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Diabetes: Vitamin K a valuable nutrient for diabetics


For diabetics, any trip to the doctor’s office, no matter how routine, should be treated as an opportunity to take stock of various health issues that can be compromised by diabetes.

In recent months, new research has emerged that every person with diabetes (either type 1 or type 2) or more importantly, doctors of diabetics, should take heed and run whatever tests are necessary to make sure liver function is carefully monitored.

Liver cancer risk among diabetics
The most recent study assessing the danger of liver cancer among diabetics comes from American researchers at the Baylor College of Medicine in Houston, Texas.

The Baylor team analysed information collected from a Medicare database that included more than 2,000 subjects over the age of 65 who had been diagnosed with liver cancer. These statistics were compared with a control group of more than 6,000 subjects who were randomly selected.

The results:

* More than 40 percent of the liver cancer patients had diabetes, compared to only 19 percent in the control group
* The chance of having liver cancer was estimated as two to three times greater for patients with diabetes

Writing in the April 2005 issue of the journal Gut, the researchers concluded that diabetes is an independent risk factor for liver cancer. This confirms the results of a 2004 Canadian study that examined rates of diabetes in more than 3,200 cancer patients and also found liver cancer risk to be about three times greater among diabetics.

Hepatitis C and diabetes
Another important result in the Baylor research concerned hepatitis C; a blood-borne infection that often develops into a debilitating liver disease called cirrhosis, which is a precursor to liver cancer. The Baylor team found that non-diabetic subjects who had hepatitis C were 24 times more likely to develop liver cancer. But those who were diabetic and also had hepatitis C were more than 35 times more likely to develop the cancer.

Diabetics are particularly susceptible to the hepatitis C virus. But for many hepatitis C patients, increasing vitamin K intake may prove to be a lifesaver.

In the e-alert ‘How vitamin K could benefit hepatitis C patients’ (8/3/05), I told you about a study from the School of Medicine at Osaka City University (Japan). Researchers 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 K team
You may have noticed that vitamin K2 was used in the Osaka study. And if you’re wondering what K2 is and how it may differ from other forms of K, I’ll call on HSI Panellist Dr Allan Spreen, to explain:

‘The plant-based source of vitamin K (K1, or phylloquinone) seems to have no toxic effects in any reasonable dose. But the synthetic form (K3, or menadione) has caused some liver toxicity and, rarely, a form of anaemia 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/her doctor, as vitamin K can interfere with its effect.’

In his Nutrition and Healing newsletter, Dr Jonathan V. Wright, describes vitamins K1 and K2 as, ‘very safe,’ and recommends 5 to 15 mg per day. Note that the K2 dosage in the Osaka study was quite a lot higher than that. And although the supplement was well tolerated by the Osaka subjects, you should talk with your doctor or a healthcare professional for advice about a dosage level that would be right for you.

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, Brussel 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 yoghurt and cheese. And these sources reveal the basic difference between K1 and K2: K1 comes from plant sources, and K2 from animal sources.

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