News - Vitamin K2 may reduce cancer risk
The recently-published European Prospective Investigation into Cancer and Nutrition study has found that those with the highest intakes of vitamin K2, but not vitamin K1, have a reduced risk of both overall cancer and cancer mortality.
There are two main forms of vitamin K: phylloquinone, also known as vitamin K1, and the menaquinone family of compounds, collectively known as vitamin K2. K1 is found in green leafy vegetables such as lettuce, broccoli and spinach and makes up about 90% of the vitamin K in a typical Western diet, while K2 is found in fermented foods, such as the Japanese food natto. Cheese and meat are also good food sources of vitamin K2, but they are often limited in the diet, due to their high saturated fat content.
The study, led by Jakob Linseisen from the German Research Centre for Environmental Health, analysed data from 24,340 participants, aged between 35 and 64, free of cancer on enrolment. At baseline, the participants were provided with a food frequency questionnaire. Using food composition data, Linseisen et al. calculated dietary intakes of phylloquinone and menaquinones at regular time intervals during the study. The participants were followed for over 10 years, during which time 1,755 cases of cancer were documented, 458 of which turned out to be fatal cases.
The results showed that cancer incidence and cancer mortality decreased with higher intakes of menaquinones. Phylloquinone, however, was not associated with a decreased cancer risk. The significant inverse association between menaquinone intake and lung and prostate cancers meant that the cancer risk reduction was more pronounced in men. The study states that dietary intake of menaquinones was more strongly inversely associated with fatal cancer than with cancer incidence. It is suggested that this is similar to previous studies, which have suggested that factors affecting apoptosis and cell cycle arrest are likely to play a role, later, in carcinogenesis.
J. Linseisen et al. (2010) 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) American Journal of Clinical Nutrition. Epub ahead of print.