The relationship between whole-grain intake and measures of cognitive decline, mood and anxiety - a systematic review

Authors: ROSS, ALASTAIR - Ag Research Limited; SHERTUKDE, SHRUTI - Tufts University; LIVINGSTON-STAFFIER, KARA - American College Of Lifestyle Medicine; CHUNG, MEI - Tufts University; JACQUES, PAUL - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; MCKEOWN, NICOLA - Boston University

Submitted to: Advances in Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2023
Publication Date: 7/1/2023
Citation: Ross, A., Shertukde, S., Livingston-Staffier, K., Chung, M., Jacques, P.F., McKeown, N.M. 2023. The relationship between whole-grain intake and measures of cognitive decline, mood and anxiety - a systematic review. Advances in Nutrition. https://doi.org/10.1016/j.advnut.2023.04.003.
DOI: https://doi.org/10.1016/j.advnut.2023.04.003

Interpretive Summary: Currently, there are no proven clinical treatments for treating or preventing age-related cognitive decline, emphasizing the need for lifestyle-based preventative strategies. The evidence relating cognitive decline with several comorbidities that are beneficially associated with higher intakes of whole grains, suggests that there could be a protective role of increased consumption of whole-grain cereal foods for cognitive decline. To clarify the quantity and quality of available evidence relating whole grain consumption to prevention of age-related cognitive decline, we conducted a systematic review to synthesize all available observational and interventional studies evaluating the association between whole-grain intake and cognitive outcomes, or measures of mood and anxiety. Our examination of existing studies indicated that the limited evidence for whole grains reducing age-related cognitive decline is inconclusive. There are consistent associations between higher levels of whole-grain intake and reduced scores for mood disorders including depression and anxiety. Our research findings suggest that the evidence is insufficient to determine if whole grains may be a modifiable lifestyle factor that affects age-related cognitive decline. Additional evidence from well-designed, long-term observational studies of dementia and randomized controlled trials of cognitive changes are necessary to understand the role of whole grains in prevention of age-related cognitive decline.

Technical Abstract: Greater intake of whole grains, compared to refined grains, is consistently associated with a reduced risk of cardiovascular disease and type 2 diabetes, both of which are associated with cognitive decline. To better understand the relationship between whole-grain intake, cognition, mood and anxiety, a systematic review was conducted to synthesize available evidence linking whole grains to these outcomes. Four electronic databases were searched from inception to August 2021 for potentially relevant observational and interventional studies. Risk of bias assessments were performed using the newly developed NUtrition QUality Evaluation Strengthening Tools (NUQUEST), and the GRADE approach was used to determine the strength of evidence for each outcome. In total, 23 studies (4 randomized controlled trials (RCT) and 19 observational studies) met the predefined eligibility criteria. Of these,12 studies included analysis of whole-grain intake and cognitive decline, nine included mood outcomes, and two included both cognition and mood outcomes. The overall evidence for an association between whole-grain intake and cognition is inconclusive. With respect to mood outcomes, evidence from RCTs prospective cohort and case-control studies suggest that higher intake is linked to improved outcomes for mood and depression while the evidence is mixed for cross-sectional studies. Reporting of whole-grain intake fell short of suggested standards, and the strength of available evidence was low or very low for all outcomes. A high risk of bias towards studies reporting results was also noted, complicating both the interpretation of some studies and the combined evidence. Of note, few well-designed RCTs assessing the effect of whole-grain intake on measures of cognition, mood and anxiety were identified, highlighting the need for more studies in this area. The available, though limited, evidence suggests that greater whole-grain intake is associated with better mood and anxiety-related scores and is inconclusive regarding cognitive outcomes.