Get Your VitD Levels Measured

People use about 4000 IU vitD per day (Heaney, et al 2003). If the US RDA is 800 IU, that leaves a 3200 IU deficit per day...EVERY DAY! Where is that extra vitD going to come from? Since most people don't practice sensible sun exposure (which means they get NO sunlight) they don't have adequate fat stores to draw vitD from. You need to supplement with vitD tablets. VitD levels are measured by a blood test and the result is presented in ng/ml (nanograms of the vitD metabolite 25(OH)D per milliliter of blood). Many scientists recommend that 50 to 80 ng/ml is the level to achieve for optimal immune system function. Americans over age 40 are at 24 ng/ml. African-Americans are at 14 ng/ml. Obviously, these figures are way below optimal.

Risk Factors for Chronic Vitamin D Starvation

  • NORTH-SOUTH GRADIENT: Autoimmune disease incidence for Psoriasis, Arthritis, MS, Heart Disease, specific Cancers, Crohn's Disease and Ulcerative Colitis is greater at higher geographic latitudes (less solar-generated vitamin D), both in the northern and southern hemisphere.
  • WHERE YOU LIVE:  If you live in an urban area or in an industrialized country, you're more likely to develop autoimmune disease. One reason is that air pollution reduces the effective Ultraviolet B spectrum of sunlight required for VitD synthesis in the skin.
  • AGE: The skin of a 50 yr old produces half as much Vitamin D per unit time when exposed to UVB rays than does a 20 year old’s skin. By age 70, the decrease is 75% compared to the 20 yr old. Considering the importance of vitD to longevity, this phenomenon is a built-in death mechanism.
  • LATITUDE: UV-B rays do not pass through clothing, glass and are absorbed by the earth's atmosphere from November to May (northern hemisphere) in higher latitudes. 
  • SKIN COLOR: The darker the skin (greater melanin content), the less Vitamin D3 production. Dark skin produces 50x vitD per unit time when exposed to sunlight vs. paler skin.
  • SUN BLOCK: Self-explanatory.
  • DIET: Dietary sources of Vitamin D3 are negligible. Enriched milk is usually 'fortified' with vitamin D2 which is 87% less bioactive than D3. Unless you're a fan of greasy, oily fish like sardines and mackerel, you're not getting much Vitamin D3 through diet.

Chances are most of those you know, including yourself, are Vitamin D3 deficient.

2009 Mar 23;169(6):626-32. doi: 10.1001/archinternmed.2008.604.

Demographic differences and trends of vitamin D insufficiency in the US population, 1988-2004.

Ginde AA1, Liu MC, Camargo CA Jr.



Vitamin D insufficiency is associated with suboptimal health. The prevalence of vitamin D insufficiency may be rising, but population-based trends are uncertain. We sought to evaluate US population trends in vitamin D insufficiency.


We compared serum 25-hydroxyvitamin D (25[OH]D) levels from the Third National Health and Nutrition Examination Survey (NHANES III), collected during 1988 through 1994, with NHANES data collected from 2001 through 2004 (NHANES 2001-2004). Complete data were available for 18 883 participants in NHANES III and 13 369 participants in NHANES 2001-2004.


The mean serum 25(OH)D level was 30 (95% confidence interval [CI], 29-30) ng/mL during NHANES III and decreased to 24 (23-25) ng/mL during NHANES 2001-2004. Accordingly, the prevalence of 25(OH)D levels of less than 10 ng/mL increased from 2% (95% CI, 2%-2%) to 6% (5%-8%), and 25(OH)D levels of 30 ng/mL or more decreased from 45% (43%-47%) to 23% (20%-26%). The prevalence of 25(OH)D levels of less than 10 ng/mL in non-Hispanic blacks rose from 9% during NHANES III to 29% during NHANES 2001-2004, with a corresponding decrease in the prevalence of levels of 30 ng/mL or more from 12% to 3%. Differences by age strata (mean serum 25[OH]D levels ranging from 28-32 ng/mL) and sex (28 ng/mL for women and 32 ng/mL for men) during NHANES III equalized during NHANES 2001-2004 (24 vs 24 ng/mL for age and 24 vs 24 ng/mL for sex).


National data demonstrate a marked decrease in serum 25(OH)D levels from the 1988-1994 to the 2001-2004 NHANES data collections. Racial/ethnic differences have persisted and may have important implications for known health disparities. Current recommendations for vitamin D supplementation are inadequate to address the growing epidemic of vitamin D insufficiency.

Disease Incidence Associated with Low VitD
Schottker, B., et. al. (2013). Strong associations of 25-hydroxyvitamin D concentrations with all-cause, cardiovascular, cancer, and respiratory disease mortality in a large cohort study. American Journal of Clinical Nutrition,


Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol

Robert P Heaney, K Michael Davies, Tai C Chen, Michael F Holick, M Janet Barger-Lux The American Journal of Clinical Nutrition, Volume 77, Issue 1, January 2003, Pages 204–210,