 Larry C. Clark, Ph.D., M.P.H., internationally known for his work in understanding the role of selenium in preventing cancer, died March 20, 2000. He was 51 at the time of his death and is survived by his wife, Louanne, and his daughter, Julia.
Dr. Clark joined the faculty of the University of Arizona College of Medicine in1987. He was associate professor in the College of Public Health and was a member of the Arizona Cancer Center. Until his death, he directed the Nutritional Prevention of Cancer Projects in Selenium at the Arizona Cancer Center. He also was an adjunct associate professor in the Department of Nutritional Sciences in the University of Arizona College of Agriculture.
His research focused on the beneficial health effects of selenium in humans. His most widely known work was published in the Journal of the American Medical Association (JAMA), Vol. 276, No 24; pp1957-1963 in December 1996. This study provided the first evidence that, while selenium had no benefit in reducing skin cancer incidence, nutritional supplementation with selenium may reduce the incidence of prostate (63%), lung (46%) and colon (58%) cancers. Dr. Clark's on-going research involves three complementary clinical trials of selenium and prostate cancer prevention and progression that should help determine the role of selenium in this disease.
Dr. Clark began his research work alongside Gerald F. Combs, Jr. Ph.D. while at Cornell University in the early 1980’s. Often referred to as the "Clark and Combs Trial" the Nutritional Prevention of Cancer Trial (NPC) was deemed a "landmark" trial following the 1996 publication in JAMA. Based on "Gold Standard" research, we learned that a simple nutritional agent like selenium could prevent significant percentages of colon, lung and prostate cancers. Today, numerous clinical studies are underway to confirm the results of the NPC Trail and validate the role selenium and SelenoExcell® play in the prevention of cancer.
A rising public face to the world of selenium research and cancer prevention is Dr. Mark Whitacre, Chief Operating Officer of Cypress Systems, Inc. Dr. Whitacre studied under Dr. Combs at Cornell University in the early 80’s in the field of Nutritional Biochemistry and completed his Ph.D. research related to the biochemical role of selenium at the cellular level in the prevention of diseases. A decade after graduating from Cornell, Dr. Whitacre became the highest level executive to turn whistleblower in what became the largest corporate price-fixing case in the history of the United States. Dr. Whitacre is the subject of a major motion picture, The Informant, starring Matt Damon as Mark Whitacre. To be released in September of this year, the media platform related to the movie will allow Dr. Whitacre to speak on major media about the great work being done to prevent cancer using selenium.
Dr. Whitacre states, "I desire to let the world know about the tremendous research being done by clinical teams around the globe to prevent cancer using a simple mineral like selenium. Like the landmark study completed by Dr. Clark and Dr. Combs in the NPC Trial, this research has the potential to change lives and reduce the incidence of a devastating disease, cancer. These scientists are conducting the necessary research, but I hope to be a voice to raise public awareness."
Footnote:
Dr. Gerald F. Combs, Jr. continues his foundational selenium research as Center Director at USDA Grand Forks Human Nutrition Research Center in Grand Forks North Dakota.
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| Q: |
What role does selenium play in cancer prevention? |
| A: |
According to the National Institute of Health, selenium helps make special proteins, called antioxidant enzymes, which play a role in preventing cell damage. There is medical evidence that certain types of selenium many have cancer prevention properties, studies are ongoing.
Research suggests that selenium affects cancer risk in two ways. As an anti-oxidant, selenium can help protect the body from damaging effects of free radicals. Selenium may also prevent or slow tumor growth. Certain breakdown products of selenium are believed to prevent tumor growth by enhancing immune cell activity and suppressing development of blood vessels to the tumor. |
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| Q: |
What foods contain selenium? |
| A: |
Foods with the highest sources of selenium are cereals, such as corn, wheat, oats and rice, brewer’s yeast, walnuts and brazil nuts, soybeans, garlic, beef, chicken, turkey, egg, cheese, tuna and cod.
