Researchers have found clues to the exact molecular reasons why antioxidant-rich foods such ar turmeric, a popular curry spice, and orange juice help to keep the heart and arteries healthy.

Using the latest genetic technology, two French research teams have reported the range of genes that are affected by curcumin, the active ingredient in turmeric, and hesperidin, an antioxidant that is prominent in orange juice.

The molecular study was conducted on mouse genes, having been preceded by a trial in live mice, and used curcumin, a polyphenol which is a form of antioxidant. In the trial with live mice, the animals were given a daily curcumin supplement for 16 weeks and the researchers found the mice had a 26 per cent lower level of fat deposits in the aorta, the main artery of the heart.

The researchers then isolated genetic material from the mice and exposed it to curcumin and found altered experssion of 2,252 genes affecting such activity as cellular signaling and adhesion, inflammation and fat metabolism.

In the study with orange juice, a second research team took 24 men who were healthy overall but who had cardiovascular risk factors such as obesity. In three one-month periods, the men drank one of three drinks a day: 500 milliliters of orange juice (containing 292 millgrams of hesperidin), 500 milliliters of an energy drink, or 500 milliliters of the same drink enriched with 292 milligrams of hesperidin.

The men who consumed hesperidin, either in orange juice or as a supplement, showed improved blood pressure and better function of the endothelium, the delicate lining of blood vessels. Subsequent genetic studies found the hesperidin affected activity of 1,820 genes from white blood cells.

Despite the positive results of the studies, the researchers say neither experiment is a reason to take a supplement of either curcumin or hesperidin because some supplements have doses that are high and could be “bad”. However, they added that supplements could be beneficial for the health if used in nutritional doses.