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Role of milk and dairy intake in cognitive function in older adults: a systematic review and meta-analysis.

Abstract

BACKGROUND

As aging populations increase across the globe, research on lifestyle factors that prevent cognitive decline and dementia is urgently needed. Therefore, a systematic review was conducted to examine the effects of varying levels of milk intake alone or in combination with other dairy products on the outcomes of cognitive function and disorders in adults.

METHODS

A comprehensive search was conducted across 3 databases (PUBMED, CINAHL, and EMBASE) from their inception through October 2017. Prospective cohort studies and randomized controlled trials (RCTs) that enrolled adults were included. Studies with follow-up durations of less than 4 weeks and studies including schizophrenic patients were excluded. Two independent investigators conducted abstract and full-text screenings, data extractions, and risk-of-bias (ROB) assessments using validated tools. Studies were synthesized qualitatively using a strength of evidence (SoE) rating tool. A random-effects model for meta-analysis was conducted when at least 3 unique studies reported sufficient quantitative data for the same outcome.

RESULTS

A total of 1 RCT and 7 cohort studies were included. One medium-quality small RCT (n = 38 participants) showed that only spatial working memory was marginally better in the high dairy diet group compared to the low dairy diet group. Two of the 7 cohort studies were rated as having a high ROB, and only 1 cohort study was rated as having a low ROB. There were large methodological and clinical heterogeneities, such as the methods used to assess milk or dairy intake and the characteristics of the study populations. It was impossible to conduct a dose-response meta-analysis because the studies utilized different categories of exposures (e.g., different frequencies of milk consumption or the amount of dairy intake). Thus, the overall SoE was rated as insufficient regarding the associations between milk intake and cognitive decline, dementia, and Alzheimer's disease outcomes. Our meta-analysis of 3 cohort studies showed no significant association between milk intake and cognitive decline outcome (pooled adjusted risk ratio = 1.21; 95% CI: 0.81, 1.82; for highest vs. lowest intake) with large statistical heterogeneity (I2 = 64.1%).

CONCLUSIONS

The existing evidence (mostly observational) is too poor to draw a firm conclusion regarding the effect of milk or dairy intake on the risk of cognitive decline or disorders in adults.

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  • Authors+Show Affiliations

    ,

    Department of Nutrition Education, Kyonggi University, Suwon-si, South Korea.

    ,

    Department of Epidemiology, University of Pittsburgh, Pittsburgh, USA.

    ,

    Department of Public Health and Community Medicine, School of Medicine, Tufts University, Boston, USA.

    ,

    Research Group of Nutrition and Diet, Korea Food Research Institute, Wanju-gun, South Korea.

    Department of Food and Nutrition, Gachon University, Seongnam-si, Gyeonggi-do, 461-701, South Korea. skysea@gachon.ac.kr.

    Source

    Nutrition journal 17:1 2018 08 27 pg 82

    MeSH

    Aged
    Aged, 80 and over
    Alzheimer Disease
    Animals
    Cognition
    Cognitive Dysfunction
    Cohort Studies
    Dairy Products
    Dementia
    Diet
    Female
    Follow-Up Studies
    Humans
    Male
    Middle Aged
    Milk
    Prospective Studies
    Randomized Controlled Trials as Topic

    Pub Type(s)

    Journal Article
    Meta-Analysis
    Research Support, Non-U.S. Gov't
    Systematic Review

    Language

    eng

    PubMed ID

    30149812

    Citation

    Lee, Jounghee, et al. "Role of Milk and Dairy Intake in Cognitive Function in Older Adults: a Systematic Review and Meta-analysis." Nutrition Journal, vol. 17, no. 1, 2018, p. 82.
    Lee J, Fu Z, Chung M, et al. Role of milk and dairy intake in cognitive function in older adults: a systematic review and meta-analysis. Nutr J. 2018;17(1):82.
    Lee, J., Fu, Z., Chung, M., Jang, D. J., & Lee, H. J. (2018). Role of milk and dairy intake in cognitive function in older adults: a systematic review and meta-analysis. Nutrition Journal, 17(1), p. 82. doi:10.1186/s12937-018-0387-1.
    Lee J, et al. Role of Milk and Dairy Intake in Cognitive Function in Older Adults: a Systematic Review and Meta-analysis. Nutr J. 2018 08 27;17(1):82. PubMed PMID: 30149812.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Role of milk and dairy intake in cognitive function in older adults: a systematic review and meta-analysis. AU - Lee,Jounghee, AU - Fu,Zhuxuan, AU - Chung,Mei, AU - Jang,Dai-Ja, AU - Lee,Hae-Jeung, Y1 - 2018/08/27/ PY - 2018/04/30/received PY - 2018/08/06/accepted PY - 2018/8/29/entrez PY - 2018/8/29/pubmed PY - 2019/4/30/medline KW - Alzheimer’s disease KW - Cognitive decline KW - Meta-analysis KW - Milk KW - Systematic review SP - 82 EP - 82 JF - Nutrition journal JO - Nutr J VL - 17 IS - 1 N2 - BACKGROUND: As aging populations increase across the globe, research on lifestyle factors that prevent cognitive decline and dementia is urgently needed. Therefore, a systematic review was conducted to examine the effects of varying levels of milk intake alone or in combination with other dairy products on the outcomes of cognitive function and disorders in adults. METHODS: A comprehensive search was conducted across 3 databases (PUBMED, CINAHL, and EMBASE) from their inception through October 2017. Prospective cohort studies and randomized controlled trials (RCTs) that enrolled adults were included. Studies with follow-up durations of less than 4 weeks and studies including schizophrenic patients were excluded. Two independent investigators conducted abstract and full-text screenings, data extractions, and risk-of-bias (ROB) assessments using validated tools. Studies were synthesized qualitatively using a strength of evidence (SoE) rating tool. A random-effects model for meta-analysis was conducted when at least 3 unique studies reported sufficient quantitative data for the same outcome. RESULTS: A total of 1 RCT and 7 cohort studies were included. One medium-quality small RCT (n = 38 participants) showed that only spatial working memory was marginally better in the high dairy diet group compared to the low dairy diet group. Two of the 7 cohort studies were rated as having a high ROB, and only 1 cohort study was rated as having a low ROB. There were large methodological and clinical heterogeneities, such as the methods used to assess milk or dairy intake and the characteristics of the study populations. It was impossible to conduct a dose-response meta-analysis because the studies utilized different categories of exposures (e.g., different frequencies of milk consumption or the amount of dairy intake). Thus, the overall SoE was rated as insufficient regarding the associations between milk intake and cognitive decline, dementia, and Alzheimer's disease outcomes. Our meta-analysis of 3 cohort studies showed no significant association between milk intake and cognitive decline outcome (pooled adjusted risk ratio = 1.21; 95% CI: 0.81, 1.82; for highest vs. lowest intake) with large statistical heterogeneity (I2 = 64.1%). CONCLUSIONS: The existing evidence (mostly observational) is too poor to draw a firm conclusion regarding the effect of milk or dairy intake on the risk of cognitive decline or disorders in adults. SN - 1475-2891 UR - https://www.unboundmedicine.com/medline/citation/30149812/Role_of_milk_and_dairy_intake_in_cognitive_function_in_older_adults:_a_systematic_review_and_meta_analysis_ L2 - https://nutritionj.biomedcentral.com/articles/10.1186/s12937-018-0387-1 DB - PRIME DP - Unbound Medicine ER -