While there is absolutely no science behind the idea, it does offer us an interesting insight into how our brains are wired up.
This is an idea that appears cross culturally, and has been recorded in some of the earliest texts on health.
The solution? To purge these from you body. How? By doing something really not very fun: Laxatives, fasting, enemas, blood letting.
But the basic premise of believing illness is one’s own fault, caused by a immoral desire for pleasure is universal.
(As is the idea that atoning for this sin by doing something grim is the only cure.)
AND that attaching weird moral labels like ‘clean’ and ‘pure’ or ‘sinful’ and ‘junk’ to different foods is bat shit crazy.
So do yourself a favour and spare yourself the agony.