[单项选择]The food we eat seems to have profound effects on our health. (67) science has made enormous steps (68) making food more fit to eat, it has, at the same time, made many foods unfit to eat. Some research has shown that perhaps eighty percent of all human (69) are related to diet and forty percent of cancer is related to the diet as well, (70) cancer of the colon (结肠癌). Different cultures are more prone to (71) certain illnesses because of the food that is (72) in these cultures. That food is related to illness is (73) a new discovery. In 1945, government researchers realized that nitrates and nitrites (硝酸盐和亚硝酸盐), commonly used to preserve color in meats, and other food additives( 加剂), (74) cancer. Yet, these carcinogenic (致癌的) additives (75) in our food, and it becomes more (76) all the time to know which things on the packaging labels of processed food are helpful or (77). The additives wh