A recent study from the Johns Hopkins University and elsewhere discovered that if protein or monounsaturated fat are replaced in your diet for some carbohydrates, it could reduce blood pressure and cholesterol levels substantially. This reduction in blood pressure and cholesterol would result in a significant reduction in overall risk of heart disease.

Imagine, just by changing about 10 percent of carbohydrate calories in the diet to either protein-rich food, mostly from plant sources, or to monounsaturated fats, contained in olive and canola oil, provided a major benefit to the heart according to the Johns Hopkins team.

According to internist Lawrence Appel, M.D., M.P.H., a professor of medicine at the Johns Hopkins School of Medicine and lead author of the study, "Our study provides strong evidence that replacing some carbohydrate with either protein or monounsaturated fat has important health benefits. There is already agreement that reducing saturated fat lowers risk for heart disease, but the question of which macronutrient to emphasize has been controversial."

However, Dr. Appel made it clear that his study did not support diets such as the Atkins diet, which is extremely high-saturate-fat, low-carbohydrate and not a healthy diet plan.

Three healthy diets were evaluated that differed mainly in the amount of macronutrients--protein, fat and carbohydrate--that provide calories used for energy in the body. All of the diets were low in saturated fat, cholesterol and sodium, and rich in fruits, vegetables, fiber, potassium and other minerals.

One diet was a traditional healthy diet rich in carbohydrate, while the other two diets had approximately 10 percent of their carbohydrates replaced with either monounsaturated fat or protein. It should be noted that about half of the protein came from plants.

"All three diets reduced overall heart disease risk, lowering blood pressure and improving cholesterol levels," says Appel. "But the protein and monounsaturated fat diets had an edge over the carbohydrate-rich diet."

These findings by the Hopkins study, called the Optimal Macronutrient Intake Trial to Prevent Heart Disease (OmniHeart), presented at the American Heart Association's Scientific Sessions 2005 and published simultaneously in the Journal of the American Medical Association, underscore the significant benefits from making dietary changes, the researchers say.

From the study, it was determined that overall, the protein-rich diet, derived from plant and animal sources, decreased cardiovascular disease risk by 21 percent. "Many people equate protein with meat, but it is not the only source of protein," said study co-author Phyllis McCarron, M.S., R.D., a dietitian at Hopkins.

"Excellent plant sources of protein are beans, nuts, seeds and certain grains."

In addition, the monounsaturated fat diet, enriched with olive and canola oils, as well as various nuts and seeds, decreased risk by almost 20 percent.

The carbohydrate-rich diet used was similar to the Dietary Approaches to Stop Hypertension, or DASH diet, which Appel helped develop in 1997 and decreased risk by roughly 16 percent.

The OmniHeart study lasted about three years, and researchers enlisted 164 generally healthy adults, both men and women ages 30 and over.

"Because of the huge risk of stroke and heart attack in African Americans, the results are particularly applicable to this group, who made up roughly 55 percent of study participants," said study co-author Jeanne Charleston, R.N., a research associate at Hopkins' Bloomberg School of Public Health. Charleston adds that all participants either had high blood pressure (almost 20 percent) or were on the verge of having high blood pressure.

Participants ate all of their food - including breakfast, lunch, dinner and snacks -- from one of the three diets in six-week intervals. After a two-to-four-week break, participants started the six-week feeding period over again, this time with a different diet. The process was repeated until all participants ate all three.

During this process, the researchers monitored each participant's levels of blood pressure, cholesterol and triglycerides on each diet.

These measurements were then factored into a standard mathematical model, called the Framingham risk equation, for estimating heart disease risk.

The OmniHeart study results, according to Appel, reconfirm the powerful effects of a diet-based approach to improving someone's cardiovascular risk profile, for blood pressure and cholesterol levels, and lowering their overall risk of heart disease.

So, if you really want to improve your overall health, and more specifically, your cardiovascular health, you need to pay more attention to your diet.