Vitamin D is a group of fat-soluble secosteroids. In humans, vitamin D is unique both because it functions as a prohormone and because the body can synthesize it (as vitamin D3) when sun exposure is adequate (hence its nickname, the "sunshine vitamin").
American Medical Association Adopts new policies:
“All patients regardless of race or ethnicity should use the same sun protection measures including sunscreen of at least SPF 15, avoid the sun during peak hours and regular exams,” said AMA Board Member Peter W. Carmel, M.D."
Back to Wikipedia:
Sunscreen absorbs ultraviolet light and prevents it from reaching the skin. It has been reported that sunscreen with a sun protection factor (SPF) of 8 based on the UVB spectrum can decrease vitamin D synthetic capacity by 95 percent, whereas sunscreen with an SPF of 15 can reduce synthetic capacity by 98 percent (Matsuoka et al., 1987).
The American Cancer Society Recommends:
Limit direct sun exposure during midday
Another way to limit exposure to UV light is to avoid being outdoors in sunlight too long. UV rays are strongest when the sun is high in the sky, usually between the hours of 10 am and 4 pm. If you are unsure about the sun's intensity, use the shadow test: if your shadow is shorter than you, the sun's rays are the strongest, and protection from the sun is most important.
Why, if the American Cancer Society recommends it, it must be true! Than why are there conflicting reports about this?
Time in the Sun: How Much Is Needed for Vitamin D?
In the winter, it's impossible to produce vitamin D from the sun if you live north of Atlanta because the sun never gets high enough in the sky for its ultraviolet B rays to penetrate the atmosphere. But summer is a great time to stock up on the nutrient. When the sun's UV-B rays hit the skin, a reaction takes place that enables skin cells to manufacture vitamin D.
If you're fair skinned, experts say going outside for 10 minutes in the midday sun—in shorts and a tank top with no sunscreen—will give you enough radiation to produce about 10,000 international units of the vitamin. Dark-skinned individuals and the elderly also produce less vitamin D, and many folks don't get enough of the nutrient from dietary sources like fatty fish and fortified milk.
What does the ACS say about UV rays from the sun?
UVA rays cause cells to age and can cause some damage to cells' DNA. They are linked to long-term skin damage such as wrinkles, but are also thought to play a role in some skin cancers.
UVB rays can cause direct damage to the DNA, and are the main rays that cause sunburns. They are also thought to cause most skin cancers.
Can? Also thought? Glad to see the ACS using definitive, scientifically proven facts to save us all from the evils of UVB exposure!
Back to the USNews Report:
The sunshine vitamin may protect against a host of diseases, including osteoporosis, heart disease, and cancers of the breast, prostate, and colon. What's more, sunlight has other hidden benefits—like protecting against depression, insomnia, and an overactive immune system.
Given all the upsides of basking at least briefly in the summer sun, many experts now worry that public-health messages warning about skin cancer have gone overboard in getting people to cover up and seek the shade.
Gee...what would happen if we had a populace that sunbathed at mid-day regularly without sunscreen, and ate lots of Vitmin D rich foods like grass fed dairy, meat and poultry? Surely the rate of cancers would decline.
This cannot be allowed to happen! The profits of pharmaceutical companies producing sunscreen and cancer treatment drugs would plummet! Donations and Non-Profit funded careers for organizations like the American Cancer Society would dry up! Giant Agricultural Food manufacturers would lose out on all the cholesterol free and fat free food products they sell! This would be an unmitigated disaster across a wide variety of industries! This cannot be allowed to happen!