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Acute effects of a deep-fried Mars bar on brain vasculature

Scotland’s purported tolerance for fried candy bars inspired this new medical study:

A randomised crossover trial of the acute effects of a deep-fried Mars bar or porridge on the cerebral vasculature,” William G. Dunn, and Matthew R. Walters, Scottish Medical Journal, epub 2014.


The authors, at the BHF Glasgow Cardiovascular Research Centre and the University of Glasow, report:

Introduction 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.

Here’s detail from the study:


The results led them to devise this conclusion:

Conclusion 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.

(Thanks to investigator Erwin Kompanje for bringing this to our attention.)

Improbable Research