"When we subject ourselves to full body sun exposure, enough to induce a slight pinkness, we probably make between 10,000 to 25,000 IU of vitamin D."
"For this reason, it appears that oral intake of 5,000 IU/day is about equal to what your body is capable of making with year-round sun exposure, though every person’s requirements vary a little."
A few additional points of understanding:
1. Determine your minimum erythemal dose (MED) - how much time do you need to spend in the sun between 10:00 am and 2:00 pm to get slighly pink?
There is a 1 - 6 scale of skin types. Type 1 skin always burns and never tans. Minimal sun exposure is needed to make a full dose of Vitamin D. Type 6 never burns and needs hours of sun exposure to make a full dose of Vitamin D.
Here is a link to determine your skin type - Click here
2. Once you determine your MED you know how long you may stay in the sun before you put on sun screen. My recommendation is to get your MED before applying sun screen.
3. If you live north of Atlanta you will get no appreciable production of Vitamin D from sun exposure from November through February. Factors determining Vitamin D production from sun exposure include:
- Day of the year
- Time of Day
- How much of your skin is exposed to the sun (shorts and a T-shirt is considered about 25% skin exposure)
- Skin type
- Cloudiness of the sky
4. Vitamin D absorption. Many of you know about the surgery I had in October 2010 (an esophagectomy). My Vitamin D level just prior to surgery was 70 ng/mL). For 10 months post surgery I took an average of 15,000 IU per day of liquid Vitamin D and my level was 34 ng/mL. That's right ... my number went DOWN BY HALF, even after 10 months of what is considered very high supplementation!
If you have a disease/condition or are simply training hard for sports, you need to check your Vitamin D levels and supplement accordingly. My recommendation is to start supplementing immediately and get your levels checked as soon as you can. Of course, get out in the sun when you can!