We interviewed Dr. Michael Holick on why sunshine is good for you and the best source for vitamin D. Here is what he said:

In your opinion what is the root cause of vitamin D deficiency?

The 2 major reasons for the global D deficiency epidemic are the lack of understanding that very few foods naturally contain vitamin D and that sunlight has been and continues to be a major source for vitamin D worldwide.  The recommendation by many health organizations that neither children or adults should be exposed to direct sunlight has been a major factor in causing this pandemic.

Do you think the risks of moderate, regular sun exposure, such as skin cancer, has been over emphasized to the public?

There is no question that the abstinence message from national and international health organizations regarding sun exposure has been a major contributor to the vitamin D deficiency pandemic.  A recent study has suggested that moderate regular sun exposure does improve a person's vitamin D status and that mechanisms are at play in the skin to reduce the damaging effects from moderate regular sun exposure.
 

What is the real risk of skin cancer from sunshine? Is it just from burning exposure or moderate exposure as well?

The major cause for skin cancer is sun burning.  Chronic excessive exposure to the sun increases risk for nonmelanoma skin cancer.  Moderate exposure experience by outdoor workers as been associated with reduced risk of the most deadly skin cancer melanoma.  The body has adapted to it sunlight environment taking advantage of the beneficial effects while minimizing the damaging effects thereby minimizing risk for both melanoma and nonmelanoma skin cancers.

Is all sun exposure bad for you and damage to your health?

There are a multitude of beneficial effects during sun exposure.  As a result sensible moderate sun exposure has overall health benefits that outweigh the risk for sun-induced damage and nonmelanoma skin cancer.

Do people who get more sunshine live longer or shorter?

There is a lot of association data reporting that those who have the most sun exposure have decreased risk for mortality especially associated with cardiovascular events.

We know sunscreen prevents vitamin D production. How do you recommend sunscreen be used to allow for vitamin D production but protect also against skin cancer?

I recommend sensible sun exposure using the free app dminder.info.  It provides guidance for when you can make vitamin D in your skin, how much vitamin D you can generate and then warns you to then put a sunscreen on or use some sun protection to prevent sunburning.

What are the key health benefits of sun exposure?  

One of the most beneficial effects is of course the production of vitamin D.  People feel better when they are exposed to sunlight most likely because they are producing beta endorphin in the skin.  They also feel more relaxed and their blood pressure decreases because of the release and production of vasodilator nitric oxide.  There are a large number of other photo biologic processes that occur in the skin that have potential health benefits including the regulation of the proopiomelanocortin gene that not only produces beta endorphin but adrenocorticotropin hormone which is responsible for regulating cortisol production in the adrenal glands.

In your opinion do the benefits of moderate non-burning sun exposure greatly outweigh the risks?

Yes

Why do you recommend sunshine first if possible over supplements for vitamin D?

I recommend sensible sun exposure as a good source of vitamin D.  However it's unrealistic to get enough vitamin D to satisfy the body's requirement as our Hunter gatherer's had done.  This is because we cannot be exposed to sunlight from 10 AM until 3 PM on a daily basis as our hunter gatherer forefathers were.  I therefore recommend that children take 1000 international units vitamin D daily and adults 2000 IUs daily along with sensible sun exposure.

What additional photoproducts are produced in sunshine that have a positive health effect that are not available in a vitamin D supplement?

We know that during sun exposure several vitamin D photoproducts are produced.  Their biologic function(s) have not been fully characterized.  However these photoproducts are not available in a vitamin D supplement.
 

Thank you Dr. Holick for your insight into vitamin D and sunshine! It is always greatly appreciated.