British Journal of Nutrition

Full Papers

Dietary Surveys and Nutritional Epidemiology

Cognitive performance among the elderly in relation to the intake of plant foods. The Hordaland Health Study

Eha Nurka1a2, Helga Refsuma1a3, Christian A. Drevona1, Grethe S. Tella4, Harald A. Nygaarda4a5, Knut Engedala6 and A. David Smitha3 c1

a1 Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway

a2 Department of Surveillance and Evaluation, National Institute for Health Development, Tallinn, Estonia

a3 Department of Physiology, Anatomy and Genetics and the Oxford Project to Investigate Memory and Ageing (OPTIMA), University of Oxford, Oxford, UK

a4 Department of Public Health and Primary Health Care, University of Bergen, Bergen, Norway

a5 NKS Olaviken Hospital for Old Age Psychiatry, Erdal, Norway

a6 Department of Geriatric Medicine, Norwegian Centre for Dementia Research, Oslo University Hospital, Oslo, Norway


Fruits and vegetables are among the most nutritious and healthy of foods, and are related to the prevention of many chronic diseases. The aim of the study was to examine the relationship between intake of different plant foods and cognitive performance in elderly individuals in a cross-sectional study. Two thousand and thirty-one elderly subjects (aged 70–74 years; 55 % women) recruited from the general population in Western Norway underwent extensive cognitive testing and completed a comprehensive FFQ. The cognitive test battery covered several domains (Kendrick Object Learning Test, Trail Making Test – part A, modified versions of the Digit Symbol Test, Block Design, Mini-Mental State Examination and Controlled Oral Word Association Test). A validated and self-reported FFQ was used to assess habitual food intake. Subjects with intakes of>10th percentile of fruits, vegetables, grain products and mushrooms performed significantly better in cognitive tests than those with very low or no intake. The associations were strongest between cognition and the combined intake of fruits and vegetables, with a marked dose-dependent relationship up to about 500 g/d. The dose-related increase of intakes of grain products and potatoes reached a plateau at about 100–150 g/d, levelling off or decreasing thereafter, whereas the associations were linear for mushrooms. For individual plant foods, the positive cognitive associations of carrots, cruciferous vegetables, citrus fruits and high-fibre bread were most pronounced. The only negative cognitive association was with increased intake of white bread. In the elderly, a diet rich in plant foods is associated with better performance in several cognitive abilities in a dose-dependent manner.

(Received November 30 2009)

(Revised March 10 2010)

(Accepted March 30 2010)

(Online publication June 16 2010)


c1 Corresponding author: Professor A. David Smith, fax +44 1865 272420, email


Abbreviations: HADS-A, Hospital Anxiety and Depression Scale anxiety subscale; HADS-D, Hospital Anxiety and Depression Scale depression subscale; HUSK, Hordaland Health Study; KOLT, Kendrick Object Learning Test; m-BD, Block Design short form; m-DST, modified version of Digit Symbol Test; m-MMSE, modified version of the Mini-Mental State Examination; S-task, abridged version of Controlled Oral Word Association Test; tHcy, total homocysteine; TMT-A, Trail Making Test part A