What Makes McDonald's Iconic Shamrock Shake Green?

Shamrock Shakes are back at McDonald's, and that means St. Patrick's Day will be here before we know it. Fans eagerly await the annual arrival of the creamy mint-flavored milkshake that's joined shamrocks and leprechauns as a hallmark of the holiday. This time, it returns with an unexpected Grimace twist as long-forgotten mascot Uncle O'Grimacey is making a comeback. A big part of why Shamrock Shakes get so much love is their trademark green hue, but what is it that makes them that color?

The shake blends vanilla soft serve ice cream with what McDonald's calls its Shamrock Shake syrup, topped off with whipped light cream. According to the posted ingredient list on McDonald's website, the minty syrup gets its color from food dyes Yellow No. 5 and Blue No. 1. If you remember your color chart from school, those shades combine to make green. When the syrup is swirled together with the white ice cream, you get the Shamrock Shake's festive light green color with a yummy vanilla and mint taste.

Yellow No. 5 and Blue No. 1 are artificial food dyes made from petroleum, like Red No. 3, which was recently banned in the U.S. after being linked to cancer in test animals. Both have been linked to potential attention or behavioral problems in children, leading California to ban these dyes (and four others) in food and drinks in public schools. If you'd like to naturally dye food green for St. Patrick's Day, you can do so with spinach instead.

After debuting in 2020, the Oreo Shamrock McFlurry has also made its annual St. Patrick's Day return to McDonald's. The holiday version of the regular McFlurry dessert is made with vanilla soft serve ice cream, Shamrock Shake syrup, and Oreo cookie pieces. These ingredients create a delicious flavor similar to that of the Girl Scouts' iconic Thin Mint cookies.

Of course, McDonald's has other fan-favorite limited-time offerings that customers hope to see return to the menu, most famously the McRib. This sandwich is filled with boneless pork, slathered in barbecue sauce, and topped with onions and pickles. Although many are unsure what cut of meat the McRib is actually made of, its devotees love it so much that there's an online McRib Locator to alert followers when the sandwich has been spotted at a McDonald's location.

The McLobster, McDonald's version of a lobster roll, was something of a regional secret that debuted in 1993 and used to occasionally appear at New England-based locations. It hasn't been seen in a while due to high lobster prices. Spicy Chicken McNuggets, a hotter take on the classic kids' favorite, have been back every year since they first appeared in 2020. Additionally, the Double Big Mac, with a whopping four beef patties instead of two, and the Chicken Big Mac, which contains two deep-fried chicken patties instead of burgers, havealso made limited appearances in recent years.