OK, first: food is rich in C4. Food is made from carbohydrates, which as the name suggests is made from Carbon, and the amount of C4 in the carbon is homogenous across compounds.

So the answer to your question is: insignificant amounts of smoke occur in fire-cooked foods, and the C4 composition wouldn't be affected anyway.

I am incorrect: C4 is not homogenous, per the comment above yours, but really there just can't be that much smoke IN food ingested.