New European EPIC study , just published.
24 thousand participants, over 10 years, 28% reduction in cancer mortality, mostly associated with prostate and lung cancers. Only dairy (not vegetable) source of vitamin K had any effect.
24,340 participants aged 35–64 y and free of cancer at enrollment (1994–1998) were actively followed up for cancer incidence and mortality through 2008. Dietary vitamin K intake was estimated from food-frequency questionnaires completed at baseline by using HPLC-based food-composition data.
Results: During a median follow-up time of >10 y, 1755 incident cancer cases occurred, of which 458 were fatal. Dietary intake of menaquinones was nonsignificantly inversely associated with overall cancer incidence (HR for the highest compared with the lowest quartile: 0.86; 95% CI: 0.73, 1.01; P for trend = 0.08[*]), and the association was stronger for cancer mortality (HR: 0.72; 95% CI: 0.53, 0.98; P for trend = 0.03). Cancer risk reduction with increasing intake of menaquinones was more pronounced in men than in women, mainly driven by significant inverse associations with prostate (P for trend = 0.03) and lung (P for trend = 0.002) cancer. We found no association with phylloquinone intake[**].
Conclusion: These findings suggest that dietary intake of menaquinones[**], which is highly determined by the consumption of cheese, is associated with a reduced risk of incident and fatal cancer.
*) Accepted threshold for "significance" is P<=0.05 that is probability of the result being by chance are less or equal than 5%. P=0.08 means that the total cancer incidence results were also close to being significant, with the probability of being false of 8%.
**) Phylloquinone is the form of vitamin K (K1) that is present in plants. Menaquinones are forms of K2 present in non-plant food sources such as meat, organ meat and dairy (MK-4) or some types of yeasts (MK-7, MK-9).
It is interesting to reflect at this stage at the infamous "The China Study" book by Dr. T.C. Cambpell from Cornell University. For many years Campbell has been claiming that cheese (specifically caseine) supposedly caused cancer in his experimental mice and it was also presumed to be certain, according to him, to cause cancer in humans. Countless of vegans must have used Campbell's book to justify avoiding all dairy products.
Now it turnes out that the China Study must have been a mistake. Some people like Chris Masterjohn, have been pointing that out in the past, to no avail probably due to high academic credibility of the book author. (*)
False knowledge seems to be more harmful than no knowledge.
Am J Clin Nutr. 2010 May;91(5):1348-58. Epub 2010 Mar 24.
"Dietary vitamin K intake in relation to cancer incidence and mortality: results from the Heidelberg cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC-Heidelberg)."
Nimptsch K, Rohrmann S, Kaaks R, Linseisen J.
*) Updated 12-July-2010 - see also this post .