Reality Check: Claims of Vitamin D supplements being dangerous are misleading and need to be further investigated.
The next time you encounter a headline that fear-mongers the idea that Vitamin D supplements could lead to overdose consider the following:
The vast majority of people are deficient in Vitamin D. Low levels of this crucial "hormone-nutrient" are one of the biggest public health problems that the world faces. The true importance of Vitamin D for immune system function, cardiovascular health, and cancer prevention is just now starting to be understood. Much of the research about Vitamin D has occurred in the past several decades and has not made it into the mainstream medical standards of care. Here are some reference articles from the non-profit group Grassrootshealth.net. Here are a bunch of charts and graphs.
The amount of Vitamin D needed to become toxic is incredibly larger than most people would ever consider supplementing with. In the article referenced in the image above, the author cited a case study in which someone took 1000x more than they should have. Why on earth would someone do that? Considering that the daily dosage recommended on a bottle of Vitamin D to the Rescue is 5000 IU, that means that the overdose patient consumed 5,000,000 IU. The likelyhood of you accidentally taking 1000 extra capsules is nearly impossible.
Every Case Study involving a potentially dangerous level of Vitamin D involved some kind of extreme circumstance. One such case study that I read about involved an industrial accident in which a gallon of milk accidentally received a million times more Vitamin D in it than was supposed to have been added. Another overdose case involved a lab error involving a dosing miscalculation resulting in a test patient receiving dramatically more Vitamin D than they were supposed to. Overdoses of Vitamin D are not commonplace. Overdoses and toxic levels of Vitamin D don't occur from someone taking 5000 to 15,000 IU as a normal part of a healthy lifestyle.
Dr. John Cannell is one of the most prolific Vitamin D researchers in the world. In one of his many books and papers about Vitamin D, he joked that "If someone tried to commit suicide by taking an entire bottle of Vitamin D, they would actually just end up healthier". Here is the Amazon listing for his book.
Most people aren't taking enough Vitamin D to make a difference in their blood levels, let alone be at risk of toxicity. In the chart below you'll see that COVID patients taking 1000 IU of Vitamin D actually saw a decrease in their blood levels while patients taking 5000 IU saw a significant yet safe increase in their Vitamin D blood levels. It's possible that someone could take too small of a dosage and their blood level would actually continue to worsen.
In conclusion, make sure you consult with a trustworthy healthcare professional who is educated on the latest research and up to date clinical understanding of how important Vitamin D is and how much you should be taking to maintain a blood level between 40-60 ng/ml. It also wise to have your blood level tested and make sure your supplement is working.
While it is technically possible to overdose on Vitamin D supplements, it is extremely rare and actually difficult to do. A far more pressing concern is the detrimental effects of inadequate Vitamin D levels.