Basing Decisions on Science & Research
By MedExpert Science & Research | Mar 15, 2020
I continually receive marketing material to buy vitamin D supplements. I have relied on MedExpert for almost 10 years and you have always stuck to reputable research when answering my questions. Are vitamin D supplements really a cure for depression or cancer and can it prevent bone fractures?
Bottom line, recent studies are not supporting many of the claims used to entice customers to buy vitamin D supplements. Here is the problem. In 2011 a division of the CDC, the National Center for Health Statistics, designed a survey to assess the health and nutritional status of children and adults in the United States, and reported that in a population of 4,962 participants, roughly 40% of Americans were vitamin D deficient. This 2011 survey repeated the results of a similar 2005 survey. With nearly 40% of the US population being labeled vitamin D deficient, many companies leveraged the survey results to promote their Vitamin D products and marketed both low and high doses of Vitamin D with claims of curing depression; increasing energy; and preventing fractures, cancer and heart disease.
Recent studies are not supporting these claims.
- Dr. JoAnn Manson looked at 25,871 participants to determine whether supplementation with vitamin D reduces the risk of cancer or cardiovascular disease. Manson reported findings in the January 2019 issue of the New England Journal of Medicine, NEJM, and concluded that vitamin D supplementation did not result in lower incidence of invasive cancer or cardiovascular events than placebo.[i]
- Another study reported in Lancet Diabetes and Endocrinology found no scientific basis that vitamin D prevents factures and improves bone density. The study reviewed 81 randomized controlled trials and reported “vitamin D does not prevent fractures, falls, nor have clinically meaningful effects on bone density.”
- A 2019 NEJM study by The National Heart, Lung and Blood Institute PETAL Clinical Trials Network found, “Early administration of high-dose enteral vitamin D3 did not provide an advantage over placebo with respect to 90-day mortality or other, nonfatal outcomes among critically ill, vitamin D–deficient patients.”[ii]
The premise that 40% of Americans are vitamin D deficient is also being challenged. Dr. JoAnn Manson reported in a 2016 study in NEJM that “The claim that large proportions of North American and other populations are deficient in vitamin D is based on misinterpretation and misapplication of the Institute of Medicine reference values for nutrients — misunderstandings that can adversely affect patient care.”[iii]
As a result of these studies, the U.S. Preventive Services Task Force (USPSTF), the definitive authority in summarizing these types of recommendations, updated previous guidelines addressing vitamin D supplementation. The Task Force found evidence to recommend against vitamin D supplementation to prevent falls and could not recommend supplementation to prevent fractures in men and premenopausal women. For postmenopausal women, they recommend against low-dose supplementation, but evidence was insufficient to determine whether higher doses prevent fractures. These USPSTF recommendations are for Community-dwelling, nonpregnant, asymptomatic adults age 18 years and older.
Vitamin D is a fat-soluble vitamin that helps regulate calcium and bone health. Important sources of vitamin D include diet (such as fatty fish, cod liver oil, dairy products, fortified beverages and foods, and supplements) and the body’s own creation of vitamin D triggered by sun (UVB) exposure. Inadequate dietary vitamin D intake and limited UVB exposure can all decrease vitamin D levels, but the exact threshold that defines vitamin D deficiency is not well-established. Furthermore, the association between vitamin D status and health outcomes is unclear.[iv]
Commonly reported risk factors for low vitamin D levels are decreased dietary vitamin D intake, absorption, or synthesis due to decreased sun exposure or darker skin pigmentation; older age; inflammatory bowel disease, malabsorptive conditions, or history of gastric bypass; being homebound or institutionalized; routinely wearing clothing that prevents sun exposure on most of the skin; and living at high latitudes. [v]
Most people receive sufficient vitamin D through UV radiation from sun and diet. According to Chris Gallagher, a professor of Medicine at Creighton University, “About 80 to 90 percent of vitamin D comes from sunlight, and even 15 minutes in the midday will boost vitamin D levels to a good level.”
[v] National Institutes of Health. Vitamin D: Fact Sheet for Health Professionals. Bethesda, MD: National Institutes of Health; 2011. Accessed at http://ods.od.nih.gov/factsheets/VitaminD-HealthProfessionalThis link goes offsite. Click to read the external link disclaimer on 21 October 2014.