What is Vitamin D?
Vitamin D is called the “sunshine vitamin” because the skin of humans and most mammals produce vitamin D when they are exposed to UVB rays from the sun. In fact, vitamin D3, also known as cholecalciferol, is a fat-soluble pro-hormone essential to good health [Samefors et al. 2014]. Vitamin D is generally measured in the blood serum as 25-hydroxyvitamin D (25(OH)-D), also known as calcidiol.
Ninety percent of the body’s total vitamin D levels come from sun exposure, but at latitudes where summer is shorter, such as Canada, it is particularly important to get your vitamin D from food and/or supplementation. Food sources of vitamin D3 include egg yolk, fatty fish, some mushrooms, fortified milk and cereals.
Always remember to include Vitamin K2 when Supplementing with Vitamin D.
Supplemental vitamin D can be obtained from natural, sustainable sources such as the lanolin of sheep’s wool or from lichen. Supplementation of vitamin D should also include vitamin K2 since these vitamins work together to ensure that calcium levels are properly regulated and do not become too high in the bloodstream (van Ballegooijen et al. 2017].
Excess calcium in circulation can be deposited in blood vessels, which in turn may lead to cardiovascular complications, such as atherosclerosis. Many of the best supplements now combine these two complementary vitamins to alleviate this concern.
Why is Vitamin D so Important?
Vitamin D deficiency is a global health concern impacting more than one billion people worldwide [Palacios C & Gonzale 2014]. There is conflicting literature on what are adequate levels of vitamin D. The Endocrine Society defines vitamin D deficiency as serum levels of 25(OH)-D at less than 20 ng/mL (50 nmol/L). Insufficient levels are listed between 21-29 ng/mL, and sufficient levels > 30 ng/mL (75 nmol/L). These levels are particularly crucial for optimal skeletal development but are likely not ideal for optimal immune function [Michael et al. 2011, Holick 2017].
This classification has been accepted by the National Osteoporosis Foundation, International Osteoporosis Foundation, American Association for Clinical Endocrinologists, and the American Geriatric Society [Holick 2017]. Serum levels of 25(OH)D less than 30 ng/mL are associated with an increased risk of cardiovascular complications, including myocardial infarction [Giovannucci et al 2008, Ringe & Kipshoven 2012]. In terms of optimal immune function, serum 25(OH)D concentrations between 40-60 ng/mL (100-150 nmol/L) have been proposed [Charoenngam & Holick].
The Government of Canada states 68% of Canadians have reached sufficient vitamin D levels just for skeletal growth, which Health Canada defines as a serum 25(OH)D concentration > 20 ng/mL (50 nmol/L) [Vitamin D and Calcium Updated Dietary Reference Intake. Government of Canada].
Vitamin D levels in the blood can be tested using a variety of methods, including a simple home test kit available at Immunoceutica.