You may have heard the buzz about vitamin D deficiency over the past several years. Because of years of sun-phobia and overuse of sunscreens, largely due to worry over skin cancer, as well as improper diet and compromised overall health, collective Vitamin D levels are much lower than they should be. In fact, over 70% of US children suffer from insufficient or deficient vitamin D levels (source).
Why does this matter? Vitamin D is necessary for a multitude of functions in our body, some of which are only beginning to be understood by science.
Once thought to only be of importance for bone health, it now seems Vitamin D plays a role in everything from muscle function, our immune system, brain, and cardiovascular health, to reproductive health and our mood.
There is even quite a bit of evidence that proper Vitamin D levels actually protect us from skin cancer!
Now a note about skin cancer.
I know many people who have either personally been affected or know someone who has been affected by skin cancer. Skin cancer is serious and I am certainly not advocating for unsafe, long-term sun exposure that causes sunburns.
It is sunburn, not safe and responsible sun exposure, that contributes to skin cancer.
We are definitely talking about safe sun exposure that allows our body to absorb and manufacture Vitamin D to promote our overall health.
So does any and all sun exposure allow your body to get Vitamin D?
It turns out that, no, there are only certain times per year, depending upon where you live, that you can actually get Vitamin D from the sun.
The sun has to be at the correct angle in the sky and you need to go outside at the right time of day to be able to take advantage of the UVB (not UVA) rays. This is one reason some people experience mood changes during the darker, winter months, in northern latitudes, along with compromised immune systems (hello, winter colds!) when their Vitamin D levels drop - they simply can't get optimal sun exposure for their latitude.
How to Get Vitamin D from the Sun
Depending on the sun for our Vitamin D is the smartest, easiest, and least expensive option.
The lighter your skin, the less time you need in the sun - as little as 10-15 minutes in the midday sun, exposing as much skin as possible (your back, abdomen, or legs absorbs faster than just your face and arms, for example), while darker skins need longer - up to 2 hours in some cases - to produce the same amount.
You want to aim for exposure for about half the time your skin would need to turn pink, or tan, and certainly not long enough to burn.
The further away from the equator you live, the less time of the year you can actually experience UVB rays. Pollution, cloudy days, and getting sun through glass also drastically reduce your availability to absorb UVB rays.
What's the best time to get sun?
In order for your skin to produce Vitamin D from sunshine, you need exposure to UVB rays, which are only available when the sun is above an angle of about 50° from the horizon. When the sun is lower than 50°, UVB rays are reflected and only UVA (the more damaging type of ray implicated in skin cancer) gets through.
Check out this calendar to find the best times and days of the year in your location when the sun is above 50 degrees from the horizon. This video explains how to do this in detail, as it can be a bit tricky to understand the timetable.
Generally, midday, on clear sunny days, between 10 am-2 pm, during the late spring, summer and early fall months are appropriate for much of North America. In the north, no matter what time of day you go out during the winter, you will not be able to access UVB rays.
To additionally boost your absorption of Vitamin D, avoid showering directly before or after sun exposure- and if you must shower, minimize the use of soap (that is, don't lather all over the body). You don't have to go crazy with this, but even allowing a few hours after sun exposure before showering (again, mainly with soap) can possibly allow you to absorb more Vitamin D.
Getting Vitamin D from Food
We aren't able to absorb all the Vitamin D we need from food, and though we can supplement with Vitamin D3 (make sure to get a blood test for your Vitamin D [25(OH)D] levels before implementing heavy or prolonged supplementation), some people do not tolerate or respond to supplements the same way they do to the sun.
The conversion of Vitamin D in our bodies involves many co-factors and depends upon a healthy gut, liver, and kidneys as well.
Real food sources containing Vitamin D would be cod liver oil, fatty fish, oysters, beef liver, and egg yolks. Fortified processed foods do not contain the right form of Vitamin D (D2 instead of the correct D3) and are not real food diet-friendly.
Vitamin D aside, a wholesome and nutrient-dense diet rich in healthy fats and antioxidants like lycopene and astaxanthin can play a big role in sun protection - so check out these foods for sun protection.
