Tham khảo tài liệu 'chapter sumary 4', ngoại ngữ, anh ngữ phổ thông phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | CBEST PRACTICE EXAM 2 Answer questions 18 and 19 on the basis of the following passage. A healthy diet with proper nutrition is essential for maintaining good overall health. Since vitamins were discovered earlier in this century people have routinely been taking vitamin supplements for this purpose. The Recommended Dietary Allowance RDA is a frequently used nutritional standard for maintaining optimal health. The RDA specifies the recommended amount of a number of nutrients for people of both sexes and in many different age groups. The National Research Council s Committee on Diet and Health has proposed a definition of the RDA to be that amount of a nutrient which meets the needs of 98 percent of the population. The RDA approach. First it is based on the assumption that it is possible to accurately define nutritional requirements for a given group. However individual nutritional requirements can vary widely within each group. The efficiency with which a person converts food intake into nutrients can also vary widely. Certain foods when eaten in combination actually prevent the absorption of nutrients. For example spinach combined with milk reduces the amount of calcium available to the body from the milk. Also the RDA approach specifies a different dietary requirement for each age and sex however it is clearly unrealistic to expect a homemaker to prepare a different menu for each family member. Still although we cannot rely solely upon RDA to ensure our overall long-term health it can be a useful guide so long as its limitations are recognized. 18. Which of the following would best fit in the blank in the first sentence of paragraph two a. is based on studies by respected nutritionists b. has a number of shortcomings c. has been debunked in the last few years d. is full of holes e. is constantly being refined 19. With which of the following would the author most likely agree a. The RDA approach should be replaced by a more realistic nutritional guide. b. The RDA
