Back when we thought low-fat everything was the way to go, nuts were cast off as fatty calorie bombs best saved for occasional splurges like long road trips or Sundays at the ballpark. Boy, have times changed. Now we know that nuts actually have unsaturated (a.k.a "good") fat plus piles of other nutrients. We also know that they fill you up, and reams of research backs their many other health benefits. In fact, with all the stir surrounding the heart-healthy Paleo and Mediterranean diets, nuts, a key component of both meal plans, are having a heyday.

It seems like every day we read an article, study, or blog telling us to load up on almonds, walnuts, macadamias, and more, but one nut gets little mention: pistachios. Although they've been the focus of fewer studies, these little green powerhouses should start getting more of the spotlight. A research review published in the 'American Journal of Lifestyle Medicine' in March found that pistachios in particular offer serious cardio perks.

"Pistachios decrease bad cholesterol and triglycerides and increase good cholesterol, which lowers heart disease risk," says study author Roman Pawlak, professor of nutrition science at East Carolina University. "They also improve blood vessel elasticity, which helps prevent high blood pressure."

Pawlak says these heart benefits come from pistachios' solid nutritional package. They contain no trans fats or dietary cholesterol, but are high in fiber, vitamins, minerals, and phytochemicals. Plus, he says pistachios are the only nuts besides peanuts that offer resveratrol, a compound also found in the skin of red grapes. "Intake of foods and beverages containing resveratrol is linked to decreased risk of heart disease and some cancers," Pawlak explains.

Of course, as with all nuts, pistachios pack in the calories, so don't go whole hog. "Stick to the recommended intake of 1.5 ounces of nuts on most days of the week – that's about a handful of pistachios," says Pawlak.