Is apple pie is healthier with maltitol? which of the sugar alcohols don't cause as much gas or diarrhea (eg: maltitol, xylitol, erithritol, etc.)?

NO: All will cause gas.

I have no idea!: I tell my patients that a well balanced diet of fruits and vegetables, lean meats in moderation, three meals a day and plenty of grains as in a mediteranean diet, these are the most healthy. Just eat food! sounds silly, but avoiding processed, packaged, precooked, stuff by shopping in the produce and fresh meats and fish aisle serves you best. If the ingredients need a dictionary, stay away.