Is Guinness really 'good for you'?

(CNN)Guinness, like other Irish stouts, enjoys a seasonal popularity every St. Patrick's Day. It has also been touted as being "good for you," at least by its own advertising posters decades ago.

But can this creamy, rich and filling beer really be added to a list of healthy beverages? Or is its reputation just good marketing? We researched the beer's history and talked to brewing experts and break out the good, the not-so-great and the ingenuity of Guinness.

The good

    The original Guinness is a type of ale known as stout. It's made from a grist (grain) that includes a large amount of roasted barley, which gives it its intense burnt flavor and very dark color. And though you wouldn't rank it as healthful as a vegetable, the stouts in general, as well as other beers, may be justified in at least some of their nutritional bragging rights.
      According to Charlie Bamforth, a professor of brewing sciences at the University of California, Davis, most beers contain significant amounts of antioxidants, B vitamins, the mineral silicon (which may help protect against osteoporosis), soluble fiber and prebiotics, which promote the growth of "good" bacteria in your gut.
      And Guinness may have a slight edge compared with other brews, even over other stouts.
      "We showed that Guinness contained the most folate of the imported beers we analyzed," Bamforth said. Folate is a B vitamin that our bodies need to make DNA and other genetic material; it's also necessary for cells to divide. According to his research, stouts on average contain 12.8 micrograms of folate, or 3.2% of the recommended daily allowance.
      Because Guinness contains a lot of unmalted barley, which contains more fiber than malted grain, it is also one of the beers with the highest levels of fiber, according to Bamforth. (Note: Though the USDA lists beer as containing zero grams of fiber, Bamforth said his research shows otherwise.)
      Bamforth researched and co-authored studies published in the Journal of the Institute of Brewing and the Journal of the American Society of Brewing Chemists, The Science of Beer.
      Here's more potentially good news about Guinness: Despite its rich flavor and creamy consistency, it's not the highest in calories compared with other beers. A 12-ounce serving of Guinness Draught has 125 calories. By comparison, the same size serving of Budweiser has 145 calories, a Heineken has 142 calories, and a Samuel Adams Cream Stout has 189 calories. In the United States, Guinness Extra Stout, by the way, has 149 calories.
      This makes sense when you consider that alcohol is the main source of calories in beers. Guinness Draught has a lower alcohol content, at 4.2% alcohol by volume (AB