Last month I told you about natural treatments and nutritional support for hepatitis C in the alert "Show of Support". Hepatitis C is a common blood-borne infection that often develops into cirrhosis (a debilitating liver disease) and can transform into primary liver cancer. But according to a Japanese study, an increased intake of one vitamin may significantly lower the risk of liver cancer in patients with cirrhosis. And as we'll see, this vitamin is also important for anyone with a family history of osteoporosis or arteriosclerosis. When researchers in the Graduate School of Medicine of Japan's Osaka City University began their study of vitamin K use among women with cirrhosis of the liver, their goal was to evaluate potential advantages in using vitamin K to prevent bone loss. But the final analysis of data reaped an unexpected benefit, as reported in The Journal of the American Medical Association. The Osaka team recruited a group of 40 women with viral cirrhosis. Most of the subjects also had hepatitis C. The average age for the group was about 60. For two years, 21 subjects took a daily 45 mg dose of vitamin K2. The other 19 women took a placebo. Of the women in the K2 group, only two developed liver cancer, while nine of the women in the placebo group developed cancer. Larger studies will be needed to confirm any liver cancer preventive benefits of vitamin K2, but because of the length of the study, the researchers feel confident that K2 supplements may reduce the risk of liver cancer by as much as 20 percent in patients with viral cirrhosis. The study also found that vitamin K2 supplementation helped prevent bone loss in women with cirrhosis of the liver. "Do we really need to take a vitamin K supplement?" Jonathan V. Wright, M.D., posed that question in his Nutrition & Healing newsletter, and provided this answer: "If there's a family history of osteoporosis, definitely. There's also enough preliminary evidence to say that if there's a family history of arteriosclerosis ('hardening of the arteries'), you probably should." When I asked panelist Allan Spreen, M.D., about vitamin K, he told me that K intake also provides another kind of protection: "An old study from the late '40s showed that vitamin K was clearly helpful against tooth decay. But the biggest news more recently has been concerning vitamin K as a strong bone-builder. It seems to not only help with poorly healing fractures, but at the same time helps prevent excess calcium from getting deposited in arterial walls. "The plant-based source of vitamin K (K1, or phylloquinone) seems to have no toxic effects in most any reasonable dose. But the synthetic form (K3, or menadione) has caused some liver toxicity and, rarely, a form of anemia when taken in high doses. There's also K2 (or menaquinones), but K1 and K2 are fine. As usual, it seems best to avoid synthetic forms, if possible. If the individual is on coumadin (blood thinner), he needs to talk with his doctor, as vitamin K can interfere with its effect." Dr. Wright agrees that vitamins K1 and K2 are "very safe," and recommends 5 to 15 mg per day. Note that the K2 dosage in the Osaka study was quite higher than that. Nevertheless, the supplement was well tolerated by the Osaka subjects. As for dietary sources of vitamin K, Dr. Spreen tells me that dark, leafy green vegetables, such as kale and carrot tops, are the best for vitamin K1. "The highest amounts of it are in chestnut leaves and fish meal. Spinach leaves, cabbage leaves and cauliflower are also right up there." In addition to those sources, broccoli, Brussels sprouts, endive, and lettuce are also abundant in vitamin K1, as are olive oil and avocados. Vitamin K1 is converted into K2 in the intestine, but we get some amount of K2 in meat, liver and egg yolk, and fermented products such as yogurt and cheese. And these sources reveal the basic difference between K1 and K2; K1 comes from plant sources, and K2 from animal sources.