Kori Ireland says
I would love some more info on the reason to avoid showering right before or after sun exposure. This blog is the first time I have seen the info on not showering before. I have not been able to find anything explaining why this would matter.
Jenny says
Your skin contains oils that act as precursors to vitamin D synthesis. Showering before (and especially after) exposure to sunlight can wash away these oils, thereby lowering vitamin d production. Researchers discovered this link by comparing the vitamin D levels of populations in Hawaii and Africa, and found that though people in Hawaii were exposed to as much as 11 hours of sunlight a day, they had low levels. After looking hard at the mechanisms behind why, they found that the surfers in Hawaii were also immersing their bodies in water frequently which caused them to effectively wash away the skin's oil.
Kori Ireland says
Interesting. Thank you!
razz says
Great information, thank you. Living in a northern Canadian climate I'm curious if there are is more UVB radiation as the suns angle increases? Is 60 deg.produce more UVB than 50 deg?
David says
Do you absorb vitamin D from the Sun, or manufacture it in the skin?
Jenny says
You manufacture it in the skin after having been exposed to sunlight.
Ashabi says
I was surprised by the info that D3 is the form wanted and not D2. In some health pointers I've read that D3 supplementation is the synthetic form of supplementation. When blood test assessed by Vit D level as really low, the test read D2 as 0 and D3 as 13. The prescription supplement my doctor put me on was 50,000 units of
D2 once a week for 10 weeks. No D3 supplementation at all. Any insight in this would be welcome.
Jenny says
Hi Ashabi,
Either you're confused, or your health care provider is confused, as it's pretty well documented that vitamin D3 is the optimal form, and that D2 is suboptimal. Vitamin D3 is the form you find naturally in foods like fish eggs or salmon or oysters or other foods rich in vitamin D.
Also, 50,000 IU once a week is kind of strange dosing. Most health care providers will recommend a smaller, daily dose of D3.
I'd reach out to your health care provider again for clarity and should s/he repeat the same recommendation (particularly on D2), I'd get a second opinion.
More here: http://ajcn.nutrition.org/content/84/4/694.full
Tom Malterre, MS, CN, CMFP says
Great conversation! The D2 dosing is based on old conventional information. As the pharmaceutical dosing has been at 50,000 of D2 a week for decades, many practitioners are slow to adopt the new information that D3 dosing at 3,000 IU+ per day is the way to go. Not only does it raise 25OH D levels more effectively than D2, but it is more shelf stable and less likely to spoil. By the way...D2 (ergocalciferol) is from plant sources and D3 (cholecalciferol) is from animal sources.
Cynthia Smith says
I was found to be very low in Vitamin D and put on the same 10 week ,50,000 IU once a week dose , but with D3 . After that , they will re-test my levels to see where I'm at . I have since read where you should also take vitamin K2 , since the K2 helps the D3 to be absorbed in the body .
My symptoms ( weak , exhausted , shaky ) have all stopped since I started on the D3 ; and I am only on my fourth week !
Carey says
Man, I love the sun! As a rule, I've always been energized by sun exposure: thanks for the details on how and why.
TIna says
My uncle is a die-hard Vitamin D fanatic. 🙂
His rule-of-thumb is that you need your shadow to be shorter than you are for you to get the benefits of D from the sunshine. If you do the geometry, that's about a 45 degree angle (versus the 50 you mentioned, so close!).
Here in my latitude (Seattle) that's from mid-April to Sept AND in the middle of the day.... AND when there aren't any clouds around, which is sometimes the kicker. HA!
Amy [email protected] Food Whole Health says
Excellent rule of thumb! A great visual explanation. The clouds definitely impact UVB rays- so tough in Seattle 🙂 Most of the northern US has limited months for exposure and time of day is certainly important. Thanks for sharing the shadow trick!
Marianela says
Awesome article =) Getting enough vitamin D from sun exposure is a good idea, but if you are not doing this properly, you may increase your risk of skin cancer.
Alicia says
I don't understand what the table read out is telling me...
Jenny says
Hi Alicia,
Amy recently added some more information and clarification that should help you to better read and understand the table.
Heather says
Maybe I overlooked it, but in using the link for the sun altitude calendar, I read that (for Vitamin D purposes) one wants the altitude to be 50* of greater.