It is a common misconception that frozen vegetables have less nutrition than fresh vegetables. However, there are a number of reasons why vegetables from the freezer have just as much nutrition as fresh vegetables--if not more.
Why Freezing Is Not a Problem
The fact is that the vegetables you thaw from your freezer are much older than the ones you can buy fresh at the market, leading some people to think that some of the nutrients must be lost over time. However, freezing food effectively freezes it in time and protects the food from decay and bacteria, meaning that the frozen vegetables retain just as much nutrition as they had the day they were frozen.
Why Frozen Might Get a Bad Reputation
Many people confuse the bad reputation that canned vegetables have with that of frozen vegetables. It's true that canned vegetables have a number of preservatives and salt added. Perhaps more devastatingly, most canned vegetables go through a cooking process in which they are heated at great temperatures. It's this heating process that makes vegetables lose much of their nutrients. The results would be the same if you heated fresh vegetables yourself.
However, vegetables that have been frozen are never heated before packaging, meaning that they never lose nutrients by being cooked. They are merely washed and frozen.
When Frozen Might Not Be Better
That's not to say that frozen vegetables are always pure, nutritious vegetables. Avoid vegetables in the freezer section that have any added minerals or salt. The minerals might not be an unhealthy addition, but the salt certainly is. In any case, vegetables have enough nutrients without any additives.
Why Frozen Is Usually Better Than "Fresh"
Nevertheless, most vegetables in your grocer's freezer are purely vegetables with no additives. These are the optimal kinds of vegetables to use for cooking, snacking and making your own salads. The reason for this is if you consider the source of your fresh vegetables. If you pick the vegetables yourself from your own garden, you might indeed be getting the most nutritious kind of vegetable because you can prepare and eat the vegetable at the perfect moment of ripeness, when all nutrients are at their peak.
However, if you purchase your fresh vegetables from a market or grocer, the vegetables were likely picked before their optimal ripeness. This means that they have less nutrients than if they had been picked later. However, if they had been picked later, they would have gotten rotten in the time necessary for transport. Vegetables that are flash frozen are picked at the optimal moment of ripeness and then frozen before many nutrients are lost. This is the only way to ensure optimal freshness when vegetables must be transported to the store before they make it to your dinner table.
Because frozen vegetables typically have even more nutrition than fresh vegetables, you can save money and stock up on healthy foods to eat by purchasing more frozen than fresh. However, that's not to say you can't occasionally treat yourself to the fresh vegetables, as they can be tastier.