Systematic evaluation and meta-analysis of the effects of major dietary patterns on cognitive function in healthy adults

ABSTRACT

Purpose

Evidence shows diet promotes brain health. Combining foods and nutrients may have beneficial synergistic effects, but the effects on cognitive function interventions are inconsistent. So, a meta-analysis of RCTs was conducted to examine the specific effects on cognitive function.

Methods

We searched four databases from creation to April 2023. Eligible randomized controlled trials were identified. A random-effects meta-analysis was used to combine standardized mean differences (SMD) (95% confidence intervals [CI]), and homogeneity tests for a variance were calculated.

Results

A total of 19 studies involving 12,119 participants were included in this systematic review. The dietary intervention group had a positive effect on overall cognitive functioning compared to the control group (SMD = 0.14, 95% CI [0.08, 0.20], P < 0.00001). The dietary intervention improved executive function, processing speed and language skills (SMD = −0.10, 95% CI [−0.17,−0.04], P = 0.002, I² = 0%), (SMD = −0.16, 95% CI [−0.23,−0.09], P < 0.00001, I² = 0%), (SMD = 0.10, 95% CI [0.01, 0.20], P = 0.03, I² = 0%). The dietary intervention had no effect on delayed memory and spatial ability (SMD = 0.04, 95% CI [−0.02, 0.09], P = 0.20, I² = 0%), (SMD = 0.08, 95% CI [−0.01, 0.16], P = 0.08, I² = 0%).

Conclusion

The Mediterranean diet, a diet with restricted caloric intake, a diet incorporating aerobic exercise, a low-carbohydrate diet, and a healthy lifestyle diet (increased intake of fruits and vegetables, and weight and blood pressure management) appear to have positive effects on cognitively healthy adults, as reflected in their overall cognitive, processing speed, executive, and language functions.

PROSPERO registration number

CRD42023414704.

KEYWORDS:

• Eating patterns
• dietary intervention
• cognitive function
• meta-analysis

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The datasets used in the current study were created and evaluated by our team. If you need access to the dataset, please contact the corresponding author with a valid reason.

Additional information

Funding

The National Natural Science Foundation of China (NSFC) program provided financial support for this study [grant number: 82060596].

Notes on contributors

HanQing Guo

HanQing Guo with clinical and nutritional higher education holds a Master's degree in nutrition.

Qi Tian

Qi Tian has higher education in nutrition and food and holds a Master's degree in nutrition.

XueMei Qin

XueMei Qin has higher education in nutrition and food and holds a Master's degree in nutrition.

Qing Luo

Qing Luo has higher education in clinical and nutrition and holds a Master's degree in nutrition.

XiuMei Gong

XiuMei Gong, with advanced nutrition education, is a dietitianand Deputy Director of the Nutrition Center of Laizhou People's Hospital affiliated with Binzhou Medical College.

Qinghan Gao

Qinghan Gao a nutritionist holds a doctor's degree in nutrition. She is a council member of the Ningxia Nutrition Society, and also a professor at the School of Public Health at Ningxia Medical University. She mainly studies the relationship between polyphenols and nervous system diseases.