| Food |
Micrograms
(μg) |
Percent
DV* |
| Brazil nuts, dried, unblanched, 1 ounce |
544 |
780 |
| Tuna, light, canned in oil, drained, 3 ounces |
63 |
95 |
| Beef, cooked, 3½ ounces |
35 |
50 |
| Spaghetti w/ meat sauce, frozen entrée, 1 serving |
34 |
50 |
| Cod, cooked, 3 ounces |
32 |
45 |
| Turkey, light meat, roasted, 3½ ounces |
32 |
45 |
| Beef chuck roast, lean only, roasted, 3 ounces |
23 |
35 |
| Chicken Breast, meat only, roasted, 3½ ounces |
20 |
30 |
| Noodles, enriched, boiled, 1/2 cup |
17 |
25 |
| Macaroni, elbow, enriched, boiled, 1/2 cup |
15 |
20 |
| Egg, whole, 1 medium |
14 |
20 |
| Cottage cheese, low fat 2%, 1/2 cup |
12 |
15 |
| Oatmeal, instant, fortified, cooked, 1 cup |
12 |
15 |
| Rice, white, enriched, long grain, cooked, 1/2 cup |
12 |
15 |
| Rice, brown, long-grained, cooked, 1/2 cup |
10 |
15 |
| Bread, enriched, whole wheat, commercially prepared, 1 slice |
10 |
15 |
| Walnuts, black, dried, 1 ounce |
5 |
8 |
| Bread, enriched, white, commercially prepared, 1 slice |
4 |
6 |
| Cheddar cheese, 1 ounce |
4 |
6 |
Source: Office Of Dietary Supplements
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| Q: |
How much selenium do I need? |
| A: |
The Food and Nutrition Board of the Institute of Medicine recommends the following dietary reference intakes (DRIs) of selenium:
• 0 - 6 months: 15 µg/day
• 7 - 12 months: 20 µg/day
• 1 - 8 years: 30 µg/day
• 9 - 13 years: 40 µg/day
• 14 and older: 55 µg/day
Selenium is also available in 'high selenium yeasts', which may contain as much as 1,000 to 2,000 micrograms of selenium per gram. Observational studies indicate that death from cancer, including lung, colorectal, and prostate cancers, is lower among people with higher blood levels or intake of high selenium yeast.
In addition, the incidence of nonmelanoma skin cancer is significantly higher in areas of the United States with low soil selenium content. The evidence isn’t clear as to why this occurs. Studies show that taking a daily supplement containing 200 μg of selenium may not affect recurrence of skin cancer, but significantly reduces the occurrence and death from total cancers. The incidence of prostate cancer, colorectal cancer, and lung cancer was notably lower in groups given high selenium yeast selenium supplements. |
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| Q: |
Will any type of selenium supplement reduce the risk of cancer? |
| A: |
Form of selenium does make a difference. SelenoExcell High selenium yeast has been shown to be a very effective form in studies published in JAMA. |
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| Q: |
How do I know if my supplement or food product contains SelenoExcell? |
| A: |
In an effort to assist consumers in selecting the right selenium supplement, Cypress has featured the SelenoExcell Branding Partners on the company web site at http://www.cypsystems.com/products/branding.html. By selecting one of these SelenoExcell branded products you will be assured that you are purchasing the research proven natural food form of selenium. |
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| Q: |
I read recently from the SELECT study that selenium doesn't reduce cancer risk? |
| A: |
The SELECT study did indeed show that one single form of selenium, selenomethionine, may not reduce prostate cancer risk. The only form of selenium that in currently in clinical trials for its role in cancer prevention is SelenoExcell. One of the reasons that SelenoExcell has proven its merit is that it contains more than one type of selenium and the form of selenium is what researchers call organic, meaning it is attached to several amino acids. This factor may make it more bioavailable than others. |
Research shows SelenoExcell® may reduce lung, colon and prostate cancers by as much as 63%.
In October, 2008, a human cancer study was halted abruptly because the results showed that selenium and vitamin E did not reduce the incidence of prostate cancer. In truth, this study was nothing new. The results were consistent with other previous animal studies showing that a specific form of selenium, selenomethionine, made no real difference in reducing the incidence of prostate cancer.
What the news reports failed to mention is that other forms of selenium have much greater success in reducing cancer risk. For example, research at Purdue University found SelenoExcell® High-Selenium Yeast to be more effective than selenomethionine in the reducing DNA damage in canine prostate cells. Researchers at the University of Arizona and Cornell University reported in the Journal of American Medical Association in 1996 that regular use of 200 micrograms per day of selenium in the form of SelenoExcell® reduced the incidences of lung, colon, and prostate cancers by 50-63 %. And, researchers at the Penn State University Cancer Institute found that supplementation with SelenoExcell®, reduced serum PSA levels, a risk indicator for prostate cancer.
"Clearly we believe that the SELECT trial should have included the standardized high-selenium yeast, which has been found effective in reducing cancer risk in animal studies and human clinical trials," said Paul A. Willis, CEO & President of Cypress Systems, Inc. In 1998, Cypress signed a Clinical Trial Agreement (CTA) with the National Cancer Institute (NCI) in order to reconfirm previous clinical results.
To date, all the research points to the fact that high-selenium yeast is different from selenomethionine. It contains several different forms of organically-bound selenium in addition to selenomethionine.
The effectiveness of SelenoExcell over other forms of selenium may well be because it contains multiple forms of selenium. "We suspect that the advantage of SelenoExcell® High-Selenium Yeast lies in its content of multiple forms of selenium, including some that are more direct acting in anti-carcinogenesis," says Dr. Mark Whitacre, Cypress Systems’ COO, "such as selenomethionine, selenocysteine, and several other selenium compounds, all organically bound."
Another possibility for the trial outcome is the manner in which different forms of selenium oxidize, which may reduce bioavailability. Above all, it is important to note that none of the clinical trials have shown that SelenoExcell falls within the same limited effectiveness as the selenium used in the recent SELECT trial.
For more on the specific research, www.cypsystems.com
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