加钙食品有助于骨骼成长吗

Giving children foods fortified with calcium to help build up their bones may be a waste of time, say experts.

The mineral is added to many breakfast cereals, snack bars and drinks as manufacturers woo the parental market.

But scientists have found that such products do not produce significantly stronger bones, nor do they reduce the chance of a child suffering fractures. Notefortified: 被添加了...calcium: 钙cereal: 谷类woo: 吸引fracture: 骨折

It is thought that calcium artificially added to food passes through the body too quickly to be properly absorbed and therefore fails to perform the same functions as foods which are naturally rich in calcium, such as milk, cheese and leafy green vegetables.

It is now built into such things as Kellogg's Coco Pops, breakfast bars such as the Frosties Cereal and Milk bar, some Tropicana orange juices and even a calcium-enriched water called Danone Activ. The theory is that if children build strong bones it will protect them better against problems such as osteoporosis in later life. But the research casts doubt on the usefulness of such products. Experts analysed 19 studies where children aged between three and 19 were given extra calcium in their diet in this way. They then measured the impact by measuring their bone mineral density and mineral content.

The team found few significant increases in bone mass and none in the two bones which are most vulnerable to fracture - the lower spine and upper part of the thigh. A small impact was noted in bone density in the arm, but it cut the risk of fracture by just 0.2 per cent, according to the report published in the Cochrane Library. The influential publication is produced by the international health research organisation, the Cochrane Collaboration.

Lead researcher Professor Frank R Greer, of the University of Wisconsin, said the findings for children echo those seen in adult studies. "You can get some short-term improvements but as soon as you stop the supplements it goes right back to where it was," he said. 为了让孩子的骨骼健康成长，给他们吃添加了钙质的食品是众多家长们的选择。而美国有关专家日前表示，这种做法可能纯粹是在浪费时间。

加钙食品有助于骨骼成长？

据英国《每日邮报》4月19日报道，为了吸引家长们购买自己的产品，食品生产商在诸如谷类早餐、小零食以及饮料中都添加了钙这种矿物质。但美国科学家发现，此类食品并不能使骨骼明显变得强壮，同时不能减少孩子们发生骨折的危险。

科学家们认为，这些被人工添加到食品中的钙在人体内快速通过，以致不能被完全吸收。因此，这些人工添加钙质的食品就无法起到和天然富含钙质的食品相同的功效。天然富含钙质的食品包括牛奶、干酪以及多叶的绿色蔬菜等。

报道说，医生曾对众多青少年饮食中的钙摄入量不足的情况提出了警告，在此之后就出现了在食品中添加钙质的这种趋势。现在，一些谷物早餐、果汁饮料甚至是水饮料中都被商家加入了钙质。他们依靠的理论就是，如果想让孩子在日后的生活中不易受到诸如骨质疏松症等疾病的影响，从小就要拥有强壮的骨骼。但是，一项最新研究却对这些食品的有效性提出了置疑。

加钙食品对骨骼作用甚微！

美国有关专家对19项研究进行了分析。在这些研究中，年龄在3岁至19岁不等的儿童或青年通过上述方法补充钙质。随后，通过测量其骨骼矿物密度和矿物含量的方法来检验其补钙的效果。研究小组发现，这些人的骨骼质量几乎没有明显的增强，而两处最易骨折的部位——脊骨下部和大腿骨上部的骨骼质量也未得到改善。尽管研究人员发现，这些被调查者手臂处的骨密度得到了很小的改善，但是这只能将该部位发生骨折的危险降低区区0.2％。

此项研究的负责人、美国维斯康辛大学的弗兰克·格瑞尔教授表示：“你可以从中得到短期的改善，但是一旦停止补充，马上就会回到原来的样子。”