May 7, 2005 WASHINGTON, D.C., April 30 -- Some structural and functional measures of cardiovascular disease risk may improve by the eighth week of a diet and exercise regimen, according to a study presented today at the American Heart Association's Sixth Annual Conference on Arteriosclerosis, Thrombosis and Vascular Biology.
"Our lifestyle management program appears to improve the health of the vasculature, so it might lower the risk of high blood pressure, diabetes, heart attacks and stroke," said presenter and lead author Kunihiko Aizawa, M.Sc., a Ph.D. candidate at the University of Western Ontario in London, Ontario, Canada. "We found that there probably are some things that happen in even eight weeks."
Researchers studied the combined effects of personalized physical exercise and Mediterranean-style diet plans in volunteers with pre-clinical risk factors for cardiovascular disease. The study reported preliminary data from the larger randomized Staged Nutrition and Activity Counseling (SNAC) trial.
A Mediterranean-style diet has impressive cardio-protective effects, according to a 2001 American Heart Association scientific advisory. The diet is high in fruits, vegetables, bread, other forms of cereals, potatoes, beans, nuts and seeds with olive oil as an important fat source, and low to moderate amounts of dairy, fish and poultry.
"There have been studies looking at diet and exercise to prevent or treat cardiovascular disease," said primary investigator Robert J. Petrella, M.D., Ph.D., associate professor in the Schulich School of Medicine at the University of Western Ontario. "The difference here is that the calories and composition of the diet and physical activity prescribed were matched to fitness level in an individually tailored fashion and delivered in a family practice setting as opposed to a hospital or laboratory."
The randomized, single-blind trial of SNAC intervention versus usual care lifestyle counseling included 38 patients with high-normal blood pressure (systolic greater than 130 mmHg to 139 mmHg, diastolic greater than 85 mmHg to 89 mmHg) or pre-diabetes indicated by impaired fasting glucose or impaired glucose tolerance. The average age of patients was 53.3 years.
Researchers found that the 22 female and 16 male participants lost weight and improved their exercise capacity on the program. Treadmill tests were used to measure exercise capacity (VO2 max, the maximal volume of oxygen exchanged during exercise) at the beginning and end of the eight-week period. Average VO2 max increased from 32.1 milliliters per minute per kilogram (mL/min/kg) to 35.3 mL/min/kg. Average body weight decreased from 92.5 kg to 90.9 kg (203.5 pounds to 200 pounds).
"We were surprised that we saw such a weight reduction with the Mediterranean diet," Petrella said. "It was not a weight reduction program."
Blood pressure did not change significantly.
Ultrasound measurements of the heart and blood vessels at rest were performed as well.
Left ventricular diastolic filling (LVDF) measurements indicate the efficiency of the heart to relax. Left ventricular mass is a measure of end organ damage often following the onset of LVDF abnormalities.
The brachial (arm) and carotid (neck) arteries were tested for intima-media thickness and arterial distensibility. Both reflect the health of the blood vessels. The thicker and less distensible (elastic) the arteries are, the greater the load on the heart. This often results from changes in blood pressure, blood glucose or cholesterol disorders such as dyslipidemia.
Carotid artery distensibility was the only structural factor that significantly improved. It rose about 16 percent. Petrella said that the other factors may improve as patients are followed for one year.
One in three American adults has high blood pressure and two-thirds to three-fourths of people with diabetes mellitus die of some form of heart or blood vessel disease, according to the American Heart Association.
"For both of these groups, their lifetime risk of developing hypertension is high," Petrella said. "Anything we can do to reduce that is important."
Co-authors are Mauricio Marin, M.D.; Isidro Torres Castro, M.D.; Michele A. Lawrence; Jeniffer A. Manley, B.Sc.; Leonard A. Piche, Ph.D.; and Kevin J. Shoemaker, Ph.D.
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