Advertisement

Fruit and Vegetable Juices and Alzheimer’s Disease: The Kame Project

      Abstract

      Background

      Growing evidence suggests that oxidative damage caused by the β-amyloid peptide in the pathogenesis of Alzheimer’s disease may be hydrogen peroxide mediated. Many polyphenols, the most abundant dietary antioxidants, possess stronger neuroprotection against hydrogen peroxide than antioxidant vitamins.

      Methods

      We tested whether consumption of fruit and vegetable juices, containing a high concentration of polyphenols, decreases the risk of incident probable Alzheimer’s disease in the Kame Project cohort, a population-based prospective study of 1836 Japanese Americans in King County, Washington, who were dementia-free at baseline (1992-1994) and were followed through 2001.

      Results

      After adjustment for potential confounders, the hazard ratio for probable Alzheimer’s disease was 0.24 (95% confidence interval [CI], 0.09-0.61) comparing subjects who drank juices at least 3 times per week with those who drank less often than once per week with a hazard ratio of 0.84 (95% CI, 0.31-2.29) for those drinking juices 1 to 2 times per week (P for trend < .01). This inverse association tended to be more pronounced among those with an apolipoprotein Eε-4 allele and those who were not physically active. Conversely, no association was observed for dietary intake of vitamins E, C, or β-carotene or tea consumption.

      Conclusions

      Fruit and vegetable juices may play an important role in delaying the onset of Alzheimer’s disease, particularly among those who are at high risk for the disease. These results may lead to a new avenue of inquiry in the prevention of Alzheimer’s disease.

      Keywords

      In vitro and in vivo data show that chronic accumulation of reactive oxygen species in the brain may exhaust antioxidant capacity, including antioxidant vitamins, and lead to the onset and progression of Alzheimer’s disease.
      • Butterfield D.A.
      • Drake J.
      • Pocernich C.
      • Castegna A.
      Evidence of oxidative damage in Alzheimer’s disease brain: central role for amyloid beta-peptide.
      • Honda K.
      • Casadesus G.
      • Petersen R.B.
      • Perry G.
      • Smith M.A.
      Oxidative stress and redox-active iron in Alzheimer’s disease.
      • Markesbery W.R.
      Oxidative stress hypothesis in Alzheimer’s disease.
      A recent large clinical trial
      • Petersen R.C.
      • Thomas R.G.
      • Grundman M.
      • et al.
      Vitamin E and donepezil for the treatment of mild cognitive impairment.
      and several previous prospective epidemiologic studies
      • Luchsinger J.A.
      • Tang M.X.
      • Shea S.
      • Mayeux R.
      Antioxidant vitamin intake and risk of Alzheimer disease.
      • Morris M.C.
      • Beckett L.A.
      • Scherr P.A.
      • et al.
      Vitamin E and vitamin C supplement use and risk of incident Alzheimer disease.
      • Zandi P.P.
      • Anthony J.C.
      • Khachaturian A.S.
      • et al.
      Reduced risk of Alzheimer disease in users of antioxidant vitamin supplements: the Cache County Study.
      • Engelhart M.J.
      • Geerlings M.I.
      • Ruitenberg A.
      • et al.
      Dietary intake of antioxidants and risk of Alzheimer disease.
      • Morris M.C.
      • Evans D.A.
      • Bienias J.L.
      • et al.
      Dietary intake of antioxidant nutrients and the risk of incident Alzheimer disease in a biracial community study.
      suggest that antioxidant vitamins
      • Morris M.C.
      • Evans D.A.
      • Bienias J.L.
      • et al.
      Dietary intake of antioxidant nutrients and the risk of incident Alzheimer disease in a biracial community study.
      from dietary fruits and vegetables, but not from supplements, play a role in delaying the onset of Alzheimer’s disease.
      • Recent clinical trials have generated disappointing results for several promising agents, including sex hormones, antioxidant vitamins, and anti-inflammatory drugs, in the prevention of Alzheimer’s disease.
      • In this study, the risk for probable Alzheimer’s disease was significantly reduced among people who drank fruit and vegetable juices, a potential source of antioxidant polyphenols, 3 or more times per week, compared with those who drank these juices less than once per week
      Other than antioxidant vitamins, the most abundant dietary antioxidants come from nonvitamin polyphenols.
      • Manach C.
      • Scalbert A.
      • Morand C.
      • Remesy C.
      • Jimenez L.
      Polyphenols: food sources and bioavailability.
      • Scalbert A.
      • Williamson G.
      Dietary intake and bioavailability of polyphenols.
      Several thousand polyphenols have been identified in plants.
      • Manach C.
      • Scalbert A.
      • Morand C.
      • Remesy C.
      • Jimenez L.
      Polyphenols: food sources and bioavailability.
      • Scalbert A.
      • Williamson G.
      Dietary intake and bioavailability of polyphenols.
      Most polyphenols exist primarily in the outer sections of fruits and vegetables,
      • Manach C.
      • Scalbert A.
      • Morand C.
      • Remesy C.
      • Jimenez L.
      Polyphenols: food sources and bioavailability.
      • Scalbert A.
      • Williamson G.
      Dietary intake and bioavailability of polyphenols.
      • Bates B.P.
      • Morris J.R.
      • Crandall P.G.
      • Bazemore R.
      • Rouseff R.
      • Naim M.
      Linalool in orange juice: origin and thermal stability.
      and therefore culinary preparation has a critical impact on the concentrations.
      • Manach C.
      • Scalbert A.
      • Morand C.
      • Remesy C.
      • Jimenez L.
      Polyphenols: food sources and bioavailability.
      • Scalbert A.
      • Williamson G.
      Dietary intake and bioavailability of polyphenols.
      For example, peeling or boiling can lead to the loss of a majority of the quercetin content in apples, tomatoes, and onions.
      • Manach C.
      • Scalbert A.
      • Morand C.
      • Remesy C.
      • Jimenez L.
      Polyphenols: food sources and bioavailability.
      • Scalbert A.
      • Williamson G.
      Dietary intake and bioavailability of polyphenols.
      None of the food frequency questionnaires used in current epidemiologic studies are able to collect data on food preparation; therefore it is impossible to accurately measure total intake of polyphenols. Beverages, such as tea, juices, and wine, are major sources of polyphenols, although many fruits and vegetables and herbs possess polyphenols.
      • Scalbert A.
      • Williamson G.
      Dietary intake and bioavailability of polyphenols.
      Several studies have found that consumption of polyphenols from wine,
      • Lindsay J.
      • Laurin D.
      • Verreault R.
      • et al.
      Risk factors for Alzheimer’s disease: a prospective analysis from the Canadian Study of Health and Aging.
      but not tea,
      • Lindsay J.
      • Laurin D.
      • Verreault R.
      • et al.
      Risk factors for Alzheimer’s disease: a prospective analysis from the Canadian Study of Health and Aging.
      • Forster D.P.
      • Newens A.J.
      • Kay D.W.
      • Edwardson J.A.
      Risk factors in clinically diagnosed presenile dementia of the Alzheimer type: a case-control study in northern England.
      • Rogers M.A.
      • Simon D.G.
      A preliminary study of dietary aluminium intake and risk of Alzheimer’s disease.
      • Laurin D.
      • Masaki K.H.
      • Foley D.J.
      • White L.R.
      • Launer L.J.
      Midlife dietary intake of antioxidants and risk of late-life incident dementia: the Honolulu-Asia Aging Study.
      may be associated with a reduced risk of Alzheimer’s disease. A number of studies have reported that commercial fruit and vegetable juices, normally made from frozen concentrates,
      • Bates B.P.
      • Morris J.R.
      • Crandall P.G.
      also possess a high concentration of powerful antioxidant polyphenols.
      • Lugasi A.
      • Hovari J.
      Antioxidant properties of commercial alcoholic and nonalcoholic beverages.
      • Manach C.
      • Morand C.
      • Gil-Izquierdo A.
      • Bouteloup-Demange C.
      • Remesy C.
      Bioavailability in humans of the flavanones hesperidin and narirutin after the ingestion of two doses of orange juice.
      • Bub A.
      • Watzl B.
      • Blockhaus M.
      • et al.
      Fruit juice consumption modulates antioxidative status, immune status and DNA damage.
      • Vinson J.A.
      • Liang X.
      • Proch J.
      • Hontz B.A.
      • Dancel J.
      • Sandone N.
      Polyphenol antioxidants in citrus juices: in vitro and in vivo studies relevant to heart disease.
      Furthermore, under high extracting mechanical pressure, high concentrations of both peel and pulp components from whole fruits or vegetables enter the liquids from which juice concentrates are produced.
      • Bates B.P.
      • Morris J.R.
      • Crandall P.G.
      • Bazemore R.
      • Rouseff R.
      • Naim M.
      Linalool in orange juice: origin and thermal stability.
      No epidemiologic study has yet investigated the association between consumption of fruit and vegetable juices and Alzheimer’s disease risk. Growing evidence from in vitro,
      • Heo H.J.
      • Lee C.Y.
      Protective effects of quercetin and vitamin C against oxidative stress-induced neurodegeneration.
      • Heo H.J.
      • Kim D.O.
      • Shin S.C.
      • Kim M.J.
      • Kim B.G.
      • Shin D.H.
      Effect of antioxidant flavanone, naringenin, from Citrus junoson neuroprotection.
      • Nakayama T.
      • Yamada M.
      • Osawa T.
      • Kawakishi S.
      Suppression of active oxygen-induced cytotoxicity by flavonoids.
      in vivo studies,
      • Patil C.S.
      • Singh V.P.
      • Satyanarayan P.S.
      • Jain N.K.
      • Singh A.
      • Kulkarni S.K.
      Protective effect of flavonoids against aging- and lipopolysaccharide-induced cognitive impairment in mice.
      and clinical trials
      • O’Byrne D.J.
      • Devaraj S.
      • Grundy S.M.
      • Jialal I.
      Comparison of the antioxidant effects of Concord grape juice flavonoids alpha-tocopherol on markers of oxidative stress in healthy adults.
      has shown that polyphenols from apple, grape, and citrus fruit juices possess a stronger neuroprotection than antioxidant vitamins. On the basis of these findings, we hypothesized that consumption of fruit and vegetable juices, as a rich source of polyphenols, would be protective and would delay the onset of Alzheimer’s disease in a prospective cohort study of Japanese Americans in King County, Washington (the Kame Project).

