Is there a difference between canned / frozen / fresh vegetables in terms of nutrition?
A busy lifestyle and a rigorous semester may not always allow us to have fresh vegetables on hand. But, there are benefits and drawbacks of fresh, frozen, and canned vegetables. For starters, no matter which way you store it, a vegetable is always going to contain carbohydrates, protein, vitamins, minerals, fiber, and other plant chemicals, known as "phytochemicals," all of which are good for us no matter what. You’ll be happy to know that none of these nutrients are completely lost from processing.
While most people feel that fresh veggies are optimal, they may lose nutrients before they even get into your stomach. Raw vegetables lose some vitamins just by sitting around. It could take up to two weeks from the time they've been picked until they reach your plate. By this time, 10 to 50 percent of the less stable nutrients may have disappeared. Still, raw, lightly prepared, or minimally processed veggies (and fruits) often have a higher nutrient value than well-cooked ones. To help preserve the nutrient content of veggies (and fruits) during cooking or other preparation:
- Stick with shorter cooking times and lower temperatures (e.g., avoid deep frying)
- Cook with little or no water to help retain water-soluble vitamins, such as vitamin C and the B vitamins. For example, steam or microwave rather than boil. To limit exposure to heat when cooking this way, wait until the water is boiling before adding veggies.
- For more information, read Cooking veggies and vitamin loss?
Frozen and canned vegetables are often processed shortly after they are picked, so that nutrient losses would not occur during shipping, on the grocer's shelf, or in your home. Frozen vegetables actually retain a high proportion of their original nutrients. Sometimes, though, they are blanched (dipped in hot water), which preserves color and texture, but may compromise some vitamins. In order to avoid extra calories, salt, and/or fat, choose frozen vegetables without added sauces or cheese. Sodium is often added to canned products. A portion of this may be rinsed off with water, or you can choose the low sodium or no sodium that are often available (check the label!).
Whether fresh, frozen, or canned fits into your lifestyle, select any type that you'll enjoy eating. The number of servings needed in a day varies depending on your age and other factors, however, adults generally need about 2.5 to 3 cups of vegetables and 1.5 to 2 cups of fruit each day. Read Food Guidelines — How much is a serving? in the Go Ask Alice! Nutrition & Physical Activity archive for specific veggie and fruit serving size information. You can also check out Choosemyplate.gov for personalized recommendations.
As a side note, you may think that nutritional supplements are a quick and easy way of getting the nutrients you need in case you don't follow a healthy eating plan. However, a well-balanced diet rich in veggies and fruits can offer you much, much more than these supplements ever could, such as phytochemicals, which could protect against cancer, heart disease, other illnesses, and who knows what else? Beneficial substances such as these are found in vegetables no matter what form they are in.Alice!