Over the past couple of decades, tens of thousands of studies have evaluated the benefits of vitamin D, linking low blood levels to a whole host of chronic health conditions. In fact, this site was one of the leaders helping to catalyze interest in vitamin D over 15 years ago. Today, many doctors have finally caught on and are taking vitamin D seriously; testing their patients and recommending supplementation when necessary. The progress made makes the present backlash all the more shocking and disappointing.

“Many Americans Taking Too Much Vitamin D,” Reuters recently announced.¹ “More people than ever are taking way too much vitamin D,” Popular Science declared, adding, “You may have a deficiency, but overdosing isn’t the answer.”² ABC News warned its viewers that taking more than 4,000 international units (IUs) of vitamin D is “far above safe levels,” and could potentially cause heart disease.³ Ditto for Consumer Affairs⁴ and many others^{. 5,6}

Where is this coming from? If you’ve followed the progression of vitamin D science, you will be aware of the fact that recommended vitamin D levels — and the dosages typically needed to achieve those levels if you’re not getting regular sun exposure — have dramatically risen over the years.

Researchers have also pointed out a basic mathematical flaw that led to vitamin D recommendations being underestimated by a factor of 10. Unfortunately, the study now being promoted by the media takes none of these things into consideration, instead promulgating decades’ old fallacies.

Are Americans Taking Too Much Vitamin D?

According to the featured study,⁷ nearly 20 percent of American adults are taking supplemental vitamin D, and many are taking “excessively high doses” — amounts linked to “an increased risk of fractures, falls, kidney stones and certain cancers” — even an increased risk of death from all causes.

An “excessively high dose,” the study warns, is anything over 4,000 IUs a day, adding that this is the maximum recommended dosage, and that anything higher than this may result in dangerous side effects. Senior author Pamela Lutsey, public health researcher at the University of Minnesota in Minneapolis, told Reuters:

“Vitamin D is essential for bone metabolism, as it helps the body absorb calcium and maintain appropriate concentrations of calcium and phosphate in the blood. Excessive intake of vitamin D can, however, be harmful, as it can cause over absorption of calcium. Excess blood calcium can, in turn, lead to detrimental deposition of calcium in soft tissues, such as the heart and kidneys.”

Reuters does note that the study was “not a controlled experiment designed to examine the risks and benefits of varying amounts of vitamin D supplementation.” Unfortunately, that important piece of information is likely to get lost in the fearmongering, no matter how flawed the conclusions.

For starters, the study’s authors assume the vitamin D dosage recommended by the National Academy of Medicine (NAM; formerly the Institute of Medicine, IOM) is scientifically substantiated. As it turns out, it is not, and dedicated vitamin D researchers have for a long time urged NAM to update its recommendation, as it is based on flawed math.

https://www.youtube.com/watch?v=48dNVHg9FcU