美国罗彻斯特大学医学中心(University of Rochester Medical Center)的研究团队,调查了387位在2000到2005年怀孕的妇女,发现在怀孕期间摄取大量牛肉(每周吃超过七份牛肉)的妇女,其儿子的精虫浓度会比一般标准值低24.3%,其中有18%的人被WHO判定为不孕(sub-fertile)。研究人员认为罪魁祸首应是饲养牛只的饲料或饲草含有的杀虫剂、污染物,或饲主为了使牛只快速生长而施打的荷尔蒙。此研究发表于Human Reproduction期刊。
Shanna Swan博士说:「虽然在研究中发现怀孕妇女吃大量牛肉会导致其子的精虫浓度降低的现象,但这个现象仍需持续仔细的追踪及分析,才能有所结论,因为男子的精虫浓度过低可能和很多因子都有相关性。」不过,一份先前在动物模式的研究中,的确已证实环境荷尔蒙会降低动物的精虫数目。
这项研究从2000年就开始进行,研究人员设计了一些问卷给那些精虫受测者的母亲填写,Swan自己也承认这份研究在某些程度上是有瑕疵的,因为许多的数据来源是藉由这些母亲们回忆而得到的,不过,Swan也确信,大部份的怀孕妇女都会特别留意什么食物该吃或吃的最多。Swan研究团队接下来要调查的对象,是住在欧盟的年轻男性,因为欧盟在1988年就禁止在牛只身上施打荷尔蒙。藉由这些后续的研究来验证怀孕妇女吃牛肉与其子精虫数减少之间的关联性。 (资料来源 : Reuters)
英文原文:
Eat a lot of beef? It may affect your son's sperm
Wed Mar 28, 2007 3:55AM EDT
By Maggie Fox, Health and Science Editor
WASHINGTON (Reuters) - U.S. women who eat a lot of beef while pregnant give birth to sons who grow up to have low sperm counts, researchers reported on Tuesday.
They believe pesticides, hormones or contaminants in cattle feed may be to blame. Chemicals can build up in the fat of animals that eat contaminated feed or grass, and cattle were and are routinely given hormones to boost their growth.
"In sons of 'high beef consumers' (more than seven beef meals/week), sperm concentration was 24.3 percent lower," the researchers wrote in their report, published in the journal Human Reproduction.
The team at the University of Rochester Medical Center in New York studied data on the partners of 387 pregnant women in five U.S. cities between 2000 and 2005, and on the mothers of the fathers-to-be.
Of the 51 men whose mothers remembered eating the most beef, 18 percent had sperm counts classified by the World Health Organization as sub-fertile.
"The average sperm concentration of the men in our study went down as their mothers' beef intake went up. But this needs to be followed carefully before we can draw any conclusions," said Shanna Swan, who led the team.
Swan said she would like to study infertile men to see if similar findings might hold for them.
"I was really surprised when we found this. It was a really strong association," Swan said in a telephone interview.
Swan is perhaps best known for controversial findings that male sperm counts are falling in many regions. She has been doing research to find out if environmental hormones may be to blame.
"We know from rodent studies that even tiny amounts of estrogen in utero (while in the womb) can affect sperm count," Swan said.