Vitamin K may cut lymph cancer risk: US study

20-Apr-2010 - Last updated on 21-Apr-2010 at 09:58 GMT

Increased intakes of vitamin K from dietary and supplementary sources may reduce the risk of cancer of the lymphatic system, according to new findings from the Mayo Clinic.

The risk of developing non-Hodgkin lymphoma was approximately 45 per cent lower in people with a vitamin K intake of at least 108 micrograms a day, compared with people with an intake of less than 39 micrograms per day, according to findings presented at the 101st Annual Meeting of the American Association for Cancer Research (AACR).

“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,” said the study’s lead investigator, James Cerhan, MD, PhD. “However, as with all new findings, this will need to be replicated in other studies.”

Non-Hodgkin lymphoma is a cancer that starts in the lymphatic system and ecompasses about 29 different forms of lymphoma. According to the American Cancer Society, over 50,000 new cases are diagnosed in the US every year.

The new study – the first to report that vitamin K may lower the risk of non-Hodgkin lymphoma – adds to a growing body of data supporting the health benefits of the vitamin, with previous studies reporting improvements in bone, joint and skin health, cardiovascular benefits, and reduced risks of prostate cancer.

Based on a link between vitamin K and inhibition of inflammatory cytokines thought to play a role in Non-Hodgkin lymphoma, the researchers Mayo researchers enrolled 603 patients who were newly diagnosed with Non-Hodgkin lymphoma. Another 1,007 healthy control subjects with no cancer were recruited for comparison.

Using data obtained from food questionnaires, Dr Cerhan and his co-workers noted a clear trend supporting a lowering in the risk of lymphoma with increasing vitamin K intakes from the diet. NutraIngredients has not seen the full data for the study.

Interestingly, vitamin K from supplements also protected against Non-Hodgkin lymphoma, said the researchers, but reached a point where the highest intake offered no reduction in risk.

“The significance of this finding is unclear, but suggests that taking high doses of supplements is unlikely to be helpful,” said Dr Cerhan.

“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,” he added. “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.”

The study was funded by the National Cancer Institute.

The unKnown vitamin

The vitamin is less well known than vitamins A to E. Vitamin K has long been linked to blood health because about half of the 16 known proteins that depend on the vitamin are necessary for blood coagulation.

There are two main forms of vitamin K: phylloquinone (vitamin K1) and menaquinones (vitamins K2). K1 is found in green leafy vegetables such as lettuce, broccoli and spinach, and makes up about 90 per cent of the vitamin K in a typical Western diet.

K2 makes up about 10 per cent of consumption and can also be obtained from the dietary sources like animal meat, and fermented food products like cheese, and natto. Multivitamins contain either small amounts or no vitamin K at all.