【第一次来养生版】美加研究报告显示,维生素D和补钙对多数人无意义

Vitamin D, Calcium Supplements Are Unnecessary, U.S.-Canadian Report Says
美加研究报告显示,维生素D和补钙对多数人无意义

Vitamin D, Calcium Supplements Are Unnecessary, U.S.-Canadian Report Says
By Allison Connolly and Elizabeth Lopatto - Dec 1, 2010 12:43 AM

Vitamin D and calcium supplements are unnecessary for most people and may be harmful to some, a study commissioned by the U.S. and Canadian governments found.

While vitamin D and calcium are important for bone health, most residents of North America get enough of both through a diet that includes fortified foods and sun exposure, an expert committee commissioned by the U.S. Institute of Medicine found.

The panel reviewed more than 1,000 studies and comments from scientists in drawing its conclusions. The report said labs that test for vitamin D may overestimate the number of people who are deficient because their tests aren’t based on “rigorous scientific studies.”

“What we concluded may be surprising to some,” said Catherine Ross, the committee chair and a professor of nutrition at Pennsylvania State University, in a news conference. “We couldn’t find solid evidence that consuming more of either nutrient would protect the public from chronic diseases.”

The report was posted today on the Web site of the Washington-based Institute of Medicine, an independent, non- profit group that advises U.S. policy makers and the public.

The committee also found while most people get enough calcium through diet, girls between the ages of 9 and 18 can probably gain health advantages through use of supplements. On the other hand, postmenopausal women taking extra calcium may get too much, raising risks for kidney stones, the panel said.

“Confusion has grown among the public about how much vitamin D is necessary,” the report’s authors said.

Fortifying Food

Some researchers have questioned whether current levels used to fortify food are enough to meet people’s needs, according to the Mayo Clinic website. Recommended intake for adults aged 19 through 70 is 600 IU, and 800 IU for adults 71 years and older, according to the National Institutes of Health.

Almost all milk in the U.S. is fortified with 400 IU of vitamin D per quart, according to the NIH. The vitamin is also added to some breakfast cereals, orange juice, yogurt, margarine, and soy beverages, according to the Office of Dietary Supplements website.

The body also makes vitamin D from the sun, although in the winter in the northern half of the U.S., the sun is not strong enough for vitamin D production. While their diet may not supply enough vitamin D for many people, the sun provides enough to make up the difference, the report said.

People who may not get enough vitamin D can include those with darker skin, older adults, the obese, and those with some digestive disorders such as Crohn’s disease may not get enough vitamin D unless they make an effort, the NIH has said.

美加研究报告显示,维生素D和补钙对多数人无意义


美国和加拿大政府进行的一项研究发现，维生素D和补钙对于大多数人来说并非必要，甚至可能对一些人带来伤害。

虽然维生素D和补钙对于骨健康至关重要，但美国医学研究院的一个专家委员会发现，大多数北美居民通过日常饮食（包括摄入强化食物和日光照射）已摄入足够的维生素D和钙。

该研究小组回顾了超过1000项研究和评论 ，最终得出结论。他们的报告称检测维他命D的实验室可能高估了维生素D缺乏人群的数目，因为他们的检测不是基于严格的科学研究。

Catherine Ross是该委员会的主席，同时是宾夕法尼亚州立大学营养学教授，在一次新闻发布会上，她说：我们的结论可能会使一些人感到惊讶，但我们没有找到确凿证据支持摄入更多的钙或维生素D能使人们远离慢性疾病。

该报告今天被发布在位于华盛顿的美国医学研究院网站上，美国医学研究院是一个非营利性组织，负责为美国政策制定者和公众出谋划策。

该委员会还发现虽然人们通过饮食可摄取足够钙质，但年龄介于9-18岁间的女孩摄入钙补充剂很可能会受益。另一方面，绝经期妇女额外摄入钙剂可能会导致体内钙过多，增加肾结石的风险。

报告的作者们还称：目前公众已经对究竟需要多少维生素D感到困惑不解。

强化食品

据Mayo Clinic网站称，一些研究人员已经质疑目前对食品进行强化的程度是否足以满足人们的需要。据美国国立卫生研究院的建议，19-70岁间成人的推荐摄入量为600IU，71岁以上为800IU。

另据NIH报告，在美国几乎所有牛奶都被加以强化，每品脱添加400IU维生素D。据膳食补充剂事务办公室网站称，维生素D还被添加至某些谷类早餐、橙汁、奶酪、人造黄油和豆类饮品中。

机体可以通过日光合成维生素D，但冬天在北美的一半区域，光照不足以令机体合成足够的维生素D。报告还称，即使膳食可能不能提供多数人所需的维生素D水平， 光照也足以弥补这种不足（膳食和光照可相互补充）

NIH曾称，维生素D摄入不足者可能包括深色皮肤的人、老年人、肥胖者，克隆氏肠病等消化疾病患者除非主动摄取，否者也会摄入不足。

不错，谢谢分享。