Eating green, leafy vegetables may help minimize tissue damage caused by heart attacks, said a U.S. study released Monday.

'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.'

—Dr. David Lefer

A team of researchers from the University of Texas-Houston Health Sciences Centre and the Albert Einstein School of Medicine in New York found that boosting consumption of the chemical nitrite — found in vegetables such as celery, beets, spinach and lettuce — protected heart tissues from heart-attack related injuries in mice.

Nitric oxide, which is produced by cells lining arteries, assists in heart health by dilating arteries and aiding blood flow. Damage to artery linings impairs the production of nitric oxide, leading to heart attacks and strokes.

Previous research had found that when a heart attack is underway, triggered by falling oxygen levels, enzymes in the heart muscle convert stored nitrite into nitric acid as an emergency response.

Prior to this research, published in the Nov. 12 issue of the journal Proceedings of the National Academy of Sciences, it was unknown whether boosting consumption could translate into increased protection for the heart.

For their experiment, the researchers administered nitrite in the drinking water of a group of mice for seven days. A second set of mice were given a standard diet but no nitrite supplement.

The team then simulated heart attacks by stopping blood flow to the animals' hearts for 30 minutes, then waited 24 hours for reperfusion — the return of blood to the heart.

The researchers found that the hearts of the supplemented mice contained significantly more nitrite and damage was reduced by 48 per cent compared to the non-nitrite supplemented mice.

The team also ran a similar test using nitrate found in cured meats such as bacon and sausage, which is converted to nitrite by bacteria in the salivary glands.

Like the previous trial, the nitrate-supplemented mice had more nitrite in their heart and had less heart damage, although the reduction was not as dramatic as in the first trial, the researchers said.

"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," explained researcher Dr. David Lefer in a release.

"And since nitrite also accumulate in the brain, they could potentially help minimize the damage from strokes as well."

The study said that the levels used in the experiments could be easily reached in humans by "modest changes in the diet" to include more foods rich in nitrite and nitrate.