Twelve Weeks of Additional Fish Intake Improves the Cognition of Cognitively Intact, Resource-Limited Elderly People: A Randomized Control Trial

J Nutr Health Aging. 2022;26(2):119-126. doi: 10.1007/s12603-021-1723-2.


Introduction: Dietary omega 3 polyunsaturated fatty acids (PUFA) may reduce the risk of dementia. Many studies have investigated PUFA supplementation in high-income countries, yet food-based randomized control trials using omega 3 PUFA rich fish in lower to middle income countries, are lacking.

Objective: To determine the effect on cognition of adding either fish or non-fish foods for twelve weeks to an enhanced diet of cognitively intact, independently living, resource-limited elderly people.

Design: Randomized control trial (National Health Trial register: DOH-27-061-6026).

Setting: Retirement center in urban South Africa.

Participants: Fifty-seven (74% female, mean age: 72±7 years) elderly participants with cognitive function exceeding 22 on the Mini Mental State Examination were randomized into an intervention (n=31) and control (n=26) group.

Intervention: The usual diets of both groups were enhanced with context-appropriate foods to mimic elements of the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet. The intervention group additionally received canned pilchards and fish spread every week amounting to an additional (theoretical) intake of 2.2g omega 3 PUFA daily. The control group received canned meatballs and texturized soya every week.

Measurements: Cognition was measured twice before and once after the intervention phase using the Cognitive Abilities Screening Instrument (CASI). Adherence was assessed by a study-specific food frequency questionnaire and red blood cell (RBC) PUFA biomarkers. Data were analyzed using a non-parametric analysis of covariance (ANCOVA) with, and without, bootstrap imputation.

Results: Participants in the intervention group had a significantly higher post intervention (P=0.036) CASI score than the control group, when the model was fitted with imputation and controlled for baseline scores. Participants in the intervention group also had a significantly higher intake of calculated dietary omega 3 PUFA and higher levels of RBC eicosapentaenoic acid and docosapentaenoic acid content than the control group (P < 0.05).

Conclusion: Twelve weeks of fish intake in the context of a modified MIND diet may improve the cognition of cognitively intact, resource-limited elderly people.

Keywords: Fish; cognition; diet; elderly; omega 3 fatty acids; resource-limited.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Animals
  • Cognition
  • Diet
  • Dietary Supplements
  • Eicosapentaenoic Acid
  • Fatty Acids, Omega-3*
  • Female
  • Fishes
  • Male


  • Fatty Acids, Omega-3
  • Eicosapentaenoic Acid