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Should I take magnesium with vitamin D?

Medically reviewed by Kristianne Hannemann, PharmD. Last updated on May 2, 2025.

Official Answer by Drugs.com

Current research strongly indicates that taking magnesium with vitamin D is beneficial for most people, as these nutrients work synergistically in the body. Magnesium plays a crucial role in vitamin D metabolism, helping convert it from an inactive to an active form that your body can use effectively. Without adequate magnesium, vitamin D supplementation alone may not effectively address deficiencies or provide intended health benefits.

The Relationship Between Magnesium and Vitamin D

Magnesium and vitamin D have a complex relationship in which one significantly impacts the function of the other. Magnesium serves as a cofactor for all enzymes involved in vitamin D metabolism, making it essential for proper vitamin D activation and function. Without sufficient magnesium, your body cannot effectively use vitamin D, even if blood levels appear adequate. This relationship is particularly important considering that approximately 50% of people worldwide have low vitamin D levels, and between 10% and 30% of the population are thought to have insufficient magnesium levels.

Too Much Vitamin D Can Worsen Magnesium Deficiency

Taking vitamin D supplements in large doses without adequate magnesium can actually worsen magnesium deficiency. Research indicates that vitamin D supplementation can increase the body's demand for magnesium, as magnesium is required for vitamin D transport in the blood and for its activation. This means that vitamin D supplementation without concurrent magnesium supplementation may deplete already limited magnesium stores.

Benefits of Co-Supplementation

For most people, taking vitamin D and magnesium together offers significant advantages over taking vitamin D alone. When both nutrients are present in adequate amounts, vitamin D can be properly metabolized and utilized by the body. Observational studies have found that magnesium intake significantly interacts with vitamin D in relation to vitamin D status. In subjects with high vitamin D intake, those who also had high magnesium intake maintained much higher serum vitamin D levels compared to those with low magnesium intake.

What are the Health Benefits of Vitamin D and Magnesium?

Both magnesium and vitamin D contribute to numerous bodily functions. Together, they support:

Recommended Dosages of Magnesium and Vitamin D

Research suggests that the effect of magnesium supplementation on vitamin D status may depend on baseline vitamin D levels. This indicates that supplementation should be approached in a personalized manner, ideally with guidance from healthcare providers who can assess individual needs and monitor responses to supplementation.

Related questions

Vitamin D Guidelines

The Recommended Dietary Allowance (RDA) for vitamin D for adults 19 years and older is 600 IU (15 mcg) daily, and for adults over 70 years, it increases to 800 IU (20 mcg) daily. However, various studies suggest different dosages may be necessary depending on baseline levels and individual factors. The upper limit for vitamin D intake from all sources is set at 100 mcg (4000 IU) per day for anyone ages 9 or older.

Magnesium Guidelines

For magnesium, the RDA for adults 19 years and older is 400-420 mg daily for men and 310-320 mg for women. During pregnancy, the requirement increases to 350-360 mg daily for women, and during lactation, it remains at 310-320 mg for women. It's important to note that the tolerable upper intake level (UL) for magnesium from supplements only is 350 mg per day for those 9 years and older. This limit does not include magnesium from food sources.

Potential Side Effects

While both supplements are generally considered safe when taken within recommended limits, excessive intake can cause adverse effects:

When to Consider Supplementation

You may consider taking magnesium with vitamin D if:

Before starting any supplementation regimen, consult with a healthcare provider who can:

Conclusion

Evidence strongly suggests that magnesium and vitamin D should be taken together for optimal health benefits. Magnesium is essential for vitamin D metabolism, and taking vitamin D without adequate magnesium can potentially worsen deficiency. While supplementation can be beneficial, it should be approached thoughtfully, with attention to recommended dosages and preferably under medical guidance. Ultimately, maintaining adequate levels of both nutrients is important for bone health, immune function, and overall well-being.

References
  1. DiNicolantonio, J. J., et. al. 2018. Subclinical magnesium deficiency: a principal driver of cardiovascular disease and a public health crisis. Open Heart. DOI: https://doi.org/10.1136/openhrt-2017-000668
  2. Kaur, J., et al. Vitamin D Deficiency. [Updated 2025 Feb 15]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Accessed May 2, 2025 at https://www.ncbi.nlm.nih.gov/books/NBK532266/
  3. National Institutes of Health. 2021. Magnesium Fact Sheet for Consumers. Accessed May 2, 2025 at https://ods.od.nih.gov/factsheets/Magnesium-Consumer/
  4. National Institutes of Health. 2022. Magnesium Fact Sheet for Healthcare Professionals. Accessed May 2, 2025 at https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/
  5. National Institutes of Health. 2022. Vitamin D Fact Sheet for Consumers. Accessed May 2, 2025 at https://ods.od.nih.gov/factsheets/VitaminD-Consumer/
  6. Oregon State University. Magnesium. Accessed May 2, 2025 at https://lpi.oregonstate.edu/mic/minerals/magnesium
  7. Reddy, P., et. al. Magnesium Supplementation in Vitamin D Deficiency. American Journal of Therapeutics 26(1):p e124-e132, January/February 2019. | DOI: https://doi.org/10.1097/MJT.0000000000000538
  8. Uwitonze, A. M., et. al. (2018). Role of Magnesium in Vitamin D Activation and Function. The Journal of the American Osteopathic Association, 118(3), 181–189. https://doi.org/10.7556/jaoa.2018.037
  9. Zittermann, A. Magnesium deficit - overlooked cause of low vitamin D status?. BMC Med 11, 229 (2013). https://doi.org/10.1186/1741-7015-11-229

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