What are vitamin D levels in sunny southern California? Los Angeles, at 34 degrees latitude, is surely a haven for vitamin D sufficiency. Or is it?
Dr Elaine Kaptein and colleagues of the University of Southern California Medical Center recently studied 3,276 inner city patients from LA.
Using Quest Diagnostic commercial lab [which uses Liquid Chromatography – Tandem Mass Spectrometry (LCMS/ MS)] they found that 6.5% of people had severe vitamin D deficiency [25(OH) D <10 ng/mL]. They found it in 5% of Hispanics, 7% of Asians, 9% of Whites, and 15% of African Americans.
Prevalence of 25(OH) D <20 ng/mL was 35% overall, 34% in Hispanics, 32% in Asians, 33% in Whites, and 49% in African Americans. While the authors failed to state what percentage of people were above 30 ng/ml, a figure in the paper looked to only show about 35% above the threshold. Only about 5% of the population appeared to have natural levels, which are greater than 40 ng/ml.
The southern California researchers found significant risk factors for deficiency, many of which are well-known risk factors. This included:
- being in the hospital
- being African American
- having your blood tested in winter months(although not much seasonal variation was found)
The significant relative risks for diseases in severe vitamin D deficiency [25(OH) D <10 ng/mL] were 1.5 for diabetes mellitus, 2.2 for chronic kidney disease, 2.1 for any cardiac disease, and 1.7 for liver diseases.
The authors stated that,
“Obviously, fortified foods and 25(OH) D supplements were inadequate in most of our patients.”
“Since 25(OH) D deficiency has the potential to contribute to morbidity, this problem should be suspected, diagnosed, and adequately treated to improve the health status in this at risk population.”