In a world where the general populace is not only less healthy, but more health obsessed, there is a major misconception as to the nutritional value in certain foods. One of the major misconceptions in fact is the belief that frozen foods are of a lower nutritional value than fresh.
In actuality, it partly depends on what your dealing with that is frozen. In the case of fruits and vegetables, there is a general loss of some Vitamin C and D because of the blanching process used to kill bacteria and prepare food for freezing commercially. This process arrests some of the enzyme production that breaks down food and causes it to spoil as well, however, except for these water-soluble vitamins, the overall nutritional content of the fruits and vegetables is actually rather good, as the produce used in freezing is usually picked and prepared at the height of its overall ripeness and thus, nutritional value. Frozen produce is much healthier for you than canned or dried preserved foods because its preparation doesn’t include the excessive addition of preservatives such as salt and sugar that is required in the canning preservation.
In the case of meats, on the other hand, freezing can be less nutritionally sound. One of the affects that freezing has, on any previously living tissue, whether it is fruits, vegetables, or animal proteins, is that it weakens the cellular structure. This can cause a breakdown of proteins, a much denser and more delicate cellular structure than that of plant fiber. Not only does this breakdown of the cellular structure negatively impact the taste and texture of proteins, it affects how well the amino acids are absorbed into the body through the digestive system.
Overall, of course, fresh foods are generally better for you from a nutritional standpoint, but again, as was mentioned previously, whatever the food is, it should be prepared at the height of its ripeness. Fresh vegetables and fruits picked out of season are generally not fully ripe, and thus, lack in some nutritional value, and thus the choice of going with frozen produce in the off season is generally better than picking a pear before its time.
Except in the case of frozen preparation staples such as ice cream, frozen yogurt and the like, dairy products should not in general be used in a frozen format at all. Anyone who has frozen a block of cheese and then thawed it realizes that the proteins have been loosened to the extent that it becomes crumbled and loses its smoother textures. This is the cellular breakdown mentioned before, but on a much more obvious scale. It is similar to the breakdown that happens when you melt and remelt cheese over and over again, each successive time breaking down the nutrition and texture until the cheese becomes inedible.
Remember, fresh, local foods are ultimately the best for anyone. Local because those foods have adapted to the environment and thus are less likely to trigger or encourage excessive allergic reactions as well, and can help your immune system in combating such negative reactions. This is why holistic enthusiasts will not tell you just to eat honey to fight off allergies, but to make sure it is locally collected honey, as the allergies are usually local in origin as well. Even if you are not local yourself, the locally grown and raised foods will help your system adapt to the new environment you are in and acclimate you so that your system will not experience as much of an allergic reaction to the change.
In conclusion, frozen foods is more nutritionally sound than canned or dried foods, but nothing beats fresh, locally grown and raised food taken at the peak of its ripeness.