Dr. Mehmet Oz also believes that vitamin D is important and discusses the potential benefits of supplementation and sun exposure. He shows the map of North America which shows the line from Los Angeles and Atlanta – those below this line have much greater levels than those above. Reminder we live in Saskatoon…. way above that line. Not only do we not get a lot of potential for sun exposure seasonally, but we typically do not receive enough sun exposure in the summer either as we are in side buildings or clothed. Mehmet mentioned that it takes 10-15 minutes of sun exposure to get enough vitamin D, but this is typically studied with full skin exposure not just face and hands (as most of us are clothed when outside). Also sun screen diminishes the potential for vitamin D absorption, so it is not ideal to wear sun screen unless exposed to the sun very infrequently and for long periods of time.
Season, time of day, length f day, cloud cover, smog, skin melatonin content, and sun screen all affect the amount of vitamin D absorbed within the body. Complete cloud cover reduces absorption by 50% and shade reduces absorption by 60% and sun screen blocks the absorption of vitamin d (SPF 8 or higher). Most vitamin D researchers believe that 5-30 minutes of sun exposure between 10am and 3pm at least 3-5 times a week with exposure to the face, arms, legs, and back without sunscreen can lead to sufficient vitamin d synthesis.
With the above paragraph in mind I think it is necessary for most of us to supplement with vitamin D as for the majority of us the levels of sun exposure needed are not being met. Now that the summer months are coming up the need may be lower, but not completely eliminated as most of us still do not see the sun (with that little amount of clothing on) enough.