      Methods

      The Kame Cohort

      Data for the current analysis were derived from the Kame Project, a large population-based prospective study of Japanese Americans in King County, Washington, who were followed from 1992 to 2001, as part of the Ni-Hon-Sea Project, a cross-cultural study of prevalence and incidence rates of Alzheimer’s disease and vascular dementia among Japanese populations living in Hiroshima, Japan; Oahu, Hawaii; and the metropolitan area of Seattle, Washington.
      • Graves A.B.
      • Larson E.B.
      • Edland S.D.
      • et al.
      Prevalence of dementia and its subtypes in the Japanese American population of King County, Washington state The Kame Project.
      • Larson E.B.
      • McCurry S.M.
      • Graves A.B.
      Standardization of the clinical diagnosis of the dementia syndrome and its subtypes in a cross-national study: the Ni-Hon-Sea experience.
      A cohort of 3045 eligible individuals aged 65 years and more, 96% of whom were of 100% self-identified Japanese origin, were enumerated in a census of Japanese Americans in King County, Washington, in November 1991. Those identified as eligible by the study census were found to represent 90% of the Japanese American population in King County enumerated by the decennial US Census in 1990. Of those eligible, 1985 (65.2%) participated in the baseline evaluation (1992-1994), of whom 1836, found to be dementia-free at baseline, form the eligible sample for this study. Details of the study census and results from the prevalence study have been described elsewhere.
      • Graves A.B.
      • Larson E.B.
      • Edland S.D.
      • et al.
      Prevalence of dementia and its subtypes in the Japanese American population of King County, Washington state The Kame Project.

      Clinical Diagnostic Procedures

      All participants were interviewed by trained interviewers using highly structured questionnaires. The Cognitive Abilities Screening Instrument (CASI)
      • Teng E.L.
      • Hasegawa K.
      • Homma A.
      • et al.
      The Cognitive Abilities Screening Instrument (CASI): a practical test for cross-cultural epidemiological studies of dementia.
      was administered to assess cognition at baseline and at each of 4 follow-up waves, each 2 years apart for a total of 4 incidence waves. An individual scoring of 87 or less of 100 points at any follow-up was invited for a standardized full clinical and neuropsychologic evaluation, the procedures of which have been described in detail elsewhere.
      • Graves A.B.
      • Larson E.B.
      • Edland S.D.
      • et al.
      Prevalence of dementia and its subtypes in the Japanese American population of King County, Washington state The Kame Project.
      Briefly, the evaluation included protocol-driven physical, neurologic, and laboratory examinations administered by the study physicians
      • Graves A.B.
      • Larson E.B.
      • Edland S.D.
      • et al.
      Prevalence of dementia and its subtypes in the Japanese American population of King County, Washington state The Kame Project.
      and informant interview including the Clinical Dementia Rating Scale.
      • Hughes C.P.
      • Berg L.
      • Danziger W.L.
      • Coben L.A.
      • Martin R.L.
      A new clinical scale for the staging of dementia.
      Neuropsychologic evaluation was conducted by a trained psychometrist using the Consortium to Establish a Registry for Alzheimer’s Disease criteria
      • Morris J.C.
      • Heyman A.
      • Mohs R.C.
      • et al.
      The consortium to establish a registry for Alzheimer’s disease (CERAD). Part I. Clinical and neuropsychological assessment of Alzheimer’s disease.
      • Welsh K.A.
      • Butters N.
      • Mohs R.C.
      • et al.
      The Consortium to Establish a Registry for Alzheimer’s Disease (CERAD). Part V. A normative study of the neuropsychological battery.
      and other tests.
      • Welsh K.A.
      • Butters N.
      • Mohs R.C.
      • et al.
      The Consortium to Establish a Registry for Alzheimer’s Disease (CERAD). Part V. A normative study of the neuropsychological battery.
      • Kiernan R.J.
      • Mueller J.
      • Langston J.W.
      • Van Dyke C.
      The Neurobehavioral Cognitive Status Examination: a brief but quantitative approach to cognitive assessment.
      • Reitan R.M.
      • Wolfson D.
      • Shipley W.C.
      • Tiffin J.
      • Wechsler D.
      • Wechsler D.
      The presence of dementia and its subtypes were determined by consensus committee.
      • Graves A.B.
      • Larson E.B.
      • Edland S.D.
      • et al.
      Prevalence of dementia and its subtypes in the Japanese American population of King County, Washington state The Kame Project.
      The committee filled out the dementia criteria of the Diagnostic and Statistical Manual, Fourth Edition,
      the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer’s Disease and Related Disorders Association criteria (NINCDS-ADRDA),
      • McKhann G.
      • Drachman D.
      • Folstein M.
      • Katzman R.
      • Price D.
      • Stadlan E.M.
      Clinical diagnosis of Alzheimer’s disease: report of the NINCDS-ADRDA Work Group under the auspices of Department of Health and Human Services Task Force on Alzheimer’s Disease.
      and a number of criteria for vascular dementia.
      • Roman G.C.
      • Tatemichi T.K.
      • Erkinjuntti T.
      • et al.
      Vascular dementia: diagnostic criteria for research studies Report of the NINDS-AIREN International Workshop.
      • Chui H.C.
      • Victoroff J.I.
      • Margolin D.
      • Jagust W.
      • Shankle R.
      • Katzman R.
      Criteria for the diagnosis of ischemic vascular dementia proposed by the State of California Alzheimer’s Disease Diagnostic and Treatment Centers.
      In these analyses, only subjects who developed an incident diagnosis of probable Alzheimer’s disease according to NINCDS-ADRDA criteria were considered as cases. Others were censored at the date they were last seen, died, or refused to continue their participation. The study was approved by the University of Washington Human Subjects Committee and supported by a Japanese American Community Advisory Board.

