TABLE 1.
Summary of studies included in the meta-analysis
| Author, year, cohort name, country | Follow-up (y) | Male (%) | Baseline age (y) | Number of participants | Exposure (method of assessment) | Dairy products dose (g/d) | Outcome (method of assessment) | Adjustments |
|---|---|---|---|---|---|---|---|---|
| Almeida, 2006 [23], NR, Australia | 4.8 | 100 | 77.5 | 601 | Consumed full-cream milk (self-reported questionnaire) | - | Cognitive function (MMSE, GDS-15) | Age, history of diabetes, consumption of full-cream milk, high school or university education, and vigorous physical activity |
| Dobreva, 2022 [39], UK Biobank, UK | 11.4 | 46.7 | 62 | 249,511 | Cheese intake (FFQ) | - | All-cause dementia (ICD 9 and 10) | Sociodemographic (age, sex, Townsend deprivation score, age left education, household income), lifestyle (physical activity, smoking status, weekly alcohol units), mental health factors (loneliness, depression), and physical health factors (BMI, cholesterol, diabetes, hypertension, cardiovascular events, major dietary changes) and all other food categories |
| Kesse-Guyot, 2016 [40], The SU.VI.Max 2 Observational Follow-Up Study, France | 13 | 52 | 53.7 | 3076 | Total dairy products (24-h dietary records) | - | Cognitive function (RI-48 test, verbal fluency tasks, digit span tests, and TMT) | Age, sex, education and follow-up time between baseline and cognitive evaluation, occupational status, intervention group during the trial phase, smoking status, physical activity, alcohol consumption, depressive symptoms, baseline memory troubles, BMI, energy intake, number of 24 h dietary records and history of diabetes, hypertension and CVD, Western and healthy dietary pattern score |
| Lu, 2023 [15], The Ohsaki Cohort 2006 Study, Japan | 5.7 | 44.5 | 73.5 | 11,636 | Total dairy intake (FFQ), milk, yogurt and cheese intake | Mean (SD) 116.8 (81.4) g/1000 kcal/d |
Incidence of dementia (LTCI system based on Dementia Scale) | Sex, age, education level, BMI, smoking status, alcohol drinking status, time spent walking, psychological distress, history of diseases, energy intake, energy-adjusted vegetable and fruit intake, and energy-adjusted fish intake |
| Nicoli, 2021 [16], The Monzino 80-Plus Study, Italy | 12 | 31 | 91.1 | 512 | Milk and cheese intake (FFQ) | - | Incidence of dementia (DSM-IV) | Age, sex, education, total energy intake, smoking, alcohol, physical activity, chronic obstructive pulmonary disease, lifetime depression, previous stroke, previous transient ischemic attack, and place of residence |
| Otsuka, 2014 [24], National Institute for Longevity Sciences – Longitudinal Study of Aging, Japan | Male: 8.0; female: 8.2 | 51.6 | Male: 67.7; female: 68.0 | Male: 1137; female: 1065 | Milk and dairy products (3-d dietary record) | Mean (SD) 164.77 (129.3) |
Cognitive function (MMSE) | Age, follow-up time, MMSE score at baseline, education, BMI, household annual income, current smoking status, energy intake, and history of heart disease, hypertension, hyperlipidemia, and diabetes |
| Ozawa, 2014 [43], The Hisayama Study, Japan | 17 | 42.3 | 69.4 | 1081 | Milk and dairy consumption (FFQ) | Median (IQR) 97 (45–197) | All-cause dementia, AD, VaD (DSM-III) | Age, sex, low education, history of stroke hypertension, diabetes mellitus, total cholesterol, BMI, smoking habits, regular exercise and energy, vegetable, fruit, fish, and meat intake |
| Petruski-Ivleva, 2017 [44], ARIC (The Atherosclerosis Risk in Communities) Cohort, United States | 20 | 44 | 57.5 | 13,752 | Milk intake (FFQ) | Categorical | Cognitive function (DWRT, DSST, WFT) | Age, sex, race center, education level, APOE4, BMI, smoking, alcohol intake, diabetes, physical activity, total energy intake, diet quality |
| Talaei, 2020 [17], Singapore Chinese Health Study, Singapore | 23 | 40.8 | 53 | 16,948 | Dairy products (FFQ) | Median (IQR) (28.7 11.0–83.7) |
