Top 5 Heart-Healthy Snacks

Of all the nutritious snack options available, new research suggests that raisins and soy may pack some of the biggest wallop when it comes to being heart-healthy.

At the American College of Cardiology's annual meeting this past weekend, researchers presented results of separate studies that evaluated the effects of raisins and soy on blood pressure. The studies found that both foods lowered blood pressure when consumed regularly.

Experts weighed in on these and a few other snacks that offer heart-healthy benefits. ABCNews.com compiled a list of the top five.

Raisins

It's long been believed that raisins have a positive effect on blood pressure, and a study by doctors at the Louisville Metabolic and Athetosclerosis research Center (L-MARC) now offers some proof to that claim.

In their study, Dr. Harold Bays and his colleagues randomly assigned 46 men and women who had borderline high blood pressure to consume either about 60 raisins or a pre-packaged snack three times a day.

"We monitored blood pressure, and when we did that and looked at the final result, we found that compared to the snack group, the raisin group showed a significant decrease in systolic blood pressure," said Bays, who is medical director and president of L-MARC.

Bays believes the potassium in the raisins brought about the decrease in blood pressure.

"Prior studies had already supported that if you give people potassium, blood pressure would go down," he said.

What is also significant about his study, Bays added, is that it is one of the only studies that evaluated the relationship between blood pressure and raisins.

"There has not been any objective research to study this," he said.

Soy Products

Soy products are protein-rich dietary staples found to have positive cardiovascular effects, including lowering blood pressure.

Researchers led by Safiya Richardson, a fourth-year medical student at Columbia University's College of Physicians and Surgeons studied the relationship between isoflavones, compounds found in soy, and blood pressure among subjects participating in the nationwide Coronary Artery Risk Development in Young Adults (CARDIA) study.

They found that consuming only 2.5 milligrams of isoflavones a day (by comparison, an 8-ounce glass of soy milk has 22 milligrams) lowered blood pressure by about 5 points. The effect was especially strong among African Americans.

"Studies have shown that one particular isoflavone, genistein, has been found to have cause blood vessels to dilate, which is why it can lower blood pressure," Richardson said. Genistein was one of three isoflavones examined in the study.

Walnuts

While experts consider nuts as a whole to be heart smart if they are consumed in moderation, walnuts are a particularly healthy choice.

"With walnuts, you are getting alpha-linoleic acid, which converts to an omega-3 fatty acid, which can help prevent cardiovascular disease," said Allison Stowell, dietitian at Guiding Stars, XXX.

Omega-3 fatty acids are also abundant in fish, and according to the American Heart Association, they can lower the risk of developing abnormal heart rhythms and can also decrease the levels of triglycerides in the blood.