Following a vegan diet for five weeks may decrease risk factors for heart disease, new research shows.

The study included 50 African Americans who were asked to eat only prepared meals delivered to their homes. A cardiovascular risk calculator was used to assess their risk of heart attack or stroke over the next 10 years. For 36 participants who had pre- and post-diet risk scores, their risk fell by about 19% – from 10.83% to 8.74%.

"Heart disease is the leading killer of Americans, and African Americans have the highest risk of cardiovascular disease," said the study's senior investigator Dr. Kim Allan Williams Sr., chief of the Division of Cardiology at Rush Medical College in Chicago. "We did this study to see what we can do about it."

The preliminary research was presented recently at the American Heart Association's Scientific Sessions conference.

A vegan diet includes only plant-based foods. The meals the participants received included no meat, seafood or dairy. This means they had no dietary cholesterol. The meals also were low in sodium and calories.

Marcia Otto, an assistant professor of epidemiology, human genetics and environmental sciences at the University of Texas Health Science Center's School of Public Health in Houston, said the findings suggest benefits of a low-salt, low-meat diet on LDL cholesterol and blood pressure, important risk factors for cardiovascular disease.

According to AHA statistics, about 60% of African American men and 57% of African American women ages 20 and older have some form of cardiovascular disease, such as heart disease, stroke, high blood pressure and other conditions.

A recent report from the Centers for Disease Control and Prevention found that for heart disease alone, death rates in 2015 were 21% higher in African Americans than in whites. Because the study found the five-week diet reduced cardiovascular risk by 19.4%, Williams said "with this diet, the excess risk is almost gone."

But he and Otto agreed more research is needed.

The findings "need to be confirmed by additional investigations including a larger, more representative sample of African Americans to provide a stronger body of evidence supporting statements about long-term reduction in health disparities," said Otto, who was not involved with the research.

Cardiovascular disease includes many types of heart and blood vessel diseases caused by atherosclerosis, a condition that occurs when a substance called plaque builds up in the walls of the arteries. This buildup makes it hard for blood to flow through the arteries, increasing the risk for a heart attack or stroke.

The study found the diet reduced LDL cholesterol levels by 14%. LDL is the "bad" cholesterol because it contributes to atherosclerosis.

The diet also reduced systolic blood pressure by 10 points. Systolic blood pressure, the top number in a blood pressure reading, represents the force of blood against the artery walls when your heart beats.

High cholesterol and high blood pressure both increase the risk of heart disease and stroke.

Although participants were on the vegan diet for only five weeks as part of the study, the 10-year reduction in risk assumes they remain on the diet for those 10 years.

"It would be particularly important to follow study participants to evaluate whether they would continue to follow a healthy diet after the end of the intervention," Otto said, "and whether short-term benefits to cholesterol levels and blood pressure would be sustained over time."

Find more news from Scientific Sessions.

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