Recent research found that supplemental vitamin D doesn’t prevent fractures or have any effect on the diseases it has been claimed to help, and blood tests for vitamin D are useless.
Half of all postmenopausal women will have an osteoporosis-related fracture in their lifetime. Hip fractures are common in the elderly and have serious consequences. More than 300,000 people are hospitalized every year in the US for hip fractures. When untreated, the one-year mortality is 70%; with surgery, the one-year mortality is 21%. Patients may never return to their pre-fracture level of activity and may not even regain the ability to walk. The US Preventive Services Task Force (USPSTF) recommends screening women age 50-64 and younger women at high risk, but their strategy has been tested and found to be little better than chance.
Vitamin D supplements are among the most popular supplements on the market.
A typical pro-vitamin D website, LifeExtension.com, tells us:
Most people can benefit from taking vitamin D. Since it’s unlikely that you’re getting enough vitamin D from the sun and from diet, vitamin D supplements are going to be a good idea for many individuals…Approximately 42% of Americans have vitamin D deficiency.
They acknowledge that experts disagree on what constitutes a normal vitamin D level. Commonly accepted categories are:
- Deficiency: < 20 ng/mL
- Insufficiency: 20-30 ng/mL
- Sufficiency: > 30 ng/mL
But they warn that “normal” may not be optimal. Some authorities define optimal levels as 40-60 ng/mL. They go a step further and recommend aiming for 50-80 ng/mL. They suggest having your vitamin D level tested repeatedly along with your routine blood tests for total blood count and lipid profile.
The USPSTF used to recommend vitamin D and calcium supplements to prevent falls in community-dwelling adults aged 65 years or older who are at increased risk for falls.
Having read information like this, I was worried because I am seldom exposed to the sun and I don’t drink milk. For many years I took a calcium and vitamin D pill prescribed by my doctor. At one point I asked my doctor if I could stop taking it and she said it was probably best to continue.
I thought it was protecting me from hip fractures, but recent research says otherwise. There is a lot of research suggesting associations of low vitamin D levels with mortality, ADHD, depression, cognitive impairment, schizophrenia, diabetes, and some infectious diseases; but the evidence is mixed, often flawed, and low quality. Increasing low vitamin D levels with supplements may not be effective for reversing these conditions. The evidence is summarized in the Wikipedia article on vitamin D.
The VITAL trial was a large placebo-controlled study designed to address the cardiovascular and cancer benefits of omega-3 fatty acids and vitamin D for healthy adults. It found that vitamin D supplements don’t protect against developing cancer or cardiovascular disease, falls, cognitive decline, migraines, stroke, macular degeneration, or joint pain—nor do they reduce body weight or BMI. In an ancillary study published in The New England Journal of Medicine the authors found no difference in the incidence of fractures between those taking vitamin D and those taking placebo. An accompanying editorial by two MDs, Steven Cummings and Clifford Rosen, was titled “A Decisive Verdict on Vitamin D Supplementation”.
They found:
…no substantial between-group differences in fracture incidence among participants who were at high fracture risk (i.e., those taking osteoporosis medications [1240 participants] or with a history of fragility fractures [2578 participants].
And when the blood levels of vitamin D were stratified, even those with levels below 20 ng/mL did not benefit from supplements. There was also no benefit for levels below 12 ng/mL, but the number of people in this group was small, so doubt remains.
Complications: there were no substantial differences in the incidence of hypercalcemia and kidney stones between the vitamin D and placebo groups.
In the light of the VITAL study and other recent research, the editorialists concluded:
Providers should stop screening for 25-hydroxyvitamin D levels or recommending vitamin D supplements, and people should stop taking vitamin D supplements to prevent major diseases or extend life.
They said the terms “deficiency” and “insufficiency” should be reconsidered. And of course, the “sufficient” level of vitamin D has yet to be determined.
They did point out that some uncertainties remained. Blood tests might be useful for some patients who might have severe deficiency, such as people living in residential settings with no sun exposure, patients with malabsorption, or those receiving treatments for osteoporosis that might cause hypocalcemia and may benefit from vitamin D.
I decided to stop taking the calcium/vitamin D pills, and this new information confirms that it was a good decision.
This article was originally published in the Science-Based Medicine Blog.
