MONDAY, Dec. 1 (HealthDay News) -- Daily supplementation with phylloquinone (vitamin K) over three years protects against insulin resistance in older men, but not women, according to data released online in advance of publication in an upcoming issue of Diabetes Care.
Makiko Yoshida, Ph.D., of Tufts University in Boston, and colleagues conducted a randomized, double-blind, controlled trial in 355 non-diabetic men and women aged 60 to 80 years. Participants were divided into either a treatment group or a control group, and received a daily multivitamin either with or without phylloquinone added, respectively. The trial continued over three years, at which point insulin resistance was measured by the homeostasis model.
The investigators found that among men, insulin resistance was significantly lower in the treatment group compared with the control group (adjusted homeostasis score: -0.12 versus 0.39, respectively). However, no such difference was noted among women in the study. The authors noted a significant increase in the mean percentage of body fat among women participants but not men, and suggested this could explain the gender difference, as adipose tissue has previously been shown to modulate the response to vitamin K supplementation.
"These findings need to be replicated in a study designed specifically to test the hypothesis that vitamin K plays a protective role in insulin resistance in older adults," the authors write.
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