Life Extension Magazine®

Issue: Jan 2006

Red and processed meats tied to pancreatic cancer; curcumin may impede breast cancer metastasis; processed foods increase prostate cancer risk; Feds revise potassium iodide guidelines; huperzine A promotes nerve cell growth; improving diet, lifestyle slows prostate cancer; omega-3s protect against dry eye syndrome.

Red and Processed Meats Tied to Pancreatic Cancer

A diet high in red and processed meats increases pancreatic cancer risk, according to researchers at the University of Hawaii and University of Southern California.* Pancreatic cancer is a particularly aggressive, deadly malignancy that can be difficult to detect and treat. Preventive strategies, including dietary modification, are thus vitally important in preventing deaths from the disease. Past studies on the relationship between diet and pancreatic cancer, however, have produced conflicting results.

The investigators analyzed data from the Multiethnic Cohort Study, which enrolled 190,545 African-American, Latino, Japanese-American, Native Hawaiian, and Caucasian men and women between the years of 1993 and 1996. Each participant completed a detailed survey of demographic information, personal and family medical history, diet, and lifestyle factors. By the end of 2001, 482 incident cases of pancreatic cancer were identified among the study participants.

The scientists found that individuals who consumed the most processed meat had a nearly 70% higher risk of pancreatic cancer compared to those with the lowest intake. Similarly, those who consumed the most pork and total red meat had a 50% greater risk of pancreatic cancer than their cohorts with the lowest intake. The investigators found no association between pancreatic cancer and intake of poultry, fish, dairy products, eggs, cholesterol, total fat, or saturated fat. Intake of total and saturated fat from meat was associated with a statistically significant increase in pancreatic cancer risk, but that from dairy products was not.

Intake of red and processed meat thus appears to increase pancreatic cancer risk, though the investigators believe that fat and saturated fat are unlikely to contribute to an underlying carcinogenic mechanism, as dairy fat was not associated with similar risk. The researchers concluded, “Carcinogenic substances related to meat preparation methods might be responsible for the positive association.”

—Linda M. Smith, RN

Reference

* Nothlings U, Wilkens LR, Murphy SP, Hankin JH, Henderson BE, Kolonel LN. Meat and fat intake as risk factors for pancreatic cancer: the multiethnic cohort study. J Natl Cancer Inst. 2005 Oct 5;97(19):1458-65.

Curcumin May Impede Breast Cancer Metastasis

A recent study published in the journal Clinical Cancer Research found that curcumin, a substance in the spice turmeric, prevents breast cancer from spreading to the lungs of mice given the compound.*

Researchers at the University of Texas MD Anderson Cancer Center injected 60 mice with human metastatic breast cancer cells. When the tumors reached the size of 10 millimeters, they were surgically removed. Five days later, half the mice were fed diets enhanced with curcumin, while the remainder received standard diets until the study’s conclusion. Fifteen of the mice in each group were injected with paclitaxel (Taxol®) at days 10, 17, and 24 following tumor removal. Although paclitaxel is effective in treating breast cancer, it also encourages metastasis when used for an extended period and therefore is not effective in treating the advanced form of the disease.

Upon examination of the animals’ lungs five weeks after removal of the tumors, 96% of the mice who received neither curcumin nor paclitaxel had visible metastases. While paclitaxel alone elicited a modest reduction in visible metastases, curcumin produced a significant reduction, and the combination of curcumin and paclitaxel prevented the macrometastases entirely. Microscopic metastases were found in only 28% of the mice receiving the curcumin/drug combination, and these consisted of only a few cells, suggesting that the treatment prevented the growth of tumor cells present in the lungs before the primary tumors were removed.

Paclitaxel’s toxicity activates an inflammatory protein—nuclear factor-kappa beta—that induces metastasis, but curcumin inhibits this response. The finding that adding curcumin to paclitaxel results in reduced metastases could allow for a lower dose of the potentially toxic drug to be administered.

Lead researcher Bharat Aggarwal, PhD, commented, “We are excited about the results of the study and the possible implications for taking the findings into the clinic in the next several years. At this time, advanced breast cancer is a difficult foe to fight with few proven treatments available after surgery, chemotherapy, and radiation therapy.”

—Dayna Dye

Reference

* Available at: http://clincancerres.aacrjournals.org/. Accessed October 18, 2005.

Processed Foods Increase Prostate Cancer Risk

A diet consisting primarily of refined grain products and processed and red meats increases men’s risk of developing prostate cancer, according to Canadian researchers.* These findings confirm and expand on the results of the Health Professionals Follow-up and Physicians’ Health studies, which demonstrated the relationship between prostate cancer and intake of dietary fat and red meat, while complementing myriad studies establishing the protective effects of diets rich in vegetables.

