Vitamin D Supplementation Protects Against Dementia Risk

by | Jan 4, 2021 | 2020, Aging, Alzheimer's Disease, Brain Health, Cognitive Health, Vitamin D - General

Written by Joyce Smith, BS. This study suggests that in a multiethnic cohort of older adults higher vitamin D intake was associated with decreased risk of dementia.

agingVitamin D deficiency, even at low levels, is prevalent worldwide 1,2 and a known risk factor for cognitive decline and dementia; yet it is a modifiable risk factor. Multiple mechanisms for its protective brain role have been hypothesized, including the presence of vitamin D receptors  throughout the brain that function as autocrine and perocrine hormone signaling, as well as regulating the clearance of amyloid  beta (Aß) from the brain, maintaining calcium homeostasis, regulating the immune system and modulating oxidative stress 3. Many studies have implicated higher vitamin D levels with reduced dementia and improved cognitive performance 4,5; however, they lacked the presence of a diverse ethnic population to allow for generalization of results to other ethnic groups. The following study by Zhao and colleagues is a multiethnic longitudinal study 6 that recruited 1,759 non-demented 65 year or older Medicare beneficiaries from northern Manhattan, New York between 1991 and 1996. Annual follow-up visits included food frequency questionnaires to determine food intake. These were completed before the first follow-up.  Analysis of the final 980 participants revealed a diverse ethnic population of 67% women, 25% white, 43% Hispanic, and 32% African-American. During a mean follow-up of 5.8 years, 329 participants developed dementia.  Analysis found that higher vitamin D intake was associated with significantly decreased dementia risk in this multiethnic elderly population.

  • Participants with the highest vitamin D intake from food sources had decreased risk for dementia (hazard ratio [HR] 0.72, 95% confidence interval [CI] 0.54-0.97, P = .030) compared to those with the lowest vitamin D intake after adjusting for age, sex, race/ethnicity, education, apolipoprotein E (APOE)- 4, physical activity, Mediterranean diet (MeDI) score, income, depression, hypertension, diabetes, cardiovascular disease, and smoking.
  • Those with the highest vitamin intake from food sources tended to be non-blacks who were more highly educated and had a higher income, were non-smokers, and who consumed a healthier overall diet (higher MeDI score).
  • Compared to those with the lowest vitamin D intake, those with the highest vitamin D intake (no supplements) had an approximately 30% decreased risk of AD ( P = .027), while those with the highest total vitamin D intake (food and supplements) had a decreased risk of dementia (P = .0005)
  • Those with the lowest and middle levels of total vitamin D intake did not meet the estimated average requirement of vitamin D intake of 400 IU for infants (under one year of age) 7. However, those with the highest total vitamin D intake met the estimated average requirement and were close to meeting the recommended dietary allowance of 600 IU for ages 1 to 70 and 800 IU for adults over 70 7.

Study limitations include potential unmeasured confounders, lack of disease severity data, an absence of adjustments for medication use, and FFQ recall bias. Future studies should distinguish between vitamin D intake from food and from sun exposure by using both objective measures (serologic levels) and subjective measures (FFQ) of vitamin D.

Source: Zhao, Chen, Angeliki Tsapanou, Jennifer Manly, Nicole Schupf, Adam M. Brickman, and Yian Gu. “Vitamin D intake is associated with dementia risk in the Washington Heights‐Inwood Columbia Aging Project (WHICAP).” Alzheimer’s & Dementia 16, no. 10 (2020): 1393-1401.

© 2020 the Alzheimer’s Association

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Posted January 4, 2021.

Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from  the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.

References:

  1. Cashman KD, Dowling KG, Škrabáková Z, et al. Vitamin D deficiency in Europe: pandemic? Am J Clin Nutr. 2016;103(4):1033-1044.
  2. Holick MF. High prevalence of vitamin D inadequacy and implications for health. Mayo Clin Proc. 2006;81(3):353-373.
  3. Gezen-Ak D, Yılmazer S, Dursun E. Why vitamin D in Alzheimer’s disease? The hypothesis. Journal of Alzheimer’s disease : JAD. 2014;40(2):257-269.
  4. Annweiler C, Rolland Y, Schott AM, et al. Higher vitamin D dietary intake is associated with lower risk of alzheimer’s disease: a 7-year follow-up. The journals of gerontology Series A, Biological sciences and medical sciences. 2012;67(11):1205-1211.
  5. Gu Y, Manly JJ, Mayeux RP, Brickman AM. An Inflammation-related Nutrient Pattern is Associated with Both Brain and Cognitive Measures in a Multiethnic Elderly Population. Curr Alzheimer Res. 2018;15(5):493-501.
  6. Zhao C, Tsapanou A, Manly J, Schupf N, Brickman AM, Gu Y. Vitamin D intake is associated with dementia risk in the Washington Heights-Inwood Columbia Aging Project (WHICAP). Alzheimer’s & dementia : the journal of the Alzheimer’s Association. 2020;16(10):1393-1401.
  7. Del Valle HB, Yaktine AL, Taylor CL, Ross AC. Dietary reference intakes for calcium and vitamin D. National Academies Press; 2011.