Cognitive impairment (MMSE) | Age, sex, dialect, year of interview, educational level, marriage status, BMI, physical activity, smoking status, alcohol use, baseline history of self-reported hypertension, diabetes, heart attack, and stroke, history of cancer, sleep status, total energy intake, soy, red meat, poultry, fish, vegetables, fruits, tea, coffee, and soda, vegetable-fruit-soy dietary pattern |
| Tanaka, 2008 [41], InCHIANTI Study, Italy | Mean 10.1; max 18.2 | 43.5 | 75.4 | 832 | Dairy products (FFQ) | Mean (SD) 170.3 (141.7) |
Cognitive function (MMSE and additional neuropsychological tests) | Age, sex, study site, chronic diseases, years of education, total energy intake, physical activity, BMI, APOE4 carrier status, CRP, IL-6, plasma omega (ω)-3, plasma ω-6, plasma beta-carotene, and plasma alpha-tocopherol |
| Trichopoulou, 2015 [25], EPIC-Greece (European Prospective Investigation into Cancer and Nutrition-Greece), Greece | Median 6.8; range 5.1–8.2 | 35.9 | 74 | 401 | Dairy products (FFQ) | Median (IQR) 205 (130–333) |
Cognitive decline (MMSE) | Sex, age, years of education, BMI, physical activity, smoking, diabetes, hypertension, cohabiting, and total energy intake |
| Vercambre, 2009 [42], E3N (Etude Epidémiologique auprès de femmes la Mutuelle Générale de l’Education Nationale) Subcohort, France | 13 | 0 | 65.5 | 4809 | French Dietary History Questionnaire | Mean (SD) 283.6 (231.1) |
Cognitive decline (DECO) | Age at cognitive assessment, education level, BMI, physical activity, energy intake, smoking status, use of supplements, use of postmenopausal hormones, depression, cancer, CHD, stroke, diabetes, hypertension, hypercholesterolemia |
| Yamada, 2003 [26], Adult Health Study Follow-Up Study, Japan | 25 | 26.8 | >30 | 1774 | Milk intake (dietary questionnaire) | Categorical | AD, VaD (DSM-IIIR and DSM-IV) | Age, sex, education, and 10 mm Hg systolic blood pressure increase |
| Ylilauri, 2022 [18], Kuopio Ischemic Heart Disease Risk Factor Study, Finland | 21.9 | 100 | 53 | 2416 | Dairy products (4-d dietary records) | Mean (SD) [median] 711 (360) [688] 27% fermented |
Any dementia, AD (ICD 8, 9 and 10) | Age, baseline examination year, energy intake, education years, pack-years of smoking, BMI, diabetes, leisure-time physical activity, history of coronary artery disease, use of lipid-lowering medication, intakes of alcohol, fiber, the sum of fruits, berries, and vegetables and dietary fat quality (ratio of PUFAs plus MUFAs to SFAs plus trans fatty acids) |
| Zhang, 2021 [19], Chinese Longitudinal Healthy Longevity Survey, China | 6 | 50.7 | 77.8 | 3029 | Dairy intake (frequency dietary questionnaire) | - | Cognitive decline (MMSE) | Sex, age, education, occupation before retirement, marital status, smoking, alcohol drinking, physical exercise, BMI, hypertension, diabetes, heart disease, and cerebrovascular disease |
AD, Alzheimer’s disease; ApoE4, apolipoprotein E4; BMI, body mass index; CHD, chronic heart failure; CRP, C reactive protein; CVD, cardiovascular disease; DECO, détérioration cognitive observée; Dementia Scale, degree of independence in daily living for elderly with dementia; DSM, diagnostic and statistical manual; DSST, digit symbol substitution test; DWRT, delayed word recall test; FFQ, frequency food questionnaire; GDS, geriatric depression scale; ICD, International Classification of Disease; IL, interleukin; IQR, interquartile range; LTCI, long-term care insurance; MMSE, Mini-Mental State Examination; MUFA, monounsaturated fatty acid; NR, not reported; PUFA, polyunsaturated fatty acid; RI-48 test, Rappel indicé; SD, standard deviation; SFA, saturated fatty acid; TMT, trail making test; UK, United Kingdom; USA, United States of America; VaD, vascular dementia; WFT, word fluency test.