Harbin Medical University.Meanwhile 66 controls of the same age with good visual acuity and no eye or systemic diseases were selected at the Physical Examination Center of the same hospital and asked to complete the same FFQ and natural situation questionnaire as the ARC study group.The frequency and quantity of consumption the 139 kinds of food in the past year were obtained.The database used for flavonoid contents of different food items was derived from US Department of Agriculture 2014 and the energy,the intakes of 25 dietary nutrients and flavonoids were estimated using the Epidata,Chinese nutrition calculator and EXCEL software.25 dietary nutrients,flavonoid,fruit and vegetable intakes were adjusted for total energy.SAS9.13 software was used to statistical analyse,compare the difference between the case and the control and the correlativity between flavonoid intakes and age-related cataract.Median and interquartile range were used to measure the data does not obey the normal distribution,chi-square test was used.Significant statistically difference was accepted p<0.05.Single factor logistic regression is adjusted for anthocyanins,flavanols,flavanone,flavone,flavonol,total flavonoids,apigenin,luteolin,kaempferol,myricetin,quercetin and isorhamnetin for energy and division into quartiles,odds ratio(OR)and 95% confidence interval(CI)were estimated the correlation between age-related cataract,regard p<0.05 as statistically significant difference.Multivariate adjusted OR was adjusted for correlated non-dietary factors,correlated dietary variables and potential confounders.Factors making a significant contribution were retained in the regression model,including variables with significant correlations with favonoid intake.Adjusted odds ratio(OR)and 95% confidence interval(CI)were estimated the correlation between age-related cataract,regard p<0.05 as statistically significant difference.Results In the modified food frequency questionnaire,the range of correlation coefficient of the validity is 0.49 ~ 0.58,the range of correlation coefficient of the reliability is 0.57 ~ 0.66.Energy,age at diagnosis,education,hypertension,diabetes,family economic income,waistline/hipline,dietary fiber,vitamin B6,vitamin B12,folate,vitamin C,vitamin E,calcium,potassium,copper,manganese,which were significant different(p<0.05)between cases and controls.Energy-adjusted intakes of flavonoids(include anthocyanidins,flavanols,flavanone,flavones and flavonols),anthocyanidins,flavanols,flavones(include apigenin and luteolin),flavonols(include kaempferol,myricetin,quercetin and isorhamnetin)was significant different(p<0.05)between cases and controls.Energy-adjusted luteolin,kaempferol,myricetin,quercetin and isorhamnetin were significant different(p<0.05)between cases and controls.The intakes of cases(energy corrected)are lower than the controls(energy corrected).The statistically significant epidemiological factors between the cases and the controls were adjusted as the multiple factors of age-related cataract.After multivariate adjustment,no linear associations between risk of developing age-related cataract and intakes of total dietary flavonoids,anthocyanidins,flavon-3-ol,flavanone,total flavones or total flavonols were found(p>0.05).No linear associations between risk of developing age-related cataract and intakes of apigenin,luteolin,kaempferol,myricetin were found(p>0.05),but quercetin and isorhamnetin intake was inversely associated with age-related cataract risk(the higest & the lowest: OR 11.78,95% CI: 1.62-85.84,p<0.05;the higest & the lowest: OR 6.99,95% CI:1.12-43.44,p<0.05,respectively).In this study,the main dietary sources of quercetin were from onion which supplied 25%,then apple 12%,hot pepper 11%,and green Chinese onion 7%.Conclusion Of all the flavonoids,the higher intakes of quercetin and isorhamnetin decrease the incident of age-related cataract merely.We concluded that higher dietary quercetin intakes may be an important factor in reducing the risk of age-related cataract.To prevent the occurrence and development of age-related cataract,further nutritional education should be prompted for the elderly.