Could Free Radicals Help the Heart?


Experts have been telling us for years that molecules called free radicals can damage cells and cause cancer. Now researchers at Kings College London say these “bad” molecules may protect the heart against disease.

All free radicals may not be created equal

Free radicals cause oxidation, a natural chemical process by which oxygen is added to a substance and a change then occurs. A cut apple, for example, begins to turn brown once oxygen interacts with the sugar in the exposed flesh and forms oxygen radicals. These radicals break down the flesh of the apple. A similar process occurs to cells in the body.

To protect against free radical damage, the body needs antioxidants. While an apple’s “antioxidant” is the outer peel, which protects the flesh against oxidation, in humans antioxidants are obtained through a wide variety of foods and are available in supplements.

Countless studies have been done exploring the potential protective powers of antioxidant supplements, but not all of them have proven successful. One possible reason they have failed may be found in the results of the King’s College London study.


In the study, scientists evaluated the effect of an enzyme that leads to oxidation on the hearts of mice. One group of mice was engineered to lack the enzyme (Nox4) while another group was made to over produce it. They discovered that mice that had extra Nox4 adapted better to stress, which protected the heart from becoming enlarged or from failing.

Ajay Shah, professor of cardiology at King’s, noted that “some of these reactive molecules act as signals to promote protective pathways.” He further explained that some trials of antioxidant therapies have not show any benefits for the heart, and that “our discovery could partly explain why.”

One case in point is a recent study of pine bark supplements which are said to lower blood pressure and benefit the heart. The study, which was published in the Archives of Internal Medicine, did not find the supplement to provide benefits for cardiovascular health, and led the authors to report that “our results are consistent with a general failure of antioxidants to demonstrate cardiovascular benefits.”

Shah pointed out the need “to develop targeted therapies that remove damaging free radicals or promote the protective ones,” indicating that not all free radicals may be harmful. Indeed, some free radicals may help the heart. Professor Jeremy Pearson, associate medical director at the British Heart Foundation, which funded the study, warned the public that these findings do not “change the fact that a diet rich in fruit and vegetables, which contain antioxidants, can reduce your risk of developing heart disease.”

Drieling RL et al. Archives of Internal Medicine 2010 Sep 27; 170(17): 1541-47
King’s College London