Chronic obstructive pulmonary disease (COPD) affects at least 16 million Americans. Often associated with cigarette smoking, COPD is the nation’s #4 leading cause of death. Researchers at the Johns Hopkins Medical School have just published the findings of a recent study that suggests a diet rich in vegetables, particularly broccoli, may help the body produce enzymes that fight the negative effects of tobacco smoking.

As described in the American Journal of Respiratory and Critical Care Medicine’s second September issue, the researchers examined tissue samples taken from the lungs of a group of smokers diagnosed with COPD and compared them with lung tissue samples taken from smokers without COPD. The research team measured levels of an enzyme, NRF2, and the biochemical regulators which inhibit and stabilize it.

The enzyme, NRF2, is thought to be a vital component of the lungs’ defense mechanism against injury caused by inflammation. One of the antioxidant benefits of eating broccoli is that a compound in the vegetable is thought to prevent NRF2 degradation.

Analysis of lung tissue samples revealed that patients with COPD had significantly lower levels of antioxidants dependent on NRF2 and they had more biochemical markers that indicate oxidative stress, less of the NRF2 protein, and significantly lower levels of DJ-1, a biochemical regulator which stabilizes NRF2. The most severe cases of COPD are associated with the lowest levels of NRF2-dependent antioxidants and expression of DJ-1.

Broccoli contains sulforapane, which can restore the gene expression of antioxidants in tissue showing evidence of DJ-1 depletion. A second broccoli compound, isothicyanate, inhibits the synthesis of KEAP1, which, in turn, inhibits the production of NRF2.

The research team, led by Shyam Biswal, PhD, suggests future studies that target NRF2, with increased antioxidant protection to lung tissue, and improved lung function, as the goal. Biswal, principle investigator for this study, also serves as associate professor in the Bloomberg School’s Department of Environmental Health Sciences as well as the Johns Hopkins Division of Pulmonary and Critical Care.

Source: American Thoracic Society