Scientist tests if dietary supplement relieves pain of peripheral artery disease
Study seeks volunteers diagnosed with PAD who suffer severe leg pain
John Cooke
BY MITZI BAKER
When atherosclerosis attacks the legs—hardening and thickening the arteries—it leaves the patient in severe pain. As less blood gets through the vessels, cramping and weakness occurs in the thigh and calf when the person walks or stands. Eventually the pain grows so great that even sitting or lying down offers no relief.
For more than 20 years, John Cooke, MD, PhD, professor of cardiovascular medicine, has specialized in studying this condition, known as peripheral arterial disease, or PAD.
Cooke has focused on developing a simple treatment for the pain. In his work, he has scrutinized the molecules that regulate blood flow, and he has zeroed in on one particular compound that could offer a solution: arginine, an amino acid, one of the building blocks of a protein, that is found in dairy, meat, poultry and fish, among other foods.
Cooke is currently looking for volunteers to participate in a a study to determine whether arginine supplements can make people with PAD feel better and allow them to increase the distance they can walk.
“Right now we really don’t have an optimal treatment for peripheral artery disease, which affects up to 12 million people,” said Cooke, who directs the Program in Vascular Medicine and Biology. Although there are two drugs on the market for the treatment of the condition, he added, neither works as well as he would like for his patients.
Such measures as quitting smoking, eating a low-fat, low-salt diet and exercising can halt or even reverse the narrowing of the arteries. But Cooke noted that that sometimes a patient is in so much pain that exercising isn’t a realistic option.
“Arginine could be a cheap, simple and safe way for people with peripheral arterial disease to increase their walking distance,” said Cooke, who started a company called Cooke Pharma in 1997 to make nutritional bars enriched with arginine. (The product was acquired in 2000 by United Therapeutics Corp., which develops a line of arginine-enriched products.)
The National Institutes of Health has funded his latest arginine study, in which Cooke and his colleagues are aiming to examine more than 100 patients at Stanford who suffer from debilitating leg pains and have been diagnosed as having PAD. They will test whether arginine can improve circulation and restore blood vessel function.
As part of the study, some participants will receive arginine supplements, as it’s not possible to get adequate amounts of arginine from eating regular food, even in larger quantities. The supplements are produced by a firm in Japan.
Cooke is one of a number of scientists nationwide studying arginine. Another researcher, Amir Lerman, MD, professor of medicine at the Mayo Clinic College of Medicine, has been leading a group that has been using arginine to improve cardiac blood flow at amounts up to 9 grams per day—or 18 500-mg capsules—with no ill effects. The Stanford study uses lower amounts than this. “There is a scientific basis to [Cooke’s] study,” Lerman said. “It is based on previous studies and on a scientific mechanism.”
The participants in the Stanford study will be randomly divided to take either an arginine supplement or a placebo for six months. Neither the patients nor the researchers will know who is taking the active supplement.
Patients will undergo a full medical exam, blood tests to look for molecules that can indicate risk for cardiovascular diseases, a treadmill test to determine walking ability and visualization of the vasculature by magnetic resonance imaging and ultrasound.
More participants are needed for the study. Call 723-4064 for more details or to volunteer.
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