Repeating earlier work in Europeans, they compared the genetic profiles of Japanese groups of prostate cancer sufferers with non-sufferers. . . . The joint numbers included 7,141 prostate cancer sufferers and 11,804 non-sufferers. The most recently identified loci are on chromosomes 11, 10, 3 and 2. . . .The locus on chromosome 2 is linked with GGCX, a vitamin K-dependent [actually, vitamin K2] enzyme that regulates blood clotting [Vitamin K2 does not regulate blood clotting], bone formation and cancer biology. Japanese foods such as natto and seaweeds are rich in vitamin K, which is thought to protect against cancer. Interestingly, the association of this SNP with prostate cancer was significant in all populations except for the Japanese in the USA, indicating that environmental factors, such as diet, are involved.
Here is the paper. Why would the correlation not show up for Japanese in the USA? Maybe because Japanese in the USA all get too little Vitamin K2.
Neither the press release nor the article make clear what I am saying: These results make it a lot more plausible that Vitamin K2 protects against prostate cancer. A lot of mainstream nutritional advice is based on epidemiology. The K2/prostate cancer connection is especially interesting because it does not suffer from the usual problems of epidemiology: difficulty measuring intake (do you have any idea how much K2 you consume?) and vast confounding (Vitamin K2 intake is probably correlated with many other things).