Dairy intake and cognitive function in older adults in three cohorts: a mendelian randomization study
Abstract Background Meta-analyses of observational studies on the effect of dairy on cognitive function have yielded inconclusive results, potentially due to unmeasured confounding. To avoid the no-unmeasured confounding assumption, we used lactase persistence genetic variant as an instrumental vari...
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2025-01-01
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| Online Access: | https://doi.org/10.1186/s12937-025-01083-y |
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| author | Natalia Ortega Nick J. Mueller Abbas Dehghan Tosca O. E. de Crom Armin von Gunten Martin Preisig Pedro Marques-Vidal Marco Vinceti Trudy Voortman Nicolas Rodondi Patricia O. Chocano-Bedoya |
| author_facet | Natalia Ortega Nick J. Mueller Abbas Dehghan Tosca O. E. de Crom Armin von Gunten Martin Preisig Pedro Marques-Vidal Marco Vinceti Trudy Voortman Nicolas Rodondi Patricia O. Chocano-Bedoya |
| author_sort | Natalia Ortega |
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| description | Abstract Background Meta-analyses of observational studies on the effect of dairy on cognitive function have yielded inconclusive results, potentially due to unmeasured confounding. To avoid the no-unmeasured confounding assumption, we used lactase persistence genetic variant as an instrumental variable, for which the CC genotype is associated with lower lactase production and, consequently, lower dairy consumption. We used it to assess the effect of long-term consumption of total and non-fermented dairy on cognitive function. Methods We included 43,836 individuals over 55 years old with genotyping, dietary data, and cognitive function measurements from three population-based studies: CoLaus|PsyCoLaus (Switzerland), the Rotterdam Study (the Netherlands) and the Canadian Longitudinal Study on Aging (CLSA - Canada). We performed a one-sample Mendelian randomization using two-stage least-squares regression. First, we estimated total and non-fermented dairy consumption by T-allele frequency. Second, we used the estimated dairy consumption in linear regression models on general cognition, assessed by the Mini-Mental State Examination (MMSE) and the Mental Alternation Test, executive function, verbal fluency, verbal learning, and memory. Results Per T-allele, total dairy intake and non-fermented was 24.8 and 15.3 g/day higher in PsyCoLaus, 57.9 and 49.8 g/day in the Rotterdam Study, and 0.31 and 0.29 times/day in CLSA, respectively. We found no association between the genetically predicted difference and the MMSE in PsyCoLaus and the Rotterdam Study. However, lactase persistent individuals scored 3.4 (95% CI 2.1− 4.7) and 3.5 (95% CI 2.3–4.7) points more in the Mental Alternation Test for total and fermented dairy, respectively, in CLSA. Similarly, lactase persistent participants in CLSA had higher verbal fluency, verbal learning and executive function, but no differences were found in the other cohorts. Such inconsistencies might stem from different FFQs across cohorts and consumption ranges. Nonetheless, the generally small magnitude of effect sizes may suggest that there is no real effect between total or non-fermented dairy intake and cognitive function. Conclusion The evidence for a causal effect of dairy consumption on general cognitive function is weak, consistent with previous results from classic analysis from observational studies. Interventions targeting dairy are unlikely to have a relevant effect on cognitive function. |
| format | Article |
| id | doaj-art-aa11d18a26904ce58d02f86d10d105a4 |
| institution | Kabale University |
| issn | 1475-2891 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | BMC |
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| series | Nutrition Journal |
