在重新看美国国立癌症研究所官网上关于大蒜防癌的网页http://www.cancer.gov/cancertopics/factsheet/prevention/garlic-and-cancer-prevention

，上面列出的唯一真正有效的随机试验是2004年发表的在《中华医学杂志》英文版上的。NCI是这么总结的：

In one study, which involved over 5,000 Chinese men and women at high risk for stomach cancer, researchers compared the effects of taking a combination of 200 mg synthetic allitridum (an extract of garlic used as a medicine in China for over 3,000 years) daily and 100 micrograms selenium every other day with taking a placebo (an inactive substance or treatment that looks the same as, and is given the same way as, an active drug or treatment being tested) for 5years. In the group that received allitridum and selenium, the risk for all tumors combined was reduced by 33 percent and the risk for stomach cancer was reduced by 52 percent in comparison with the group that received only the placebo (13).

看看怎么吃蒜的：每天200毫克大蒜素、每两天100微克硒，吃了5年。

13引用的是Li H, Li HQ, Wang Y, et al. An intervention study to prevent gastric cancer by micro-selenium and large dose of allitridum. Chinese Medical Journal (English) 2004; 117(8):1155–1160. 

好吧，看看原文http://www.cmj.org/ch/reader/view_abstract.aspx?file_no=200481155&flag=1

上面是这么说的：

Each person of the intervention group orally took 200 mg synthetic allitridum every day and 100 μg selenium every other day for one month of each year during November 1989 to December 1991.

看看怎么吃蒜的：每天200毫克大蒜素、每2天100微克硒，只吃1个月，连续吃了3年。

尼玛，NCI管官博的是临时工吧？

3年中每年只吃1个月到了NCI那里成了5年中天天吃。

为什么会出现这种低级错误？是因为按正常的思维，每年吃1个月的蒜也能防癌的话，猪都会笑的。

论文的结果是玩统计游戏罢了，例如最后结论说对男性有效，因为介入组发现42例男性肿瘤，对照组65例，减少了35%。但对女性无效。为什么无效？因为介入组发现21例女性肿瘤，对照组14例，增加了50%。是不是可以理解为女性吃蒜能致癌呀？