Long gone are the days of gulping down cod liver oil to ensure your body is getting the recommended amount of Vitamin D. In fact, your best and cheapest source is right outside the window: the sun, specifically UVB rays. It’s true; ten to fifteen minutes in the sun, three times a week is enough for most people to produce about 90% of the recommended amount you need.
This “Sunshine Vitamin” plays an important role in the health of your bones, the strength of your immune system and even the expression of your genes. Deficiency of vitamin D is known to cause osteoporosis in adults and rickets in children. And, more and more studies show that it may have a protective effect on bone health and immunity.
Why is this important? Because surprisingly, Vitamin D deficiency is fairly common in the US.
Now, before we all run outside in our birthday suits to get our D, let’s take a look at the various factors that can affect the amount of UVB rays that penetrate the skin and work on vitamin D production.
- Age – Older adults produce much less vitamin D from sun exposure than young adults.
- Skin type – Unrelated to race, D production depends upon the skins sensitivity to sun and the amount of melanin it has. Melanin absorbs UVB rays and reduces the production of vitamin D. Darker skin means more melanin and longer sun exposure required to make the same amount of vitamin D compared to those with lighter skin (and less melanin).
- Where you live – In latitudes above 35° (north of Atlanta, GA) little to no vitamin D production happens November through February. Further north no production of D happens for about six months! Those below the 35° can enjoy year long vitamin D production from the sun.
- Season – Late spring through early fall is when the sun’s UVB rays are the strongest and your skin is best able to produce vitamin D.
- Time of day – The greatest production happens between 11am and 2pm.
- Use of sunscreen – Sun protection factor (SPF) ranges from 2 - 60. SPF 8 blocks skin capacity to produce vitamin D by 95% and SPF 15 blocks 98%.
How can you enjoy your summer, get your vitamin D and avoid getting sunburned? Remember, this is a total of 30 to 45 minutes a week and it doesn’t have to be consecutive.
For those who are unable to make enough vitamin D through sun exposure alone — speak to your medical professional about having your levels tested to know for sure — vitamin D supplements are available as an option.
So next time you are out and about, park a little further away from your destination, read a book and let your legs sit in the sun, walk your dog or toss a Frisbee with your kids.
What do you do to ensure you get enough vitamin D?
Reference Source: Vitamin D Deficiency in Adults: When to Test and How to Treat; Kurt A. Kennel, Matthew T. Drake, Daniel L. Hurley; Mayo Clin Proc. 2010 August; 85(8): 752–758. doi: 10.4065/mcp.2010.0138; PMCID: PMC2912737