Zinc aids the brain as part of a metabolic process that eliminates harmful free radicals. It also strengthens neuronal membranes for greater protection and helps get rid of lead, which can enter the brain by way of automobile exhaust and other sources and adversely affect mental function. Zinc is part of the molecular structure of dozens of important enzymes. It is a component of the insulin that regulates your energy supply, and it works with red blood cells to transport waste carbon dioxide from body tissue to the lungs, where it is expelled. Zinc is also vital to the production of the RNA and DNA that oversee the division, growth, and repair of the body’s cells, including brain cells. Dietary sources of zinc include beef, her- ring, seafood, pork, poultry, milk, soybeans, and whole grains. The recommended dietary allowance (RDA) for zinc is 15 milligrams, not to exceed 40 milligrams per day, for adults over eighteen years of age. Women who are pregnant may want to take an additional 5 milligrams of zinc daily, and women who are breastfeeding should take an extra 10 milligrams daily.