I had a patient quit taking vitamin D because he thought that it caused erectile dysfunction (ED). I have now seen this happen in several men. This seems contradictory, as vitamin D is thought to improve cardiovascular and sexual health: studies actually show that the more depleted a man is in vitamin D, the more likely he is to have severe sexual dysfunction.[1] It turns out that when vitamin D actually creates sexual problems, it may reveal important information about deficiency of another nutrient—a mineral that is involved in more than 300 reactions in the body.

When we look closely at the biochemistry, we see that magnesium is required for the conversion of vitamin D to its active form (1, 25-dihydroxyvitamin D). Vitamin D that is taken orally needs to go through this conversion, a process that can deplete magnesium stores. If a person begins to supplement vitamin D but does not have adequate magnesium intake, symptoms of magnesium deficiency can appear. Further investigation revealed that the patient mentioned above had also developed high blood pressure and heart palpitations since taking the vitamin D—symptoms of magnesium depletion.

Under normal circumstances, magnesium helps blood vessels relax. Low magnesium can lead to blood vessel constriction and high blood pressure. Additionally, low magnesium may not allow the penile vein to fully relax leading to erectile dysfunction. Other symptoms of low magnesium can include anxiety, insomnia, migraine headaches, muscle cramps, muscle twitches, or chronic pain.

Good food sources of magnesium include spinach, Swiss chard, pumpkin seeds, sunflower seeds, quinoa, and black beans. Magnesium is present in most beans, nuts, and whole grains, but half of the US population does not meet the minimum recommended intake of magnesium from food.[2] I have seen supplemental magnesium help hundreds of patients with a variety of concerns, but not all magnesium products are equal. I most often recommend magnesium threonate[SC1] , a new and emerging form of magnesium that has excellent absorption and ability to penetrate body tissues and cells. Magnesium threonate also has a unique ability to increase magnesium in the brain, improving memory, learning, and sleep.[3]

When we added magnesium to the protocol for the patient described here, his sexual function improved, his blood pressure returned to normal, and his palpitations stopped. The interaction between vitamin D and magnesium is complex: magnesium is required to activate vitamin D, those who consume more magnesium have higher levels of vitamin D,[4] and now we see that vitamin D supplementation can deplete magnesium. Vitamin D status should not be ignored, but magnesium deficiency is probably one of the most under-diagnosed deficiencies today. For the patient described here, it was magnesium that gave a man his life back.


[1] Barassi A, Pezzilli R, Colpi GM, Corsi Romanelli MM, Melzi d’Eril GV. Vitamin D and erectile dysfunction. J Sex Med. 2014;112792-2800.

[2] Rosanoff A, Weaver CM, Rude RK. Suboptimal magnesium status in the United States: are the health consequences underestimated. Nutr Rev. 2012;70(3):153-164.

[3] Li W, Yu J, Liu Y, et al. Elevation of brain magnesium prevents synaptic loss and reverses cognitive deficits in Alzheimer’s disease mouse model. Mol Brain. 2014;765.

[4] Zittermann A. Magnesium deficit ? overlooked cause of low vitamin D status. BMC Med. 2013;11229.

About the Author: Dr. Gerard Guillory, MD is Board Certified in Internal Medicine and has published two books on Irritable Bowel Syndrome (IBS). In 1985, he opened The Care Group, PC. Today, his clinic is a Primary Care facility that is a hybrid of functional and traditional medicine treating patients with digestive disorders, autoimmune disease, and other conditions. You can learn more about Dr. Guillory here.