The value of vitamin K

Vitamin K is found in several forms in our food: Vitamin K1 (phylloquinone), is found in green leafy vegetables. Vitamin K2 (menaquinone) is found predominantly in cheese and meat. This study looked at the role of these different forms of vitamin K in the incidence and mortality risk of cancer and included more than 24,000 participants enrolled in the European Prospective Investigation into Cancer and Nutrition-Heidelberg cohort study. Participants were free of cancer at enrollment and were followed for at least ten years. The amount of dietary vitamin K that participants ate was determined through dietary questionnaires. Results showed:

• People who ate the highest amount of dietary menaquinones (of which cheese was the main food source) had a decreased risk of cancer mortality and incidence compared with people who ate the least. This was particularly true in men and particularly for lung and prostate cancer
• Dietary phylloquinone intake was not associated with overall cancer incidence or mortality

The study authors comment that "the findings of our study imply that the consumption of cheese may have a beneficial effect with respect to cancer, particularly prostate and lung cancer in men." They state, however, that research on vitamin K and cancer is just beginning and that more studies are needed before dietary recommendations for cancer prevention can be made.

It is important to note that people taking certain medications, like the blood thinner warfarin (Coumadin), should talk with their doctor about the amount of vitamin K they eat because it can interfere with the effects of their medicine and lead to serious side effects.

Tips for keeping cancer away

Experts suggest that we may cut our risk of cancer nearly in half by choosing to live a healthy lifestyle. That means we need to be wise about food choices, get plenty of exercise, and put bad habits down for good. Read on for more tips:

• Get regular check-ups. Talk to your doctor about important cancer prevention screening tests such as mammograms, colonoscopies, PAP tests, and others that may be appropriate for you. Regular physical examinations and screening tests are key for preventing cancer or catching it in the early stages when it is more treatable.
• Eat a healthy diet. Eat an abundance of fruits and vegetables, include a source of protein (meat, fish, tofu, legumes), choose low-fat dairy products, and limit high-fat, refined, and processed foods.
• Maintain a healthy weight. Being overweight increases the risk of cancer, so talk with your doctor about how much you should weigh and how to shed extra pounds.
• Exercise regularly. Get out there and move to lose pounds, prevent disease, and optimize your health.
• Stop smoking. Smoking significantly increases your risk for several types of cancer including lung and bladder cancer. If you smoke, talk with a doctor or other expert about how to quit.
• Limit alcohol. Drinking more than the recommended guidelines for alcohol can increase cancer risk. If you drink, women should stick with no more than one drink per day and men, no more than two drinks per day.

(Am J Clin Nutr doi: 10.3945/ajcn.2009.28691)