Counting steps is Good. What about Sunshine Goals for Health?
Even though vitamin D can be made in skin exposed to sunshine, vitamin D insufficiency is a global health concern. Normal serum 25(OH)D3 concentrations can usually be achieved by exposing arms and face to sunshine for 15-20 minutes daily. Clothing, use of sunscreens, skin color, geographical location (near the equator or the poles of the earth) and time of day also affect vitamin D synthesis.
Mazahery and colleagues examined serum 25(OH)D3 status of Middle Eastern women living in New Zealand. Two monthly prescription supplementation regimens, 50,000 and 100,000 IU vitamin D3, were evaluated. Despite the fact that 21% were already being prescribed vitamin D by their physician and 37% were using a multivitamin containing vitamin D, mean serum 25(OH)D3 concentration (Part I) was <20 nmol/L in 48% of subjects at baseline. Serum 25(OH)D3 concentrations were higher in vitamin D supplement users (31 nmol/L) than non-users (20 nmol/L) (P < 0.005).
Dose-response curves in serum 25(OH)D3 concentration were measured over the 6 month supplementation period. Only ~30% of subjects achieved serum vitamin D concentrations above 75 nmol/L with 50,000 IU vitamin D monthly. 95% and 100% were > 50 nmol/L after 50,000 IU and 100,000 IU orally per month, respectively.
According to the Institute of Medicine DRI, serum 25(OH)D3 levels must be at least 50 nmol/L to be ‘sufficient”. In a review of multiple health outcomes, Bischoff-Ferrari and colleagues concluded 75 nmol/L is the desirable concentration for optimal health.
Vitamin D deficiency causes rickets, and unfortunately persists even in the U.S. Sunshine State (FL) (and other regions of the world). Although US regulations restrict fortification to 100 IU per 8 ounces, the major dietary source is still vitamin D-fortified dairy and orange juice. Since most people do not consume 6 glasses a day, or eat other vitamin D-rich foods such as fatty fish, supplementation is the primary dietary option.
Mazahery H, Stonehouse W, von Hurst PR. The effect of monthly 50,000 IU or 100,000 IU vitamin D supplements on vitamin D status in premenopausal Middle Eastern women living in Auckland. 2014 EJCN doi: 10.1038/ejcn.2014.264
Bischoff-Ferrari HA, Giovannucci E, Willett WC, Dietrich T, Dawson-Hughes B. Estimation of serum concentrations of 25-hydroxyvitamin D concentrations for multiple health outcomes. 2006 Am J Clin Nutr 84:1:18-28
Holick MF, Binkley NC, Bischoff-Ferrari HA, Gordon CA, Hanley DA, Heaney RP, Murad MH, Weaver CM. Guidelines for preventing and treating vitamin D deficiency and insufficiency revisited. 2012 JCEM doi: 10.1210/jc.2011-2601