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。

　　On the other hand,it is easy to consume more than the 2,000 mg a day that the IOM considers the safe upper limit for adults.'A number of health-care providers say,'Oh,the requirement is 1,200 mg daily,so take 1,200 mg in supplements,'regardless of what the patient is consuming in food,'says Dr.Dawson-Hughes.'If you have a bowl of Total in the morning and a yogurt and a glass of milk for lunch,you can get to 2,000 mg easily.'Multivitamins also contain calcium in widely varying amounts.Chewable chocolate,caramel and gummy-bear varieties have made calcium supplements as appealing as candy.

　　从另一方面来说，人一天的钙摄入量很容易超出2,000毫克(被药学研究所视为成年人的安全上限)。博士说，“许多医疗服务机构会说，‘哦，一天必须摄入1,200毫克钙，所以要服用1,200毫克补充剂，’他们不管患者吃的是什么样的饮食。如果你早晨喝一碗Total牌谷物片，中餐喝一盒酸奶和一杯牛奶的话，很容易就能摄入2,000毫克钙。”复合维生素片中也或多或少地含有钙。钙补充剂能制成可以嚼着吃的巧克力、太妃糖和小熊糖等品种，像糖果一样吸引人。

　　任何人体无法吸收的维生素或者矿物质都会被排泄出去

　　In general,any vitamins or minerals the body can't absorb are simply excreted.But studies linking calcium supplements to heart attack and kidney stones have made experts more wary of excess calcium than before.

　　总体而言，任何人体无法吸收的维生素或者矿物质都会被排泄出去。但由于研究发现钙补充剂与心脏病和肾结石存在关联，专家们对过量摄入钙这一问题比从前更加警惕。

　　In a 2006 report from the Women's Health Initiative,a large government study,women who took 1,000 mg of calcium daily had 17%more kidney stones than those who got a placebo.But subjects were allowed to eat their usual diet,and take calcium supplements on their own,no matter what group they were in,so their total calcium intake was unknown.

　　大型政府研究项目“妇女健康倡议”(Women's Health Initiative)2006年的一份报告显示，每日服用1,000毫克钙补充剂的女性患肾结石的风险比服用安慰剂的女性高17%。不过在此项研究中，两个组别的实验对象都被允许按照她们的日常饮食习惯来吃东西，钙补充剂也是自行服用，因此她们摄入的钙的总量是未知的。

　　In the 12-year Nurses'Health Study of 90,000 women,those who consumed a high level of calcium in food had fewer kidney stones than those who consumed less.

　　为期12年的“护士健康研究”(Nurses'Health Study)对九万名女性进行了研究，研究发现，从饮食中摄取大量钙的女性患肾结石的风险要低于钙摄入量较少的女性。

　　Studies linking calcium intake and heart-attack risk are similarly confusing.A study of 24,000 Germans published in the journal Heart last month,found that those who consumed about 820 mg of calcium a day had a 31%lower risk of heart attack than those who consumed much less.But those who got their calcium exclusively from supplements were more than twice as likely to have a heart attack as those who took no supplements.

　　揭示钙摄入量与心脏病风险之间关联的研究也令人感到有些困惑。《心脏医学期刊》(Heart)上月刊登了一项针对24,000名德国人的研究，研究发现，每日摄入约820毫克钙的人患心脏病的风险比摄入量少得多的人低31%。但仅从补充剂中摄取钙的人患心脏病的风险则比不服用任何补充剂的人高出一倍以上。

　　In 2010,researchers in New Zealand analyzed 11 clinical trials involving 12,000 people,and found that those taking calcium supplements had a 30%higher risk of heart attack than those who didn't.However,the studies didn't include people taking vitamin D,which some researchers believe is protective for the heart.

　　2010年，新西兰的研究人员对涉及12,000名试验对象的11项临床试验进行了分析，发现服用钙补充剂的人患心脏病的风险比不服用钙补充剂的人高30%。然而，相关研究未将服用维生素D的人包括在内，一些研究人员认为，维生素D可保护心脏。

　　钙补充剂究竟是怎么导致心脏病呢?

　　Exactly how calcium supplements might contribute to heart attacks baffles cardiologists.'Nobody has associated the calcium in your bloodstream with calcification in your arteries,'says Nieca Goldberg,medical director of the Joan H.Tisch Center for Women's Health at New York University Langone Medical Center.Still,she says she now urges patients get their recommended calcium from food than from supplements to avoid possible problems.

　　钙补充剂究竟是怎么导致心脏病呢?这个问题令心脏病学家疑惑不解。纽约大学朗格尼医学中心(New York University Langone Medical Center)琼蒂施女性健康中心(Joan H.Tisch Center for Women's Health)的医学主任(Nieca Goldberg)说，“没有人发现血液中的钙与动脉血管钙化有什么联系。”不过，她说她现在会敦促患者通过膳食而非补充剂来摄取推荐量的钙，以避免潜在风险。

　　Osteoporosis experts also urge patients not to take more than the recommended amount of calcium.'Women should definitely stop taking two big calcium supplements a day,'says Dr.Dawson-Hughes.Even if the risks remain unclear,taking more than the body can absorb doesn't benefit bones,'so it's not worth any risk--real,imaginary,uncertain,possible or probably,'she adds.

　　骨质疏松症专家也敦促患者不要摄取超过推荐量的钙。道森休斯博士说，“女性肯定不应该再一天服用两大片钙补充剂了。”即使相关风险我们还不清楚，但摄入超过身体吸收能力的钙对骨骼没有好处，她还说，“所以不值得去冒险──不管是真正的、想象的、不确定的、有一定可能的还是可能性很大的风险。”