glicerin

Question

Dear Rabbi, I was studying with rabbis and friends and I brought up the subject of whether it is allowed to eat anything that includes glicerin, such as chewing gum. They told me that it is preferable not to, because even if the glicerin is not considered food and have taste, it does add consistency to the food item, and therefore it is relevant (otherwise, why would they include glicerin in it in first place?). They told me that it's always best to be Mamchir about food because according to our sages "G-d does not allow a tzadik to stumble in matters of kosher". Certainly they didn't mean that any of us are tzadikim, but just that being stringent about kosher food is so important. (Certainly we could be strigent about this, but where would we draw the line about any other stringency in Judaism?) I am not sure how to respond to this challenge and to feel at ease about this matter. If you don't mind, I would like to share an insight about stringency that is relevant to my question: in the Talmud (Tractate Berachot) it is written that it is painful for a person to come home from a trip and have doubt whether his wife is a Niddah. Rashi explains the following: if the person knew for a fact that his wife is a Niddah, it's okay because he will just resign to the fact. (If he knew that she is not a Niddah, it would not be an issue to begin with). But the painful aspect is the doubt that remains: if she isn't a Niddah, he is abstaining from something that he derives pleasure from. The same thing, I believe, applies to aspects of kosher discussed by gedolim, such as your father and others. If I and other people knew for a fact that something is not kosher, fine, we can live with it. It's the doubt that makes the process difficult. I understand that one should follow what one's rabbi says, but it is always possible that any rabbi, who does not have constant Ruach HaKodesh should make a mistake. Thank you for your patience, time and effort.