I wonder why it's usually one or the other form of D that is low...either D2 or D3. I guess if your body has trouble absorbing D3, you can go back to D2 supplements. But, D2 supplements only raise D2 levels, so it's good to try and get some D3 if you can.
Greengables mentioned that showering after sun exposure as a hinder to absorbing vitamin D. So basically unless we don't shower for 48 hours (or atleast 24 hours), we don't fully absorb Vitamin D from the sun. Not sure how valid this theory is, though, but it does make some sense. I'm not about to give up showering though! This is a quote from Dr. Mercola's site:
What Does Showering Have to Do With Your Vitamin D Levels?
First, it’s important to understand that vitamin D3 is an oil soluble steroid hormone. It’s formed when your skin is exposed to ultraviolet B (UVB) radiation from the sun (or a safe tanning bed). When UVB strikes the surface of your skin, your skin converts a cholesterol derivative in your skin into vitamin D3.
However, the vitamin D3 that is formed is on the surface of your skin does not immediately penetrate into your bloodstream. It actually needs to be absorbed from the surface of your skin into your bloodstream.
The critical question then is: how long does it take the vitamin D3 to penetrate your skin and reach your bloodstream?
If you’re thinking about an hour or two, like I did until recently, you’re wrong. Because new evidence shows it takes up to 48 hours before you absorb the majority of the vitamin D that was generated by exposing your skin to the sun!
Therefore, if you shower with soap, you will simply wash away much of the vitamin D3 your skin generated, and decrease the benefits of your sun exposure. So to optimize your vitamin D level, you need to delay washing your body with soap for about two full days after sun exposure.
Now not many people are not going to bathe for two full days.
However you really only need to use soap underneath your arms and your groin area. , so this is not a major hygiene issue. You’ll just want to avoid soaping up the larger areas of your body that were exposed to the sun.