From Rosemary Duckett, Westbury, Wiltshire, UK
James Wong reports that the calorific value of celery after chewing and digesting it is tiny, but not negative as some people believe 22 May, p 24. A few years ago, I read an article that came to the same conclusion, but expanded it by stating that if the celery was eaten when very cold – close to freezing, in fact – its calorific value did indeed become negative.