      Dietary Measurement

      At baseline interview, we used a self-administered, semiquantitative food frequency questionnaire developed for Asian populations to obtain usual dietary intake of food, including tea, wine, and fruit and vegetable juices.
      • Hankin J.H.
      • Wilkens L.R.
      Development and validation of dietary assessment methods for culturally diverse populations.
      • Hankin J.H.
      • Nomura A.M.
      • Lee J.
      • Hirohata T.
      • Kolonel L.N.
      Reproducibility of a diet history questionnaire in a case-control study of breast cancer.
      • Hankin J.H.
      • Wilkens L.R.
      • Kolonel L.N.
      • Yoshizawa C.N.
      Validation of a quantitative diet history method in Hawaii.
      Each food item had eight frequency options and 3 usual portion sizes, which were chosen from provided pictures.
      • Hankin J.H.
      • Nomura A.M.
      • Lee J.
      • Hirohata T.
      • Kolonel L.N.
      Reproducibility of a diet history questionnaire in a case-control study of breast cancer.
      • Hankin J.H.
      • Wilkens L.R.
      • Kolonel L.N.
      • Yoshizawa C.N.
      Validation of a quantitative diet history method in Hawaii.
      Of 1836 dementia-free cohort members, 1589 (86.5%) completed the food frequency questionnaire. Usual dietary intake of nutrients, including total energy, vitamins C and E, and β-carotene, was calculated from an assembled food composition database, which included the US Department of Agriculture’s database and other sources that factor in dietary diversity across ethnic groups.
      • Hankin J.H.
      Dietary methods for estimating vitamin A and carotene intakes in epidemiologic studies of cancer.
      A validation study of this food frequency questionnaire was conducted among 262 randomly selected subjects from 5 ethnic groups including Japanese. Japanese men and Chinese women had the highest correlation for major nutrients between intake from 4-week food records throughout 1 year and from the food frequency questionnaire.
      • Hankin J.H.
      • Wilkens L.R.
      • Kolonel L.N.
      • Yoshizawa C.N.
      Validation of a quantitative diet history method in Hawaii.
      The intraclass correlation coefficients for Japanese men and women were 0.77 and 0.42 for β-carotene and 0.50 and 0.42 for vitamin C, respectively.
      • Hankin J.H.
      • Wilkens L.R.
      • Kolonel L.N.
      • Yoshizawa C.N.
      Validation of a quantitative diet history method in Hawaii.

      Covariates

      Baseline risk factor information was elicited, including smoking and alcohol drinking habits, education, birthplace, place of education before 18 years old, birth date, physical activity, use of antioxidant vitamin supplements in the past month, usual eating preference (Asian or Western), and olfaction diagnostic group (anosmia, microsmia vs normosmia).
      • Doty R.L.
      • Marcus A.
      • Lee W.W.
      Development of the 12-item Cross-Cultural Smell Identification Test (CC-SIT).
      • Graves A.B.
      • Bowen J.D.
      • Rajaram L.
      • et al.
      Impaired olfaction as a marker for cognitive decline: interaction with apolipoprotein E epsilon4 status.
      We obtained apolipoprotein E (ApoE) status on 1047 individuals who also completed the food frequency questionnaire (65.9%). For ApoE genotyping, DNA was prepared from buffy coat preparations by a modification of the salting-out procedures.
      • Miller S.A.
      • Dykes D.D.
      • Polesky H.F.
      A simple salting out procedure for extracting DNA from human nucleated cells.
      Genotypes were determined using previously described methods.
      • Emi M.
      • Wu L.L.
      • Robertson M.A.
      • et al.
      Genotyping and sequence analysis of apolipoprotein E isoforms.
      • Hixson J.E.
      • Vernier D.T.
      Restriction isotyping of human apolipoprotein E by gene amplification and cleavage with HhaI.

      Statistical Analysis

      We estimated the main associations using hazard ratios (HRs) in Cox proportional hazard regression models,
      • Hosmer D.W.
      • Lemeshow S.
      using age at onset as the time axis and age at entry as the truncation variable;
      • Korn E.L.
      • Graubard B.I.
      • Midthune D.
      Time-to-event analysis of longitudinal follow-up of a survey: choice of the time-scale.
      therefore all models are adjusted for age.
      • Borenstein A.R.
      • Wu Y.
      • Mortimer J.A.
      • et al.
      Developmental and vascular risk factors for Alzheimer’s disease.
      Intake of antioxidant vitamins was categorized into tertiles based on the distribution of the cohort. Tea, wine, and juice drinking were classified as “less often than once per week,” “once or twice per week,” and “three times or more per week.” Additional models were run adjusting for years of education and other potential confounders. We also adjusted for dietary intake of vitamins C, E, and β-carotene to examine whether the associations between juices, tea, and wine and Alzheimer’s disease may be attributable in part to such intake from food. Other variables, including history of chronic vascular diseases, cancers, self-rated health status, birthplace, place of education, and usual eating preference, did not appreciably alter the risk estimates and were not adjusted for in our final analyses. Stratified analyses by years of education, smoking status, tea-drinking frequency, regular physical activity (yes/no), ApoE ε-4 (present/absent), and total fat intake (by median) were conducted. Multiplicative interactions also were evaluated in Cox regression models by likelihood ratio tests. P values of less than .05 (2-sided probability) were interpreted as being statistically significant.