The study enrolled 414 men, including 80 with primary prostate cancer and 314 controls matched for age, body mass index, socioeconomic status, and lifestyle characteristics (such as tobacco use, alcohol consumption, and physical activity). All subjects completed a questionnaire on how often they consumed 67 food and beverage items during the previous two years.

Four dietary patterns emerged among the participants, which were designated as: 1) Healthy Living, consisting of vegetables, fruits, whole grains, fish, and poultry; 2) Traditional Western, including red and processed meats, milk, sweets, and hard liquor; 3) Processed Diet, characterized by red and processed meats, organ meats, refined grains, white bread, onions and tomatoes, vegetable oils, juices, and soft drinks; and 4) Beverages, comprising tap water, soft drinks, fruit juices, potatoes, and poultry.

Although not statistically significant, the Healthy Living and Beverages dietary patterns were associated with a lower risk of prostate cancer, while the Traditional Western diet was associated with a higher risk. The Processed Diet pattern, however, was strongly and positively associated with an increased risk of prostate cancer. This dietary pattern is likely to contain heterocyclic and polycyclic aromatic amines formed during the cooking and preservation of meat. Moreover, there was a dose-dependent relationship between the Processed Diet pattern and prostate cancer risk, with the highest levels of consumption associated with a nearly threefold greater risk.

—Linda M. Smith, RN

Reference

* Walker M, Aronson KJ, King W, et al. Dietary patterns and risk of prostate cancer in Ontario, Canada. Int J Cancer 2005. Sept 10; 116(4):592-8.

Feds Revise Potassium Iodide Guidelines

The Office of Public Health Emergency Preparedness has issued new guidelines for the distribution, stockpiling, and use of potassium iodide tablets, as used in the prophylactic treatment of radioactive iodine exposure, according to The Federal Register.* As set forth in Section 127 of the Bioterrorism Act, the Strategic National Stockpile has been tasked with making potassium iodide tablets available to state, local, and tribal governments for their at-risk citizens.

Nuclear power plants may release radioactive isotopes, including iodine 131, into the environment either accidentally or by terrorist intent. Exposure to radioactive iodine significantly increases the risk of thyroid cancer and hypothyroidism, especially in those less than 18 years of age. In the event of exposure to radioactive iodine, administering potassium iodide within four hours can saturate the iodine receptors in the thyroid gland, preventing the accumulation of radioactive iodine. This may reduce the risk of thyroid cancer when used in conjunction with appropriate sheltering and avoidance of contaminated sources of food and water.

Following a radiation accident, the area considered to be contaminated has now been expanded from the previously recommended 10-mile radius surrounding a nuclear power plant to a 20-mile radius. The American Association of Clinical Endocrinologists and the American Thyroid Association recommend that chemical protection in the form of potassium iodide tablets should be made available to anyone residing within a 200-mile radius of a nuclear plant, with pre-distribution of potassium iodide to anyone residing within a 50-mile radius. Potassium iodide is considered safe and effective, and its over-the-counter sale is approved by the FDA.

—Linda M. Smith, RN

Reference

* Available at: http://frwebgate1.access.gpo.gov/cgi-bin/waisgate.cgi?WAISdocID=435636837+0+0+0&WAISaction=retrieve. Accessed October 10, 2005.

Huperzine A Promotes Nerve Cell Growth

Huperzine A, a phytochemical derived from the Chinese medicinal herb club moss (Huperzia serrata), promotes nerve cell growth and may benefit those suffering from Alzheimer’s disease and other neurodegenerative disorders, according to researchers at State Key Laboratory of Drug Research in Shanghai, China.*

Previous studies have demonstrated that huperzine A inhibits the breakdown of the neurotransmitter acetylcholine by inhibiting the enzyme acetylcholinesterase. Acetylcholine is responsible for relaying messages throughout the central and peripheral nervous systems. Numerous acetylcholinesterase-inhibiting drugs have been approved for treating Alzheimer’s disease.

This study investigated huperzine A’s effects on neurite outgrowth and nerve growth factor expression in a model of primary neuronal cells (PC12) in the laboratory. Neurites are outgrowths of neurons that form connections between cells, allowing for the transmission of messages. Nerve growth factor promotes neurite growth and may protect normal nerves from oxidative damage.

After just 24 hours of treatment with huperzine A, levels of nerve growth factor increased in the PC12 cells. After 48 hours of treatment, the number of neurite-bearing cells increased dramatically. Furthermore, treating PC12 cells with huperzine A inhibited acetylcholinesterase activity. The researchers concluded that huperzine A has direct or indirect neurotrophic (nerve-growth-promoting) activity, and suggested that huperzine A may be beneficial in treating neurodegenerative disorders such as Alzheimer’s disease.

