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 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 recently 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 (ABV), compared with 5% for Budweiser and Heineken, and 4.9% for the Samuel Adams Cream Stout.
In general, moderate alcohol consumption -- defined by the USDA's dietary guidelines for Americans as no more than two drinks per day for men or one drink per day for women -- may protect against heart disease. So you can check off another box.
Guinness is still alcohol, and consuming too much can impair judgment and contribute to weight gain. Heavy drinking (considered more than 15 drinks a week for men or more than eight drinks a week for women) and binge drinking (five or more drinks for men, and four or more for women, in about a two-hour period) are also associated with many health problems, including liver disease, pancreatitis and high blood pressure.
According to the National Council on Alcoholism and Drug Dependence, "alcohol is the most commonly used addictive substance in the United States: 17.6 million people, or one in every 12 adults, suffer from alcohol abuse or dependence along with several million more who engage in risky, binge drinking patterns that could lead to alcohol problems."
And while moderate consumption of alcohol may have heart benefits for some, consumption of alcohol can also increase a woman's risk of breast cancer
for each drink consumed daily.