      Results

      The sample with dietary information (n = 1589) had a mean age at enrollment of 71.8 years; 54.4% were women; 6.5% of subjects drank sake or wine at least once per week; more than 80% of subjects drank tea at least once per week; 65% drank fruit or vegetable juices at least once per week; and 19.9% of subjects possessed one or more ApoE ε-4 alleles. Overall, the analyzed sample was comparable to the whole cohort who were dementia-free (n = 1836) by age, gender, baseline CASI scores, education, follow-up time, smoking and alcoholic drinking status, use of antioxidant vitamin supplements, and ApoE*4 allele (data not shown). Over an average of 6.3 years (standard deviation = 2.6), 81 incident cases were diagnosed with probable Alzheimer’s disease by NINCDS-ADRDA criteria in the dementia-free cohort; 63 of whom (77.8%) completed the food frequency questionnaire at baseline and were included in the analyzed sample.
      After adjustment for total energy intake, subjects who drank fruit and vegetable juices more frequently had a lower intake of fat (either saturated or unsaturated fatty acids) and a higher dietary intake of vitamin C, but not vitamin E or β-carotene. They also tended to have a higher educational attainment and more regular physical activity, and were more likely to be nonsmokers, hypertensive, and ApoE ε-4 allele negative (Table 1).
      Table 1Baseline Lifestyle Factors and Demographics by Fruit and Vegetable Juice Intake Frequency Among 1589 Subjects 65 Years and Older (the Kame Project, 1992-2001)
      Fruit and Vegetable Juices Intake Frequency
      Less Often Than Weekly1-2 Times per Week3 Times or More per Week
      Number free of probable Alzheimer’s disease547257785
      Mean dietary intake
       Vitamin C, mg/d
      Total energy-adjusted means.
      90.7104.1160.7
       Vitamin E, mg/d
      Total energy-adjusted means.
      6.046.106.07
       β-carotene, μg/d
      Total energy-adjusted means.
      3631.33489.33749.1
       Total fat, g/d
      Total energy-adjusted means.
      34.334.832.4
       Saturated fat, g/d
      Total energy-adjusted means.
      10.510.89.9
       Monounsaturated fat, g/d
      Total energy-adjusted means.
      11.912.311.2
       Polyunsaturated fat, g/d
      Total energy-adjusted means.
      8.17.97.7
      Women (%)53.950.655.8
      Baseline CASI score ± SD91.0±5.791.2±6.190.8±6.0
      Age, mean ± SD, y71.7±5.471.6±5.072.1±5.2
      Education, mean ± SD, y12.8±3.013.3±2.713.2±2.7
      BMI, mean ± SD24.1±3.424.7±3.124.3±3.3
      Smokers, former and current (%)49.656.447.9
      Alcohol drinkers, current and past (%)37.242.238.6
      Drinking tea weekly (%)77.984.180.4
      Olfaction diagnostic group (%)
       Normosmia40.846.744.1
       Microsmia48.644.747.1
       Anosmia10.68.68.8
      Regular physical activity (%)61.360.668.6
      ApoE-ε4 positive (%)24.617.017.4
      Hypertension (%)42.546.849.7
      Diabetes mellitus (%)17.017.215.6
      Vitamin supplementation
       Vitamin C user (%)24.029.427.4
       Vitamin E user (%)20.019.021.0
       Multivitamin user (%)41.038.542.2
      CASI = Cognitive Abilities Screening Instrument; SD = standard deviation; ApoE = apolipoprotein E; BMI = body mass index.
      low asterisk Total energy-adjusted means.
      Table 2 shows the associations between intake frequencies of fruit and vegetable juices, wine and tea, and Alzheimer’s disease. Tea drinking, the most commonly consumed beverage in the study population, was not associated with Alzheimer’s disease risk. Only a small proportion of subjects drank wine, and the association with Alzheimer’s disease was inverse but not statistically significant. The risk of Alzheimer’s disease was substantially decreased with increasing frequency of intake of juices. Risk was even lower after adjustment for other potential confounding factors. The risk was further reduced after taking into account dietary intake of vitamins E and C and β-carotene, with an HR of 0.24 (95% confidence interval [CI], = 0.09-0.61) for subjects who drank juices at least 3 times per week versus those who drank juices less often than once per week (P for trend < .01). We also found that dietary consumption of vitamins E, C, and β-carotene was not related to the risk of Alzheimer’s disease (data not shown).
      Table 2Hazard Ratios for Incident Probable Alzheimer’s Disease by Frequency of Intake of Tea, Sake, and Fruit and Vegetable Juices Among 1589 Subjects 65 Years and Older (the Kame Project 1992-2001)
      Intake frequencyP for Trend
      Less Often Than Weekly HR1-2 Times per Week HR (95% CI)3 Times or More per Week HR (95% CI)
      Fruit and vegetable juice
       Cases/unaffected30/51711/24622/763
        Model 1
      Adjusted for years of education in model 1.
      1.000.89(0.44-1.79)0.49(0.28-0.86).01
        Model 2
      Additionally adjusted for gender, regular physical activity, body mass index, baseline CASI score, olfaction diagnostic group, total energy intake, intake of saturated, monounsaturated, and polyunsaturated fatty acids, ApoE genotype, smoking status, alcohol drinking, supplementation of vitamin C, vitamin E, and multivitamin, and tea drinking, and fruit and vegetable juice drinking in model 2.
      1.000.74(0.28-1.94)0.28(0.13-0.63)<.01
        Model 3
      Further adjusted for dietary intake of vitamin C, vitamin E, and β-carotene in model 3.
      1.000.84(0.31-2.29)0.24(0.09-0.61)<.01
      Tea drinking
       Cases/unaffected9/3068/16546/1056
        Model 1
      Adjusted for years of education in model 1.
      1.002.00(0.76-5.24)1.29(0.63-2.64).69
        Model 2
      Additionally adjusted for gender, regular physical activity, body mass index, baseline CASI score, olfaction diagnostic group, total energy intake, intake of saturated, monounsaturated, and polyunsaturated fatty acids, ApoE genotype, smoking status, alcohol drinking, supplementation of vitamin C, vitamin E, and multivitamin, and tea drinking, and fruit and vegetable juice drinking in model 2.
      1.001.24(0.37-4.22)1.61(0.64-4.05).29
        Model 3
      Further adjusted for dietary intake of vitamin C, vitamin E, and β-carotene in model 3.
      1.001.49(0.43-5.16)1.70(0.67-4.33).27
      Wine (sake) drinking
      Only two categories were used because the number of cases was too small in one category and alcohol drinking was not adjusted in the model.
       Cases/unaffected60/14120/452/54
        Model 1
      Adjusted for years of education in model 1.
      1.000.49(0.11-2.10)
        Model 2
      Additionally adjusted for gender, regular physical activity, body mass index, baseline CASI score, olfaction diagnostic group, total energy intake, intake of saturated, monounsaturated, and polyunsaturated fatty acids, ApoE genotype, smoking status, alcohol drinking, supplementation of vitamin C, vitamin E, and multivitamin, and tea drinking, and fruit and vegetable juice drinking in model 2.
      1.000.10(0.00-2.28)
        Model 3
      Further adjusted for dietary intake of vitamin C, vitamin E, and β-carotene in model 3.
      1.000.09(0.01-1.43)
      HR = hazard ratio; CI = confidence interval.
      low asterisk Adjusted for years of education in model 1.
      Additionally adjusted for gender, regular physical activity, body mass index, baseline CASI score, olfaction diagnostic group, total energy intake, intake of saturated, monounsaturated, and polyunsaturated fatty acids, ApoE genotype, smoking status, alcohol drinking, supplementation of vitamin C, vitamin E, and multivitamin, and tea drinking, and fruit and vegetable juice drinking in model 2.
