Vitamin K Linked to Insulin Resistance

A three-year clinical trial conducted at the Jean Mayer Human Nutrition Research Center on Aging at Tufts University has found that vitamin K can slow the development of insulin resistance in elderly men.

The study involved 355 non-diabetic men and women between the ages of 60 and 80. They were instructed to take 500 micrograms of vitamin K (naturally found in Brussels sprouts, broccoli, and spinach), which is five times the amount recommended as Adequate Intake (AI) as defined by the Institute of Medicine’s Food and Nutrition Board, as well as a calcium and vitamin D supplement and daily multivitamins. In addition to this, participants continued their usual diet and were not permitted to take any additional supplements. The participants in the control group did not receive the vitamin K supplements, but were given the multivitamin, and calcium and vitamin D supplement.

“Men who received vitamin K supplementation had less progression in their insulin resistance by the end of the clinical trial,” said senior author Sarah L. Booth, PhD. They also had lower blood insulin levels than men in the control group. “Conversely, we saw progression in insulin resistance in women who received vitamin K supplementation, and in the men or women who were not given vitamin K supplements,” said Booth.

In study results published in Diabetes Care, Booth and colleagues hypothesized that the reason the vitamin K supplements improved insulin resistance only in the men might be because “there was a higher prevalence of obese or overweight women in the vitamin K supplementation group compared to the male supplementation group.”

Because the study was limited to Caucasian adults, and so few vitamin K studies related to insulin resistance have been conducted, the authors encourage further investigation with other study designs that may be applied to a more general population.

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