New Vitamin D Guidelines, Not Everyone Agrees
Although vitamin D is essential for bone health and has been touted as having an important role in dozens of health conditions, experts cannot seem to agree on how much vitamin D people need. Now a new study from Loyola University Chicago Stritch School of Medicine has come out with new vitamin D guidelines that lower the previous recommended levels, and not everyone agrees.
New vitamin D guidelines raise questions
Numerous studies have reported that most Americans are deficient in vitamin D, including a large study published in the Archives of Internal Medicine in 2009 which stated that three-quarters of teens and adults are vitamin D deficient. In that study, the authors warned that "Current recommendations for dosage of vitamin D supplements are inadequate to address this growing epidemic of vitamin D insufficiency."
The standard used in that study and dozens of others is 30 nanograms per milliliter (30 ng/mL) or more of vitamin D in the blood, which is how vitamin D levels are measured. That is the level many experts and doctors have followed for years.
Now the Loyola study has stated that nearly everyone has enough vitamin D when their blood levels are 20 ng/mL or greater. The authors based this number on data they evaluated from 15,099 adults who participated in the Third National Health and Nutrition Examination Study (NHANES III), which the 2009 study also used.
Of the 15,099 adults, 1,097 had chronic kidney disease (an estimated glomerular filtration rate [eGFR] less than 60 ml/min/1.73 m2), which is associated with a vitamin D deficiency. The researchers found that:
- 70.5 percent of adults without kidney disease had vitamin D levels deemed insufficient under the older guidelines, but only 30.3 percent of them would be considered deficient in vitamin D under the newer guidelines
- Significantly higher death rates were seen among adults with vitamin D levels less than 12 ng/mL compared with those with levels in a comparison group (24 ng/mL to less than 30 ng/mL)
- The investigators concluded the death rates among adults with vitamin D levels of 20 ng/mL to 40 ng/mL were similar, regardless of an eGFR of less than 60 ml/min/1.73 m2, and therefore a vitamin D level of 20 ng/mL is sufficient for most adults
Not everyone agrees with new guidelines
Among the experts who still believe vitamin D levels should be 30 ng/mL or greater are many of the 550 attendees at the vitamin D conference, "Vitamin D--Minimum, Maximum, Optimum," held in Warsaw, Poland, October 19-20, 2012. The main recommendation of the experts was that vitamin D concentration should range from 30 ng/mL to 60 ng/mL, with at least a few experts recommending the top of the range be 80 ng/mL.
The Endocrine Society also adheres to the higher figure of 30 ng/mL, according to its clinical practice guideline. The Vitamin D Council is an advocate of higher vitamin D concentrations, stating on its website that "Recent evidence reveals beneficial effects of vitamin D at serum levels around 50 ng/mL (125 nmol/L) or higher--effects not seen at levels below 40 ng/mL (100 nmol/L), indicating a need for upward revision of the deficiency reference threshold."
The new guidelines from Loyola have an impact on a "large proportion of the population," according to Holly Kramer, MD, MPH, who headed the study, as she and her team estimate that nearly 79 million adults once deemed to be vitamin D insufficient would now be considered to have sufficient levels.
These new statement regarding vitamin D has muddied the waters on the question of how much of this essential nutrient people really need, and individuals should consult knowledgeable healthcare providers to determine their individual requirements. Otherwise, for now it's clear not everyone agrees on the guidelines for vitamin D.
Ginde AA et al. Demographic differences and trends of vitamin D insufficiency in the US population 1988-2004. Archives of Internal Medicine 2009. 169(6): 626-32
Holick MF et al. Evaluation, Treatment, and Prevention of Vitamin D Deficiency: an Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology and Metabolism 2011 Jul; 96(7)
Kramer H et al. Mortality rates across 25-hydroxyvitamin D (25[OH]D) levels among adults with and without estimated glomerular filtration rate PLoS ONE 2012; 7(10): e47458
Vitamin D Council