I once received a forwarded e-mail from my friend which stated that: "Everything with yellow 5 is Haram"! The e-mail said that one Muslim brother who is doctor and his wife who is a chemist said Yellow 5 is Haram, after reading the ingredients of Mountain Dew because it had Yellow 5. Since then, I feared eating anything that had Yellow 5 on it such as my favorite chips, candies, powder juice like Tang, to name a few for fearing Allah (SWT). Therefore, my question is to clarify for me this question about Yellow 5 and if it is really Haram? This issue has confused me so much because when I told some members of my family to not eat anything with Yellow 5 they ignored and laughed at me saying, "You are crazy and Yellow 5 is just a food coloring and has nothing to do with pig"! Your assistance will be highly appreciated.

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

We do not know the reality of the product you are asking about.  But the principle about this food is that it is permissible (Halal) to eat, and we cannot say it is Haram just by doubt.  A Muslim is not required to investigate its ingredients.  It is enough for him to check what is written on it.

If these letters are sent by trustworthy people, and they have a proof about their claim that it contains pork, then you have to take that advice, but if it is only a question of doubt and fears then you do not have to.

Anyway, a Muslim has to be cautious, but he cannot oblige others to act accordingly.

There is a Hadith reported by Ahmad "Leave what you doubt about, and take what you do not doubt about meaning (when in doubt, avoid it)."