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vitamin d from sun

Are You Really Getting Vitamin D from The Sun or Just ‘Nuking’ Your DNA?

vitamin d from sun

Vitamin D Update: Almost every person that I've recently spoken with misunderstands the ways to get vitamin D from the sun. Even physicians give incorrect advice. I see simple mandates telling people to go out and get sun for optimum health. But confusion abounds! about Vitamin D and Sun Exposure surrounds how much sun, what time of the day, how many days a week, how long in the sun, and of course, should a person even use sun for vitamin D production in the first place. I’ve answered a lot of these questions about sun exposure and vitamin D in a previous post, but I want to give an update on some really good information I’ve found since I wrote that post.

Confusion about Vitamin D from Sun Exposure:

  • How much sun do you need to create vitamin D from sun exposure?
  • What time of day do you need to be outdoors to create vitamin D from sun exposure?
  • How many days a week do you need to sun expose your skin to make enough vitamin D?
  • How long do you need to be in the sun to make enough vitamin D?
  • Do you even need to use your skin for a vitamin d factory or is your vitamin D level normal already?

People are rightly concerned about their vitamin D levels.  Scientists are learning more and more about how critical vitamin D is for overall health.  Everybody’s talking about it.  I was at my hair stylist just the other day and when another woman there found out I was a dermatologist, she sat down next to me, looked me directly in the eyes, worry written all over her face, and said,

“I just have to ask what do about my vitamin D.  I’m a cancer survivor, I’ve heard that cancer survivors have low vitamin D and that it’s dangerous.  I’ve been told to get sun, but how much? Will I get more sun damage? What do I do?  I want to be healthy.”


She’s right.  Cancer patients often do have low vitamin D levels and it’s frightening.  Vitamin D is known to be important for immune strength, including immune strength against cancer. Sunny weather is here and frightened cancer survivors, and anyone who’s health conscious, are searching for answers about the sun and what’s best for their vitamin D level.  Here’s what I told her:

Update on Vitamin D and Health

Fair-skinned people make the maximum amount of vitamin D3 possible within a few minutes of mid-day summer sun exposure. This occurs with less sun exposure than would cause skin redness.  Longer sun exposure adds nothing to vitamin D stores, but it does increase DNA damage.

The vitamin D3 that you do make from the sun breaks down if you keep getting more sun exposure, meaning you actually lose the vitamin D3 that you just produced in those first few minutes of summer sun.

Only UVB (middle of the day summer sun from about 11 to 3pm) makes vitamin D3, I mentioned this in the previous post.

Dietary vitamin D supplements should be vitamin D3, not D2.

eat vitamin d rich foods

You should eat foods that contain D3 including fish liver, fish liver oils, fatty fish including salmon (thank goodness), mackerel and bluefish, and egg yolks.  You also need to try to eat wild caught fish, not farmed; studies show that in the US, farmed salmon contains only ¼ the amount of D3 compared to wild salmon from Alaska.

2000 IU of Vitamin D3 may well end up being the new dosage recommended for prevention of vitamin D3 deficiency for people at risk of low levels.  Recommendations are currently being reevaluated by the medical community, but it appears that 2000 IU is generally the latest recommendation.  This is the dose that I take.

Important tips about your vitamin D levels and skin health:

Simplified recommendations bounced around by ‘experts’ telling you to go in the sun are way too simple.  Ignore advice about how much skin you need to expose, how often and for how long.  Too many things affect how well the sun produces vitamin D3 in your skin, including:

Too many things affect how well the sun produces vitamin D3 in your skin, including:

  • Where you are in the world (your location latitude and altitude).
  • The time of the day.
  • The time of the year.
  • The ozone concentration above you.
  • The pollution in the air.
  • The presence of clouds in the sky.
  • The presence of reflective surrounding surfaces (water, cement, sand, etc.).
  • How much pigmentation is in your skin to block UV?
  • How much of the pre-vitamin your skin has in it at the time of sun exposure?

You can see the variables make it complicated to use your skin as a vitamin D factory. And, remember, that the vitamin D3 your skin does produce is broken down if you stay in the sun after you’ve made that initial dose.

Doctor's simple tips for vitamin D and your skin:

Forget simple recommendations.   

  • Get your vitamin D level measured by your doctor.
  • Take supplements and eat foods with vitamin D3. 
  • If that doesn’t keep your vitamin D level in the healthy range, then experiment with exposing your tummy for a few minutes like I mentioned in the previous vitamin D post. 
  • Get your level re-measured, your sun-produced vitamin D level peaks in 12 to 24 hours after exposure. 

In summary, customize your approach to a healthy vitamin D level.  And remember, chances are, your level is just fine anyway and all that sun exposure is just nuking your DNA, making wrinkles, age spots and skin cancers.

Bodo Lehmann & Michael Meurer, Vitamin D metabolism, Dermatologic Therapy, Vol 23, 2010, 2-12

Joseph W. Diehl & Melvin W. Chiu, Effects of ambient sunlight and photoprotection on vitamin D status, Dermatologic Therapy, Vol. 23, 2010 48-60

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