While many people aren't getting enough calcium,new research cautions that some people may have the opposite problem:They could be getting too much.
尽管有很多人钙摄入量不足，但新的研究提醒我们，也有一些人面临的问题可能恰好相反：他们的摄入量太多了。
Americans spend more than$1 billion a year on calcium supplements in hopes of staving off osteoporosis,the brittle bone disease that cripples many elderly women and some men.
美国人一年花费逾10亿美元购买各类钙补充剂，期望能推迟骨质疏松症的发生。骨质疏松症是一种让骨头变脆的疾病，许多老年女性和部分男性都会因骨质疏松致残。
钙补充剂有可能导致心脏病和肾结石风险升高
Yet recent studies link calcium supplements to a higher risk of heart attacks and kidney stones.Last month,the U.S.Preventive Services Task Force issued a draft recommendation against taking calcium and vitamin D,saying there wasn't enough evidence of benefit to justify the risk.
但近期的研究揭示，钙补充剂有可能导致心脏病和肾结石风险升高。美国预防医学工作组(U.S.Preventive Services Task Force)上月发布了一份建议书草案，不主张服用钙和维生素D补充剂，称并没有充足的证据显示这样做利大于弊。
For generations of Americans who grew up exhorted to drink their milk to maintain strong bones,the reports raised troubling questions:Is calcium not so important after all?Are the supplements unsafe?And how much is too much?
对从小就被劝说要多喝牛奶以维持强健骨骼的几代美国人来说，这些报告引发了一些麻烦的问题：钙是不是其实并不太重要?钙补充剂是不是不安全?摄入钙量多少算超量?
'It's gotten very confusing but it doesn't need to be,'says Ethel Siris,director of the Toni Stabile Osteoporosis Center at Columbia University Medical Center in New York.
纽约哥伦比亚大学医学中心(Columbia University Medical Center)托尼•斯塔比尔骨质疏松研究中心(Toni Stabile Osteoporosis Center)主任说，“问题变得令人非常费解，但其实不至于如此。”
The links to heart attack and kidney stones involved calcium supplements,not calcium from food sources,Dr.Siris and other experts note.Many other studies have not found such health risks,so more research is needed to understand what levels,if any,might be hazardous.
博士和其他专家指出，可能引起心脏病和肾结石的是钙补充剂，而不是从食物中获取的钙。许多其他研究并未发现这类健康风险，因此，若要了解钙摄入量过多是否会有危险以及达到多少可能会有危险，还需要做更多研究。
Meanwhile,experts say they are still more concerned that too many Americans aren't getting enough calcium,since the body can't make it on its own.
专家们同时也说，他们更担心的仍然是有太多美国人钙摄入量不足，因为人体无法自己制造钙。
'Unless you take in enough calcium,by mouth,every day,you have to keep borrowing it from your skeleton,so over your lifetime,you need to get enough,'says Dr.Siris.'If you have low bone mass,or are at risk for fractures,you want to minimize any need to take calcium from the skeleton.'
博士说，“除非每天都能经口服摄入充足的钙，否则你不得不一直向骨骼借用钙，所以人一生中必须摄取足够的钙。如果你骨密度低，也就是说有骨折风险的话，你就得尽量避免从骨骼中获取钙。”
How much calcium people need varies by age and gender.Adults generally need 1,000 milligrams daily,rising to 1,200 mg for women over 50 and men over 70,according to guidelines issued in 2010 by the Institute of Medicine,an independent advisory group.Children need 1,300 mg daily during the peak growing years of 9 to 18.
人体需要的钙量依年龄和性别而有不同。根据独立顾问组织药学研究所(Institute of Medicine)2010年发布的指导原则，成年人一般需要每天摄入1,000毫克钙，50岁以上的女性和70岁以上的男性每天需要摄入的钙量会增加到1,200毫克。孩子在九到18岁的生长高峰期每天需要1,300毫克钙。
People also need sufficient levels of vitamin D to absorb the calcium.The IOM recommends 600 international units a day for most adults,and 800 daily after age 70,although many physicians recommend more.It is difficult to take in that much vitamin D from food sources,and prolonged sun exposure,the best source of vitamin D,can lead to skin cancer,so experts say many people should take vitamin D in supplement form.
人体要吸收钙，还需要摄取充足的维生素D。药学研究所建议多数成年人每天摄入600国际单位的维生素D，并建议70岁以上的人每天摄入800国际单位，不过许多医生推荐的摄取量要大于这个数。从食物中摄入这么多的维生素D很难，而长时间阳光照射(维生素D的最佳来源)可能导致皮肤癌，因此专家称，许多人都应该服用维生素D补充剂。
Getting adequate calcium from food is easier.For example,8 ounces of milk or 6 ounces of yogurt has 300 mg of calcium,and one cup of spinach has 270 mg.But studies show on average,Americans get only about 750 mg of calcium from their diets.
从食物中获取充足的钙则比较简单。比方说，八盎司牛奶或六盎司酸奶中含有300毫克钙，半品脱菠菜中含有270毫克钙。但研究显示，美国人平均只能从食物中获得约750毫克钙。
Many of the more than 30 million Americans who are lactose intolerant don't get
逾3,000万乳糖不耐受的美国人无法获得充足的钙，或者要依赖钙补充剂。
'For people who can't or won't get more in their diet,it's better to fill that gap with supplements than to stay on the low side,'says Bess Dawson-Hughes,director of the Bone Metabolism Laboratory at the USDA Nutrition Center at Tufts University.
塔夫茨大学(Tufts University)美国农业部营养中心(USDA Nutrition Center)
骨骼新陈代谢实验室(Bone Metabolism Laboratory)主任说，“对无法或没能通过饮食摄取更多钙的人来说，用营养片剂来补钙比缺钙要好。”
Consuming too little calcium can contribute to osteoporosis,a thinning of the bones that causes more than 2 million fractures a year.Once osteoporosis sets in,taking extra calcium and vitamin D won't prevent fractures.But not getting enough of the nutrients can make bone loss worse.
摄入钙量过少会引起骨质疏松，骨质疏松症导致每年逾200万例骨折事件发生。一旦得了骨质疏松症，即使摄入额外的钙和维生素D也无助于防范骨折。但如果这些营养物质摄入不足的话，骨耗损会加重。
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