Researchers at the University of California in San Diego have established that trans fats contained in fast food, frozen pizzas and pastries have a negative impact on brain performance.Trans fats are created in the hydrogenation of vegetable oils. Memory tests involving 1,000 men under the age of 45 showed that those who ate hydrogenated fats could recall less information than those who had not been fed fast food. Trans fats also increase the risk of heart disease and cancer.