The Overwhelming Evidence That Sunlight Fights Cancer (Mercola.com)
A new paper analyzes the case for vitamin D’s cancer-fighting power by looking at the well-known Hill criteria for examining causality in a biological system. The Hill criteria look at:
2. Consistency (repeated observation)
3. Specificity (one agent, one result)
4. Temporality (exposure precedes effect)
5. Biological gradient (dose-response relation)6. Plausibility (e.g., mechanisms)
7. Coherency (no serious conflict with the generally known facts of the natural history and biology of the disease)
8. Experimental verification (randomized, controlled trial)
9. Analogy with other causal relationships
The theory that solar ultraviolet radiation — and by extension, vitamin D, which is produced when such radiation strikes your skin — is a potent cancer fighter satisfies most, if not all, of the criteria. From a scientific point of view, therefore, vitamin D reduces the risk of many forms of cancer and increases survival rates once cancer reaches a detectable stage.
However, public policy often lags behind scientific research. It is to be hoped that the acceptance of the beneficial nature of vitamin D in reducing the risk of cancer and many other diseases will not have too much longer to wait. It is encouraging that the National Academy of Sciences’ Institute of Medicine is currently embarking on a two-year study of vitamin D, and is expected to issue a report in 2010.
|Dr. Mercola’s Comments:|
|In the last few years the evidence has been pouring in that sunlight fights cancer by producing vitamin D in your skin. Yet, public health officials have been shuffling their feet when it comes to putting the evidence into action.
This paper by Dr. William Grant, Ph.D., internationally recognized research scientist and vitamin D expert, shows just how strong the evidence that sunlight fights cancer really is.
In it he has applied the criteria for causality, originally suggested by Robert Koch to show that tuberculosis was caused by a bacterium and further organized in recent times by A. Bradford Hill.
This approach was used to evaluate whether the association between sunlight and decreased cancer rates can be considered causal, and after he applied the evidence, he found that the theory satisfied most, if not all, of the Hill criteria (the nine-step system listed above). There have also been numerous studies that speak to the power of sunlight in reducing your risk of cancer.
If health officials would simply recommend that you get some sensible sun exposure, or supplement with oral vitamin D3 if you can’t get out into the sun, there could be major advances made in the fight against cancer.
In short, your risk of cancer could be cut in half. This is according to a large-scale, randomized, placebo-controlled study that looked at almost 1,200 women, aged 55 and older, over the course of four years.
Those in a group that was given supplemental calcium and vitamin D had a 60 percent lower risk for all cancers than those who received a placebo.
Other research conducted by Dr. Grant found that about 30 percent of cancer deaths — which amounts to 2 million worldwide and 200,000 in the United States — could be prevented each year with higher levels of vitamin D.
Vitamin D has a protective effect against cancer in several ways, including:
• Increasing the self-destruction of mutated cells (which, if allowed to replicate, could lead to cancer)
• Reducing the spread and reproduction of cancer cells
• Causing cells to become differentiated (cancer cells often lack differentiation)
• Reducing the growth of new blood vessels from pre-existing ones, which is a step in the transition of dormant tumors turning cancerous
And for those who already have cancer, I believe it is virtually criminal malpractice, or at least gross medical negligence, to not optimize vitamin D levels when treating someone with this disease. As Dr. Grant wrote in his article:
“From a scientific point of view, vitamin D reduces the risk of developing many types of cancer and increases survival once cancer reaches the detectable stage.”
You Don’t Have to Wait for a Change in Health Policy
Making sure that your vitamin D levels are optimized is one of the simplest, yet most profound, things you can do to protect your health. It will likely be many decades before health policy catches up to what the evidence has already revealed, and widespread recommendations for increased sunlight exposure and vitamin D levels become the norm.
But you don’t have to wait, as you can optimize your levels right now.
The ideal way to optimize your vitamin D level is by exposing your skin to appropriate amounts of sunlight on large areas of your skin. Unfortunately for most of us there simply isn’t enough sun exposure for nearly half of the year. However, even when the sun is shining many of us are modern-day cavemen and spend the majority of the day inside at work or in our home. Not many of us are regularly out in the sun.
You typically need enough exposure to turn your skin the lightest shade of pink. If you have enough skin exposed you will produce about 20,000 units of vitamin D. Exposures any longer than turning your skin the lightest pink will not produce any additional vitamin D and potentially lead to premature skin aging and increase your risk of skin cancers.
Most of us struggle with vitamin D winters in which we may not be able to get enough sun exposure during certain parts of the year. In that case, I also advise using a safe tanning bed (one that has the harmful emissions shielded) to have your own body produce vitamin D naturally.
A third option is taking a high-quality vitamin D supplement. The most important thing to keep in mind if you opt for oral supplementation is that you only want to supplement with natural vitamin D3 (cholecalciferol), which is human vitamin D. Do NOT use the synthetic and highly inferior vitamin D2.
For those in the winter with no or very limited exposure to sunshine, 4,000-5,000 units per day is appropriate for most adults. If you are very heavy you may need to double that dose, and for children the dose can be half that.
When supplementing, make sure you have your levels monitored to make sure your levels are in the therapeutic range. For an in-depth explanation of what you MUST know before you get tested, please read my updated article Test Values and Treatment for Vitamin D Deficiency. If you live in the U.S. please be sure and use Lab Corp. Quest labs is not as accurate and you will likely need to multiply your results by 0.6 to give you a more accurate measurement of your true vitamin D levels.
One of the Most Important Videos You Will Ever Watch
If you are under the impression that your vitamin D levels are probably fine as they are, I have to warn you that vitamin D deficiency is pandemic in the United States. In fact, the late winter average vitamin D in the U.S. is only about 15-18 ng/ml, which is considered a very serious deficiency state. Meanwhile, it’s thought that over 95 percent of U.S. senior citizens may be deficient, along with 85 percent of the American public.
Making sure that you implement the simple steps necessary to optimize your vitamin D levels is therefore of crucial importance for your own, and your family’s, health. This is why I recorded a one-hour video lecture about vitamin D — so you can learn the nearly unbelievable benefits you will receive by understanding this vital nutrient.
Please set aside one hour to watch the video, as it is easily one of the most important messages you will hear this year.