评论
打印
Our next fat soluble vitamin
下一个要说的脂溶性维生素
is often called the sunshine vitamin: vitamin D.
常被叫做阳光维生素:维生素D
Vitamin D is unique among vitamins
在众多维生素中,维生素D之所以独特
because it is produced naturally in the body
是因为阳光照射皮肤时
when skin is exposed to sunlight.
身体能自然地合成维生素D
Sunlight transforms cholesterol
日光将皮肤里存在的胆固醇
which is present in the skin into vitamin D.
转化为维生素D
Theoretically then anyone exposed to sunlight
所以理论上讲,任何一个晒过太阳的人
should have adequate amounts of vitamin D.
体内都应该有充足的维生素D
However this is not the case.
但实际情况并非如此
Recent evidence suggests that most Americans
最新的证据表明大多数美国人
are marginally deficient in vitamin D.
都有轻度缺乏维生素D
This is probably so because most people
这也许是可能因为大多数人
do not receive regular amounts of sun exposure,
没有接受到正常量的阳光照射
especially during the winter.
尤其是在冬季
The body's ability to produce vitamin D
人体合成维生素D的能力
decreases with age and the use of sun screen
随年龄增长而降低,而使用防晒霜
also blocks vitamin D synthesis.
也阻止了维生素D的合成
Vitamin D is important in bone health because
维生素D对于骨骼健康很重要
it enhances calcium absorption in the intestine.
因为它能提高肠道对钙的吸收
Calcium is then the building blocks for bones
而钙是骨骼生长的基石
so adequate vitamin D is needed to
因此人体需要足够的维生素D
properly use calcium for bone mineralization.
来促进骨质矿化
Without adequate vitamin D and calcium
如果体内没有充足的维生素D和钙
risk of osteoporosis and bone factures can occur.
就有患骨质疏松症的危险,容易骨折
Recent research also suggests
近期的研究也表明
vitamin D may have a role in immune function,
维生素D可能对免疫系统
cancer prevention and cardiovascular health.
癌症预防,及心血管健康有一定作用
For the immune system vitamin D may aid
对免疫系统来说,维生素D可能
in the prevention of autoimmune diseases
有助于预防自身免疫病
where the immune system attacks
这种病是由于免疫系统攻击
the body's own cells
自身的细胞
such as inflammatory bowel syndrome
比如炎症性肠病
and inflammatory arthritis.
和发炎性关节炎
Vitamin D also aids the immune system
维生素D还通过
by increasing the body's ability to
提高人体消灭致感染微生物的能力
eliminate microbes which can cause infection.
来增强免疫系统的功能
Vitamin D has also been found to have roles
人们还发现维生素D的其他作用
in preventing cell differentiation
那就是防止细胞分化
and decreasing the production of damaged cells
及减少可能发展为癌细胞的
which could develop into cancer cells.
不正常细胞的产生
In this way recent research has suggested
最近的研究显示
vitamin D may be important
维生素D可能对于
in the prevention of cancer in the breast, prostate,
预防乳腺癌,前列腺癌
stomach, ovary, bladder, esophagus, kidney,
胃癌,卵巢癌,膀胱癌,食道癌,肾癌
lung, pancreas, uterus and other organs.
肺癌,胰腺癌,子宫癌及其他器官的癌症十分重要
The current recommendation for vitamin D
当前对于50岁以下成年人
for adults under the age of 50 is
推荐的维生素D摄入量
200 to 400 IUs or 5 to 10 micrograms.
为200到400国际单位或5到10微克
However a recent research suggests that
但最近的一项研究表明
these levels may not be adequate.
这个摄入量可能不够
The National Research Council is currently discussing
美国国家研究委员会正在讨论
whether to raise the vitamin D recommendations.
是否提高维生素D的推荐摄入量
Research suggests that recommended intake
研究显示对于大多数成年人
should be increased to 1300 IUs per day for most adults,
推荐摄入量应该增加到每天1300国际单位
especially those who are older
尤其是对于年纪更大
or live in a colder climate with a long winter season.
或者生活在冬季较长,气候寒冷环境中的人
There is no evidence that
没有证据表明
increased intake at this level is harmful.
增加到这一水平的摄入量有害
Good food sources of vitamin D are very limited.
好的维生素D的食物来源很有限
Fish and fish oils are among
鱼和鱼油是两种
the most abundant sources of vitamin D.
维生素D含量最充足的食物
Because of the low availability of vitamin D in foods
因为从食物获得维生素D较少
fortification has been done.
就需要有营养强化
Milk and dairy foods with added vitamin D are
添加了维生素D的牛奶和奶制品是
among the most available sources
最常见的食物来源
as are fortified breakfast cereals.
相同的还有强化早餐谷物
Other sources of vitamin D include
其他维生素D的来源有
eggs but only in the yolk and then beef liver.
鸡蛋,不过仅仅是蛋黄,还有牛肝
To ensure adequate vitamin D,
为了确保摄入足量的维生素D
especially in the absence of
尤其是在没有规律地
regular consumption of dairy foods,
食用奶制品的情况下
a dietary supplement may be recommended.
也建议服用一种膳食补充剂
Look for supplements that contain
找找那些维生素D含量
no more than 200% of the RDA for vitamin D.
不多于推荐日摄入量200%的补品
You may also consider a supplement
你也可以考虑
that contains vitamin D and calcium.
含有维生素D和钙的补品
These are especially valuable for women
这些对女性尤其有用
because of the bone strengthening effects.
因为有强健骨骼的效果
Once again as reviewed during this presentation
在这里再次回顾一下这堂课
the fat soluble vitamins are vitamin A, vitamin K,
脂溶性维生素有维生素A,维生素K
vitamin E and vitamin D
维生素E和维生素D
