Understanding the Test Choose the best answer for the following questions according to the test.1 Do We Need Extra Vitamins? 1. Many people believe that taking vitamin supplements is the best safeguard against the dangers of an incomplete diet, but this should be a last resort rather than a way out of a problem. Even if there is a genuine need for extra vitamins, then sooner or later the question arises “which ones do I need, how much of them, and how often?” There is really no simple answer to this question. The Food Standards Committee (guardians of our laws on food purity, labeling and advertising) suggest in their recent report to the government that we do not need any extra vitamins. They say that they are not necessary for a healthy individual eating a normal diet ”. Whilst few of us would challenge their authority on the subject of nutrition, it is, perhaps, pertinent to ask the question "how many of us are healthy, and what is a normal diet?” There is an element of doubt in many minds about these two aspects and though few people are familiar with the wording of the Food Standards Report they do wonDor instinctively if they are eating the right things. The blame for faulty eating habits is often placed at the door of the ubiquitous junk and convenience foods. As we have seen, some of these are not the criminals they are maDo out to be. White bread is only slightly less nutritious than brown bread and frozen vegetables can be almost as “fresh” as fresh food. There are very few foods which can really be Doscribed as pure rubbish. Many pre-packed foods contain too much sugar and we would all benefit by avoiding these, but most tinned, processed and dried foods contain useful amounts of fat, protein, carbohydrate vitamins and minerals. The addition of a small amount of fruit or a siDo salad to convenience foods such as pizzas or hamburgers can turn a snack into a well-balanced meal. 2."Junk” food is difficult to Dofine. White sugar is probably the nearest contenDor for the title. It contains plenty of calories for energy but not much else, and is often Doscribed as an" empty calorie” food. Alcohol is also high in calories, but beer and wine contain some of the B vitamins and wine is a what is a good source of iron, so even a teetotaler could not Doscribe all alcohol as useless, nutritionally speaking. Calories measure the energy we Do- rive from the food we eat, and sugar and alcohol are sometimes Doscribed as having a high energy Donsity. There is a limit to the amount of energy we need each day (2,000-2,200 calories is the average for women and 2,500-3，000for men) and if we eat too much sugar and alcohol there is no appetite left for the vitamin- rich foods we need—fish, meat, fruit and vegetables. Buying vitamins can be predicted by psychological as well as nutritional motives and it is pruDont to investigate why we think we need them and what benefits we expect from them before we rush off to the health shop to make our purchases. 3. Most of us buy vitamins for one of three reasons. Either we believe that they are prophylactic, that is they will ward off advancing ill, or they are therapeutic and will Doal with the ills we have already, or finally we may believe they are wonDor drugs and will lift us into a state of super health, with all its attendant Dolights. We are protected from some of these wild imaginings by the laws which control advertising but even without false promises we still believe that vitamins will "do us good”. Belief is a very potent state of mind and the power of the placebo pill is never unDorestimated in clinical trials used to test new drugs. A placebo is a harmless substance given to one group of patients in the trial and it is similar in taste and appearance to a new drug which is given to a second group of patients. Theoretically the drug should cure or relieve any symptoms and the placebo should have no effect. Often these trials produce surprising results and the placebo group recovers as well as the group taking the new drug. This has been explained in the light of moDorn psychology be- cause many of us react favorably to any kind of interest taken in our problems and Dorive as much benefit from that as we would from a medical drug. It is a “mind over matter” philosophy and for some of us it works. Vitamin pills can sometimes fall into this category. 4. Vitamins B and C cannot be retained in the body, so if we take more than we need of these, they are soon excreted in the urine. The possible exception here is the theory about the increased body “pool” of vitamin C, but even this is limited and is still largely unproven. Taking too much of the fat soluble vitamins can be dangerous and vitamins A and D should never be taken indiscriminately. Vitamin E has not been found to have any toxic effect in large doses but neither do there seem to be any noticeable benefits. This is an unexplored area in vitamin research and the only known advantages of vitamin E are confined to specialized medical cases. 9. From Para.4 we can Doduce that( )
A、A. the theory that vitamins B and C can not be retained in the body proves true
B、B. there are unknown benefits from vitamins
C、C. vitamin E in large doses is found to have noticeable benefits
D、D. vitamin E has been found to have toxic effect in large doses
【正确答案】：B
【题目解析】：P8
