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  3. The Action of Vitamin D I, a mother of two girls, gave birth to a third girl one month ago. The pediatrician recommended a l

The Action of Vitamin D I, a mother of two girls, gave birth to a third girl one month ago. The pediatrician recommended a l

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问题                         The Action of Vitamin D
    I, a mother of two girls, gave birth to a third girl one month ago. The pediatrician recommended a liquid multivitamin that contains 400 international units (IUs) of Vitamin D for the new born baby, which confused me a lot. When my first girl, who is now 4, was born, the doctor told us to simply get her out in the sun from time to time to let her body produce Vitamin D. When our second child was born two years ago, we were told to give her a multivitamin that had 200 lUs of Vitamin D. So there is a big change, and what do we really know about its risks and benefits?
    Turns out the debate about how much Vitamin D we need has intensified over the past 10 years. One part of the discourse focuses on the growing body of research that point to numerous health benefits of the chemical (actually a hormone) ; it can help prevent rickets in children and severe bone loss in adults and potentially lowers the risk of multiple sclerosis, juvenile diabetes, cancer, heart disease, colds and influenza.
    Amid all this new evidence, the Institute of Medicine (IOM) has assembled a panel of experts to reevaluate just how much Vitamin D we really need and can safely tolerate. Current IOM recommendations, set in 1997, are 200 Ills a day from birth to age 50 and a bit more after that. The upper limit of safety, according to the institute, is 2, 000 lUs daily—too much can lead to, among other things, nausea and kidney stones—yet some vitamin D proponents are pushing for up to 4,000 lUs a day for adults.
    The IOM review won’t be completed until May 2010. In the meantime, Dr. Frank Greer, chairman of the nutrition committee at the American Academy of Pediatrics, is confident that the academy’s new guideline of 400 IDs is enough for kids under 2. But, he wonders, "what about adolescents? Do they need 800?" That remains to be seen.
    In addition to the question of how much Vitamin D, there is debate over the best way to get it. About 10 to 15 minutes spent outside in full sun will give a fair-skinned person dressed only in his skivvies 10,000 to 20,000 lUs. Some vitamin D advocates point to the vigorous use of sunscreen as the reason studies show that so many Americans don’t get enough D. But we don’t want taking advantage of the potential benefits of Vitamin D to mean increased risk of contracting skin cancer. In addition to supplements, there are foods that naturally contain Vitamin D (salmon, egg yolks, liver) and others that are fortified with it (milk, cereals, juices, breads). And, of course, there is always codliver oil.
What can we learn from the passage?
选项 A、People can hardly get Vitamin D from daily diet.
B、Heavy use of sunscreen can promote the Vitamin D production by the body.
C、The Vitamin D density is strengthened in milk and bread.
D、The standard amount of Vitamin D intake keeps no change for kids and adolescents.
答案C
解析 推理判断题。最后一段第一句明显指出补充维生素D的多种方法，食物如牛奶和面包中都含有强化的维生素D，故[C]正确。[A]说人们不能从食物中获取维生素D，故排除[A]；最后一段第三句指出过多地使用防晒产品使美国人维生素D摄入不足，故排除[B]；第四段最后一句说明对于儿童的摄入量有一定的建议标准，但对青少年就还没有定论，故排除[D]。
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