Ahhh… a beautiful Colorado Fall is upon us. The leaves are beginning to change color,
farmers are harvesting the fields, the air is become crisper, and most
importantly, vitamin D production from sunlight is going away.
Most Americans do not realizes the global Vitamin D
deficiency epidemic. Vitamin deficiency contributes to obesity, depression, heart
disease and cancer. To prevent Vitamin D
deficiency an individual must simple get 15 minutes of sunlight exposure a day,
or a little longer for darker skin. But,
the catch is getting the right sunlight.
UV rays, that give us wonderful sunburns, are the key ingredients in sun light for Vitamin D production. There are three types of UV rays that make it the surface: UV-A, UV-B, UV-C. UV-B rays are stronger of the UV-A while weaker than UV-C. UV-B is also the radiation required for Vitamin D synthesis in the skin.
However, several factors filter or block UV-B rays, which reduce or inhibit Vitamin D synthesis. This
includes sunscreen, clothing, windows, cloud cover, time of day, time of year,
altitude, and latitude. Sunscreen and clothing simple blocks UV –B thus prevent sunburns. Windows let UV-A through, but not UV-B. The time of day is critical because of
where the Sun sits in the horizon changes thought the day. At “high noon” the sun sits high in the sky
and the sunrays travel through less atmosphere.
Compared to dawn and dusk when the sun is low the sun rays travel
through more atmosphere filtering out more UV-B. As result, optimal Vitamin D synthesis is from 10am and 3pm. Similarly,
the time of year also effects where the sun sits. As we move closer to winter the sun sits
lower and lower in the sky. Likewise, at higher latitudes
the sun sits lower in the sky. Those who live at latitudes south of Atlanta, GA receive UV-B rays year round. Latitudes North of Atlanta, UV-B rays only make it to the surface from March
to October. One saving grace for Colorado is
higher altitudes reduce the amount of atmosphere that filters UV-B, thus
increasing the window of UV-B exposure.
References:
Michael F
Holick and Tai C Chen, “Vitamin D Deficiency: a Worldwide Problem with Health
Consequences.,” American Journal of Clinical Nutrition 87, no. 4 (April
2008): 1080S–6S.
O Engelsen et al., “Daily Duration of
Vitamin D Synthesis in Human Skin with Relation to Latitude, Total Ozone,
Altitude, Ground Cover, Aerosols and Cloud Thickness,” Photochemistry and
Photobiology 81, no. 6 (2007): 1287–1290.
I know that there are a lot of ways to get vitamin D from your diet; the cereal and orange juice I had for breakfast both have about 25% of the daily recommended value. But I was curious about the supplements and if they contain different forms or precursors of the vitamin D pathway.
ReplyDeleteI found that vitamin D comes in two forms: the more common cholecalciferol (D3) and less common ergocalciferol (D2). Vitamin D3 supplements aren't fully synthesized, though, and are actually partly derived from the fat from sheep wool. This can pose a problem for vegetarians and vegans, who may prefer to take the plant-derived D2 supplements.
There is some controversy as to which vitamin D derivative is most effective. A 2010 study from the Journal of Clinical Endocrinology & Metabolism found that vitamin D3 is 87% more effective than vitamin D2 at increasing serum vitamin D levels. They also found that the body stores D3 more effectively. Vitamin D2 is often given in higher doses than D3 to make up for this potential difference. However, a 2008 study from the same journal states that there is no significant difference between D3 and D2 efficiency.
Here is the source: http://www.livestrong.com/article/377268-vitamin-d3-vs-d2/?utm_source=undefined_R1.
DeleteI have a quick question about whether it is more beneficial to get vitamin D from the sun or from supplements. Sure the sun is a great mood stabilizer and makes people happy, but UV-B has been shown to produce reactive oxygen species (ROS) in the skin which can have all sorts of negative effects (Heck et al., 2010). It has been shown that UV-B is highly damaging to DNA structure and function which can result in different forms of cancer as well as defective cell signalling as a result of the ROS. If supplements can effectively deliver vitamin D in all of the necessary forms, would that be preferable to sun exposure from a physiology stand point?
ReplyDeleteHeck, D., Vetrano, A.M., Mariano, T.M., Laskin, J.D. (2003). UVB Light Stimulates Production of Reactive Oxygen Species: Unexpected Role for Catalase. Journal of Biological Chemistry, 22432-22436.
Steven,
ReplyDeleteI was recently diagnosed with a vitamin D defiency, and I was prescribed a huge amount of vitamin D to compensate for it. I found this interesting article that suggests that adding vitamin D to your diet can also help out with Hypothyroidism (which I have been diagnosed too) (Parisi 2010). Although, I cannot find anything else as to why Hypothyroidism causes Vitamin D inefficiency, I found an article that links low levels of vitamin D with many autoimmune diseases such as Hashimoto's disease, diabetes, and many other diseases (Kriegel 2011).
Pirisi, A. (2010). wellness. The hypothyroid DIET. Delicious Living, 26(10), 53.
Kriegel, M. A., Manson, J. E., & Costenbader, K. H. (2011). Does Vitamin D Affect Risk of Developing Autoimmune Disease?: A Systematic Review. Seminars In Arthritis & Rheumatism, 40(6), 512-531.e8.