Vitamin D Update: Supplementation and Pregnancy and Perinatal Outcomes and 25-hydroxy-vitamin D as a Marker for Nutrient Deficiency and Sufficiency
Posted:
2020-02-07
Vitamin D has been a very active area of research in recent decades. Not only have there been numerous research studies published, there have also been numerous systematic reviews published summarizing these studies. Recently, researchers in Alberta, Canada undertook a systematic review of the systematic reviews that investigated the importance of vitamin D in pregnancy for important perinatal and infant outcomes (1).
This systematic review of systematic reviews found 42 systematic reviews of 204 primary studies that evaluated either vitamin D supplementation in pregnant women and/or examined the association between serum vitamin D levels for at least one predefined perinatal outcome (1). The researchers evaluated the systematic reviews for research quality using the AMSTAR tool and only analyzed data from the 13 systematic reviews with high AMSTAR scores.
The systematic reviews of randomized controlled trials (RCTs) with the highest quality of evidence showed no benefits from vitamin D supplementation regarding preterm birth, preeclampsia, gestational diabetes, stillbirth, low birth weight or caesarean section (1). A significant difference was found for small-for-gestational age; however, this evidence was low quality for two reasons: 1) the high risks of bias in the included studies without an accompanying sensitivity analysis to examine the low risk of bias studies separately, and 2) imprecision due to the small numbers of small-for-gestational age births in the included studies. Systematic reviews of observational studies showed that women with low 25-hydroxy-vitamin D levels had higher rates of preterm birth, preeclampsia, gestational diabetes and small-for-gestational age.
The findings of this systematic review (1) reinforce the findings of a 2017 systematic review (2) that found that the superior health of people with higher vitamin D serum levels suggested by the frequent associations observed in observational studies are not seen in randomized trials of vitamin D supplementation. Additionally, there is increasing evidence that serum 25-hydroxy-vitamin D, the vitamin D status marker, is a negative acute phase reactant, which decreases in response to other variables (2-9). Specifically, researchers have observed that 25-hydroxy-vitamin D decreases in response to inflammation (3), acute illness (4), ill health (2), critical illness (5), surgery (6,7) and when C-reactive protein increases (3,7-9). If a marker changes in response to other variables, then it has limited use as a nutritional adequacy marker.
References
- Bialy L, Fenton T, Shulhan-Kilroy J, Johnson DW, McNeil DA, Hartling L. Vitamin D supplementation to improve pregnancy and perinatal outcomes: an overview of 42 systematic reviews. BMJ Open. 2020 Jan 20;10(1):e032626. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/31964667
- Autier P, Mullie P, Macacu A, Dragomir M, Boniol M, Coppens K, et al. Effect of vitamin D supplementation on non-skeletal disorders: a systematic review of meta-analyses and randomised trials. Lancet Diabetes Endocrinol. 2017 Dec;5(12):986-1004. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/29102433
- McMillan DC, Maguire D, Talwar D. Relationship between nutritional status and the systemic inflammatory response: micronutrients. Proc Nutr Soc. 2019 Feb;78(1):56-67. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/30220267
- Kostoglou-Athanassiou I, Pantazi E, Kontogiannis S, Kousouris D, Mavropoulos I, Athanassiou P. Vitamin D in acutely ill patients. J Int Med Res. 2018 Oct;46(10):4246-57. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/30157690
- Czarnik T, Czarnik A, Gawda R, Gawor M, Piwoda M, Marszalski M, et al. Vitamin D kinetics in the acute phase of critical illness: a prospective observational study. J Crit Care. 2018 Feb;43:294-9. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/28968524
- Binkley N, Coursin D, Krueger D, Iglar P, Heiner J, Illgen R, et al. Surgery alters parameters of vitamin D status and other laboratory results. Osteoporos Int. 2017 Mar;28(3):1013-20. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/27826645
- Waldron JL, Ashby HL, Cornes MP, Bechervaise J, Razavi C, Thomas OL, et al. Vitamin D: a negative acute phase reactant. J Clin Pathol. 2013 Jul;66(7):620-2. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/?term=23454726
- Kruit A, Zanen P. The association between vitamin D and C-reactive protein levels in patients with inflammatory and non-inflammatory diseases. Clin Biochem. 2016 May;49(7-8):534-7. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/?term=26778547
- Silva MC, Furlanetto TW. Does serum 25-hydroxyvitamin D decrease during acute-phase response? A systematic review. Nutr Res. 2015 Feb;35(2):91-6. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/?term=25631715