About 5 years ago I made the link between vegetable oils and diarrhoea, since when I've found eating out rather demanding. These oils are so common, they're virtually impossible to avoid altogether and so I'm caught about twice a month. For instance, raisins/sultanas/currants are coated with sunflower oil so they don't stick together. Olive oil is fine so long as cold pressed. Coconut oil, ghee, dairy & animal fats are all fine. I've kept a detailed log all this time and have a high degree of certainty. It's not full-blown diarrhoea most of the time, but is urgent and is followed by constipation for a day or so until back to normal. Always read the ingredients list. Thought I was unique until finding this site, thanks.