One More Reason to Eat Leafy Greens

In the first study of vitamin K and Non-Hodgkin lymphoma : ( www.mayoclinic.org/non-hodgkins-lymphoma/ : ) risk, researchers at the Mayo Clinic campus in Minnesota have found that people who have higher intakes of vitamin K from their diet have a lower risk of developing Non-Hodgkin lymphoma. At the 101st Annual Meeting of the American Association for Cancer Research (AACR), the researchers report that the risk of developing Non-Hodgkin lymphoma was approximately 45 percent lower for participants who had vitamin K intakes in the top quartile of intake in the study (>108 ug/day), compared to participants who had intakes in the bottom quartile (<39 ug/day).

While vitamin K is best known for its essential function in several proteins involved in blood clotting (the name of the vitamin is derived from the German word “Koagulations”), it also appears to be important in other biological processes, including inhibition of inflammatory cytokines thought to play a role in Non-Hodgkin lymphoma, as well as pathways involved in cell cycle arrest and cell death.

“These results are provocative, since they are the first work we have done on the connection between vitamin K and Non-Hodgkin lymphoma, and this is a fairly strong protective effect,” says the study’s lead investigator, James Cerhan, M.D., Ph.D, a cancer epidemiologist. “However, as with all new findings, this will need to be replicated in other studies.”

Vitamin K is a fat-soluble vitamin and is derived from either plants (phylloquinone or vitamin K1) or bacterial synthesis. This study estimated intake of the plant form of vitamin K from diet and supplement use. The most common sources of vitamin K1 in the diet include leaf lettuce and spinach, with smaller amounts found in other vegetables, vegetable oils and some fruits.

“Whether the protective effect we observed is due to vitamin K intake, or some other dietary or lifestyle exposure, cannot be definitely assessed in this study,” notes Dr. Cerhan. “But these findings add to a lot of other data that support a diet that includes plenty of green leafy vegetables in order to prevent many cancers as well as other diseases.”