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There is recent evidence that adequate
有新研究证明，膳食中充足的维生素D含量
levels of vitamin D in the diet may play a role
能够在某些癌症的防治方面起到作用
in the prevention of certain cancers. Thus far
能够在某些癌症的防治方面起到作用
the best studied role for vitamin D has been found
迄今为止，研究发现，维生素D的最显著作用
in cancers of the colon and breast.
是对于结肠癌和乳腺癌的防治
In general vitamin D plays a role
总之，维生素D在维持健康细胞方面
in maintaining healthy cells and
能够起到作用
when vitamin D levels are low
当维生素D水平比较低时
these protective effects may be compromised.
保护的效果就会弱化
Early studies that correlated cancer incidence
早期的研究将癌症发病率
with sun exposure rates in populations
和人口的阳光照射率相联系
began the search for a role of vitamin D in cancer.
这开始了对维生素D在癌症防治方面的探索
This map illustrates the colon cancer mortality rates
这个地图展示了美国各地的
in men throughout the United States.
直肠癌死亡率
Areas shown in red have the highest colon cancer
红色的区域表示的是直肠癌死亡率最高的地区
mortalities while those in blue have the lowest.
蓝色的区域则是最低的区域
It is fairly clear that states in the north
这幅图清晰地向我们展示了
and eastern parts of the US, those with
在美国北部和东部
the longest winters, have the higher colon cancer
那些冬天最长的地区，直肠癌死亡率相对较高
mortality rates. Vitamin D may have a role
维生素D可能在癌症防治方面
in cancer prevention. The graph above came
是起到作用的
form an epidemiological study and shows
上面这个来自于流行病学研究的图表
geographic correlation. And inverse relationship
展示了地理上的关联
was found between sunlight exposure levels and
阳关照射率和某些癌症的发病
the rates of incidence and death for certain cancers.
和死亡率呈反比
Individuals living in northern latitudes
在北半球生活的人们要比在南半球生活的人们
were found to have higher rates of incidence
比在南半球生活的人们
and death for these cancers than those living
有更高的癌症发病率
in the southern latitudes. The researchers
和死亡率
hypothesized that this is because UV B rays from
研究人员猜测该现象的原因是
sunlight are necessary to synthesize vitamin D.
阳光的紫外线对于合成维生素D是必要条件
This map illustrates the mortality of white females
这幅地图体现的是 1970年到1994年
due to breast cancer from 1970 to 1994.
白人女性的乳腺癌死亡率
As shown here there is a correlation
此图展示了美国北部，东北部和西部的
between the northern, northeastern and
一些州之间的关联
some western states and increased rates
以及增长的乳腺癌发病率
of breast cancer. Again areas shown in red
红色的区域仍然表示的是
have the highest breast cancer mortalities
是乳腺癌死亡率最高的地区
while those in blue have the lowest.
蓝色的区域则是最低的区域
Most of the southern states are bright blue
南部的大部分州都是明亮的蓝色
suggesting much lower incidence of breast cancer.
表明那里的乳腺癌发病率相对来说是很低的
The graph above came from the same
这幅图表与之前幻灯片展示的那幅图表
epidemiological study as shown on the previous slide.
来自于同一个流行病学研究
And again shows the geographic correlation.
这幅图表再一次展现了地理上的关联
And inverse relationship was found
以及太阳照射率和某些癌症的
between sunlight exposure levels and
发病和死亡率
the rates of incidence and death for certain cancers.
成反比
The exact role of vitamin D in cancer prevention
人们对维生素D在癌症防治方面的确切作用
is still unclear. However researchers know
还不是很清楚，但是研究人员知道
that vitamin D plays an integral role in
维生素D在细胞分化上起到了全部作用
cellular differentiation. Increased levels of vitamin D
维生素D水平的提高
decrease the growth of cancer cells and
能够抑制癌细胞的扩散
stimulate cell death. Most vitamin D cancer research
加快癌细胞死亡,大多数已经完成的
that has been done is observational and
与维生素D相关的癌症研究都是在观察性研究
more epidemiological studies are needed
为了支持这些已有的发现
to support the findings that have been made.
还要进行更多流行病学研究
Observational studies include things like
观察性研究包括食物摄取频率问卷
food frequency questionnaires, interviews
访谈，记录饮食摄入量等内容
and recording dietary intakes which are
这些形式都会出现
all subject to a large amount of misinformation and
大量的错误信息
error. Epidemiological studies are aimed where possible
流行病学研究目的是在可能的情况下
at revealing unbiased relationships between
揭示???与癌症发病率和死亡率之间
exposures such as biological agents, stress
的同等关系，例如生物制剂
or chemicals to mortality or morbidity.
压力以及化学制品等
