Heinz Ketchup used to be part of the fabric of the McDonald's experience. Now it's nowhere to be found. Even though this news is now years old, perhaps you still haven't recovered from the shock. So what happened? We're here to fill in all the gaps in your knowledge about this major change in the fast food landscape, but we should warn you, this isn't the only major change that has altered the McDonald's french fry experience over the years. And there's no easy way for you to recreate the taste of your childhood if you're old enough to remember how they used to taste. This is the real reason McDonald's stopped serving Heinz Ketchup.