When fresh fruits and vegetables are not readily available, there is no shame in substituting frozen varieties, and in fact in many cases, they are probably more nutritious. Nothing can beat the quality and flavor of fresh strawberries or sweet peas at the peak of summer, but during other months, fresh fruits and vegetables are harder to acquire and when you can find them, chances are they have traveled many miles to get to you.
The problem is that as soon as most produce has been picked, both its flavor and nutritional value begin to quickly wane. Even after just a few days, the taste and vitamin content is markedly diminished. So if you're buying asparagus that was grown in Chile, and you live in Oregon, chances are it has taken days for this asparagus to get to you and it will likely not only taste like cardboard, but its vitamin content is negligible at best. On top of that, the environmental impact of shipping fresh produce across the world has got to be taking its toll.
What most people don't realize is that frozen fruits and vegetables are usually picked, blanched to retain their color and nutrients and then deep frozen shortly after being harvested, thus sealing in much of the flavor and most of the nutrients. Sure there are downsides to frozen vegetables, such as a sometimes compromised texture as well as some brands that are pumped with excessive amounts of salt, but in the dead of winter, when the options are few and the prices are high, and you just can’t stomach another rutabaga or bunch of kale, going frozen is often the easiest, smartest choice you can make.
When choosing frozen vegetables, be sure to read the labels and buy those that contain the least amount of added salt, fats and sugars. When choosing frozen fruits, try to buy only unsweetened fruit and if it needs sweetening, you can do so yourself, using only as much sweetener as you require.