A daily multivitamin tablet may boost the memory and slow mental decline, the Daily Mail reported Sunday. According to new studies, taking supplements has a beneficial effect on memory and may work by increasing the efficiency of brain cells. One study showed that after just four weeks there were measurable changes in electrical activity in the brain when carrying out memory tests.The body needs 13 vitamins to function properly and maintain health. Vitamins A, C, D, E and K and the eight B vitamins each have specific job in the body. Vitamin C keeps cells healthy, D regulates calcium and E maintains cell structure, while the B vitamins, including folic acid, have a wide range of functions. David Kennedy, of the Brain, Performance and Nutrition Research Center at Northumbria University, said: "The evidence is still limited but the studies hint at some possible beneficial effects. "Optimal brain function depends on an adequate level of all of the vitamins."