Mayo Clinic Proceedings Jan. tip sheet

ROCHESTER, Minn. -- Featured articles from the January issue of Mayo Clinic Proceedings include the effects of antioxidant supplements on cancer, guidelines for workplace drug screening and the safety and effectiveness of nasal spray flu vaccine.

Do antioxidant supplements reduce the risk of cancer and deaths related to cancer? That’s a question answered by Mayo researchers in an article in the January issue of Mayo Clinic Proceedings. While some trials have suggested that antioxidants have beneficial effects, results from other trials have been negative. It has been unclear which antioxidant compounts are more beneficial (or more harmful), and how individual antioxidants affect target organs and specific patient populations. To examine these issues, Mayo researchers conducted a systematic review on the topic.

“Systematic reviews can provide reliable summaries of the research, and help understand why different studies give different results,” says Victor Montori, M.D., senior author on the study and lead for Mayo Clinic’s Knowledge and Encounter Research (KER) unit. For the study, two authors reviewed all randomized trials on antioxidants for cancer prevention(1968-2005) and identified 12 clinical trials with a total eligible population of 104,196. The review yielded a number of interesting findings including:

• Overall, antioxidant supplementation did not reduce the risk of cancer.

• Beta carotene supplementation was actually found to increase the risk of smoking-related cancers, as well as cancer mortality, and thus should be avoided, especially by tobacco users.

• Vitamin E appeared to have no beneficial or harmful effects.

• Selenium supplementation was found to lower the risk of cancer in men (not in women), but the number of trials were few and further research is required. A large trial assessing the effect of selenium in lowering the risk of prostate cancer is currently underway.

The bottom line according to Aditya Bardia, M.D., lead author of the study, is that antioxidants do not lower the risk of cancer and beta carotene might actually increase cancer risk among smokers. Selenium might have beneficial properties, but it cannot be recommended for general use until more evidence is available.

In addition to Drs. Montori and Bardia, authors of the article include James Cerhan, M.D., Ph.D.; Amit Sood, M.D.; Paul Limburg, M.D.; and Patricia Erwin, all of Mayo Clinic; and Imad Tleyjeh, M.D., King Fahd Medical City, Riyadh, Saudi Arabia.

Commonly used in health care, workplace and criminal settings, drug testing has become widespread during the past decade. Urine drug screens have been the most common method for analysis because of ease of sampling. But this form of testing does not always yield accurate results, and serious medical or social consequences can occur when results are not confirmed by additional testing. In the January issue of Mayo Clinic Proceedings, researchers provide up-to-date information about proper evaluation of urine drug screens. The authors also examine the potential problems associated with testing for several commonly abused drugs (including alcohol, amphetamines, benzodiazepines, opioids, marijuana, cocaine, phencyclidine (PCP), and tricyclic antidepressants) and they discuss how to evaluate urine drug screens for adulterations, substitutions and potential false-positive results.

Authors of this article are Karen Moeller, PharmD., Pharmacy School, University of Kansas Medical Center, Kansas City; Kelly Lee, PharmD., Department of Clinical Pharmacy, UCSD Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, Calif.; and Julie Kissack, PharmD., Department of Pharmacy Practice, Mercer University, College of Pharmacy and Health Sciences, Atlanta.

Influenza is a viral infection that affects millions of people each year and potentially can cause serious complications, especially in children and older adults. The flu vaccine -- available as an injection or a nasal spray -- offers protection against the flu. Although it’s been available since 2003, the nasal spray form of the flu vaccine, known as Flu Mist, has not gained widespread acceptance. In the January issue of Mayo Clinic Proceedings, Mayo Clinic researchers review current research analyzing the nasal vaccine and explain that much of the hesitancy about its use appears to stem from unsubstantiated fears and misperceptions, rather than research data. Addressing five pervasive misconceptions about the nasal vaccine, Mayo researchers conclude that current research shows that nasal spray flu vaccine is a safe and effective way to prevent flu in healthy, nonpregnant adults and children ages 2 years and older.

Authors of this article are Pritish Tosh, M.D.; Thomas Boyce, M.D.; and Gregory Poland, M.D., all from Mayo Clinic.

A peer-review journal, Mayo Clinic Proceedings publishes original articles and reviews dealing with clinical and laboratory medicine, clinical research, basic science research and clinical epidemiology. Mayo Clinic Proceedings is published monthly by Mayo Foundation for Medical Education and Research as part of its commitment to the medical education of physicians. The journal has been published for more than 80 years and has a circulation of 130,000 nationally and internationally. Articles are available online at www.mayoclinicproceedings.com.