      Further adjusted for dietary intake of vitamin C, vitamin E, and β-carotene in model 3.
      § Only two categories were used because the number of cases was too small in one category and alcohol drinking was not adjusted in the model.
      The inverse association between fruit and vegetable juices and Alzheimer’s disease appeared in all strata of education, smoking status, tea drinking, regular physical activity, ApoE genotype, and total fat intake (Table 3). However, the association tended to be stronger among those who were former or current smokers, drank tea less often, were positive for the ApoE ε-4 allele, and were less physically active. Although no statistically significant interactions were found, the tests for interactions by ApoE genotype (P for interaction, .07) and regular physical activity (P for interaction, .06) were of borderline significance. In Table 4, the characteristics at baseline by disease status are presented (Table 1 describes the characteristics with regard to fruit and vegetable juice consumption).
      Table 3Numbers of Individuals and Hazard Ratios for Incident Probable Alzheimer’s Disease by Frequency of Intake of Fruit and Vegetable Juices Stratified by Potential Modifying Effects Among 1589 Subjects 65 Years and Older(the Kame Project, 1992-2001)
      Intake FrequencyP for Trend
      Less Often Than Weekly HR1-2 Times per Week HR (95% CI)3 Times or More per Week HR (95% CI)
      StratumStratified analysis of fruit and vegetable juices
      Adjusted for years of education, gender, regular physical activity, body mass index, baseline CASI score, olfaction diagnostic group, total energy intake, intake of saturated, monounsaturated, and polyunsaturated fatty acids, smoking status, alcoholic drinking, supplementation of vitamin C, vitamin E, and multivitamin, tea drinking, and dietary intake of vitamin C, vitamin E, and β-carotene.
       Education
        <12 y9/1104/255/103
      1.000.28(0.02-3.71)0.05(0.00-0.98).05
        ≥12 y21/4077/22117/660
      1.000.51(0.18-1.41)0.20(0.08-0.49)<.01
      P for interaction, .29
       Smoking status
        Never smokers17/2587/10514/392
      1.000.78(0.23-2.61)0.32(0.12-0.84).02
        Ever smokers13/2584/1418/365
      1.000.27(0.06-1.14)0.04(0.01-0.24)<.01
      P for interaction, .98
       Tea drinking
        <3 times/wk12/1682/753/223
      1.000.04(0.00-0.46)0.01(0.00-0.09)<.01
        ≥3 times/wk17/3468/16619/527
      1.000.58(0.19-1.73)0.43(0.17-1.06).06
      P for interaction, .33
       Regular physical activity
        No16/1944/956/233
      1.000.86(0.23-3.20)0.06(0.01-0.23)<.01
        Yes14/3195/14716/507
      1.000.57(0.16-1.97)0.45(0.16-1.26).13
      P for interaction, .06
       ApoE genotype
        ApoE-ε4 negative12/2646/1458/404
      1.000.93(0.30-2.88)0.25(0.07-0.93).05
        ApoE-ε4 positive11/791/307/80
      1.000.13(0.02-0.83).02
      P for interaction, .07
       Total fat intake(g/d)
        ≤29.917/3017/1329/334
      1.000.76(0.26-2.21)0.23(0.07-0.78).02
        >29.913/2164/11413/429
      1.000.36(0.07-1.85)0.14(0.04-0.46)<.01
      P for interaction, .28
      HR = hazard ratio; CI = confidence interval; ApoE = apolipoprotein E.
      low asterisk Adjusted for years of education, gender, regular physical activity, body mass index, baseline CASI score, olfaction diagnostic group, total energy intake, intake of saturated, monounsaturated, and polyunsaturated fatty acids, smoking status, alcoholic drinking, supplementation of vitamin C, vitamin E, and multivitamin, tea drinking, and dietary intake of vitamin C, vitamin E, and β-carotene.
      Table 4Baseline Lifestyle Factors and Demographics by Fruit and Vegetable Juice Intake Frequency and Subsequent Alzheimer’s Disease Status Among 1589 Subjects 65 Years and Older (the Kame Project, 1992-2001)
      AD = 63 Non-AD = 1526Fruit and Vegetable Juices Intake Frequency
      Less Often Than Weekly1-2 Times per Week≥3 Times per Week
      Mean dietary intake
       Vitamin C, mg/d
      Total energy-adjusted means. AD stands for subsequently diagnosed cases of Alzheimer’s disease. Non-AD stands for subjects without AD after 9 years of follow-up.
      AD124.8101.3172.2
      Non-AD88.8104.3160.3
       Vitamin E, mg/d
      Total energy-adjusted means. AD stands for subsequently diagnosed cases of Alzheimer’s disease. Non-AD stands for subjects without AD after 9 years of follow-up.
      AD8.16.67.5
      Non-AD5.96.16.0
       β-carotene, μg/d
      Total energy-adjusted means. AD stands for subsequently diagnosed cases of Alzheimer’s disease. Non-AD stands for subjects without AD after 9 years of follow-up.
      AD5142.23527.14182.9
      Non-AD3546.43490.73733.4
       Total fat, g/d
      Total energy-adjusted means. AD stands for subsequently diagnosed cases of Alzheimer’s disease. Non-AD stands for subjects without AD after 9 years of follow-up.
      AD33.934.129.4
      Non-AD34.334.832.5
       Saturated fat, g/d
      Total energy-adjusted means. AD stands for subsequently diagnosed cases of Alzheimer’s disease. Non-AD stands for subjects without AD after 9 years of follow-up.
      AD10.511.08.7
      Non-AD10.510.89.9
       Monounsaturated fat, g/d
      Total energy-adjusted means. AD stands for subsequently diagnosed cases of Alzheimer’s disease. Non-AD stands for subjects without AD after 9 years of follow-up.
      AD11.011.510.2
      Non-AD12.012.311.3
       Polyunsaturated fat, g/d
      Total energy-adjusted means. AD stands for subsequently diagnosed cases of Alzheimer’s disease. Non-AD stands for subjects without AD after 9 years of follow-up.
      AD8.77.87.2
      Non-AD8.17.97.7
      Women (%)AD60.054.568.2
      Non-AD53.750.255.6
      Baseline CASI score ± SDAD88.0±6.480.4±15.382.6±7.9
      Non-AD91.2±5.791.7±4.891.1±5.8
      Age, mean ± SD, yAD76.0±5.477.5±6.677.5±6.5
      Non-AD71.5±5.371.3±4.871.9±5.0
      Education, mean ± SD, yAD12.0±2.511.6±2.411.4±2.5
      Non-AD12.8±3.013.4±2.713.2±2.7
      BMI, mean ± SDAD23.1±3.525.6±3.823.7±3.6
      Non-AD24.1±3.424.7±3.024.3±3.3
      Smokers, former and current (%)AD43.336.436.4
      Non-AD49.957.548.1
      Alcohol drinkers, current and past (%)AD33.336.436.4
      Non-AD37.542.638.7
      Drinking tea weekly (%)AD75.9100.090.9
      None-AD78.083.480.1
      Olfaction diagnostic group (%)
       NormosmiaAD30.09.127.3
       MicrosmiaAD50.072.759.1
       AnosmiaAD20.018.213.6
       NormosmiaNon-AD41.448.444.6
       MicrosmiaNon-AD48.543.546.8
       AnosmiaNon-AD10.18.18.6
      Regular physical activity (%)AD46.755.672.7
      Non-AD62.260.668.6
      ApoE-ε4 positive (%)AD47.814.346.7
      Non-AD23.017.116.7
      Hypertension (%)AD36.790.063.6
      Non-AD42.945.349.1
      Diabetes mellitus (%)AD20.027.314.3
      Non-AD16.916.815.6
      Vitamin supplementation
       Vitamin C user (%)AD30.018.245.4
      Non-AD23.729.426.7
       Vitamin E user (%)AD23.39.19.1
      None-AD19.819.621.1
       Multivitamin user (%)AD46.79.140.9
      Non-AD40.839.642.5
      AD = Alzheimer’s disease; CASI = Cognitive Abilities Screening Instrument; SD = standard deviation; ApoE = apolipoprotein E.
      low asterisk Total energy-adjusted means. AD stands for subsequently diagnosed cases of Alzheimer’s disease. Non-AD stands for subjects without AD after 9 years of follow-up.

