High in fibre and polyphenols, popcorn has been touted as the perfect snack for the health-conscious. It’s also the ideal vehicle for salt, sugar, butter, bacon fat … Popcorn became indelibly associated with cinema-going during the Great Depression (it was cheap and hugely profitable), but it also has an established reputation as a superfood – recently given a boost by longevity expert Dan Buettner, who described popcorn as the best snack to eat if you want to live to 100. “It’s very high in fib