The Centers for Disease Control and Prevention's latest data show markedly high prevalence rates of severe vitamin D deficiency among Americans of all ages. Because of the numerous negative health consequences associated with vitamin D deficiency, we must consider all potential causes including insufficient exposure to the sun's ultraviolet B radiation.
This article presents data from the National Weather Service that documents how few days in Minnesota offer the opportunity to make vitamin D. Thus, even Minnesotans who spend a significant amount of time outdoors and consider themselves to have sufficient sun exposure may still be at risk for vitamin D deficiency.
This is especially true for:
• The elderly,
• Those with high melanin content in their skin,
• And those with a higher body mass index…
…all of whom require significantly more sun to achieve adequate levels of vitamin D.
Given the lack of sufficient ultraviolet B radiation people in Minnesota get from the sun between October and April, measurement of vitamin D status is required for rational replenishment and maintenance dosing.
The goal of replenishment should be at least 32 ng/mL and, ideally, more than 50 ng/mL.
Source: Minnesota Medicine, Nov 2009;92(11):43-6. PMID: 20069998, by Plotnikoff GA. Penny George Institute for Health and Healing, Abbott Northwestern Hospital, Minneapolis, Minnesota, USA.