| spelling | doaj-art-aa11d18a26904ce58d02f86d10d105a42025-02-02T12:09:57ZengBMCNutrition Journal1475-28912025-01-0124111010.1186/s12937-025-01083-yDairy intake and cognitive function in older adults in three cohorts: a mendelian randomization studyNatalia Ortega0Nick J. Mueller1Abbas Dehghan2Tosca O. E. de Crom3Armin von Gunten4Martin Preisig5Pedro Marques-Vidal6Marco Vinceti7Trudy Voortman8Nicolas Rodondi9Patricia O. Chocano-Bedoya10Institute for Primary Health Care (BIHAM), University of BernInstitute for Primary Health Care (BIHAM), University of BernDepartment of Epidemiology and Biostatistics, School of Public Health, Imperial College LondonDepartment of Epidemiology, Erasmus MC University Medical Center RotterdamCenter for Primary Care and Public Health, University Center of General Medicine and Public HealthService of Old-Age Psychiatry, Department of Psychiatry, Lausanne University HospitalDepartment of Medicine, Internal Medicine, Lausanne University HospitalDepartment of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio EmiliaDepartment of Epidemiology, Erasmus MC University Medical Center RotterdamInstitute for Primary Health Care (BIHAM), University of BernInstitute for Primary Health Care (BIHAM), University of BernAbstract Background Meta-analyses of observational studies on the effect of dairy on cognitive function have yielded inconclusive results, potentially due to unmeasured confounding. To avoid the no-unmeasured confounding assumption, we used lactase persistence genetic variant as an instrumental variable, for which the CC genotype is associated with lower lactase production and, consequently, lower dairy consumption. We used it to assess the effect of long-term consumption of total and non-fermented dairy on cognitive function. Methods We included 43,836 individuals over 55 years old with genotyping, dietary data, and cognitive function measurements from three population-based studies: CoLaus|PsyCoLaus (Switzerland), the Rotterdam Study (the Netherlands) and the Canadian Longitudinal Study on Aging (CLSA - Canada). We performed a one-sample Mendelian randomization using two-stage least-squares regression. First, we estimated total and non-fermented dairy consumption by T-allele frequency. Second, we used the estimated dairy consumption in linear regression models on general cognition, assessed by the Mini-Mental State Examination (MMSE) and the Mental Alternation Test, executive function, verbal fluency, verbal learning, and memory. Results Per T-allele, total dairy intake and non-fermented was 24.8 and 15.3 g/day higher in PsyCoLaus, 57.9 and 49.8 g/day in the Rotterdam Study, and 0.31 and 0.29 times/day in CLSA, respectively. We found no association between the genetically predicted difference and the MMSE in PsyCoLaus and the Rotterdam Study. However, lactase persistent individuals scored 3.4 (95% CI 2.1− 4.7) and 3.5 (95% CI 2.3–4.7) points more in the Mental Alternation Test for total and fermented dairy, respectively, in CLSA. Similarly, lactase persistent participants in CLSA had higher verbal fluency, verbal learning and executive function, but no differences were found in the other cohorts. Such inconsistencies might stem from different FFQs across cohorts and consumption ranges. Nonetheless, the generally small magnitude of effect sizes may suggest that there is no real effect between total or non-fermented dairy intake and cognitive function. Conclusion The evidence for a causal effect of dairy consumption on general cognitive function is weak, consistent with previous results from classic analysis from observational studies. Interventions targeting dairy are unlikely to have a relevant effect on cognitive function.https://doi.org/10.1186/s12937-025-01083-yLactase persistenceDairyCognitive functionMendelian randomizationCLSA |
| spellingShingle | Natalia Ortega Nick J. Mueller Abbas Dehghan Tosca O. E. de Crom Armin von Gunten Martin Preisig Pedro Marques-Vidal Marco Vinceti Trudy Voortman Nicolas Rodondi Patricia O. Chocano-Bedoya Dairy intake and cognitive function in older adults in three cohorts: a mendelian randomization study Nutrition Journal Lactase persistence Dairy Cognitive function Mendelian randomization CLSA |
| title | Dairy intake and cognitive function in older adults in three cohorts: a mendelian randomization study |
| title_full | Dairy intake and cognitive function in older adults in three cohorts: a mendelian randomization study |
| title_fullStr | Dairy intake and cognitive function in older adults in three cohorts: a mendelian randomization study |
| title_full_unstemmed | Dairy intake and cognitive function in older adults in three cohorts: a mendelian randomization study |
| title_short | Dairy intake and cognitive function in older adults in three cohorts: a mendelian randomization study |
| title_sort | dairy intake and cognitive function in older adults in three cohorts a mendelian randomization study |
| topic | Lactase persistence Dairy Cognitive function Mendelian randomization CLSA |
| url | https://doi.org/10.1186/s12937-025-01083-y |
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