Though we live where the sun is iconic, we Idahoans are likely deficient in vitamin D – “the sunshine vitamin” – due to our geographical location, layering clothes during long winters, and lathering sunscreen during intense summers. This week, many of us are probably vacationing closer to the equator, basking the sunshine of Southern California, the Mexican coast or Florida – ideal locations for vitamin D intake.
Despite being called a vitamin, D functions more like a hormone. UVA and UVB rays from the sun give us a form of vitamin D that is considered both a previtamin and a prohormone. It is transported to the liver and then the kidneys to become the active form of vitamin D to be utilized in the body. Because our skin regulates how much previtamin D converts into the active form, we cannot overdose on vitamin D from sun exposure; however, there is risk of toxicity with supplemental D intake.
Primarily, we need vitamin D to help regulate minerals, particularly calcium homeostasis in our bones, for bone mineral density, to decrease bone turnover and to prevent osteoporosis and fracture.
Vitamin D’s other key function is hormonal, helping release the neurotransmitters dopamine and serotonin, and affecting estrogen and testosterone levels, which, in turn, affect sex drive and mood. With depression a leading cause of disability worldwide, vitamin D status should be prioritized.
Further, Vitamin D affects immunity by warding off bacteria and viruses; reduces inflammation; improves cardiovascular health by regulating blood pressure, lowering reducing LDLs and increasing HDL; and influences gene regulation by turning on/of off genes that play a key role in cancer prevention or onset.
In fact, research shows that individuals with higher serum vitamin D levels have a lower risk of 70% of cancers, and that skin cancer results from occasional sunburns and tanning beds in high-risk populations. Also, individuals with optimal vitamin D status appear to have increased risk of surviving cancer.
Those of us who live well north of the 35th parallel do not receive direct rays, even in summer. That means we must receive vitamin D in other ways, such as from food or supplementation.
Few foods naturally contain vitamin D, and we’re unlikely to obtain adequate amounts from food intake alone. Wild, fatty fish and cod liver oil contain the highest amount of D3. Some other good sources of vitamin D include eggs and dairy products, such as raw/whole milk, cheese and butter. Note that animals raised on pasture produce dairy and egg products three to six times higher in vitamin D than conventional. Look for pasture-raised eggs as opposed to “free range.”
Ample foods rich in niacin and phosphorus are required to change vitamin D into its usable form. We absorb only about 50% of what we consume, and absorption is also affected by liver, kidney and intestinal function, the ability to digest fats, skin thickness, and age.
Supplementing with vitamin D3 drops first warrants a visit to a nutritionist who would be able to advise on proper dosing after analyzing your blood work. Next time you see your doctor, ask to test 25-OH-Vitamin D3.
As winter transcends into spring, take caution with sun overexposure. Start with 5 minutes per day of direct, midday exposure on your back, arms, and legs, then either cover up or apply a toxin-free sunscreen. When skin adapts by bronzing, 15-30 minutes of direct rays 2 times per week will provide most people with ample vitamin D, and without risk of burning.
Living in Idaho’s mountains offers many advantages, including 200+ days of sunshine. Rather than fear the sunshine, safely soak up direct rays to boost your vitamin-D levels.
Beerman, K. & McGuire, M. (2013). Nutrition Sciences: From Fundamentals to Food (3rd ed. ). Belmont, CA: Yolanda Cossio
Lindqvist, P. G., Epstein, E., Landin-Olsson, M., Ingvar, C., Nielsen, K., Stenbeck, M., & Olsson, H. (2014). Avoidance of sun exposure is a risk factor for all-cause mortality: results from the Melanoma in Southern Sweden cohort. Journal of Internal Medicine, 276(1), 77–86. http://doi.org/10.1111/joim.12251
Lips, P. & van Schoor, M. (2011). The effect of vitamin D on bone and osteoporosis. Best Pract Res Clin Endocrinol Metab., 25(4), 585-91. doi: 10.1016/j.beem.2011.05.002.
Morris, H. A. (2005). Vitamin D: A Hormone for All Seasons - How much is enough? Understanding the New Pressures. Clinical Biochemist Reviews, 26(1), 21–32.
Penckofer, S., Kouba, J. Byrn, M. & Ferrans, C. (2010). Vitamin D and Depression: Where is all the Sunshine? Issues Ment Health Nurs. 31(6), 385–393. doi: 10.3109/01612840903437657