Studies show little difference in nutrient levels between fresh and frozen vegetables. Nevertheless, vegetables freshly picked from your garden or a local farmer's likely contain the most nutrients.
When it comes to canned vegetables, the heating process used during manufacturing may also reduce certain nutrient levels.
What’s more, canned vegetables often contain salt or added sugar. They may also contain trace amounts of bisphenol-A (BPA), a chemical linked to poor fertility, low birth weight, heart disease, and type 2 diabetes.
Juicing has become a popular and easy way to add vegetables to your diet. However, juicing tends to remove fiber, which is very important to health.
Studies also show that antioxidants naturally bound to plant fibers may also be lost in the juicing process.
For these reasons, fresh or frozen vegetables are generally preferred over canned or juiced varieties.