1.
The combination effect of vitamin K and vitamin D on human bone quality: a meta-analysis of randomized controlled trials.
Kuang, X, Liu, C, Guo, X, Li, K, Deng, Q, Li, D
Food & function. 2020;(4):3280-3297
Abstract
BACKGROUND Previous studies did not draw a consistent conclusion about the effects of vitamin K combined with vitamin D on human skeletal quality. METHOD AND FINDINGS A comprehensive search on Web of Science, PubMed, Embase and the Cochrane Library (from 1950 to February 2020) and bibliographies of relevant articles was undertaken, with the meta-analysis of eight randomized controlled trials (RCTs) including a total of 971 subjects. Vitamin K combined with vitamin D significantly increased the total bone mineral density (BMD): the pooled effect size was 0.316 [95% CI (confidence interval), 0.031 to 0.601]. A significant decrease in undercarboxylated osteocalcin (-0.945, -1.113 to -0.778) can be observed with the combination of vitamin K and D. Simultaneously, subgroup analysis showed that K2 or vitamin K (not specified) supplement was less than 500 μg d-1, which when combined with vitamin D can significantly increase the total BMD compared with the control group fed a normal diet or the group with no treatment (0.479, 0.101 to 0.858 and 0.570, 0.196 to 0.945). CONCLUSIONS The combination of vitamin K and D can significantly increase the total BMD and significantly decrease undercarboxylated osteocalcin, and a more favorable effect is expected when vitamin K2 is used.
2.
Maternal Vitamin D Status and Risk of Gestational Diabetes: a Meta-Analysis.
Hu, L, Zhang, Y, Wang, X, You, L, Xu, P, Cui, X, Zhu, L, Ji, C, Guo, X, Wen, J
Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology. 2018;(1):291-300
Abstract
BACKGROUND/AIMS: Whether maternal vitamin D deficiency is associated with gestational diabetes remains controversial. This meta-analysis aimed to systematically evaluate published evidence on the association between maternal vitamin D status and the risk of gestational diabetes. METHODS We retrieved relevant articles from the PubMed, Medline and Embase databases up to May 2017 for observational studies investigating the association between vitamin D status and the risk of gestational diabetes. Odds ratios (OR) or risk ratios (RR) from individual studies were pooled using the fixed and random effect models. RESULTS The meta-analysis of 29 observational studies included 28,982 participants, of which 4,634 were diagnosed with gestational diabetes, and showed that maternal vitamin D insufficiency was associated with a significantly increased risk of gestational diabetes by 39% (pooled OR = 1.39, 95%CI = 1.20-1.60) with moderate heterogeneity (I2 = 50.2%; P = 0.001). Moreover, the 25(OH)D level was significantly lower in gestational diabetes cases than in controls with a pooled effect of -4.79 nmol/L (95% CI = -6.43, -3.15). Significant heterogeneity was also detected (I2 = 65.0%, P < 0.001). Further subgroup analysis indicated that this association was also evident in most subpopulations. CONCLUSION This meta-analysis indicated a significant association between vitamin D insufficiency and increased risk of gestational diabetes. Further well-designed large-scale clinical trials are essential to verify this association.