https://vitamindhealth.org/

Dr. Michael Holick's new book on Vit. D is out. I found it to be very good and encouraging. He states that vit. D2 is just as good as vit. D3 which I found surprising. He also had the parameters for where you live and how much sun exposure you need. For example, I live in So. Cal and during the winter if I'm in the sun for 20 min. I'll make enough vit. D. (this in contrary to what I've read elsewhere which stated my shadow needed to be shorter than my height).

This is a good read. I found it at my local library.

Holick is simply wrong to state that D2 is equivalent to D3.
Vitamin D(3) is more potent than vitamin D(2) in humans.
There is another recent paper where they found elderly people given D2 showed no benefit while those given D3 lived longer.

Calculator for 1000iu vitamin d3 from wherever you live however this is for just 1000iu and most people require 5000iu or more. Also age, skin thickness, cholesterol level and local atmospheric pollution also affect the issue so you still need to check with a 25(OH)D test and if money is no object it would be interesting to buy a UVB meter to see for yourself how much UVB is available.

I have dogs and cats. They all like to sit in the sun for long periods of time. When it is cold outside, they prefer to stay in the house and sit in front of a sunny window. Is exposure to sunshine through a window of benefit to humans in terms of Vit. D?

Good question??

I also want to ask something, i was talking to someone and i mentioned vitamin D and sun exposure, the other person replied with Skin cancer...Ted i know you have strong feelings :P for Vit.D i always see you supporting it,so wussup with the skin cancer or sun causing cancer stuff? Im sure you already answered this before but tell me please?

All i could answer to the person was that yes it might but not if you balance it out and not Over expose yourself, but i wasnt ready to get into an ''argument'' bcuz i didnt have anything to support my claims...so i just kinda quickly changed the subject hehehe...So Ted?

The habitual use of sunscreen is more likely to cause skin cancer than prevent skin cancer. Sunscreen blocks the body's ability to create Vit. D through exposure to sunshine. Vit. D is necessary to good health and cancer prevention. Severe sunburn during one's youth is a cause of skin cancer down the line. Normal exposure to sunshine is not a cause of cancer.

Absolutely NOT.
UVA exposure does NOT create vitamin D3, to some extent it does help create the precursor molecule but on the other hand it also processes the Vitamin D3 remaining near the skin surface into suprasterols that the body doesn't use so if you stay in the sun too long you get to the point that vitamin d3 creation is counterbalance by vitamin d3 depletion and so obviously you cannot overdose on vitamin d3 from sun exposure alone (the human race wouldn't have survived the evolutionary process if that were the case)

It is possible that the trouble nowdays isn't that people aren't getting sufficient UVB exposures (though I think this is a major factor) BUT they may be getting TOO MUCH UVA, sitting/working behind thick glass but in full sunshine where all the light they get is UVA.
Think about office workers who work right by the window all morning the UVA is degrading any vitamin d 3 near the skin surface, they spend their lunch break sunbathing on the office roof/garden for 20mins thinking they will make lots of vitamin D3, then spend the rest of the afternoon in under UVA light either through the window or possibly from the lights?
Are they spending more time depleting vitamin d3 than creating it?

First we have to understand that humans evolved from dark-skinned individuals living in sunny tropical countries. As they moved away from the Equator those with the palest skins were better able to survive. It was the better ability to create and STORE vitamin D3 that enabled them to have higher immune status through the winter, vitamin d levels also increase calcium/magnesium intake and those people with inadequate vitamin d status would have been less fertile and less able to give birth. If you search for images of a normal female pelvis and a female with rickets pelvis you can see why the rickets mother /and baby wouldn't have survived the birthing process so pale skinned women would have been prized for their increased fertility.

So evolutionary our DNA is set to reward us for sunbathing, that's why some people become addicted to tanning beds.
The question then is why do we get cancer from excess sun exposure when our early ancestors would have benefited from spending all day naked in the sun?
Well our early ancestors ONLY ate organic free range meats, fish, veggies and fruits so would have maintained a higher omega 3 omega 6 ratio. It was probably around 1 omega 3 to 1 omega 6. The balance would have been anti inflammatory so when it was very sunny they had plenty of anti inflammatory reserves to resolve that inflammation. See healthy fellow Natural Sunscreen Options AND they would have been subject to ideal circadian rhythm will lots more melatonin secretion than available today.
Once skin is inflamed the blood comes to the surface of the skin and the iron in the blood induces skin damage, since iron is a catalyst of biological oxidations.

so having more natural iron chelators (vitamin D3 and melatonin) and greater anti inflammatory reserves enabled early humans to survive and gives modern humans the key to naturally preventing sunburn and skin damage.

Key to the change is to The ANTI INFLAMMATORY DIET but you also need an anti inflammatory lifestyle so you need to reduce stress(reduce cortisol inflammation) and get more sleep (to increase anti inflammatory iron chelating melatonin secretion)

Sun exposure is associated with increased survival from melanoma.

