Should women undergoing treatment for breast cancer take antioxidant supplements?

Posted on April 2, 2011 by Dr. Jonathan

An important study just published in Cancer Epidemiology, Biomarkers & Prevention adds to the evidence that supplementation can be helpful rather than an impediment to oxidizing therapies. The authors set out to address a concern that has persisted in the face of mounting evidence to the contrary:

“Antioxidants may protect normal cells from the oxidative damage that occurs during radiotherapy and certain chemotherapy regimens; however, the same mechanism could protect tumor cells and potentially reduce effectiveness of cancer treatments. We evaluated the association of vitamin supplement use in the first 6 months after breast cancer diagnosis and during cancer treatment with total mortality and recurrence.”

They evaluated 4,877 women diagnosed with invasive breast cancer in Shanghai, China, between March 2002 and April 2006 for the correlation between supplement use and breast cancer total mortality and recurrence. Women were interviewed approximately 6 months after diagnosis and followed up by interviews and records. What did the data show?

“Vitamin use shortly after breast cancer diagnosis was associated with reduced mortality and recurrence risk, adjusted for multiple lifestyle factors, sociodemographics, and known clinical prognostic factors. Women who used antioxidants (vitamin E, vitamin C, multivitamins) had 18% reduced mortality risk and 22% reduced recurrence risk. “

Interestingly, in this study…

“The inverse association was found regardless of whether vitamin use was concurrent or nonconcurrent with chemotherapy, but was present only among patients who did not receive radiotherapy.”

The data were sufficient for the authors to conclude:

“Vitamin supplement use in the first 6 months after breast cancer diagnosis may be associated with reduced risk of mortality and recurrence…Our results do not support the current recommendation that breast cancer patients should avoid use of vitamin supplements.”

Too high a dose of antioxidants can block DNA repair

Posted on May 21, 2010 by Dr. Jonathan

A reminder of the importance of taking a physiological approach based on objective evidence came in the form of an important paper just published in the journal Stem Cells. The authors report unexpectedly finding that too high a dose of antioxidants can increase damage to DNA. They initially wanted to see how to protect stem cells from oxidative damage:

“Stem cell cytogenetic abnormalities constitute a roadblock to regenerative therapies. We investigated the possibility that reactive oxygen species (ROS) influence genomic stability in cardiac and embryonic stem cells.”

They were surprised to observe that chromosomal abnormalities and DNA damage appeared when the ROS inside cardiac stem cells were sharply decreased by high-dose antioxidants:

“Quantification of DNA damage in cardiac stem cells and in human embryonic stem cells revealed a biphasic dose-dependence: antioxidants suppressed DNA damage at low concentrations, but potentiated such damage at higher concentrations.”

How could too high a dose of antioxidants cause this effect?

“High-dose antioxidants decreased cellular levels of the ATM (ataxia-telangiectasia mutated) and other DNA repair enzymes, providing a potential mechanistic basis for the observed effects.”

This is an immensely important key point for clinical practice and self-care alike. There are innumerable biological biphasic phenomena. Except for aggressive short-term interventions justified by acute indications, it’s important to stay within a physiological ‘window’ with everything from antioxidants to hormones. This can be determined on an individual basis by the appropriate objective tests.

The authors’ conclusion is well worth bearing in mind:

“These results indicate that physiological levels of intracellular ROS are required to activate the DNA repair pathway for maintaining genomic stability in stem cells. The concept of an oxidative optimum for genomic stability has broad implications for stem cell biology and carcinogenesis.”

Is grass-fed beef more nutritious?

Posted on March 22, 2010 by Dr. Jonathan

Like us, cattle have a very different metabolic response to eating lots of green vegetables (grass in this case) versus grains. This paper recently published in the Nutrition Journal reviews research performed over the last thirty years:

“Research spanning three decades suggests that grass-based diets can significantly improve the fatty acid (FA) composition and antioxidant content of beef, albeit with variable impacts on overall palatability.”

Personally, I much prefer the taste of grass-fed beef as do others I know. They detail some of the differences:

“Grass-based diets have been shown to enhance total conjugated linoleic acid isomers…and omega-3 FAs (fatty acids)on a g/g fat basis…grass-finished beef tends toward a higher proportion of cholesterol neutral stearic FA and less cholesterol-elevating SFAs such as myristic and palmitic FAs. Several studies suggest that grass-based diets elevate precursors for Vitamin A and E, as well as cancer fighting antioxidants such as glutathione and superoxide dismutase activity as compared to grain-fed contemporaries…”

They alert consumers to the different color grass-fed beef may have due to a higher carotenoid (vitamin A precursor) content as well as different cooking characteristics. They don’t, however, note in their paper how much more humane a BioMed Central grass-fed lifestyle is compared to grain-fed factory farming. By the way, how do you think studies on an association between red meat and various cancers might have turned out if only organic grass-fed beef was used…?

Antioxidants and chemotherapy toxicity

Posted on November 20, 2009 by Dr. Jonathan

This meta-analysis published in the International Journal of Cancer evaluates 33 studies including 2,446 subjects to evaluate “the effects of concurrent use of antioxidants with chemotherapy on toxic side effects…This review provides the first systematically reviewed evidence that antioxidant supplementation during chemotherapy holds potential for reducing dose-limiting toxicities.”