It doesn't mean you can't take these items across the border but does mean if you are asked about these items you must declare them and the agents may take these items from you if there are restrictions on any of the items.
The only thing I've had confiscated was California oranges when we were crossing into the USA. Although on our last day trip in to Alaska, the US agent told me to not leave the peelings in Alaska and he let me keep my oranges. We cross with dog food, lunch meats, frozen meats, veggies, fruits, canned goods ... everything. If asked, we tell what we have.
Crossing back into Canada I don't recall that we've ever been asked about food we've purchased in the USA and still have with us.