Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Vitamin D: Total but Not Dietary Alone Prevents Colorectal Cancer


Studies of the geographic variation of colon and rectal (colorectal) cancer mortality rates in the U.S. have long indicated that they are primariliy linked to solar ultraviolet-B (UVB) radiation: the more UVB in summer, the lower the mortality rate.

The hypothesis to explain this result is that UVB radiation produces vitamin D in the skin, and vitamin D acts to reduce the risk of colorectal and over a dozen other types of cancer. One major study found that intake of 150 IU/day of vitamin D was associated with a reduction by half in incidence of colon cancer, a result that was statistically significant. However, some studies that have investigated the link between dietary sources of vitamin D and colorectal cancer have found a smaller degree of risk reduction comparing the highest versus lowest levels of dietary vitamin D.

In a review of the literature published in the current issue of Nutrition and Cancer, Drs. William Grant and Cedric Garland report that the reason for the sometimes weak link between dietary sources of vitamin D and colorectal cancer incidence or mortality rates is that dietary sources often cannot supply enough vitamin D to be effective in quantities ordinarily consumed. In most such studies, the highest quartile or quintile of those studied consumed over 150-370 I.U./day from dietary sources. That was sufficient in some cases to provide a 10-50% reduction in colorectal cancer risk, but not always at a statistically significant level. However, studies that considered vitamin D intake from both diet and supplements for which the highest levels were over 500 I.U./day found 30-60% risk reduction for the highest versus lowest levels, and the results were uniformly tatistically significant.

These results, then, help explain the geographic variation of colorectal and other cancer mortality rates in the U.S. Colon cancer mortalty rates for males in the period 1970-94 were about 25 deaths/100,000/year (d/hk/yr) for males and 18 d/hk/yr for females in northeastern states but only 15 d/hk/yr for males and 12 d/hk/yr for females in southwestern states.

These mortality rates are inversely correlated with July average irradiances of solar UVB radiation, which are higest in the southwest, lowest in the northeast taking into further consideration that urbanites have reduced UVB exposure compared to rural residents. These results are consistent with those living in the southwestern states having an effective annual average vitamin D production of several hundred I.U./day more than those living in the northeastern states. In addition, these results provide further support for the idea that most Americans obtain most of their vitamin D from solar UVB radiation and not diet.

As reported earlier, Dr. Grant estimates that over 20,000 Americans die prematurely from over a dozen types of cancer annually due to insufficient UVB/vitamin D [Grant, 2002]. This number is much higher than the approximately 9,000 who die annually from melanoma in the U.S. or approximately 2,000 from non-melanoma skin cancer.

It should be noted that while UV radiation, especially UVA, plays a role in both melanoma and non-melanoma skin cancer, a number of other factors also play important roles, such as skin pigmentation, severe sunburning, a high-fat, high-protein, low-fruit and vegetable diet, and alcohol consumption [Millen et al., 2004] and, at least for non-melanoma skin cancer, cigarette smoking. Together, these factors explain about half of melanoma and non-melanoma death rates.

Most people should be able to obtain adequate levels of vitamin D from modest daily exposures to mid-day summer sun in the southwest up through Wyoming and the southeastern states, with longer exposures required in other locations.

When solar UVB levels are not adequate, such as during the winter in most areas, vitamin D3 supplements or artificial UV lamps that mimic the solar UVA and UVB spectrum may provide convenient alternate sources of vitamin D.

Grant WB, Garland CF. A critical review of studies on vitamin D in relation to colorectal cancer. Nutrition and Cancer, 2004;48:115-23.

William B. Grant, Ph.D.
2107 Van Ness Avenue, Suite 403B
San Francisco, CA 94109

Cedric F. Garland, Dr.P.H., F.A.C.E.
Department of Family and Preventive Medicine, 0631C
School of Medicine
University of California, San Diego
9500 Gilman Drive
La Jolla, California 92093-0631, USA

| newswise
Further information:

More articles from Health and Medicine:

nachricht Resolving the mystery of preeclampsia
21.10.2016 | Universitätsklinikum Magdeburg

nachricht New potential cancer treatment using microwaves to target deep tumors
12.10.2016 | University of Texas at Arlington

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>