I think if all the food you are served has been sacrificed to idols (as in Daniel's case) and it deeply troubles you that all the pagans will see you eating food sacrificed to idols (as in Daniel's case) then... you should go and eat what Daniel ate.
Otherwise... it probably doesn't matter.
If circumstances had been different... I'm sure Daniel would have preferred a cheeseburger.
: )
I haven't found that scripture says this food was sacrificed to idols. But if you search the scripture that Daniel knew, the Torah and Proverbs, you find this:
1 When thou sittest to eat with a ruler, consider diligently what is before thee:
2 And put a knife to thy throat, if thou be a man given to appetite.
3 Be not desirous of his dainties: for they are deceitful meat.
Proverbs 23:1-3
Also, they were told to stay away from unclean foods, and you can be sure that some of the food was from unclean animals.
Grains, at that time were whole grain so they contained protein, and vegetables contained vitamins and minerals, so they would have a much more nourishing and strength building diet than the fancy rich foods of the kings.
Besides, eating the king's food would require joining in the drinking and worldly pursuits that went along with it. Sanctified means set apart. Daniel was set apart for the Lord.