BOSTON (CBS) – A lot has been written lately about the health benefits of chocolate.

It’s important to know, however, that not every bar is created equal when it comes to health benefits.

Chocolate is often marketed now as a health food because of its antioxidants, iron, and magnesium. The most benefits come from pure cocoa.

Nutritionist Sally Eisenberg explained, “Raw chocolate really has the most flavenols of any other food. They sweep away junk and toxins in our bodies.”

Dark chocolate typically contains the most flavenols. They help relax vessels and improve blood flow.

There is growing evidence that flavenols can fight cancer, improve brain function, and even improve skin tones.

“It’s one of the best foods,” said Eisenberg.

There are many options for dark chocolate, but the problem is many of us are accustomed to really sweet chocolate.

Most of those products are loaded with sugar and fat.

“I like to say the more bitter, the better for our bodies,” said Eisenberg.

It’s a good idea to check the nutrition labels on all these products. They can still be high in calories even if they have other health benefits.

Another consideration is cost.

Many of these items are more expensive than your typical Snickers bar.