In simple terms, (polycyclic aromatic) compounds that incorporate nitrogen
into their makeup, in place of one of the carbon molecules.  Practically
speaking, the black stuff on your food when you cook out. Honey helps to
prevent its formation, which researchers in #2 considered a good thing (not
to mention the added effects of selling sweet hamburgers).

http://www-space.arc.nasa.gov/~astrochm/azaPAH%20table/N-PAHs.html

http://ift.confex.com/ift/2002/techprogram/paper_10890.htm

"Heterocyclic aromatic amines (HAAs) are formed in cooked meat and fish
products. These compounds are multi-potential carcinogens. Synthetic
phenolic antioxidants and vitamin E have been reported to inhibit their
formation. Honey contains various phenolic compounds, a-tocopherol,
b-carotene and peroxidase which all function as antioxidants under certain
circumstances."