title: A randomised crossover trial of the acute effects of a deep-fried Mars bar or porridge on the cerebral vasculature.
abstract: BACKGROUND
  The deep-fried Mars bar has been cited as 'all that is wrong with the high-fat, high-sugar Scottish diet'. We investigated the effect of ingestion of a deep-fried Mars bar or porridge on cerebrovascular reactivity. We hypothesised that deep-fried Mars bar ingestion would impair cerebrovascular reactivity, which is associated with increased risk of ischaemic stroke.
  
  
  METHODS
  Twenty-four fasted volunteers were randomised to receive a deep-fried Mars bar and then porridge (control), or vice-versa. We used transcranial Doppler ultrasound to calculate Breath Holding Index as a surrogate measure of cerebrovascular reactivity. Change in Breath Holding Index post-ingestion was the primary outcome measure.
  
  
  RESULTS
  Twenty-four healthy adults (mean (SD) age 21.5 (1.7) years, 14 males) completed the protocol. Deep-fried Mars bar ingestion caused a non-significant reduction in cerebrovascular reactivity relative to control (mean difference in absolute Breath Holding Index after deep-fried Mars bar versus porridge -0.11, p = 0.40). Comparison of the difference between the absolute change in Breath Holding Index between genders demonstrated a significant impairment of cerebrovascular reactivity in males (mean difference women minus men of 0.65, 95% CI 0.30 to 1.00, p = 0.0003).
  
  
  CONCLUSIONS
  Ingestion of a bolus of sugar and fat caused no overall difference in cerebrovascular reactivity, but there was a modest decrease in males. Impaired cerebrovascular reactivity is associated with increased stroke risk, and therefore deep-fried Mars bar ingestion may acutely contribute to cerebral hypoperfusion in men.
authors.affiliation: Final Year Medical Student, School of Medicine, University of Glasgow, Scotland.
authors.forename: William G
authors.initials: WG
authors.lastname: Dunn
authors.affiliation: Professor of Clinical Pharmacology, Institute of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre, Scotland Matthew.Walters@glasgow.ac.uk.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Walters
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D002545:Brain Ischemia / Q000150:complications / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology* / Q000517:prevention & control; D002182:Candy / Q000009:adverse effects; D002560:Cerebrovascular Circulation; D003296:Cooking; D018592:Cross-Over Studies; D059305:Diet, High-Fat / Q000009:adverse effects; D002523:Edible Grain; D005260:Female; D006801:Humans; D008297:Male; D012307:Risk Factors; D012606:Scotland / Q000453:epidemiology; D012737:Sex Factors; D020521:Stroke / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D017585:Ultrasonography, Doppler, Transcranial
keywords: Breath Holding Index; Deep-fried Mars bar; cerebrovascular reactivity