This section is from the book "Practical Dietetics With Special Reference To Diet In Disease", by William Gilman Thompson. Also available from Amazon: Practical Dietetics with Special Reference to Diet in Disease.
While fruits eaten daily and in proper moderation are very wholesome, if they are eaten too freely, or if they are either insufficiently ripe or overripe, soft, and decomposing, they undergo malfermentation in the alimentary canal, and are almost certain to cause diarrhoea with colicky pains, cramps, and sometimes nausea and vomiting. Severe attacks of gastritis may, especially in children, be produced by indulgence in unripe apples, pears, cherries, berries, etc., and even fatal choleraic diarrhoea has been occasioned by the indiscriminate consumption of fruits which have strongly laxative action. After such fruit poisoning, emesis should be excited if the patient is seen in time, and otherwise, if free purgation has not occurred, it is advisable to give a dose of castor oil or other cathartic, to remove the irritating substances as soon as possible from the alimentary canal. In bad cases, prolonged gastric fever may ensue. Some tropical fruits possess specific poisonous properties.