“Magnesium plays a crucial role in activating vitamin D in the body. If the body is deficient, vitamin D can remain in its inactive form,\u201d Angel Planells, MS, RDN<\/a>, a Seattle-based registered dietitian nutritionist and spokesperson for the Academy of Nutrition and Dietetics, told Verywell in an email.\n<\/p>\n Vitamin D helps prevent osteoporosis<\/a>, a condition in which bones become weak and fracture-prone. Research suggests that vitamin D needs magnesium to support bone health<\/a> and lower osteoporosis risk.\n<\/p>\n Because high doses of vitamin D can lower magnesium levels, talk with a healthcare provider about the right balance for your needs.\n<\/p>\n 2. Omega-3 Fatty Acids\u00a0 <\/p>\n You can find combination supplements that include vitamin D and omega-3 fatty acids<\/a>.\n<\/p>\n “Because vitamin D is fat-soluble, taking it with omega-3s or other healthy fats can improve absorption,” Planells said.\n<\/p>\n Some research suggests that taking these supplements together may help slow biological aging and improve fasting blood glucose levels<\/a> in people with prediabetes.\n<\/p>\n Omega-3 supplements such as fish, krill, and flaxseed oil are generally safe, but these may cause mild side effects like diarrhea or fishy burps<\/a>.\n<\/p>\n 3. Vitamin K2 <\/p>\n Vitamin K2, a compound known as menaquinone, supports bone and heart health. Taking K2 with vitamin D may boost these benefits.<\/p>\n “Vitamin K2 works synergistically with vitamin D by helping direct calcium into bones and teeth rather than soft tissues or arteries,” Planells said.\n<\/p>\n Studies show that combining vitamins D and K2 may increase bone mineral density and reduce the risk of fractures and osteoporosis.\n<\/p>\n 4. Probiotics <\/p>\n Researchers are still learning about the connection between vitamin D and gut health<\/a>. Some studies show that vitamin D promotes good gut bacteria and may reduce intestinal inflammation<\/a> in people with ulcerative colitis<\/a>. A 2020 review also found that taking probiotics with vitamin D may improve mental health, insulin sensitivity, and inflammation.\n<\/p>\n Gut health may also influence how the body metabolizes vitamin D. Certain strains of gut-supporting probiotics<\/a> could enhance vitamin D’s effects, but more research is needed, Planells said.<\/p>\n Take Vitamin D Supplements With Food <\/p>\n Whether you take vitamin D alone or with other supplements, it is a good idea to take it with a meal.\n<\/p>\n “Taking it on an empty stomach or without a fat source can reduce absorption substantially,” Planells said.\n<\/p>\n Vitamin D is fat-soluble, so it needs a fat source for absorption. Otherwise, you may feel nauseous or not get all the expected benefits.\n<\/p>\n Supplements to Avoid Taking With Vitamin D <\/p>\n While vitamin D supplements are generally safe, avoid taking them with certain medications, like orlistat, statins, steroids, and thiazide diuretics.\n<\/p>\n Vitamin D and calcium work together to support bone health, but taking them in high doses can cause nausea, vomiting, dehydration, or kidney stones. Check with your healthcare provider before combining them.\n<\/p>\n Planells added that vitamin D may also compete with the retinol form of vitamin A for receptor sites, and taking it with iron can reduce iron absorption.<\/p>\n Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process<\/a> to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.<\/p>\n National Institutes of Health. Magnesium<\/a>.<\/p>\n Cheung MM, Dall RD, Shewokis PA, et al. The effect of combined magnesium and vitamin D supplementation on vitamin D status, systemic inflammation, and blood pressure: a randomized double-blinded controlled trial<\/a>.