▶ Watch Video: A closer look at the Mediterranean diet

Doctors and dietitians alike have recommended the Mediterranean diet for a heart-healthy lifestyle, but for some people, it can be confusing to nail down specific parameters. After all, “there’s over 20 countries on the Mediterranean Sea,” registered dietitian Samantha Heller said Tuesday on CBSN.

“So there’s Italian, Israeli, there’s Greek, there’s Egyptian, North African — lots of different foods. But one of the staples is olive oil,” Heller said. “Other common baselines for this diet is lots of fruits and vegetables, legumes like lentils and chickpeas, lots of nuts and seeds, and water, and fresh whole grains. So it’s a great more plant-based diet, but they also have fish a few times a week, they only use meat a little bit as a condiment, a little bit of cheese as flavoring. So it’s a very balanced and beautiful approach to eating that can encompass many, many kinds of food and cuisines.”

According to the American Heart Association, a Mediterranean-style diet can play a “big role” in preventing heart disease and reducing risk factors, including obesity, high cholesterol and diabetes.

Olive oil is one of the primary sources of fat in Mediterranean-style diets. But extra virgin olive oil is less processed and preserves more polyphenols, which Heller said are “plant compounds that help us stay healthy, reduce inflammation, help promote healthy cell division, help reduce the proliferation of chemicals in our bodies that we don’t like, and help reduce the risk of a lot of diseases, act as antioxidants.”

“The refined olive oil still has some health benefits, but just not quite as many as the extra virgin olive oil. But they’re great to cook with. They have different flavorings, different flavor profiles, so you’re going to want to taste them and see if you want them added to whatever dish you’re preparing,” Heller said.

During the holiday season, Heller reminded viewers to “enjoy their food and have a good time.”

“Portion matters, so if you are actually going in person to a live event … just pick out the foods you love that you don’t get very often — like maybe you just love pecan pie and someone made a fabulous one, have a small piece of it and really enjoy it,” she said. “Enjoy your foods, enjoy the social interactions, and that’s actually a big part of the Mediterranean diet, is the social interactions and the connections and the support we feel with each other.”