Free radicals are the reactive oxygen molecules that modify, or oxidize, low-density lipoprotein cholesterol (LDL, the “bad” cholesterol). Free radical damage is believed to be one of the first steps in atherosclerosis – the buildup of material in the artery walls that narrows the vessels and makes them prone to blockages that lead to heart attack or stroke. Oxidized LDL particles are more likely to cling to the inside of blood vessel walls.
Children in families with a history of early heart disease may reap special benefits from a diet rich in fruits and vegetables, which contain high levels of antioxidants.
“Their free-radical firewall is not as strong as it should be, so they may have problems in their antioxidant defense system, which makes them susceptible to cellular and tissue damage,” says lead author Wojciech Wojakowski, M.D., Ph.D., staff physician in clinical cardiology at the Silesian Medical Academy in Katowice, Poland. “Nutrients and vitamins derived from fruits and vegetables can help build up this defense system.”
Free radicals come from many sources, including cigarette smoke and fatty food. They also are a byproduct of normal metabolic processes. Although the body has defenses to dispose of free radicals, when the balance is lost between free radicals and the body’s natural defenses, free radical damage can occur.
Antioxidants, such as vitamins E and C, attract free-radicals and prevent tissue damage. An increasing amount of evidence suggests that oxidation of LDL cholesterol can be prevented by increasing intake of fruits and vegetables, which are high in antioxidants.
“The Framingham Heart Study showed that a family history of premature heart disease is a stronger predictor of a person’s risk than high blood pressure, cigarette smoking or high cholesterol levels,” Wojakowski says. “We thought that if family history is such a strong risk factor – and, of course, it cannot be modified – it would be very interesting to know what exactly is happening and to develop a means of screening.”
Premature heart disease is defined as before age 65 for women and before age 55 for men.
In a study of 22 children from high-risk families and 18 children with no family history of early heart disease, the researchers assessed the activity of four antioxidant enzymes. The enzymes were catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and glutathione reductase.
There were no significant differences between the groups in plasma activity of SOD and glutathione reductase. However, they found that children of early heart disease sufferers have significantly lower levels of CAT and GSH-Px – enzymes that help dispose of dangerous free radicals before those particles can damage the arteries. In fact, individuals whose GSH-Px was in the least active quartile were 2.1 times more likely to come from high risk families.
Wojakowski says, although these findings are intriguing, it is too early to screen the population for low activity of these enzymes. Studies must first determine whether they are independent risk factors for coronary heart disease and define normal limits. It would also require devising tests that are inexpensive and easy to perform.
In the meantime, families with a history of early heart disease should avoid exposing their children to secondhand cigarette smoke. Those parents should also encourage their children to eat a healthy diet filled with fruits and vegetables.
Co-authors are: Jan Gminski, M.D., Ph.D.; Aneta Wojcik, Ph.D.; Barbara Posielezna, Ph.D.; and Tomasz Francuz, M.D., Ph.D. The study was carried out in the Department of Experimental and Clinical Biochemistry of the Silesian Medical Academy.
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Abstract 2298 (Poster)
NR01 – 1365 (SS01/Wojakowski)