title: Examining techniques for measuring the effects of nutrients on mental performance and mood state.
abstract: OBJECTIVE
  Intake of specific nutrients has been linked to mental states and various indices of cognitive performance although the effects are often subtle and difficult to interpret. Measurement of so-called objective variables (e.g. reaction times) is often considered to be the gold standard for assessing outcomes in this field of research. It can, however, be argued that data on subjective experience (e.g. mood) are also important and may enrich existing objective data. The aim of this review is to evaluate methods for measuring mental performance and mood, considering the definition of subjective mood and the validity of measures of subjective experience.
  
  
  METHODS
  A multi-stakeholder expert group was invited by ILSI Europe to come to a consensus around the utility of objective and subjective measurement in this field, which forms the basis of the paper. Therefore, the present review reflects a succinct overview of the science but is not intended to be a systematic review.
  
  
  RESULTS
  The proposed approach extends the traditional methodology using standard 'objective' measurements to also include the consumers' subjective experiences in relation to food. Specific recommendations include 1) using contemporary methods to capture transient mood states; 2) using sufficiently sensitive measures to capture effects of nutritional intervention; 3) considering the possibility that subjective and objective responses will occur over different time frames; and 4) recognition of the importance of expectancy and placebo effects for subjective measures.
  
  
  CONCLUSIONS
  The consensus reached was that the most informative approach should involve collection and consideration of both objective and subjective data.
authors.affiliation: Department Epidemiology and Public Health, Psychobiology Group, University College London, 1 - 19 Torrington Place, London, WC1E 7HB, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Hamer
authors.affiliation: Human Appetite Research Unit, Institute of Psychological Sciences, University of Leeds, Leeds, UK.
authors.forename: Louise
authors.initials: L
authors.lastname: Dye
authors.affiliation: Nestlé Institute of Health Sciences, EPFL Campus, Lausanne, Switzerland.
authors.forename: E
authors.initials: E
authors.lastname: Siobhan Mitchell
authors.affiliation: Nutrition et Neurobiologie Intégrée, UMR 1286, INRA, 33000, Bordeaux, France.|Nutrition et Neurobiologie Intégrée, UMR 1286, Université Bordeaux, 33000, Bordeaux, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Layé
authors.affiliation: PepsiCo, 450 South Oak Way, Green Park, Reading, RG2 6UW, UK.|Lucozade Ribena Suntory Ltd, 2 Longwalk Road, Stockley Park, Uxbridge, UB11 1BA, UK.
authors.forename: Caroline
authors.initials: C
authors.lastname: Saunders
authors.affiliation: Human Appetite Research Unit, Institute of Psychological Sciences, University of Leeds, Leeds, UK.
authors.forename: Neil
authors.initials: N
authors.lastname: Boyle
authors.affiliation: ILSI Europe, Brussels, Belgium, International Life Sciences Institute, Europe, 83 Avenue E. Mounier, B6, Brussels, BE, 1200, USA. publications@ilsieurope.be.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Schuermans
authors.affiliation: Nutricia Research, Nutricia Advanced Medical Nutrition, Utrecht, The Netherlands.
authors.forename: John
authors.initials: J
authors.lastname: Sijben
mesh_terms: D000339:Affect / Q000187:drug effects*; D000818:Animals; D003071:Cognition / Q000187:drug effects; D006801:Humans; D018977:Micronutrients / Q000008:administration & dosage*; D023421:Models, Animal; D011930:Reaction Time
chemical_list: D018977:Micronutrients
keywords: Affective assessment; Cognition; Food; Mental health; Mood; Objective; Subjective