Vitamin D does reduce the risk of pre-eclampsia William B. Grant, Sunlight, Nutrition, and Health Research Center, P.O. Box 641603, San Francisco, CA 94164-1603, USA 20 August 2015 Can you please enter the following text for the comment: In the comprehensive review of dietary factors and gestational hypertension and pre-eclampsia, the authors missed the importance of vitamin D in reducing the risk of pre-eclampsia (1), as did the accompanying commentary (2). The reason it missed this connection appears to be that they excluded studies if they reported on supplements not in combination with dietary intake. One of the papers cited reported a 27% reduction in risk of pre-eclampsia (OR = 0.73 (0.58-0.92)) for women taking 10-15 microg/d vitamin D as compared with no supplements (3). However, since the overriding purpose of the review should be to review the evidence on how dietary factors could reduce the risk of pre-eclampsia, the omission of supplement studies seems to be in error. There is considerable evidence that vitamin D does reduce the risk of pre-eclampsia. The best measure of vitamin D is blood 25-hydroxyvitamin D (25(OH)D). Several studies have reported significant inverse correlations between 25(OH)D and incidence of pre-eclampsia (4-7). According to a vitamin D randomized controlled trial, pregnant women should take 4000 IU/d vitamin D3 (8). This amount attainment of optimal circulating 25(OH)D concentrations that supported maximal circulating levels of 1,25-hydroxyvitamin D concentrations, and 1,25-hydroxyvitamin D affects the expression of hundreds of genes, which is very important for a developing fetus as well as the mother. References 1. Schoenaker D, Soedamah-Muthu SS, Mishra GD. (3)The association between dietary factors and gestational hypertension and pre-eclampsia a systematic review and meta-analysis of observational studies. BMC Med. 2014 Sep 22,12(1) 157. (Epub ahead of print) 2. Dodd JM, O'Brien C, Grivell RM. (4)Preventing pre-eclampsia - are dietary factors the key? BMC Med. 2014,12 176. 3. Haugen M, Brantsaeter AL, Trogstad L, Alexander J, Roth C, Magnus P, Meltzer HM. (5)Vitamin D supplementation and reduced risk of preeclampsia in nulliparous women. Epidemiology. 2009,20(5) 720-6. 4. Bodnar LM, Catov JM, Simhan HN, Holick MF, Powers RW, Roberts JM. (6)Maternal vitamin D deficiency increases the risk of preeclampsia. J Clin Endocrinol Metab. 2007,92(9) 3517-22. 5. Robinson CJ, Wagner CL, Hollis BW, Baatz JE, Johnson DD. (7)Association of maternal vitamin D and placenta growth factor with the diagnosis of early onset severe preeclampsia. Am J Perinatol. 2013,30(3) 167-72. 6. Hyppönen E, Cavadino A, Williams D, Fraser A, Vereczkey A, Fraser WD, Bánhidy F, Lawlor D, Czeizel AE. (8)Vitamin D and pre-eclampsia original data, systematic review and meta-analysis. Ann Nutr Metab. 2013,63(4) 331-40. 7. Tabesh M, Salehi-Abargouei A, Tabesh M, Esmaillzadeh A. (9)Maternal vitamin D status and risk of pre-eclampsia a systematic review and meta-analysis. J Clin Endocrinol Metab. 2013,98(8) 3165-73. 8. Hollis BW, Johnson D, Hulsey TC, Ebeling M, Wagner CL. Vitamin D supplementation during pregnancy double-blind, randomized clinical trial of safety and effectiveness. J Bone Miner Res. 2011,26(10) 2341-57. Competing interests I receive funding from Bio-Tech Pharmacal (Fayetteville, AR), the Sunlight Research Forum (Veldhoven), and Medi-Sun Engineering, LLC (Highland Park, IL).