Vitamin K Slows Insulin Resistance, But Only in Men

Vitamin K is known sometimes as the "coagulation" vitamin - it's a fat-soluble oily substance that's required for the synthesis of several proteins needed for both coagulation and anticoagulation. It's given to infants at birth to help prevent brain hemorrhage. Many rat poisons are made of anti-vitamin K substances, leading to lethal hemorrhage in their victims. Vitamin K is found in a number of foods, including leafy greens, cauliflower, and liver. However, the chief source is synthesis by bacteria in the large intestine, and in most cases, absence of dietary vitamin K is not a health problem.

Now a new potential use has been found for vitamin K. Tufts University scientists, reporting in the journal Diabetes Care, were conducting a study of vitamin K on bone loss in older people, where it may have therapeutic value. As an add-on to this study, insulin resistance was measured, along with fasting glucose and insulin levels, after 3 years' administration to 350+ men and women aged 60-80. The subjects were not diabetic at the start of the study.

Insulin resistance (a precursor of type 2 diabetes) was significantly lower in the men taking vitamin K supplements at their 3-year visit, but not at their 6 month visit, nor in the women at any time. The scientists suggest that women may not have reacted in the same way to vitamin K, because their fatty tissue might store the vitamin in a form that was unavailable for body tissues.

This study yields an interesting effect that deserves follow-up, although it has no immediate practical importance. No need to go out and buy some liver for dinner, unless that's your fancy.