Zinc is an important antioxidant that also helps protect DNA. Doctors in one study wanted to measure the effect of varying zinc levels on DNA. Nine healthy men who consumed an average of 11 mg of zinc per day went on a 55-day diet to deplete zinc, followed by 27 days replenishing zinc levels. During the zinc-depletion phase, DNA damage in blood cells increased, and reversed when zinc returned to healthy levels. Doctors concluded that zinc helps maintain DNA integrity, which may reduce the likelihood of cancer.