bright sun shining, sunlight, sunlight boost

Ask most people what they fear most and the answer is almost always cancer. That’s because cancer rivals heart disease as our number one killer. We now have highly effective treatments for heart disease and even if someone experiences a heart attack, doctors can frequently intervene to save his life.

Cancer, on the other hand, is still mysterious. No one knows why one person can live a normal life after a cancer diagnosis while another person succumbs within a few years despite getting the same treatment.

Is Vitamin D Helpful for Cancer Prevention?

Preventing cancer and prolonging life after a diagnosis is the primary goal. Could vitamin D provide an important element in an anticancer strategy? There is growing evidence that the sunshine vitamin might play a far more important role in both cancer prevention and survival than most people realize.

What Does Sunlight Have to Do with Cancer?

Vitamin D is made by human skin when it is exposed to sunlight. Epidemiologists have known for a long time that people who live in areas where there is a lot of sunshine have a lower likelihood of coming down with cancer and people who live in areas of less sunshine have a higher likelihood of developing cancer (Cancer Causes & Control, March, 2005; Anticancer Research, Sept, 2009; Epidemiology and Genomics Research, National Cancer Institute, May 7-8, 2007; BJU International, Nov. 2011).

Evidence is growing that people with adequate vitamin D levels are less likely to be diagnosed with cancer and more likely to survive a cancer that occurs (Dermato-Endocrinology, Apr/May/June, 2012). Women with higher vitamin D levels had better survival after diagnosis with breast cancer (Carcinogenesis, online May 24, 2012).

A large study showed higher vitamin D levels associated with a lower likelihood of lethal prostate cancer (Journal of the National Cancer Institute, May 2, 2012). One protocol showed benefit for men with prostate cancer taking 4000 IU of vitamin D3 daily (Journal of Clinical Endocrinology and Metabolism, online Apr. 16, 2012). This dose is high, so no one should undertake such a dose without medical supervision!

More recent research is beginning to clarify how vitamin D fights cancer. It inhibits the stem cells that give rise to cancer and pushes cells to differentiate (Journal of Steroid Biochemistry and Molecular Biology, online Dec. 3, 2016). When cells differentiate, they are far less likely to become out-of-control tumor cells. In addition, the vitamin D receptor is crucial in preventing inflammatory bowel disease and colon cancer (Current Medicinal Chemistry, online Dec. 2, 2016).

Sunlight or Pills?

Which is better, sunlight or vitamin D3 pills? This is a highly controversial topic, and there isn’t good evidence currently available to answer this question. Some vitamin D experts believe that 10 to 15 minutes of sun exposure three or four times a week is the best solution to the vitamin D dilemma. Dermatologists, on the other hand, believe that going out in the sun without a high SPF sunscreen is just plain dangerous.

Dutch scientists have recently pointed out that sunlight may go beyond providing adequate vitamin D (Medical Hypotheses, Dec., 2016). In addition, sunlight affects our natural clocks (circadian rhythm), and through that has an impact on the immune system. They point out that in Europe people with intermittent sun exposure are more prone to the deadly skin cancer melanoma, while those with more regular exposure are at lower risk.

Symptoms of Vitamin D Deficiency

  • Asthma
  • Fatigue
  • Fractures
  • Insomnia
  • Joint aches
  • Mood swings
  • Muscle pain

To read more about testing for vitamin D levels (and what is now considered prudent), the safest dosing range, preferable vitamin D formulations, and a variety of other practical you may wish to check out our Guide to Vitamin D Deficiency.

Meanwhile, make sure you are getting the right amount of sun or the optimal amount of vitamin D from a supplement. It just might save your life!

Revised 12/12/2016

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  1. LM

    The article says nothing about the loss of ability to convert sunlight to vitamin D that occurs with aging. I am 71. I am a naturist and get full-body exposure to sunlight. After a week mountain-hiking in the Colorado Rockies with 8 hours of complete exposure each day, followed by a week or two at a resort in Virginia with just as much exposure, my Vitamin D level was 34 mg/dl, which is right at the bottom edge of normal. After a few months of 6000 IU daily and 50,000 IU each Saturday, I’ve gotten it to 66 mg/dl.

    (There’s a theory that the liver eliminates oral Vitamin D before the body can take advantage of it. Taking a huge dose weekly overwhelms the liver and some Vitamin D is actually retained and available.)

  2. Dianne
    Asheboro, NC

    I’m sure I’ve read in Peoples Pharmacy that 6000 to 7000 IUs are recommended daily dosage of D3 for those 65 and over. Has the dosage changed?

    • Terry Graedon

      We don’t generally recommend that people take more than 4,000 IU daily except under medical supervision.

  3. Barbara

    Just curious, the comments above are almost five (5) years old. Do you not have anything more recent. Updates are always welcomed, and many things/info can and will change over a five (5) year period. And yes, Vitamin D3 is the best possible medicine, as far as I am concerned.

    Thank you, and please update info.

  4. STEVE

    I just must comment. Every article in today’s feature show everything as conflicts. Makes me feel sad. Or maybe I did or did not get enough D3, or too much or too little cholesterol, or I mixed up my statins with too many vitamin supplements. SO I better get some tests which may or may not be accurate. Or maybe I should talk with my doctor who tells me to not believe anything that I read except what he or she tells me or or or or or———–. Excuse me, but as I said I just had to comment to get it off my chest and make me feel better. Oh gee gosh, I still do not feel better and neither does my chest. I love and respect your site and advice, and I comment often. Now I feel a little better having given you a compliment.

  5. Karen

    >make sure you are getting the right amount of sun
    If you live in the US north of the Mason-Dixon line, you can’t get enough sun.

  6. HN

    Once again, misinformation from the “experts” is propagated: Some vitamin D experts believe that 10 to 15 minutes of sun exposure three or four times a week is the best solution to the vitamin D dilemma. Depending upon what latitude you’re at, the time of day, and what part of your body got the exposure (torso is most important), that may give you only a minimal amount of exposure that your body can make into D3. Plus, your body may no longer be efficient at converting that UVB on the skin into the D3 that the body uses. Like the “experts” who keep telling people that we get all the vitamins and minerals we need from our diet and that supplements just give you “expensive urine,” it’s just more misinformation that people don’t need to hear.

  7. cm

    Even Dr. Perricone, the top dermatologist of our day, says to get 10-15 minutes of sun exposure daily before putting on sunblock…. I live in FL so sunshine is not a problem for me and I find that not getting any for several days does affect me and, as I suffer from depression, I find that being in the sun really boosts my mood (Perricone also says not to shower or bath for 8 hours after sun exposure if possible to avoid washing away the beneficial oils produced on the skin that are involved in Vitamin D metabolism).

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