Selenium and colorectal cancer risk

A recent study published in the Journal of the National Cancer Institute has found that selenium intake may be related to a decreased risk of colorectal cancer. Researchers combined data from three randomized trials - the Wheat Bran Fiber trial, the Polyp Prevention Trial, and the Polyp Prevention Study - which tested the effects of various nutrients for colorectal adenoma prevention among patients who had recently had an adenoma removed. Although adenomas themselves are not cancerous, they are generally predictive of colorectal cancer incidence. Analysis of this combined data showed that the group of individuals with the highest blood selenium levels had a significantly lower likelihood of developing a new adenoma compared with those in the lowest intake group. The association between higher selenium levels and reduced adenoma recurrence supports previous research indicating that higher selenium levels may be related to a decreased risk of developing colorectal cancer.

Calcium reduces the risk of colorectal cancer

A recent study published in the American Journal of Clinical Nutrition investigated calcium intake and risk of colon adenoma. Adenomas are benign growths that are often associated with early stages of colorectal tumor development. Since previous research has shown that calcium intake reduces the risk of colorectal tumors, evaluating the association of calcium intake to the risk of colon adenoma may be useful in the prevention of colorectal cancer.

The researchers compared the total calcium intake of 3,696 participants with verified adenoma of the colon with the calcium intake of 34,817 control participants in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial.

After adjustment for known risk factors, adenoma risk was 12% lower for participants with the highest total calcium intake than for participants with the lowest calcium intake. The protective association between total calcium and colorectal adenoma was largely due to calcium supplement use, with a 27% decrease in adenoma risk for participants taking >1200 mg/d than for nonusers of supplements.

High calcium intake, particularly from supplements, is associated with a reduced risk of colorectal adenoma.

High-Dose Vitamin E May Increase Mortality?

Recent news stories have reported on a vitamin E study presented at the American Heart Association meeting in New Orleans by Edgar Miller and coworkers. The study warns that high-dose vitamin E supplementation may increase mortality in adults. After reviewing a draft of the full paper, which will be published in January 2005, we believe the research is flawed, and we see little or no evidence to support the authors' conclusions.

• The current study is not a new clinical trial, but a statistical analysis (meta-analysis) of many diverse and dissimilar studies.
• Many studies that could have been included in the analysis were eliminated because total mortality rates were low.
• Many of the studies included in the analysis were conducted with older adults who had an advanced chronic degenerative disease. In other words, most studies were not conducted on normal, healthy adults.
• Many of the studies were small, involving fewer than 1000 people. More importantly, only the smaller studies showed significant effects. None of the larger (and therefore more powerful) studies, involving several thousand subjects each, showed a statistically significant impact on mortality of vitamin E supplementation.
• One study in particular (The Heart Protection Study) skewed the results of the meta-analysis toward a conclusion of increased mortality, even though the original research paper for the Heart Protection Study concluded that vitamin E supplementation did not have a significant effect on mortality.
• Miller and coworkers state that high dosages of vitamin E are dangerous and that death rates increased with dose. However, their own secondary analysis showed that differences in death rates were statistically insignificant, and that at the highest dose, risk of death was actually lower.

In short, we find no strong and compelling evidence in the paper to support the authors' conclusions that high-dose vitamin E supplementation may increase mortality in adults.

That said, we want to make several related points. First, in most of the studies included in the meta-analysis, vitamin E was given as a stand-alone nutrient. We have never advocated taking high doses of any single nutrient. Rather, we promote a complete and balanced approach to supplementation, as evidenced by our Essentials, which contain over 40 active ingredients provided in a balanced formula.

Second, it is important to note that there is a wealth of clinical and epidemiological research supporting the health benefits of vitamin E supplementation. This research has linked elevated intakes of vitamin E with improved cardiovascular health and reduced incidence of multiple chronic diseases. These results, from dozens of studies, are at complete odds with the conclusions drawn by Miller and coworkers.

Finally, we believe that the press response to the Miller study is overblown... one that is largely designed to sell newspapers rather than to inform the public in an objective way. Our experience with these sorts of situations leads us to believe that if the Miller study had reported a 5% decrease in mortality (a health benefit) due to high-dose vitamin E supplementation, the authors would have concluded that the result was clinically insignificant and that much more research was necessary before any conclusions could be drawn. And the findings never would have ended up in the newspaper.

We firmly believe that optimal nutrition is a key to reducing the risk of chronic degenerative disease. High-quality, comprehensive and balanced supplementation, including vitamin E, is an important element of any program promoting true health.

For additional comments on this study, go to the following links:

• CRN Questions Conclusions Reached by Researchers in Recent Vitamin E Meta-Analysis
• Press release on Johns Hopkins Vitamin E study a blatant fear tactic
• Pharmavite Calls for Balanced Reporting on Vitamin E Analysis; Leading Manufacturer States Study Conclusions Are Unwarranted and Misleading for Healthy Individuals

Apple skin chemical reduces colon cancer risk

Research presented at the annual Frontiers in Cancer Prevention Research conference in Seattle has shown that a chemical in apples prevents colon cancer in laboratory and animal studies. Francis Raul of the French National Institute for Health and Medical Research, and team, exposed cancer cells to various apple-based antioxidants known as polyphenols. The investigators found that procyanidins, a polyphenol found in apple skins, blocked cancer growth.

In an experiment with laboratory rats, the rats were exposed to colon cancer- causing substances and then fed a mixture of water and apple procyanidins. Rats getting "apple water" for six weeks had half the number of precancerous lesions in their colons compared with rats eating the regular diet.

Scientists speculate that the beneficial effect of procyanidins may be due to its antioxidant properties, which ordinarily protect apples from sunlight's harmful effects.

Procyanidins are also found in abundance in red wine, cocoa and cranberry juice.