New study confirms powerful protection against breast, prostate, colon, and other cancers
by Craig Weatherby and Randy Hartnell
Vital Choices readers may recall our multi-part series on vitamin D, which ran in June of 2005 (see issues 27 to 30). These four articles highlighted the new respect that research is bringing to a sadly neglected essential nutrient, which had rarely received the attention given vitamins C and E.
One of the vitamin D's most important—but long overlooked—attributes is its potent anti-cancer power (see “The Neglected Nutrient, Part 1: Vitamin D vs. Cancer”).
New findings build on a solid foundation
Twenty-five years ago, brothers Cedric and Frank Garland conducted research that indicated that death rates from colon cancer were significantly lower in sunnier areas of the country. Their analysis showed that differences in vitamin D levels—which are affected by sun exposure—best explained this distinction.
Subsequent research has only served to confirm the link between increased risk of common cancers and inadequate blood levels of vitamin D, and elucidate the reasons why vitamin D may the most potent anti-cancer nutrient known.
Now, a new analysis led by the Garland brothers and fellow vitamin D pioneers Edward Gorham and Michael Holick has made headlines worldwide. (Gorham and the Garlands teach at the Moores Cancer Center of the University of California, San Diego, while Holick is posted at Boston University.)
The team analyzed the findings from 63 observational studies of vitamin D status in relation to cancer risk published between January of 1966 and December of 2004—virtually every observational study on the subject—which included risk of colon cancer, breast cancer, prostate cancer and ovarian cancer. This type of comprehensive analysis—called a systematic review—is considered the best way to establish a scientific consensus.
As a consequence, the researchers called for prompt public health action to increase intake of vitamin D as an inexpensive way to prevent cancers that kill millions of people every year.
As they said: “The high prevalence of vitamin D deficiency, combined with the discovery of increased risks of certain types of cancer in those who are deficient, suggest that vitamin D deficiency may account for several thousand premature deaths from colon, breast, ovarian and other cancers annually. … The evidence suggests that efforts to improve vitamin D status, for example by vitamin D supplementation, could reduce cancer incidence and mortality at low cost, with few or no adverse effects.”
And as Cedric Garland pointed out in an accompanying press release, “A preponderance of evidence, from the best observational studies the medical world has to offer, gathered over 25 years, has led to the conclusion that public health action is needed. Primary prevention of these cancers has largely been neglected, but we now have proof that the incidence of colon, breast, and ovarian cancer can be reduced dramatically by increasing the public's intake of vitamin D.”
Sources of vitamin D
Cedric Garland noted that the target blood levels of vitamin D can be most easily attained by taking supplements and eating foods high in vitamin D:
“Many people are deficient in vitamin D. A glass of milk, for example, has only 100 IU. Other foods, such as orange juice, yogurt and cheese, are now beginning to be fortified, but you have to work fairly hard to reach 1,000 IU a day. Sun exposure has its own concerns and limitations.
“We recommend no more than 15 minutes of exposure daily over 40 percent of the body, other than the face, which should be protected from the sun. Dark-skinned people, however, may need more exposure to produce adequate amounts of vitamin D, and some fair-skinned people shouldn't try to get any vitamin D from the sun.
“The easiest and most reliable way of getting the appropriate amount is from food and a daily supplement.”
Our own lab tests indicate that wild sockeye salmon contains 687 IU of vitamin D per 3.5 ounce serving, while, a single 6 oz portion contains more than 1,100 IU: a proven-safe amount just above the daily intake (1,000 IU) recommended by the authors of the new cancer-prevention study.
In fact, sockeye salmon appears to offer more vitamin D than any other whole food. This distinction is probably a function of its unusual diet, which features more vitamin D-rich plankton than other salmon and most other fish.
After sockeye, the best vitamin D sources among our seafood selection are albacore tuna (544 IU), silver salmon (430 IU), halibut (276), king salmon (236 IU), sardines (222 IU), and sablefish (182). Note: Each 1000 mg capsule of our Sockeye Salmon Oil dietary supplement contains 53 IU.
- Garland CF, Garland FC, Gorham ED, Lipkin M, Newmark H, Mohr SB, Holick MF. The Role of Vitamin D in Cancer Prevention. Am J Public Health. 2005 Dec 27; [Epub ahead of print]
- Gorham ED, Garland CF, Garland FC, Grant WB, Mohr SB, Lipkin M, Newmark HL, Giovannucci E, Wei M, Holick MF. Vitamin D and prevention of colorectal cancer. J Steroid Biochem Mol Biol. 2005 Oct;97(1-2):179-94. Epub 2005 Oct 19.
- Garland CF, Garland FC. Do sunlight and vitamin D reduce the likelihood of colon cancer? Int J Epidemiol. 1980 Sep;9(3):227-31.
- Garland CF, Garland FC, Gorham ED. Calcium and vitamin D. Their potential roles in colon and breast cancer prevention. Ann N Y Acad Sci. 1999;889:107-19. Review.
- Garland C, Shekelle RB, Barrett-Connor E, Criqui MH, Rossof AH, Paul O. Dietary vitamin D and calcium and risk of colorectal cancer: a 19-year prospective study in men. Lancet. 1985 Feb 9;1(8424):307-9.