      Discussion

      In this prospective study conducted among Japanese Americans living in King County, Washington, we found that frequent drinking of fruit and vegetable juices was associated with a substantially decreased risk of Alzheimer’s disease. This inverse association was stronger after adjustments for potential confounding factors, and the association was evident in all strata of selected variables. These findings are new and suggest that fruit and vegetable juices may play an important role in delaying the onset of Alzheimer’s disease.
      We found that subjects with a high intake frequency of fruit and vegetable juices had a higher dietary intake of vitamin C. However, dietary intakes of vitamins C and E and β-carotene were not related to the risk of Alzheimer’s disease, and the inverse association between juices and Alzheimer’s disease was strengthened after adjustment for antioxidant vitamins. These findings are in accord with those reported in a recent multicenter clinical trial that vitamin E supplementation had no effect on the annual progression rate from mild cognitive impairment to Alzheimer’s disease.
      • Petersen R.C.
      • Thomas R.G.
      • Grundman M.
      • et al.
      Vitamin E and donepezil for the treatment of mild cognitive impairment.
      Our findings also are consistent with those from the Honolulu-Asia Aging Study, a prospective study conducted among Japanese-Americans living in Hawaii whose overall methods were standardized with the Kame Project. In that study, which used a single 24-hour dietary recall, midlife intake of vitamins E and C and β-carotene was not related to the risk of Alzheimer’s disease.
      • Laurin D.
      • Masaki K.H.
      • Foley D.J.
      • White L.R.
      • Launer L.J.
      Midlife dietary intake of antioxidants and risk of late-life incident dementia: the Honolulu-Asia Aging Study.
      Results from other prospective studies also have been inconsistent.
      • Luchsinger J.A.
      • Tang M.X.
      • Shea S.
      • Mayeux R.
      Antioxidant vitamin intake and risk of Alzheimer disease.
      • Morris M.C.
      • Beckett L.A.
      • Scherr P.A.
      • et al.
      Vitamin E and vitamin C supplement use and risk of incident Alzheimer disease.
      • Zandi P.P.
      • Anthony J.C.
      • Khachaturian A.S.
      • et al.
      Reduced risk of Alzheimer disease in users of antioxidant vitamin supplements: the Cache County Study.
      In 2 studies, dietary intake of vitamin C,
      • Engelhart M.J.
      • Geerlings M.I.
      • Ruitenberg A.
      • et al.
      Dietary intake of antioxidants and risk of Alzheimer disease.
      and particularly vitamin E,
      • Engelhart M.J.
      • Geerlings M.I.
      • Ruitenberg A.
      • et al.
      Dietary intake of antioxidants and risk of Alzheimer disease.
      • Morris M.C.
      • Evans D.A.
      • Bienias J.L.
      • et al.
      Dietary intake of antioxidant nutrients and the risk of incident Alzheimer disease in a biracial community study.
      but not antioxidant supplements, was associated with a reduced risk of Alzheimer’s disease. These reports, in addition to the findings of antioxidant vitamins in the current study, identify the possibility that other underlying beneficial elements in fruits and vegetables may contribute to Alzheimer’s disease risk reduction.
      • Evans D.A.
      • Morris M.C.
      Is a randomized trial of antioxidants in the primary prevention of Alzheimer disease warranted?.
      • Grundman M.
      • Grundman M.
      • Delaney P.
      Antioxidant strategies for Alzheimer’s disease.
      Our finding for the consumption of tea concurs with previous studies. Two case-control studies examined whether tea consumption was related to a higher risk of Alzheimer’s disease, and neither of them found a significant association.
      • Forster D.P.
      • Newens A.J.
      • Kay D.W.
      • Edwardson J.A.
      Risk factors in clinically diagnosed presenile dementia of the Alzheimer type: a case-control study in northern England.
      • Rogers M.A.
      • Simon D.G.
      A preliminary study of dietary aluminium intake and risk of Alzheimer’s disease.
      Midlife flavonoid intake (from tea only) was not associated with the risk of Alzheimer’s disease 25 years later in the Honolulu-Asia Aging Study.
      • Laurin D.
      • Masaki K.H.
      • Foley D.J.
      • White L.R.
      • Launer L.J.
      Midlife dietary intake of antioxidants and risk of late-life incident dementia: the Honolulu-Asia Aging Study.
      It is possible that the reason we did not find a significant inverse association between wine or sake drinking and Alzheimer’s disease in the current study is because few subjects in our study drank wine or sake at least once per week. However, the point estimate is consistent with a French study
      • Orgogozo J.M.
      • Dartigues J.F.
      • Lafont S.
      • et al.
      Wine consumption and dementia in the elderly: a prospective community study in the Bordeaux area.
      • Commenges D.
      • Scotet V.
      • Renaud S.
      • Jacqmin-Gadda H.
      • Barberger-Gateau P.
      • Dartigues J.F.
      Intake of flavonoids and risk of dementia.
      in which drinking 3 to 4 standard glasses of wine per day was associated with more than an 80% reduced risk of dementia and a 75% reduced risk of Alzheimer’s disease.
      • Orgogozo J.M.
      • Dartigues J.F.
      • Lafont S.
      • et al.
      Wine consumption and dementia in the elderly: a prospective community study in the Bordeaux area.
      There is growing evidence indicating that oxidative damage caused by the β-amyloid peptide in the pathogenesis of Alzheimer’s disease may be hydrogen peroxide (H2O2)-mediated.
      • Smith C.D.
      • Carney J.M.
      • Starke-Reed P.E.
      • et al.
      Excess brain protein oxidation and enzyme dysfunction in normal aging and in Alzheimer disease.
      • Nunomura A.
      • Perry G.
      • Pappolla M.A.
      • et al.
      RNA oxidation is a prominent feature of vulnerable neurons in Alzheimer’s disease.
      • Smith M.A.
      • Hirai K.
      • Hsiao K.
      • et al.
      Amyloid-beta deposition in Alzheimer transgenic mice is associated with oxidative stress.
      • Opazo C.
      • Huang X.
      • Cherny R.A.
      • et al.
      Metalloenzyme-like activity of Alzheimer’s disease beta-amyloid Cu-dependent catalytic conversion of dopamine, cholesterol, and biological reducing agents to neurotoxic H(2)O(2).
      • Behl C.
      • Davis J.B.
      • Lesley R.
      • Schubert D.
      Hydrogen peroxide mediates amyloid beta protein toxicity.
      Recent studies have shown that polyphenols from apple and citrus juices, such as quercetin, are able to cross the blood-brain barrier
      • Youdim K.A.
      • Qaiser M.Z.
      • Begley D.J.
      • Rice-Evans C.A.
      • Abbott N.J.
      Flavonoid permeability across an in situ model of the blood-brain barrier.
      and show neuroprotection against H2O2..
      • Heo H.J.
      • Lee C.Y.
      Protective effects of quercetin and vitamin C against oxidative stress-induced neurodegeneration.
      • Heo H.J.
      • Kim D.O.
      • Shin S.C.
      • Kim M.J.
      • Kim B.G.
      • Shin D.H.
      Effect of antioxidant flavanone, naringenin, from Citrus junoson neuroprotection.
      • Ortiz D.
      • Shea T.B.
      Apple juice prevents oxidative stress induced by amyloid-beta in culture.
      The effect of polyphenols from citrus is similar to vitamin C, but quercetin from apple juice confers stronger neuroprotection than vitamin C.
      • Heo H.J.
      • Lee C.Y.
      Protective effects of quercetin and vitamin C against oxidative stress-induced neurodegeneration.
      Early in vitro studies reported that polyphenol flavonols, such as quercetin, protect mammalian and bacterial cells from toxicity induced by H2O2, but that α-tocopherol is not effective.
      • Nakayama T.
      • Yamada M.
      • Osawa T.
      • Kawakishi S.
      Suppression of active oxygen-induced cytotoxicity by flavonoids.
      • Nakayama T.
      Suppression of hydroperoxide-induced cytotoxicity by polyphenols.
      Recent in vitro studies show that many polyphenols, including flavonols (eg, quercetin and others), protect mouse hippocampal cells from oxidative glutamate and H2O2 toxicity, but that the polyphenol catechin, the major polyphenol from tea, was ineffective.
      • Ortiz D.
      • Shea T.B.
      Apple juice prevents oxidative stress induced by amyloid-beta in culture.
      • Ishige K.
      • Schubert D.
      • Sagara Y.
      Flavonoids protect neuronal cells from oxidative stress by three distinct mechanisms.
      This may partially explain the null association for tea in the current and previous studies. Additional animal studies showed that chronic administration of flavonols or apple juice protects against aging and cognitive impairment induced by lipopolysaccharide, genetic, and dietary vitamin deficiency in animal models.
      • Patil C.S.
      • Singh V.P.
      • Satyanarayan P.S.
      • Jain N.K.
      • Singh A.
      • Kulkarni S.K.
      Protective effect of flavonoids against aging- and lipopolysaccharide-induced cognitive impairment in mice.
      • Rogers E.J.
      • Milhalik S.
      • Orthiz D.
      • Shea T.B.
      Apple juice prevents oxidative stress and impaired cognitive performance caused by genetic and dietary deficiencies in mice.
      Aside from their antioxidant properties, many polyphenols, such as quercetin, have potent anti-inflammatory properties.
      • Manach C.
      • Scalbert A.
      • Morand C.
      • Remesy C.
      • Jimenez L.
      Polyphenols: food sources and bioavailability.
      • Scalbert A.
      • Williamson G.
      Dietary intake and bioavailability of polyphenols.
      Recent clinical trials have shown that intake of orange juice significantly reduces plasma concentrations of F2-isoprostanes (a valid biomarker of oxidative stress) and, perhaps, C-reactive protein,
      • Hodgson J.M.
      • Croft K.D.
      • Mori T.A.
      • Burke V.
      • Beilin L.J.
      • Puddey I.B.
      Regular ingestion of tea does not inhibit in vivo lipid peroxidation in humans.
      • O’Reilly J.D.
      • Mallet A.I.
      • McAnlis G.T.
      • et al.
      Consumption of flavonoids in onions and black tea: lack of effect on F2-isoprostanes and autoantibodies to oxidized LDL in healthy humans.
      • Sanchez-Moreno C.
      • Cano M.P.
      • de Ancos B.
      • et al.
      High-pressurized orange juice consumption affects plasma vitamin C, antioxidative status and inflammatory markers in healthy humans.
      whereas supplementation of vitamin E did not reduce the concentration of F2-isoprostanes.
      • Meagher E.A.
      • Barry O.P.
      • Lawson J.A.
      • Rokach J.
      • FitzGerald G.A.
      Effects of vitamin E on lipid peroxidation in healthy persons.
      In addition to antioxidant vitamins and polyphenols, fruit and vegetable juices also may possess other protective components, such as folate and minerals.
      • Kiefer I.
      • Prock P.
      • Lawrence C.
      • et al.
      Supplementation with mixed fruit and vegetable juice concentrates increased serum antioxidants and folate in healthy adults.
      For example, a high serum level of folate was found to be associated with a decreased risk of Alzheimer’s disease.
      • Wang H.X.
      • Wahlin A.
      • Basun H.
      • Fastbom J.
      • Winblad B.
      • Fratiglioni L.
      Vitamin B(12) and folate in relation to the development of Alzheimer’s disease.
      Selection bias is minimized in the Kame Project because this is a population-based cohort study. However, there may still be some errors in reporting of dietary intake associated with incipient dementia or dietary changes related to early changes in olfaction. We therefore adjusted for baseline CASI scores and olfaction diagnostic group in the analyses. Baseline CASI scores were also similarly distributed across exposure groups. Among participants with CASI scores greater than 87, the corresponding HRs (95% CI) were 0.61 (0.15-2.42) for those who drank juices once or twice per week and 0.13 (0.03-0.54) for those who drank at least 3 times per week (P for trend < .01) versus those who drank juices less than once per week. We also conducted analyses using only participants with at least 5 years of follow-up. The corresponding HRs (95% CI) were 0.21 (95% CI, 0.03-1.41) and 0.07 (95% CI, 0.01-0.42). Although we adjusted for many potential confounding factors, we still cannot exclude the possibility that residual confounding may explain our results. Our data are somewhat limited in sample size. Despite this, we still found a highly significant result for juices, even in stratified analyses.
      In the present study, the inverse association between intake of fruit and vegetable juices and Alzheimer’s disease cannot be solely explained by antioxidant vitamins. Further studies are needed to examine whether components other than antioxidant vitamins, such as polyphenols, may play a protective role. We also did not collect intake information on each specific type of juice and cannot say at present which fruit and vegetable juices might confer protection or for what duration of time they need to be consumed before delay of Alzheimer’s disease onset may be realized. Future studies are necessary to confirm our findings and to investigate how intake of different fruit and vegetable juices relate to the risk of Alzheimer’s disease.

      Acknowledgments

      We thank Drs. James D. Bowen, Wayne C. McCormick, Susan M. McCurry, and Madeline M. Rice for their assistance in clinical classification and study management.

