A few years ago I noticed my wife doing the same thing, peeling off the pith. "Don't do that", I said, "you need your vitamin P". After a couple of minutes of her laughing her head off and casting grave doubt on the existence vitamin P, she went back to de-pithing her fruit. "But my mother told me", I protested, "it must be true!". Ellie replied, "she must have been pulling your leg...".
When I was much younger, about 7 or 8, I asked my mum what 'shampoo' meant. "Well", she began, "it means 'not-real-poo'. Anything's that's a 'sham' means it's not real, and you know what poo is!". I was in my twenties before I actually thought about this and realised I may have been a bit gullible there (in fact, I believe the word is Indian in origin, an import along with verandah and bungalow etc..).
Anyway - I just decided to look up vitamin P (finally)... and it does exist! It is a bioflavonoid:
"Bioflavonoids are found in the white material just beneath citrus peel, as well as in peppers, grapes, pine bark, onions, garlic, blue and red berries, green tea as well as buckwheat."
So she was right on that one, but mum had quite a sense of humour, and I do wonder what other things she told me that might not have been the exact truth. I'm off to eat some pine bark.