Although vitamin K is a not a well-known vitamin, it has many important functions in the body. It's needed for blood clotting, which helps wounds to heal properly, and increasing evidence is showing that vitamin K is needed to help build strong bones and healthy skin. A recent study found that improved levels of vitamin K2 are associated with improved prostate health, including reduced risk of prostate cancer.

Vitamin K is a fat-soluble vitamin, so it is stored in fatty tissue in the body. Good sources of vitamin K include green leafy vegetables such as broccoli, cabbage, cauliflower, spinach, and vegetable oils, soybeans and cereals. Vitamin K is also produced in our bodies by the bacteria that line the gastrointestinal tract.

There are two main forms of this vitamin; vitamin K1 (also known as phylloquinone) and vitamin K2 (or menaquinone), which is produced by bacteria in the intestines. Synthetic forms of vitamin K are also available- vitamin K3- but this is not suitable for human consumption.

Health Benefits of Vitamin K

Researchers have found that an improved status of this vitamin in the body is linked to a lower risk of prostate cancer. One of the study authors explained:

"In this nested case-control study including 250 prostate cancer cases and 494 matched controls, we aimed to confirm this cancer-protective effect using serum undercarboxylated osteocalcin (ucOC), a biomarker of vitamin K status inversely associated with vitamin K intake."

And concluded:

"The increased risks of advanced-stage and high-grade prostate cancer with higher serum ucOC/iOC ratio strengthen the findings for dietary menaquinone intake."

Study details:

Nimptsch K, Rohrmann S, Nieters A, Linseisen J. Serum undercarboxylated osteocalcin as biomarker of vitamin K intake and risk of prostate cancer: a nested case-control study in the Heidelberg cohort of the European prospective investigation into cancer and nutrition. Cancer Epidemiology, Biomarkers & Prevention 2009, Volume 18, Number 1, Pages 49-56

Last year, the same researchers reported that increased intakes of vitamin K2, but not K1, were associated with a 35 per cent reduction in prostate cancer risk. The potential benefits of K2 were more pronounced for advanced prostate cancer.

Vitamin K also helps the body to absorb the beneficial mineral calcium. Recent studies have suggested that vitamin K can help prevent or treat osteoporosis and the loss of bone density. Several human trials have shown that vitamin K also has preventive and treatment benefits for cancer.

A further study found that increased intake of vitamin K1, and to a lesser extend vitamin D, was associated with protecting against inflammation, and positively effected chronic disease risk, as the lead author explained:

"Our findings provide one potential alternative mechanism for a putative protective effect of vitamin K in the progression of cardiovascular disease and osteoporosis, since both diseases are characterized by inflammation."

Study details:

Shea MK, et al. Vitamin K and vitamin D Status: Associations with Inflammatory Markers in the Framingham Offspring Study. Am J Epidemiol. 2008 Feb 1;167(3):313-20. Epub 2007 Nov 15.

The vitamin is less well known than the vitamins A to E, but an increasing body of research is showing that this vitamin as just as beneficial for health and is an important addition to the diet.

References

• Gast GC, et al. A high menaquinone reduces the incidence of coronary heart disease in women. Nutr Metab Cardiovasc Dis. 2009 Feb 28

• Nimptsch K, Rohrmann S, Linseisen J. Dietary intake of vitamin K and risk of prostate cancer in the Heidelberg cohort of the European Prospective Investigation into cancer and nutrition (EPIC-Heidelberg). Am J Clinical nutrition April 2008, Volume 87, Number 4, Pages 985-992

• Cranenburg ECM, Schurgers LJ, Vermeer C. Vitamin K: The coagulation vitamin that became omnipotent. Thrombosis and Haemostasis July 2007, Volume 98, Issue 1, Pages 120-125