      References

        • Butterfield D.A.
        • Drake J.
        • Pocernich C.
        • Castegna A.
        Evidence of oxidative damage in Alzheimer’s disease brain: central role for amyloid beta-peptide.
        Trends Mol Med. 2001; 7: 548-554
        • Honda K.
        • Casadesus G.
        • Petersen R.B.
        • Perry G.
        • Smith M.A.
        Oxidative stress and redox-active iron in Alzheimer’s disease.
        Ann N Y Acad Sci. 2004; 1012: 179-182
        • Markesbery W.R.
        Oxidative stress hypothesis in Alzheimer’s disease.
        Free Radic Biol Med. 1997; 23: 134-147
        • Petersen R.C.
        • Thomas R.G.
        • Grundman M.
        • et al.
        Vitamin E and donepezil for the treatment of mild cognitive impairment.
        N Engl J Med. 2005; 352: 2379-2388
        • Luchsinger J.A.
        • Tang M.X.
        • Shea S.
        • Mayeux R.
        Antioxidant vitamin intake and risk of Alzheimer disease.
        Arch Neurol. 2003; 60: 203-208
        • Morris M.C.
        • Beckett L.A.
        • Scherr P.A.
        • et al.
        Vitamin E and vitamin C supplement use and risk of incident Alzheimer disease.
        Alzheimer Dis Assoc Disord. 1998; 12: 121-126
        • Zandi P.P.
        • Anthony J.C.
        • Khachaturian A.S.
        • et al.
        Reduced risk of Alzheimer disease in users of antioxidant vitamin supplements: the Cache County Study.
        Arch Neurol. 2004; 61: 82-88
        • Engelhart M.J.
        • Geerlings M.I.
        • Ruitenberg A.
        • et al.
        Dietary intake of antioxidants and risk of Alzheimer disease.
        JAMA. 2002; 287: 3223-3229
        • Morris M.C.
        • Evans D.A.
        • Bienias J.L.
        • et al.
        Dietary intake of antioxidant nutrients and the risk of incident Alzheimer disease in a biracial community study.
        JAMA. 2002; 287: 3230-3237
        • Manach C.
        • Scalbert A.
        • Morand C.
        • Remesy C.
        • Jimenez L.
        Polyphenols: food sources and bioavailability.
        Am J Clin Nutr. 2004; 79: 727-747
        • Scalbert A.
        • Williamson G.
        Dietary intake and bioavailability of polyphenols.
        J Nutr. 2000; 130: 2073S-2085S
        • Bates B.P.
        • Morris J.R.
        • Crandall P.G.
        Principles and Practices of Small- and Medium- Scale Fruit Processing. Food Science and Human Nutrition Department, University of Florida, Gainesville, FL2001
        • Bazemore R.
        • Rouseff R.
        • Naim M.
        Linalool in orange juice: origin and thermal stability.
        J Agric Food Chem. 2003; 51: 196-199
        • Lindsay J.
        • Laurin D.
        • Verreault R.
        • et al.
        Risk factors for Alzheimer’s disease: a prospective analysis from the Canadian Study of Health and Aging.
        Am J Epidemiol. 2002; 156: 445-453
        • Forster D.P.
        • Newens A.J.
        • Kay D.W.
        • Edwardson J.A.
        Risk factors in clinically diagnosed presenile dementia of the Alzheimer type: a case-control study in northern England.
        J Epidemiol Community Health. 1995; 49: 253-258
        • Rogers M.A.
        • Simon D.G.
        A preliminary study of dietary aluminium intake and risk of Alzheimer’s disease.
        Age Ageing. 1999; 28: 205-209
        • Laurin D.
        • Masaki K.H.
        • Foley D.J.
        • White L.R.
        • Launer L.J.
        Midlife dietary intake of antioxidants and risk of late-life incident dementia: the Honolulu-Asia Aging Study.
        Am J Epidemiol. 2004; 159: 959-967
        • Lugasi A.
        • Hovari J.
        Antioxidant properties of commercial alcoholic and nonalcoholic beverages.
        Nahrung. 2003; 47: 79-86
        • Manach C.
        • Morand C.
        • Gil-Izquierdo A.
        • Bouteloup-Demange C.
        • Remesy C.
        Bioavailability in humans of the flavanones hesperidin and narirutin after the ingestion of two doses of orange juice.
        Eur J Clin Nutr. 2003; 57: 235-242
        • Bub A.
        • Watzl B.
        • Blockhaus M.
        • et al.
        Fruit juice consumption modulates antioxidative status, immune status and DNA damage.
        J Nutr Biochem. 2003; 14: 90-98
        • Vinson J.A.
        • Liang X.
        • Proch J.
        • Hontz B.A.
        • Dancel J.
        • Sandone N.
        Polyphenol antioxidants in citrus juices: in vitro and in vivo studies relevant to heart disease.
        Adv Exp Med Biol. 2002; 505: 113-122
        • Heo H.J.
        • Lee C.Y.
        Protective effects of quercetin and vitamin C against oxidative stress-induced neurodegeneration.
        J Agric Food Chem. 2004; 52: 7514-7517
        • Heo H.J.
        • Kim D.O.
        • Shin S.C.
        • Kim M.J.
        • Kim B.G.
        • Shin D.H.
        Effect of antioxidant flavanone, naringenin, from Citrus junoson neuroprotection.
        J Agric Food Chem. 2004; 52: 1520-1525
        • Nakayama T.
        • Yamada M.
        • Osawa T.
        • Kawakishi S.
        Suppression of active oxygen-induced cytotoxicity by flavonoids.
        Biochem Pharmacol. 1993; 45: 265-267
        • Patil C.S.
        • Singh V.P.
        • Satyanarayan P.S.
        • Jain N.K.
        • Singh A.
        • Kulkarni S.K.
        Protective effect of flavonoids against aging- and lipopolysaccharide-induced cognitive impairment in mice.
        Pharmacology. 2003; 69: 59-67
        • O’Byrne D.J.
        • Devaraj S.
        • Grundy S.M.
        • Jialal I.
        Comparison of the antioxidant effects of Concord grape juice flavonoids alpha-tocopherol on markers of oxidative stress in healthy adults.
        Am J Clin Nutr. 2002; 76: 1367-1374
        • Graves A.B.
        • Larson E.B.
        • Edland S.D.
        • et al.
        Prevalence of dementia and its subtypes in the Japanese American population of King County, Washington state.
        Am J Epidemiol. 1996; 144: 760-771
        • Larson E.B.
        • McCurry S.M.
        • Graves A.B.
        Standardization of the clinical diagnosis of the dementia syndrome and its subtypes in a cross-national study: the Ni-Hon-Sea experience.
        J Gerontol. 1998; 53: M313-M319
        • Teng E.L.
        • Hasegawa K.
        • Homma A.
        • et al.
        The Cognitive Abilities Screening Instrument (CASI): a practical test for cross-cultural epidemiological studies of dementia.
        Int Psychogeriatr. 1994; 6: 45-58
        • Hughes C.P.
        • Berg L.
        • Danziger W.L.
        • Coben L.A.
        • Martin R.L.
        A new clinical scale for the staging of dementia.
        Br J Psychiatry. 1982; 140: 566-572
        • Morris J.C.
        • Heyman A.
        • Mohs R.C.
        • et al.
        The consortium to establish a registry for Alzheimer’s disease (CERAD). Part I. Clinical and neuropsychological assessment of Alzheimer’s disease.
        Neurology. 1989; 39: 1159-1165
        • Welsh K.A.
        • Butters N.
        • Mohs R.C.
        • et al.
        The Consortium to Establish a Registry for Alzheimer’s Disease (CERAD). Part V. A normative study of the neuropsychological battery.
        Neurology. 1994; 44: 609-614
        • Kiernan R.J.
        • Mueller J.
        • Langston J.W.
        • Van Dyke C.
        The Neurobehavioral Cognitive Status Examination: a brief but quantitative approach to cognitive assessment.
        Ann Intern Med. 1987; 107: 481-485
        • Reitan R.M.
        • Wolfson D.
        The Halstead-Reitan Neuropsychological Test Battery. Neuropsychology Press, Tempe, AZ1985
        • Shipley W.C.
        Institute of Living Scale. Western Psychological Services Corp, Los Angeles, CA1946
        • Tiffin J.
        Purdue Pegboard: Examiner Manual. Science Research Associates, Chicago, IL1968
        • Wechsler D.
