British Journal of Nutrition

Behaviour, Appetite and Obesity

Effects of walnut consumption on cognitive performance in young adults

Peter Pribisa1 c1, Rudolph N. Baileya2, Andrew A. Russella2, Marcia A. Kilsbya3, Magaly Hernandeza1, Winston J. Craiga1, Tevni Grajalesa2, David J. Shavlika4 and Joan Sabatèa5

a1 Department of Nutrition and Wellness, Andrews University, 8475 University Boulevard, Marsh Hall 313, Berrien Springs, MI 49104-0210, USA

a2 Department of Educational and Counseling Psychology, Andrews University, 4195 Administration Drive, Bell Hall 159, Berrien Springs, MI 49104, USA

a3 Department of Clinical and Laboratory Sciences, Andrews University, 4270 Administration Drive, Halenz Hall 327, Berrien Springs, MI 49104, USA

a4 Department of Epidemiology and Biostatistics, School of Public Health, Loma Linda University, 11234 Anderson Street, Nichol Hall 2005, Loma Linda, CA 92354, USA

a5 Department of Nutrition, School of Public Health, Loma Linda University, 11234 Anderson Street, Nichol Hall 1102, Loma Linda, CA 92354, USA

Abstract

Walnuts contain a number of potentially neuroprotective compounds like vitamin E, folate, melatonin, several antioxidative polyphenols and significant amounts of n-3 α-linolenic fatty acid. The present study sought to determine the effect of walnuts on verbal and non-verbal reasoning, memory and mood. A total of sixty-four college students were randomly assigned to two treatment sequences in a crossover fashion: walnuts–placebo or placebo–walnuts. Baseline data were collected for non-verbal reasoning, verbal reasoning, memory and mood states. Data were collected again after 8 weeks of intervention. After 6 weeks of washout, the intervention groups followed the diets in reverse order. Data were collected once more at the end of the 8-week intervention period. No significant increases were detected for mood, non-verbal reasoning or memory on the walnut-supplemented diet. However, inferential verbal reasoning increased significantly by 11·2 %, indicating a medium effect size (P = 0·009; d = 0·567). In young, healthy, normal adults, walnuts do not appear to improve memory, mood or non-verbal reasoning abilities. However, walnuts may have the ability to increase inferential reasoning.

(Received January 18 2011)

(Revised June 28 2011)

(Accepted July 05 2011)

(Online publication September 19 2011)

Correspondence:

c1 Corresponding author: Dr P. Pribis, fax +1 269 471 3485, email pribis@andrews.edu

Footnotes

Abbreviations: ALA, α-linolenic acid; APM, Advanced Progressive Matrices; FA, fatty acid; POMS, Profile of Mood States; WGCTA, Watson-Glaser Critical Thinking Appraisal; WMS-III, Wechsler Memory Scale-Third Edition

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