Customize Your Vitamin D Production
Would you like more information about making vitamin D from the sun, and how to do that more effectively and safely? As part of this process, I highly recommend getting tested to see where your vitamin D levels are currently.
Did you know that you need UVB rays in order for your body to manufacture its' own vitamin D? How close to the equator you live will tell you whether you have enough exposure to UVB rays, and at what times of the year. For instance, in Santa Rosa, California in June we can take advantage of UVB radiation from 10:30 am until about 4pm, but in December there isn't enough UVB to make our vitamin D even though it may be sunny outside. To calculate the UVB exposure in different places at different times of year, use the link below:
UVB Radiation Calculator:
1) Set the month
2) Pick your state
3) Insert City Name
4) Click on 'Compute Table'
When the results come up, look in the Altitude column. Check the times of day when the altitude is at 50 degrees or greater. This is the span of time in which your body can make vitamin D from the sun's rays.
There are many, many factors that influence the levels of D in your body. How dark or light your natural skin color is, how much cloud cover there is, your age, whether your body is able to metabolize vitamin D supplements effectively, and whether you have enough cholesterol to make your own vitamin D; these are all considerations. As we get older, for example, our bodies don't manufacture vitamin D as well, so more frequent short exposure times (bare skin, without sunscreen) may be most effective for minimizing sun damage while maximizing vitamin D production. I'm going to repeat that part: You want to minimize any potential for sun damage.
There is a range in the guidelines given for sun exposure for vitamin D purposes, anywhere from half the amount of time it takes for your skin to begin to burn, to a quarter of the time. So someone with dark skin might be able to stay out in the summertime midday sun for 80 min. before their skin starts to feel the beginning of sunburn. Their vitamin D target time would be somewhere between 20-40 min. 3-4x/week with arms & legs exposed, some torso, too, if possible. Someone with very light skin might only need 4-8 minutes! There is still so much that is unknown, so remember that these guidelines are very theoretical. Get tested to see what works best for you. Most people will find that a combination of safe sun exposure with some supplementation works well. Use protective clothing, shade, broad-spectrum sunscreen, etc. to take care of your skin the rest of the time. If your skin is photosensitive due to medication, genetics, or certain skin care products, staying out of the sun & supplementing your vitamin D may be your best option.
Your body can only make so much vitamin D in one day, so keep in mind that moderate, consistent exposure is best. Short term over-exposure and excessive exposure over time is where problems develop.
Health professionals are seeing vitamin D deficiency even in people who spend a lot of time outdoors with the sun on their skin. It has been suggested that we may be washing away our vitamin D with soapy showers after sun exposure. There is a study showing that we convert about 50% of our previtamin D to vitamin D within 2 hrs., and another which demonstrated vitamin D levels peak at about 24 hrs. Current knowledge says that we produce our vitamin D in the layers of our epidermis, but our knowledge is always changing. If it turns out to be true that we produce large amounts of our vitamin D on the surface of our skin, that will make a huge change in post-sun skin care recommendations.
If you have more specific questions you'd like to ask me on this topic, feel free to call or email.
(See comments after article: Comment #5, with 2 study citations.)