I don't know whether the proper plural for 'Ryvita' is Ryvitas or 'Ryvitae' - (goes to sit in pedantry corner)... but that could be the start of a whole new thread!!
Anyway, in the 80s when as a 12 yr old I'd already started dieting (I know) it seemed as if Ryvita as a foodstuff had a much higher profile. To give the context of the time - circa 1985 - back then the F - Plan diet was in vogue and Atkins and the 5-2 diet, low carbing had barely been heard of.
Nowadays, this food seems to be hardly on anyones radar and it might be just me, but it seems to have wholly slipped out of fashion. Back then it was the go - to food of any dieter....