Vitamin K May Improve Insulin Resistance

Supplementing with vitamin K may improve insulin resistance in men, according to a new study published in Diabetes Care.

Insulin resistance is a condition in which the body fails to respond effectively to insulin, a hormone produced in the pancreas that is essential for sugar (glucose) regulation in the blood. Insulin resistance increases the risk of developing type 2 diabetes, which is associated with serious conditions such as cardiovascular and kidney disease.

Balancing blood sugar

Prior studies have shown that the body’s sensitivity to insulin may be improved by dietary and nutritional interventions, such as with high dietary intake of vitamin K and/or use of supplemental vitamin K. In this recent study, 355 nondiabetic men and women, 60 to 80 years old, were randomly assigned to receive a daily multivitamin tablet that contained 500 micrograms per day of vitamin K or a multivitamin without vitamin K along with their usual diet for 36 months. In addition, each person received a daily tablet containing 600 mg of calcium (from calcium carbonate) and 400 IU of vitamin D.

At the end of the study, men who took the multivitamin with vitamin K had less insulin resistance compared with men who did not take vitamin K. There were no differences in insulin resistance between women who took vitamin K and women who did not.

“The major finding of this study was that daily supplementation with 500 micrograms of phylloquinone [vitamin K] for 36 months had a protective effect on progression of insulin resistance in older men,” said Makiki Yoshida, PhD and his colleagues from Tufts University, Boston, Massachusetts.

The exact mechanism by which vitamin K may affect insulin’s action is not known, but the vitamin may have anti-inflammatory properties and may regulate other hormones in the body that affect insulin and glucose control. Further research is needed to determine the effectiveness and safety of using vitamin K to prevent or improve insulin resistance.

It is important to note that people who take blood thinners such as warfarin (Coumadin) have to be careful about the amount of vitamin K they consume because it can block the effects of their medicine, which can be dangerous. People taking blood thinners should talk with their doctor before taking a vitamin K supplement.

Improving insulin resistance

Adjusting lifestyle behaviors such as diet and exercise can mean better glucose control for people with insulin resistance. Sometimes lifestyle behavior change is not enough and medication is necessary to increase the body’s responsiveness to insulin. Here are some tips for maximizing the body’s ability to regulate glucose:

• Get moving. Regular exercise has been shown to help lower insulin resistance and improve glucose levels.

• Manage blood sugar with food. Diet plays a critical role in managing insulin resistance and type 2 diabetes. A person diagnosed with insulin resistance should follow a diet prescribed by a nutritionist or dietician that is experienced in working with this condition.

• Maintain a healthy weight. People who are overweight or obese are more likely to develop insulin resistance.

• Be aware of risk factors for insulin resistance. These include overweight or obesity, family history of diabetes, sedentary lifestyle, age over 45, and associated medical conditions such as high blood pressure and high cholesterol. Talk with a doctor about your risks for developing insulin resistance.

(Diabetes Care 2008 DOI: 10.2337/dc08–1204

Jane Hart, MD

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