I haven't time to explain the sunscreen causes skin cancer dilemma.
But Edward Gorham explains it here Skin Cancer/Sunscreen - the Dilemma

Ive noticed that people who spend a lot of time driving, especially in the southern USA will get large brown spots on their cheeks on the side of the face that is by the car window. This was confirmed to me by a dermatologist at one point. The sun does damage from this repeated exposure, even through glass, but may not necessarily lead to cancer on that side of the face.

I can only be in the sun for short periods of time as I will burn.. I burn less these last 15 years than previously since homeopathic treatment, but none the less, I must be careful. Burning will present a greater risk to getting sun cancer than not burning.. also people of northern European lineage will have a greater risk for common skin cancer because they don't have the pigments to help them protect against uvb.

Ultimately skin cancer is a much larger issue than too much or two little sun exposure. It can also be related to the quality of diet and presence of pathogens. A toxic body or malnourished body, I am going to assume will have a greater propensity to create cancer of all kinds including skin cancer and especially if the skin has been damaged by exposure. Damaged tissues loose the capacityt to funtion normally.

Its pretty well documented these days that too much sun can lead to basal cell carcinoma, yet it will not occur in everyone. You should assess your risk factors and live accordingly. It is also well documented that those with difficient vitamin D3 will have a higher risk for cancer. Repeated bouts of long exposures will increase the risks over a lifetime.

On the other hand melanoma, the most deadly kind of skin cancer can pop up where the sun dont shine and it is not related to skin cancer, but has a pathogen at the root cause.

The chemicals in sunblock have been showed to be linked with cancer.

Most people will be find with 15 to 20 minute exposures to each side of the body daily. You must determine exactly how long is safe for you to get lighly pink without really burning. . it may vary according to the time of day.

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Car windscreens block out the UVB, only allow the UVA to penetrate so the effect is to deplete vitamin D3 and damage the skin at the same time.

I've put a link to an online calculator earlier in this thread. It works out the exposure required at on any particular day of the year, at any latitude/altitude and adjusts for grass or concrete surroundings. BUT it's only for 1000iu so you need to either expose 5x more skin or multiply the time by 5 to get the minimum 5000iu for daily needs and it still doesn't adjust for age, skin tone weight or cholesterol level so it's only APPROXIMATE and you still need to test 25(OH)D regularly to be sure you know how your body responds to sun/uvb exposure and oral supplements.

I should perhaps have pointed out earlier that making changes to your skin's natural sunscreen ability takes TIME.
You don't change every cell on your skin surface quickly.
If you start NOW you may notice the difference next March at the earliest but getting your pro inflammatory omega 6 levels reduced, Raising your omega 3 status and ensuring your vitamin D reserves are at 60ng 150nmol/l will take longer. Dr Davis finds some of his patients take 2~3 yrs to top up their vitamin d tanks. So you have to regard it as a long term project and not think it's just a matter of weeks (though the omega 3 changes have been shown to start straight away so that some hospitals are sending out omega 3 repletion packs 3 weeks before a planned surgery so they can get the bed vacated sooner as a result of faster recovery times.

Yes but if I followed such a calculator I would likely be quite fried if I acted upon its calculations. Some people cannot tolerate the sun no matter what day of the year it is and I have always been one of them. One must individualize their plans according to what acutally happens when you are out in the sun.

Vitamin D2 can be converted to D3 only if you have very healthy liver and kidneys. Most people don't. How many of you on this forum have thought of having a liver flush? You know that your liver is healthy, but not in superior working order. So, it is best and easiest for those organs that you choose to supplement with D3.

Dogwoman, Funny that you mention how your dog loves the sunny window. Reminds me of this sweet little dachshund that greets people as they come into a local printer's shop. She pulls her bed right in front of the entrance door. That is the only place where the sunshine comes in all the way the the floor. When I open the door, she does move out of the way, looks up at me with her cute little eyes and cute little nose, but leaves the bed. Everyone has to step over the bed. It's only in the afternoon that she moves the bed, following the sun.

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- Jim
That which does not kill us makes us stronger. -Friedrich Nietzsche

But people whose skin has become maladapted to it's natural environment should be making efforts to correct that malady.
If you follow Healthy Fellows suggestions and those I've added in the comments section you will find over time your skin becomes more able to survive in it's natural environment. Of course you must never burn BUT regular short non burning exposure to UVB over winter can make life in summer much better.
UV hardening therapy: a novel intervention in patients with photosensitive cutaneous lupus erythematosus.

You should also be aware that ALL of the approaches suggested work in synergy so the combined effect is better than the sum of each individual approach. So raising 25(OH)D to 60ng/ml + anti inflammatory diet + anti inflammatory lifesyle changes + over winter skin hardening + omega 3 supplementing and omega 6 reduction ALL combined are far better than trying just one approach one year and another the following.

If you think about it our early ancestors had ALL of these advantages ALL the time.

Astaxanthin has been shown in the lab to be the strongest natural antioxidant known. But I personally think that chaparral is.

One pharmaceutical compay has received a patent for using astaxanthin in an oral sunscreen. One does not need a drug. Just supplement with astaxanthin to build up resistance to sunburn.

Aww, what a sweet visual I have of that dog. So cute that she moves her bed to follow the sun.

I wonder if laying in the sun is for warmth or it's instinctual for the sun's benefits. The poor things don't know about windows.