\u00a0Nutrition. 2022;99-100:111674. doi:10.1016\/j.nut.2022.111674<\/p>\n MedlinePlus. Osteoporosis<\/a>.<\/p>\n Liu L, Luo P, Wen P, Xu P. The role of magnesium in the pathogenesis of osteoporosis<\/a>.\u00a0Front Endocrinol. 2024;15:1406248. doi:10.3389\/fendo.2024.1406248<\/p>\n Ali ET, Mohammed AN, Khudairi AS, et al. The extensive study of magnesium deficiency, 25\u2010(OH) vitamin D3, inflammatory markers, and parathyroid hormone in relation to bone mineral density in Iraqi osteoporosis patients: a cross\u2010sectional study<\/a>.\u00a0Health Sci Rep. 2025;8(4):e70641. doi:10.1002\/hsr2.70641<\/p>\n Reddy P, Edwards LR. Magnesium supplementation in vitamin D deficiency<\/a>.\u00a0Am J Ther. 2019;26(1):e124-e132. doi:10.1097\/MJT.0000000000000538<\/p>\n Matias P, \u00c1vila G, Ferreira AC, Laranjinha I, Ferreira A. Hypomagnesemia: a potential underlooked cause of persistent vitamin D deficiency in chronic kidney disease<\/a>.\u00a0Clin Kidney J. 2023;16(11):1776-1785. doi:10.1093\/ckj\/sfad123<\/p>\n Rajabi-Naeeni M, Dolatian M, Qorbani M, Vaezi AA. The effect of omega-3 and vitamin D co-supplementation on glycemic control and lipid profiles in reproductive-aged women with pre-diabetes and hypovitaminosis D: a randomized controlled trial<\/a>.\u00a0Diabetol Metab Syndr. 2020;12(1):41. doi:10.1186\/s13098-020-00549-9<\/p>\n Bischoff-Ferrari HA, G\u00e4ngler S, Wieczorek M, et al. Individual and additive effects of vitamin D, omega-3 and exercise on DNA methylation clocks of biological aging in older adults from the DO-HEALTH trial<\/a>.\u00a0Nat Aging. 2025;5(3):376-385. doi:10.1038\/s43587-024-00793-y<\/p>\n National Center for Complementary and Integrative Health. Omega-3 supplements: what you need to know<\/a>.<\/p>\n Maresz K. Growing evidence of a proven mechanism shows vitamin K2 can impact health conditions beyond bone and cardiovascular<\/a>.\u00a0Integr Med (Encinitas). 2021;20(4):34-38.<\/p>\n Van Ballegooijen AJ, Pilz S, Tomaschitz A, Gr\u00fcbler MR, Verheyen N. The synergistic interplay between vitamins D and K for bone and cardiovascular health: a narrative review<\/a>.\u00a0Int J Endocrinol. 2017;2017:1-12. doi:10.1155\/2017\/7454376<\/p>\n Kuang X, Liu C, Guo X, Li K, Deng Q, Li D. The combination effect of vitamin K and vitamin D on human bone quality: a meta-analysis of randomized controlled trials<\/a>.\u00a0Food Funct. 2020;11(4):3280-3297. doi:10.1039\/C9FO03063H<\/p>\n MedlinePlus. Bone density<\/a>.<\/p>\n Yang Q, Liang Q, Balakrishnan B, Belobrajdic DP, Feng QJ, Zhang W. Role of dietary nutrients in the modulation of gut microbiota: a narrative review<\/a>.\u00a0Nutrients. 2020;12(2):381. doi:10.3390\/nu12020381<\/p>\n Abboud M, Rizk R, AlAnouti F, Papandreou D, Haidar S, Mahboub N. The health effects of vitamin D and probiotic co-supplementation: a systematic review of randomized controlled trials<\/a>.\u00a0Nutrients. 2020;13(1):111. doi:10.3390\/nu13010111<\/p>\n Przew\u0142\u00f3cka K, Folwarski M, Kaczmarczyk M, et al. Combined probiotics with vitamin D3 supplementation improved aerobic performance and gut microbiome composition in mixed martial arts athletes<\/a>.\u00a0Front Nutr. 2023;10:1256226. doi:10.3389\/fnut.2023.1256226<\/p>\n Ullah H. Gut-vitamin D interplay: key to mitigating immunosenescence and promoting healthy ageing<\/a>.\u00a0Immun Ageing. 2025;22(1):20. doi:10.1186\/s12979-025-00514-y<\/p>\n MedlinePlus. Vitamin D<\/a>.<\/p>\n National Institutes of Health. Vitamin D consumer fact sheet<\/a>.<\/p>\n University of Virginia. Calcium and vitamin D<\/a>.<\/p>\n![\"Stephanie](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2025\/09\/StephanieBrownnewheadshot-e5ca9ba2a404491384e9300a7871f190.jpg\")
<\/p>\n