Human studies are under way in the US to evaluate whether huperzine A benefits individuals with Alzheimer’s disease.

—Christie C. Yerby, ND

Reference

* Tang LL, Wang R, Tang XC. Effects of huperzine A on secretion of nerve growth factor in cultured rat cortical astocytes and neurite outgrowth in rat PC12 cells. Acta Pharmacol Sin. 2005 June;26(6):673-8.

Improving Diet, Lifestyle Slows Prostate Cancer

Intensive diet and lifestyle changes slow the progression of low-grade prostate cancer, according to a landmark multi-institutional study.* While it is well known that a low-fat, plant-based diet is associated with a decreased risk of prostate cancer, this new research indicates that diet can influence the outcome of established prostate cancer.

At the onset of this 12-month study of men with biopsy-confirmed prostate cancer, all 93 participants had Gleason scores (a grading system for prostate cancer) of less than 7 and prostate-specific antigen (PSA) levels of between 4 and 10 ng/mL. Due to the low-risk nature of their prostate cancer, all the subjects had chosen a “watchful waiting” approach instead of conventional treatment such as surgery, chemotherapy, or radiation. The treatment group of 44 men consumed a vegan diet and supplemented daily with one serving of tofu, 58 grams of soy protein, 3 grams of fish oil, 400 IU of vitamin E, 200 mcg of selenium, and 2 grams of vitamin C. In addition, the treatment group walked 30 minutes six days per week, engaged in 60 minutes of stress management daily, and participated in a 60-minute support group once weekly. The 49 men who made up the control group followed the diet and lifestyle advice of their personal physicians.

At the end of one year, the treatment group demonstrated an average 4% decrease in PSA level, as compared with a 6% increase in the control group, representing a statistically significant difference. Increased PSA is considered a sign of disease progression and highly predictive of men who will require treatment, as opposed to continued watchful waiting.

Additionally, the researchers examined the effects of serums from the study and control patients on a line of androgen-dependent human prostate cancer cells in the laboratory. Serum from the men in the treatment group inhibited cancer cell growth by 70%, while serum from men in the control group decreased cancer cell growth by only 9%.

Diet and lifestyle factors appear to have a positive influence on men with untreated, low-grade prostate cancer. Further investigation is indicated to determine whether such changes may similarly benefit men undergoing conventional treatment for prostate cancer.

—Linda M. Smith, RN

Reference

* Ornish D, Weidner G, Fair WR, et al. Intensive lifestyle changes may affect the progression of prostate cancer. J Urol. 2005 Sept;174(3):1065-9; discussion 1069-70.

Omega-3s Protect Against Dry Eye Syndrome

Consuming omega-3 fatty acids such as those found in cold-water fish offers protection against dry eye syndrome, according to emerging research from Brigham and Women’s Hospital in Boston.* Dry eye syndrome is a common condition marked by burning, itching, redness, and irritation. While factors such as aging, climate, medications, and cigarette smoke may contribute to dry eye syndrome, little is known about how nutrition influences the condition. Scientists previously have speculated that essential fatty acid intake may play a role in dry eye syndrome.

To study the relationship between dry eye syndrome and intake of omega-3 and omega-6 fatty acids, researchers examined data from the Women’s Health Study, which enrolled more than 32,000 female health professionals between the ages of 45 and 84. The participants completed a food-frequency questionnaire that yielded information on dietary fatty acid intake, and reported clinically diagnosed cases of dry eye syndrome. Dietary sources of omega-3 fatty acids include cold-water fish such as salmon, mackerel, and sardines, as well as flaxseed and walnuts. Omega-6 fatty acids are found in eggs, poultry, and vegetable oils.

Nearly 5% of the study group reported diagnoses of dry eye syndrome. After adjustment for demographic factors, hormone therapy, and total fat intake, the researchers noted that women consuming the most omega-3 fatty acids experienced a 17% lower risk of dry eye syndrome compared to women with the lowest intake. Furthermore, a higher ratio of omega-6 to omega-3 fatty acids was associated with a significantly increased risk of dry eye syndrome. Greater consumption of tuna, a source of omega-3 fats, was associated with a decreased risk of dry eye syndrome.

These findings suggest that dietary omega-3 fatty acid intake offers protection against dry eye syndrome. Further studies are indicated to determine whether omega-3 fatty acids may help to manage established cases of dry eye syndrome.

—Elizabeth Wagner, ND

Reference

* Miljanovic B, Trivedi KA, Dana MR, Gilbard JP, Buring JE, Schaumberg DA. Relation between dietary n-3 and n-6 fatty acids and clinically diagnosed dry eye syndrome in women. Am J Clin Nutr. 2005 Oct;82(4):887-93.