Effects of Nutrition on Cognitive Function in Adults with or without Cognitive Impairment: A Systematic Review of Randomized Controlled Clinical Trials
What this study found
Across eligible trials, significant cognitive improvements were observed in 44 of 61 studies, across dietary patterns, foods, and supplements; 17 showed no significant improvement. Mediterranean-style patterns (e.g., MedPork/MedDairy/high-phenolic EVOO) and plant-based/antioxidant-rich supplements showed the most consistent signals for improvements in processing speed, memory, attention, language and executive function, though heterogeneity and study design limitations exist. Vitamin D and B vitamins yielded mixed results; some benefits in MCI with Vitamin D3 and B9+B12 combos, but not…
- Study & population
- Systematic review of randomized controlled trials (including crossover and parallel designs) evaluating dietary interventions (diet counseling, food-based interventions, and dietary supplement trials) in adults with or without cognitive impairment, excluding diagnosed Alzheimer’s disease; age range 18–90 years; trials conducted in 18 countries; 61 articles…
- Key limitation
- Interventions were highly heterogeneous with varying ages, regions, durations (often <12 weeks), and cognitive measures; cognitive-status classifications (MCI, SCD) were inconsistently defined and sometimes not biomarker-supported; most studies were supplement trials with small samples and high risk of bias;…
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Open PDFOriginal abstract
New dietary approaches for the prevention of cognitive impairment are being investigated. However, evidence from dietary interventions is mainly from food and nutrient supplement interventions, with inconsistent results and high heterogeneity between trials. We conducted a comprehensive systematic search of randomized controlled trials (RCTs) published in MEDLINE-PubMed, from January 2018 to July 2021, investigating the impact of dietary counseling, as well as food-based and dietary supplement interventions on cognitive function in adults with or without cognitive impairment. Based on the search strategy, 197 eligible publications were used for data abstraction. Finally, 61 articles were included in the analysis. There was reasonable evidence that dietary patterns, as well as food and dietary supplements improved cognitive domains or measures of brain integrity. The Mediterranean diet showed promising results, whereas the role of the DASH diet was not clear. Healthy food consumption improved cognitive function, although the quality of these studies was relatively low. The role of dietary supplements was mixed, with strong evidence of the benefits of polyphenols and combinations of nutrients, but with low evidence for PUFAs, vitamin D, specific protein, amino acids, and other types of supplements. Further well-designed RCTs are needed to guide the development of dietary approaches for the prevention of cognitive impairment.