        Wechsler Adult Intelligence Scale—Revised. Psychological Corporation, New York1981
        • Wechsler D.
        Wechsler Memory Scale—Revised. Psychological Corporation, New York1987
      1. Diagnostic and Statistical Manual of Mental Disorders. 4th ed. American Psychiatric Press, Washington, DC1994
        • McKhann G.
        • Drachman D.
        • Folstein M.
        • Katzman R.
        • Price D.
        • Stadlan E.M.
        Clinical diagnosis of Alzheimer’s disease: report of the NINCDS-ADRDA Work Group under the auspices of Department of Health and Human Services Task Force on Alzheimer’s Disease.
        Neurology. 1984; 34: 939-944
        • Roman G.C.
        • Tatemichi T.K.
        • Erkinjuntti T.
        • et al.
        Vascular dementia: diagnostic criteria for research studies.
        Neurology. 1993; 43: 250-260
        • Chui H.C.
        • Victoroff J.I.
        • Margolin D.
        • Jagust W.
        • Shankle R.
        • Katzman R.
        Criteria for the diagnosis of ischemic vascular dementia proposed by the State of California Alzheimer’s Disease Diagnostic and Treatment Centers.
        Neurology. 1992; 42: 473-480
        • Hankin J.H.
        • Wilkens L.R.
        Development and validation of dietary assessment methods for culturally diverse populations.
        Am J Clin Nutr. 1994; 59: 198S-200S
        • Hankin J.H.
        • Nomura A.M.
        • Lee J.
        • Hirohata T.
        • Kolonel L.N.
        Reproducibility of a diet history questionnaire in a case-control study of breast cancer.
        Am J Clin Nutr. 1983; 37: 981-985
        • Hankin J.H.
        • Wilkens L.R.
        • Kolonel L.N.
        • Yoshizawa C.N.
        Validation of a quantitative diet history method in Hawaii.
        Am J Epidemiol. 1991; 133: 616-628
        • Hankin J.H.
        Dietary methods for estimating vitamin A and carotene intakes in epidemiologic studies of cancer.
        J Can Diet Assoc. 1987; 47: 219-224
        • Doty R.L.
        • Marcus A.
        • Lee W.W.
        Development of the 12-item Cross-Cultural Smell Identification Test (CC-SIT).
        Laryngoscope. 1996; 106: 353-356
        • Graves A.B.
        • Bowen J.D.
        • Rajaram L.
        • et al.
        Impaired olfaction as a marker for cognitive decline: interaction with apolipoprotein E epsilon4 status.
        Neurology. 1999; 53: 1480-1487
        • Miller S.A.
        • Dykes D.D.
        • Polesky H.F.
        A simple salting out procedure for extracting DNA from human nucleated cells.
        Nucleic Acids Res. 1988; 16: 1215
        • Emi M.
        • Wu L.L.
        • Robertson M.A.
        • et al.
        Genotyping and sequence analysis of apolipoprotein E isoforms.
        Genomics. 1988; 3: 373-379
        • Hixson J.E.
        • Vernier D.T.
        Restriction isotyping of human apolipoprotein E by gene amplification and cleavage with HhaI.
        J Lipid Res. 1990; 31: 545-548
        • Hosmer D.W.
        • Lemeshow S.
        Applied Survival Analysis. Wiley, New York1999
        • Korn E.L.
        • Graubard B.I.
        • Midthune D.
        Time-to-event analysis of longitudinal follow-up of a survey: choice of the time-scale.
        Am J Epidemiol. 1997; 145: 72-80
        • Borenstein A.R.
        • Wu Y.
        • Mortimer J.A.
        • et al.
        Developmental and vascular risk factors for Alzheimer’s disease.
        Neurobiol Aging. 2005; 26: 325-334
        • Evans D.A.
        • Morris M.C.
        Is a randomized trial of antioxidants in the primary prevention of Alzheimer disease warranted?.
        Alzheimer Dis Assoc Disord. 1996; 10: 45-49
        • Grundman M.
        • Grundman M.
        • Delaney P.
        Antioxidant strategies for Alzheimer’s disease.
        Proc Nutr Soc. 2002; 61: 191-202
        • Orgogozo J.M.
        • Dartigues J.F.
        • Lafont S.
        • et al.
        Wine consumption and dementia in the elderly: a prospective community study in the Bordeaux area.
        Revue Neurologique. 1997; 153: 185-192
        • Commenges D.
        • Scotet V.
        • Renaud S.
        • Jacqmin-Gadda H.
        • Barberger-Gateau P.
        • Dartigues J.F.
        Intake of flavonoids and risk of dementia.
        Eur J Epidemiol. 2000; 16: 357-363
        • Smith C.D.
        • Carney J.M.
        • Starke-Reed P.E.
        • et al.
        Excess brain protein oxidation and enzyme dysfunction in normal aging and in Alzheimer disease.
        Proc Natl Acad Sci U S A. 1991; 88: 10540-10543
        • Nunomura A.
        • Perry G.
        • Pappolla M.A.
        • et al.
        RNA oxidation is a prominent feature of vulnerable neurons in Alzheimer’s disease.
        J Neurosci. 1999; 19: 1959-1964
        • Smith M.A.
        • Hirai K.
        • Hsiao K.
        • et al.
        Amyloid-beta deposition in Alzheimer transgenic mice is associated with oxidative stress.
        J Neurochem. 1998; 70: 2212-2215
        • Opazo C.
        • Huang X.
        • Cherny R.A.
        • et al.
        Metalloenzyme-like activity of Alzheimer’s disease beta-amyloid.
        J Biol Chem. 2002; 277: 40302-40308
        • Behl C.
        • Davis J.B.
        • Lesley R.
        • Schubert D.
        Hydrogen peroxide mediates amyloid beta protein toxicity.
        Cell. 1994; 77: 817-827
        • Youdim K.A.
        • Qaiser M.Z.
        • Begley D.J.
        • Rice-Evans C.A.
        • Abbott N.J.
        Flavonoid permeability across an in situ model of the blood-brain barrier.
        Free Radic Biol Med. 2004; 36: 592-604
        • Ortiz D.
        • Shea T.B.
        Apple juice prevents oxidative stress induced by amyloid-beta in culture.
        J Alzheimers Dis. 2004; 6: 27-30
        • Nakayama T.
        Suppression of hydroperoxide-induced cytotoxicity by polyphenols.
        Cancer Res. 1994; 54: 1991s-1993s
        • Ishige K.
        • Schubert D.
        • Sagara Y.
        Flavonoids protect neuronal cells from oxidative stress by three distinct mechanisms.
        Free Radic Biol Med. 2001; 30: 433-446
        • Rogers E.J.
        • Milhalik S.
        • Orthiz D.
        • Shea T.B.
        Apple juice prevents oxidative stress and impaired cognitive performance caused by genetic and dietary deficiencies in mice.
        J Nutr Health Aging. 2004; 8: 92-97
        • Hodgson J.M.
        • Croft K.D.
        • Mori T.A.
        • Burke V.
        • Beilin L.J.
        • Puddey I.B.
        Regular ingestion of tea does not inhibit in vivo lipid peroxidation in humans.
        J Nutr. 2002; 132: 55-58
        • O’Reilly J.D.
        • Mallet A.I.
        • McAnlis G.T.
        • et al.
        Consumption of flavonoids in onions and black tea: lack of effect on F2-isoprostanes and autoantibodies to oxidized LDL in healthy humans.
        Am J Clin Nutr. 2001; 73: 1040-1044
        • Sanchez-Moreno C.
        • Cano M.P.
        • de Ancos B.
        • et al.
        High-pressurized orange juice consumption affects plasma vitamin C, antioxidative status and inflammatory markers in healthy humans.
        J Nutr. 2003; 133: 2204-2209
        • Meagher E.A.
        • Barry O.P.
        • Lawson J.A.
        • Rokach J.
        • FitzGerald G.A.
        Effects of vitamin E on lipid peroxidation in healthy persons.
        JAMA. 2001; 285: 1178-1182
        • Kiefer I.
        • Prock P.
        • Lawrence C.
        • et al.
        Supplementation with mixed fruit and vegetable juice concentrates increased serum antioxidants and folate in healthy adults.
        J Am Coll Nutr. 2004; 23: 205-211
        • Wang H.X.
        • Wahlin A.
        • Basun H.
        • Fastbom J.
        • Winblad B.
        • Fratiglioni L.
        Vitamin B(12) and folate in relation to the development of Alzheimer’s disease.
        Neurology. 2001; 56: 1188-1194