"Be aware that that some vegetables are more nutritious when cooked. The broccoli and cabbage family contains goitrogens, which depress thyroid function. Spinach, beets and chard contain oxalic acid, which blocks calcium and iron absorption. Goitrogens and oxalic acid are reduced by cooking.
Betacarotene in vegetables is more available to the body once it has been liberated from tough cell walls; thus shredding, juicing and cooking beets and carrots are all ways to make them more nutritious."
Credited to Nina Planck in her book: "Real Food - what to eat and why"