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Randomized Controlled Trial
. 2008 Nov;31(11):2092-6.
doi: 10.2337/dc08-1204. Epub 2008 Aug 12.

Effect of Vitamin K Supplementation on Insulin Resistance in Older Men and Women

Free PMC article
Randomized Controlled Trial

Effect of Vitamin K Supplementation on Insulin Resistance in Older Men and Women

Makiko Yoshida et al. Diabetes Care. .
Free PMC article


Objective: Vitamin K has a potentially beneficial role in insulin resistance, but evidence is limited in humans. We tested the hypothesis that vitamin K supplementation for 36 months will improve insulin resistance in older men and women.

Research design and methods: This was an ancillary study of a 36-month, randomized, double-blind, controlled trial designed to assess the impact of supplementation with 500 microg/day phylloquinone on bone loss. Study participants were older nondiabetic men and women (n = 355; aged 60-80 years; 60% women). The primary outcome of this study was insulin resistance as measured by homeostasis model assessment (HOMA-IR) at 36 months. Fasting plasma insulin and glucose were examined as the secondary outcomes.

Results: The effect of 36-month vitamin K supplementation on HOMA-IR differed by sex (sex x treatment interaction P = 0.02). HOMA-IR was statistically significantly lower at the 36-month visit among men in the supplement group versus the men in the control group (P = 0.01) after adjustment for baseline HOMA-IR, BMI, and body weight change. There were no statistically significant differences in outcome measures between intervention groups in women.

Conclusions: Vitamin K supplementation for 36 months at doses attainable in the diet may reduce progression of insulin resistance in older men.

Trial registration: NCT00183001.


Figure 1
Figure 1
Study sample selection.

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