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Cover of B Vitamins and Berries and Age-Related Neurodegenerative Disorders

B Vitamins and Berries and Age-Related Neurodegenerative Disorders

Evidence Reports/Technology Assessments, No. 134

Investigators: , MD, MPH, Principal Investigator, , MPH, Research Associate, , MD, Research Associate, , MD, Research Associate, , MPH, Research Associate, , MD, Investigator, , MLitt, Project Manager, and , MD, Project Director.

Rockville (MD): Agency for Healthcare Research and Quality (US); .
Report No.: 06-E008

Structured Abstract

Objectives:

To assess the effects, associations, mechanisms of action, and safety of B vitamins and, separately, berries and their constituents on age-related neurocognitive disorders - primarily Alzheimer's (AD) and Parkinson's disease (PD).

Data Sources:

MEDLINE® and CAB Abstracts™. Additional studies were identified from reference lists and technical experts.

Review Methods:

Vitamins B1, B2, B6, B12, and folate, and a dozen types of berries and their constituents were evaluated. Human, animal, and in vitro studies were evaluated. Outcomes of interest from human studies were neurocognitive function or diagnosis with AD, cognitive decline, PD, or related conditions. Intervention studies, associations between dietary intake and outcomes, and associations between B vitamin levels and outcomes were evaluated. Specific mechanisms of action were evaluated in animal and in vitro studies. Studies were extracted for study design, demographics, intervention or predictor, and neurocognitive outcomes. Studies were graded for quality and applicability.

Results:

In animal studies, deficiencies in vitamins B1 or folate generally cause neurological dysfunction; supplementation with B6, B12, or folate may improve neurocognitive function. In animal experiments folate and B12 protect against genetic deficiencies used to model AD; thiamine and folate also affect neurovascular function and health.

Human studies were generally of poor quality. Weak evidence suggests possible benefits of B1 supplementation and injected B12 in AD. The effects of B6 and folate are unclear. Overall, dietary intake studies do not support an association between B vitamin intake and AD. Studies evaluating B vitamin status were mostly inadequate due to poor study design. Overall, studies do not support an association between B vitamin status and age-related neurocognitive disorders.

Only one study evaluated human berry consumption, finding no association with PD. Animal studies of berries have almost all been conducted by the same research group. Several berry constituents have been shown to affect brain and nerve tissue function. Blueberry and strawberry extract were protective of markers of disease, although effects on neurocognitive tests were less consistent. Berry extracts may protect against the deleterious effects of compounds associated with AD.

Reporting of adverse events was uncommon. When reported, actual adverse events from B vitamins were rare and minor.

Conclusions:

The current research on B vitamins is largely inadequate to confidently assess their mechanisms of action on age-related neurocognitive disorders, their associations with disease, or their effectiveness as supplements. B vitamin supplementation may be of value for neurocognitive function, but the evidence is inconclusive.

Contents

540 Gaither Road, Rockville, MD 20850. www​.ahrq.gov

Prepared for: Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services.1 Contract No. 290-02-0022. Prepared by: Tufts-New England Medical Center Evidence-based Practice Center, Boston, Massachusetts.

Suggested citation:

Balk E, Chung M, Raman G, Tatsioni A, Chew P, Ip S, DeVine D, Lau J. B Vitamins and Berries and Age-Related Neurodegenerative Disorders. Evidence Report/Technology Assessment No. 134. (Prepared by Tufts-New England Medical Center Evidence-based Practice Center under Contract No. 290-02-0022). AHRQ Publication No. 06-E008. Rockville, MD: Agency for Healthcare Research and Quality. April 2006.

This report is based on research conducted by the Tufts-New England Medical Center Evidence-based Practice Center (EPC) under contract to the Agency for Healthcare Research and Quality (AHRQ), Rockville, MD (Contract No. 290-02-0022). The findings and conclusions in this document are those of the author(s), who are responsible for its content, and do not necessarily represent the views of AHRQ. No statement in this report should be construed as an official position of AHRQ or of the U.S. Department of Health and Human Services.

The information in this report is intended to help clinicians, employers, policymakers, and others make informed decisions about the provision of health care services. This report is intended as a reference and not as a substitute for clinical judgment.

This report may be used, in whole or in part, as the basis for the development of clinical practice guidelines and other quality enhancement tools, or as a basis for reimbursement and coverage policies. AHRQ or U.S. Department of Health and Human Services endorsement of such derivative products may not be stated or implied.

None of the investigators has any affiliations or financial involvement that conflicts with the material presented in this report.

1

540 Gaither Road, Rockville, MD 20850. www​.ahrq.gov

Bookshelf ID: NBK37999
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