Effect of vitamin K supplementation on insulin sensitivity: a meta-analysis

Abstract

ObjectiveTo perform a systematic review and meta-analysis of randomized, placebo-controlled trials to assess the effect of vitamin K supplementation on insulin sensitivity.Data sourcesMEDLINE, the Cochrane Library, CINAHL, Web of Science, Scopus, clinicaltrials.gov, and clinicaltrialresults.org were searched up to January 2017. Reference lists of related papers were also scanned.Study selectionRandomized controlled trials were selected if they compared vitamin K supplementation with placebo or no treatment and reported homeostasis model assessment of insulin resistance, fasting plasma glucose, fasting plasma insulin, C-reactive protein, adiponectin, leptin, or interleukin-6 levels.Data extractionData extraction and study quality assessment were performed independently by two investigators using a standardized data extraction form. Any inconsistencies were resolved by a third reviewer. Effect estimates were pooled using inverse-variance weighted method. Heterogeneity was assessed by the I2 and Q statistic.ResultsA total of eight trials involving 1,077 participants met the inclusion criteria. A wide variety of participants were enrolled, including older men, postmenopausal women, prediabetic premenopausal women, and participants with a history of diabetes, hypertension, or vascular disease. Vitamin K1 and vitamin K2 (MK-4 and MK-7 subtypes) were assessed. Supplementation period ranged from 4 weeks to 3 years. Vitamin K supplementation did not affect insulin sensitivity as measured by homeostasis model assessment of insulin resistance, fasting plasma glucose, fasting plasma insulin, C-reactive protein, adiponectin, leptin, and interleukin-6 levels.ConclusionOur analysis suggests no effect of vitamin K supplementation on insulin sensitivity.

Clinical Advances in Immunonutrition and Atherosclerosis: A Review

“…Vitamin K supplementation only led to an improvement in CRP levels ( P = 0.01) and the insulin sensitivity index ( P < 0.001). Neither did Suksomboon et al (245) (8 RCTs and 1,077 participants) find any effect of vitamin K supplementation on insulin sensitivity after observing no changes in the parameters analyzed such as insulin resistance, fasting plasma glucose, fasting plasma insulin, CRP, adiponectin, leptin, or IL-6 levels. Similar results were described in the meta-analysis by Shahdadian et al (246) in which vitamin K supplementation had no significant effect on glycemic control in healthy subjects.…”

Undercarboxylated Osteocalcin: Experimental and Human Evidence for a Role in Glucose Homeostasis and Muscle Regulation of Insulin Sensitivity

“…However, studies of vitamin K2 supplementation in young men and women, and in postmenopausal women, have found no effect on adiponectin [ 139 , 140 ]. A systematic review of eight trials involving 1077 participants reported no effect of vitamin K supplementation on insulin sensitivity, concluding that further well-designed randomized controlled trials with large sample sizes are needed [ 141 ]. Vitamin K supplementation consistently reduced ucOC, increasing the proportion of carboxylated osteocalcin [ 135 , 136 , 138 , 139 , 140 ].…”

“…Vitamin K supplementation consistently reduced ucOC, increasing the proportion of carboxylated osteocalcin [ 135 , 136 , 138 , 139 , 140 ]. Thus, the overall effect of vitamin K supplementation on indices of glucose metabolism remains to be fully clarified, reflecting the broader actions of vitamin K1 and K2 on pathways distinct from osteocalcin [ 141 , 142 , 143 , 144 ].…”

Beneficial Effects of Adiponectin on Glucose and Lipid Metabolism and Atherosclerotic Progression: Mechanisms and Perspectives

“…A meta-analysis assessed the effects of vitamin K supplementation on a homeostasis model assessment of insulin resistance (HOMA-IR), fasting plasma glucose and insulin, CRP, adiponectin, leptin, or IL-6 levels [ 129 ]. A total of eight trials involving 1077 participants met the inclusion criteria.…”