An animal study published in the Proceedings of the National Academy of Sciences Online Early Edition suggests that nitrite, a compound naturally found in green leafy vegetables, and nitrate, a preservative commonly used in cured meats, may help in reducing tissue damages following a heart attack.

Compared with the control animals, the nitrate-supplemented mice had greater stores of nitrite in their heart muscle along with significantly less heart-muscle damage, although the reduction was not as impressive as in the nitrite-fed mice.
"Our study suggests that building up nitrite stores in heart muscle could spell the difference between a mild heart attack and one that causes lasting heart damage or death," says Dr. Lefer. "And since nitrite also accumulate in the brain, they could potentially help minimize the damage from strokes as well."

See more details of the study from PNAS, or from the AECOM press release.