视频文本
It is thought to improve muscle strength and
据说，它能够改善肌肉力量
immune function and reduce inflammation.
提高免疫功能，以及治疗炎症
People at risk for vitamin D deficiency include
容易缺乏维生素D的人群
breastfed infants, older adults, people
包括母乳喂养的婴儿，老人
with limited sun exposure, people with dark skin
接受日照有限者，深肤色的人
and people with fat malabsorption. People age 50
以及脂肪吸收不良的人
and older are at increased risk of developing
50岁以后，缺乏维生素D的几率会增大
vitamin D deficiency because as they age
因为随着年龄的增长
the skin loses its ability to synthesize vitamin D
皮肤会失去有效率地合成维生素D的能力
as efficiently and the kidneys also convert
肾脏向激活型的转化也会减少
less to its active form. People living in
居住北半球的人们，居家人士
the northern latitudes, homebound individuals
以及那些因为宗教原因
and women who wear long robes and
穿长袍，带头巾的妇女
head coverings for religious reasons may not
也许无法获得来自于阳光的充足的维生素D
obtain adequate levels of vitamin D from sunlight.
也许无法获得来自于阳光的充足的维生素D
People with darker skin have more pigment melanin
肤色较深的人们有更多的黑色素
which reduces the skin's ability to produce
黑色素会降低皮肤在太阳照射下
vitamin D after sun exposure.
生成维生素D的能力
Prolonged inadequate intake of vitamin D
长期的维生素D摄入不足
will lead to impaired bone metabolism.
会导致骨骼新陈代谢受损
In children under mineralization of bone causes
对于处于骨骼矿化时期的孩子
soft and deformed bones and can lead to
维生素D摄入不足会导致软骨和畸形骨骼
the condition known as rickets. Rickets is rare
可能会发展成为佝偻病
in the US today but was fairly common
佝偻病在今天的美国是很少见到的
as recently as 100 years ago. When children developed
但是在100年前，这一疾病在美国是很常见的
rickets their legs were too weak to hold their weight
当儿童患有佝偻病时，他们的腿会疲软无力
resulting in bowed legs which often persisted
不能够支撑起他们的体重，最后导致双腿的弯曲
into adulthood. Osteomalacia is the adult form
这种情况会一直持续到成年时期
of rickets and leads to impaired mobility
软骨病是佝偻病成年化的形式
and bone fractures. And osteoporosis is the condition
会导致活动障碍和骨折
that leads to weak and porous bones.
软骨病会导致脆弱和疏松骨质
Calcium is the most abundant mineral in the body.
钙是人体最为丰富的矿物质
There are two major roles for calcium.
它有两个主要用途
By far the majority of calcium found in the body
到目前为止，研究发现
is stored in the bones and teeth providing
身体里大部分钙都贮藏在骨骼和牙齿中
structural support. However there is a very small
起到支撑身体结构的作用
and tightly controlled amount of calcium that
然而，还有一小部分钙在血液里循环
circulates in the blood. This calcium is required for
血液钙含量得到严格的控制
muscles to contract, blood vessels to expand
血液里的钙质帮助肌肉收缩
and contract, secretion of hormones and enzymes
帮助血管扩张和收缩
and transmission of impulses throughout
促进荷尔蒙和酶的分泌
the nervous system. All these functions are supported
并且帮助传播神经系统里的脉冲
with less than 1% of the total body calcium.
所有这些功能只用到了人体中全部钙质的1%
A wide range of people may be at risk for
许多人也许会因为缺钙
calcium deficiency. Children and youth require
而威胁身体健康
adequate amounts of calcium to ensure proper
儿童和青少年需要充足的钙量
bone development. Consumption of dairy products,
来保证正常的骨骼发育，在骨骼发育的时期
particularly milk, during these developmental years
乳制品，尤其是牛奶的摄入是非常重要的
is of great importance. As adults bone mineral loss
在衰老过程中，成年人骨骼中矿物质的流失
begins to exceed accumulation in the natural
超过了它的积累
aging process. Post-menopausal women and
绝经后的妇女以及老年人
the elderly can become at risk of calcium deficiency
会出现钙缺乏
associated with bone loss. People with poor diets,
并伴随着骨质疏松，这会给健康带来威胁
particularly lacking in dairy foods due to
膳食质量差的人，尤其是因乳糖不耐症
lactose intolerance or vegetarianism may also be
而缺乏乳制品摄入的人，或者素食主义
at risk for calcium deficiency. If dairy foods
可能会因为钙缺乏而对健康造成隐患
are not tolerated calcium supplements
如果无法食用乳制品
should be considered at any age.
那么很早的年纪就应该考虑食用钙补充剂

视频及简介

视频简介：

本课程的目标是，向公众提供最新的有关营养方面的信息和话题，内容涵盖饮食因素对于癌症的影响作用，健康的饮食习惯，学校能提供的营养有哪些，咖啡因与癌症的联系，水果蔬菜与癌症预防等。通过本课程的学习，人们可以学习到健康的生活饮食习惯，在每天的饮食中防癌症于未然