中老年人是否应该补钙和维生素D?

One of the most contentious questions in nutrition science over the past decade has been whether older adults should be taking supplemental vitamin D and calcium.

过去十年来，在营养科学中，有一个问题颇具争议：中老年人是否应该补钙和维生素D?

As the world's population ages and broken bones and fractures become even more of a public health concern, with huge social and economic consequences, researchers have been trying to make sense of conflicting studies on the association between supplements and fracture risk.

随着世界人口老龄化，骨折成为了公众健康问题。许多研究试图探索营养补充和骨折风险之间的联系，但得出了矛盾的结论。

A study published in the Journal of the American Medical Association on Tuesday took a fresh look at this issue by analysing 33 randomised clinical trials involving a total of more than 50,000 adults over the age of 50.

最近，中国研究人员分析了33个随机临床研究，其中涉及超过5万名50岁以上的中老年人，并将分析结果发表在《美国医学会杂志》上。

Each of these previous research papers involved comparing calcium, vitamin D, or both, with a placebo or no treatment.

其中，每一项研究都将钙或维生素D(或两者兼有)和安慰剂或无治疗进行对比。

The analysis, conducted by Jia-Guo Zhao of Tianjin Hospital in China, was focussed on older adults who live in the general community and did not include those in nursing homes, hospitals, and other facilities.

研究人员重点关注居住在普通小区里的中老年人，而不包括那些住进养老院、医院的人。

The conclusion was clear: vitamin D and calcium supplements do not seem to be warranted to prevent bone breaks or hip fractures in those adults. Such supplements had no clear benefit regardless of dose, the gender of the patient, history of fractures, or the amount of calcium in the diet.

结果非常明确：对中老年人来说，补钙和维生素D无法预防骨折。无论剂量大小、性别几何、是否有过骨折史、饮食含钙量多少，这两种营养补充品都无法带来明显的健康益处。

The US Preventive Services Task Force, an influential federal advisory body, has raised questions about these supplements since 2013, when it issued recommendations saying evidence to support the benefit of the supplements in older adults without osteoporosis or vitamin D deficiency was "insufficient".

其实，营养学家早就提醒过人们，骨骼健康涉及到许多方面。若想保护骨骼，应该健康饮食、进行负重锻炼，避免过度饮酒，避免抽烟。

Marion Nestle, a professor emerita of food sciences and nutrition at New York University, wrote in an opinion piece at that time that the UPSTF's statement should caution clinicians "to think carefully before advising calcium and vitamin D supplementation for healthy individuals".

纽约大学食品科学与营养学教授玛丽恩Nestle在当时的一篇评论文章中写道，UPSTF的声明应该提醒临床医生“在为健康个体提供钙和维生素D补充之前要慎重考虑”。

She said this week bone health involves many different aspects of eating and activity.

她说，本周骨骼健康涉及饮食和活动的许多不同方面。

"Bone preservation throughout life requires eating healthfully, engaging in weight-bearing activity, avoiding excessive alcohol, and not smoking - good advice for everyone," Nestle said.

其实，营养学家早就提醒过人们，骨骼健康涉及到许多方面。若想保护骨骼，应该健康饮食、进行负重锻炼，避免过度饮酒，避免抽烟。

Vitamin D is not a vitamin but a hormone that is produced in reaction to sunlight and seems to have many different roles in the body related to bones, cancer, heart disease, diabetes, immune function, and reproductive health.

维生素D是一种类固醇激素，能够通过晒太阳分泌。它在许多方面起到不同的作用，包括骨骼、癌症、心脏病、糖尿病、免疫功能、生殖健康。

Daniel Fabricant, president of the Natural Products Association, which represents manufacturers and retailers of dietary supplements, said the study draws its conclusions with "too broad of a brush".He said it focusses on the healthiest segment of the population by looking at people who are able to live at home."There is a lot missing," Fabricant said. "People with prior breaks or family incidence of osteoporosis may still need vitamin D."

针对这项研究，也有营养学家提出质疑，认为结论太过粗泛，只关注健康人群，忽略了很大一部分中老年人。那些有过骨折史或家人患过骨质疏松症的人也许依然需要补充维生素D。

Calcium and vitamin D have been known to be important to bone maintenance for a long time, and the best way to get the daily recommended doses are the natural way.

钙和维生素D对骨质健康很重要，这点没错，但最好通过天然方式进行补充。

For calcium, that means eating dairy products like milk, cheese, yogurt or calcium-rich leafy greens. For vitamin D, that means getting some sun exposure. Only a few foods contain vitamin D, and they include fatty fish like salmon.

想补钙，就多食用乳制品，如牛奶、芝士、酸乳等。想补充维生素D，就多晒太阳。含维生素D的食物很少，其中包括鲑鱼。

In 2010, the Institute of Medicine (IOM) released recommendations tripling the daily intake of vitamin D for most people to 600 IU per day and raising the calcium intake to 1,000 milligrams.

2010年，美国医学研究所公布了每日推荐摄入量——维生素D为600IU，钙为1,000毫克。