The eminent Muslim scholar and renowned Da`iyah, Sheikh `Abdel Khaliq Hasan Ash-Shareef, states: “As long as the food stuffs are halal it is permissible to eat whatever one likes. There is no evidence prohibiting a Muslim from eating fish and meat together for example, or to gather between a certain food stuff and another as long as there is no exaggeration. Almighty Allah says, ‘… and eat and drink, but be not prodigal. Lo! He loveth not the prodigals.‘ (Al-A`raf 7: 31)
Also, there is a special case of a man who is sensitive or may be harmed if he has eaten a certain kind of food, this has a special ruling that differs from the general ruling of eating two kinds of food together.