Smoking depletes the body of vitamin C. It is estimated that smokers require 2-3 times the amount of vitamin C than nonsmokers and may play a protective role with regard to Alzheimers in smokers. A multi vitamin "fills in the gaps" because we know that you do not always eat 5 servings daily of fresh fruits and vegetables. Try guava, oranges, lemons and melons as vitamin C sources. The BEST natural source of vitamin C in our opinion is an apple. A medium sized apple including its skin contains 1,000 mg of bioavailable vitamin C.