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An old Guinness poster, courtesy of Flickr user Joan_Thewlis

Happy St. Patrick’s Day, the one day of the year when eating your greens can mean cupcakes, beer, even bacon.

It’s oddly appropriate that we celebrate our country’s Irish heritage by binging on fatty food and drink; after all, Ireland is the home of the fry-up, a typical breakfast consisting of fried eggs, bacon (rashers), sausages and black pudding (made from pig’s blood), with a few other fried things thrown in for good measure. Not surprisingly, Ireland’s also near the top of the list of countries with the highest heart disease death rates.

But there is some good health-related news on the Irish front: You know those charming old Guinness beer ads that proclaim it to be good for you? Turns out, they might be right—though not for the reasons originally thought.

Back in the 1920s, when the “Guinness is Good for You” slogan was introduced, the claim was based on market research that found that people felt good after they drank a pint of the dark and foamy stout. Um, duh.

This flimsy claim was eventually bolstered by the fact that Guinness contains iron. Pregnant women were even advised to have an occasional pint. Of course, it would take something like a dozen pints a day for a woman to get her recommended daily allowance of iron, in which case the alcohol and calories would cause more harm than good.

But another health benefit was discovered in 2003: stout beer like Guinness (as opposed to lager and other light beer) is high in the antioxidant compounds called flavonoids—similar to those found in red wine, tea and chocolate—that can reduce the risk of heart attack from blood clotting. Researchers at the University of Wisconsin carried out laboratory tests on dogs (Irish setters, I wonder?) with clogged arteries, comparing the effects of Guinness and Heineken. Only those dogs fed Guinness had reduced clotting.

In the interest of having a heart-healthy St. Pat’s Day, I decided to double my antioxidant dose by baking a Chocolate Guinness Cake. A little tip from this novice baker: measure the amount of Guinness carefully. I lost track of how much I put in, and ended up with a cake batter volcano in my oven. Luckily, I was able to scoop out about a 1/3 of the batter and bake the remainder. I doubt it came out the way it was supposed to, but it was still pretty delicious—moist and flavorful.

And one last interesting fact I learned about Guinness—it isn’t vegan; it (and some other beers) contains isinglass, a fish product used in the clarifying process to get rid of excess yeast. Be sure to share that little nugget of wisdom at the pub tonight.

Now, get out there and celebrate.