The Sweet Ingredient You’ll Be Surprised To Find In A McDonald’s Filet-O-Fish

A trip to McDonald’s can be a guilty pleasure or a quick way to stave off hunger. With a ton of menu options, there’s something to suit a variety of tastes and ages. The Big Mac is a favorite among adults, while kids often gravitate toward Chicken McNuggets. And let’s not forget the fries. Everyone gets their own fries when you go to McDonald’s.

Some days, you might find yourself craving fish, and that’s where McDonald’s Filet-O-Fish comes in. Its main ingredient is pollock, followed by water, vegetable oil, wheat flour, and starch. Like many fried foods, it’s no surprise that the Filet-O-Fish contains a good amount of sodium — 580 milligrams, to be exact. But have you ever noticed a hint of sweetness in this fish sandwich? That’s because it contains 4 grams of added sugar.

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Now, it might not be shocking that sugar finds its way into fast foods like the Filet-O-Fish. After all, sugar enhances flavor and, when paired with salt and fat, can make foods that much more tasty. But in this case, a little sugar also helps mask the fishy taste and improves the texture.

If you’ve ever tried a Blue Apron recipe, you’re probably familiar with seasoning meat and fish with salt and pepper as soon as it’s unpacked. This jumpstarts the flavor. Adding a small amount of sugar before cooking fish can also work wonders. According to Chowhound, sprinkling about half a tablespoon of sugar on the side of the fish that touches the pan helps create a crispy, golden crust without overcooking it.

However, McDonald’s isn’t sprinkling sugar on its fish fillets before frying them. The sugar in a Filet-O-Fish likely comes from the batter. Some chefs add sugar to fish batter recipes because it caramelizes during cooking, enhancing the color and flavor. While 4 grams of added sugar in a Filet-O-Fish might sound like a lot, it’s roughly equivalent to a teaspoon. That total includes sugar from the fish fillet itself, the bun, and the tartar sauce.

Interestingly, if you skip the bun, cheese, and tartar sauce, the fish fillet alone has no added sugars listed in its nutritional information. While sugar is still an ingredient, there’s not enough to count as added sugar. Most of the added sugar in a Filet-O-Fish comes from the bun and tartar sauce.

While it’s expected in candy, cookies, and ice cream, sugar is often hidden in foods that aren’t known to be sweet, like pasta sauce. Sugar doesn’t just enhance flavor — it’s also a preservative that extends shelf life. 

If your diet leans heavily on fast or processed foods, it’s easy to consume more added sugar than you might realize — even if you never eat sweets. For example, if you eat an Egg McMuffin for breakfast, a Filet-O-Fish for lunch, and a Big Mac for dinner, you’d consume 10 grams of added sugar. The American Heart Association recommends limiting added sugar to 6% of your daily calories. For a 2,000-calorie diet, that’s about 30 grams of added sugar per day, meaning those three McDonald’s items would use up one-third of your limit.

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Sugar is also thought to be addictive. It activates reward centers in the brain, making you crave more. While it’s fine to enjoy sugar in moderation, too much sugar can lead to health issues like obesity, heart disease, type 2 diabetes, and even cancer. Not only that, but the right combination of sugar, salt, and fat in many processed foods makes them more irresistible.