In 1935 a scientist in Copenhagen observed that newly hatched chickens receiving a diet containing all of the known essential nutrients were developing a bleeding disorder. He soon discovered that the chicks were deficient in a nutrient that is crucial for normal blood clotting. He called this nutrient vitamin K. Vitamin K refers to a group of three vitamins called the quinones. Vitamin K1 is produced in plants and is scientifically known as phytonadione, phylloquinone and phytomenadione. Vitamin K2 is produced in animals and is scientifically known as menaquinone. Vitamin K3 is synthetically produced and is scientifically known as menadione. Today, vitamin K deficiency is rare, except in infants, for whom such a deficiency can be fatal. The best sources of vitamin K are liver, green leafy vegetables, members of the cabbage family and most cheeses.
Prostate cancer is the most common form of cancer, excluding skin cancer, in men in the United States. It is primarily diagnosed in men over 65, although it may begin much earlier. Some cancers of the prostate are very slow growing, while others behave aggressively. Prostate cancer often metastasizes to other tissue, including the brain, lungs, lymph nodes, and bones. Early detection is critical in order to increase the chances for survival. The cancer can be felt upon digital rectal examination (DRE). These examinations are recommended routinely for all men over the age of 50 and high-risk men should commence at age 40.
A study based on data from the European Prospective Investigation into Cancer and Nutrition was published in the American Journal of Clinical Nutrition evaluating the link between vitamin K and prostate cancer. The trial involved 11,319 men, a food-frequency questionnaire was used to determine the amount of dietary intake of vitamin K1 (phylloquinone) and vitamin K2 (menaquinone) and a follow-up time of 8.6 years. The results were a 35 percent reduction in prostate cancer risk when there was a higher intake of vitamin K2. Also, a 63 percent reduction in advanced prostate cancer risk was associated with higher intakes of vitamin K2. A link was not found between higher intakes of vitamin K1 and reduced prostate cancer risk. The authors stated that their “results suggest an inverse association between the intake of menaquinones, but not that of phylloquinone, and prostate cancer. Further studies of dietary vitamin K and prostate cancer are warranted.”1
1 Nimptsch K, Rohrmann S, Linseisen J. Dietary Intake of vitamin K and risk of prostate cancer in the Heidleberg cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC-Heidleberg). Am J Clin Nutr. Apr2008;87(4):985-992.