There are a bunch of things you can do which will apparently help reduce the appearance of stretch marks. Using a loofah when you shower helps stimulate circulation. Massage cocoa butter into them. Use vitamin E oil (recommended for healing scars, so I'd guess this would work fairly well). Bio oil.
Diet wise you can eat foods high in vitamins A, E and C. Get more zinc in your diet, apparently good for skin. Eat foods containing silica (beets, brown rice, bell peppers, soybeans, leafy green vegetables and whole grains), which helps form collagen, the supporting fibers in the skin. Eat foods that contain essential fatty acids, which help make cell walls. Essential fatty acids can be found in many vegetables, vegetable oils and fish oils.