Male hormone replacement therapy may lower Alzheimer's disease risk
The December 20, 2006 issue of The Journal of Neuroscience published results of a study that suggests that androgen replacement therapy could help prevent the development of Alzheimer's disease. Age-related depletion of testosterone, the primary male hormone, is a newly identified Alzheimer's disease risk factor.
Christian Pike, PhD, who is associate professor at the Leonard Davis School of Gerontology at the University of Southern California, and his colleagues at USC and the University of California, Irvine castrated mice that were genetically modified to develop Alzheimer's disease and administered dihydrotestosterone or a placebo for four months. A control group of the mice received sham surgeries. At the end of the study, mice who received the placebo showed evidence of diminished working memory and had elevated levels of amyloid beta, a substance that develops in the brains of Alzheimer's patients, compared to those that were not castrated or received hormone therapy.
The results of the study suggest that reduced testosterone may promote the accumulation of amyloid beta. "We've known that low testosterone is a risk factor for Alzheimer's disease but now we know why," Dr Pike commented. "The implication for humans is that testosterone therapy might one day be able to block the development of the disease"
"Although the results of the study predict that androgen therapy has the potential to reduce the risk of Alzheimer's disease in at least some men, clinical studies will be required to determine when and how to use androgen therapy," he added. "These results are exciting because they tell us that we are on to something that is worth pursuing. The next step is to look at what the long term effects of testosterone therapy are in aging men."
Children of mothers given fish oil have better hand-eye coordination
The Archives of Disease in Childhood (Fetal and Neonatal Edition) published an early online report on December 21, 2006 which revealed that pregnant women who consumed fish oil supplements had children with better hand-eye coordination than those born to mothers who did not receive the supplements.
In a double-blind trial, researchers in Perth, Western Australia gave 98 pregnant women daily supplements containing 4 grams of fish oil which provided 2.2 grams docosahexaenoic acid (DHA) and 1.1 grams eicosapentaenoic acid (EPA), or 4 grams olive oil from the twentieth week of their pregnancies until their infants' birth. Eighty-three women completed the study. Thirty-three children of the women who received fish oil and 39 children of those who received olive oil were tested for language, behavior, practical reasoning, and hand-eye coordination.
While there were no significant differences in growth and overall language skills between the two groups, children whose mothers received fish oil had higher scores for measures of language comprehension, average phrase length, and vocabulary. Test scores for hand and-eye coordination skills were significantly greater among the children of mothers who were given fish oil . Cord blood levels of omega-3 polyunsaturated fatty acids measured at birth were also associated with better hand-eye coordination scores, and these scores had an inverse association with cord blood levels of the omega-6 polyunsaturated fatty acid known as arachidonic acid.
"Maternal fish oil supplementation during pregnancy is safe for the fetus and infant, and may have potentially beneficial effects on the child's eye and hand coordination," the authors conclude.
MS risk lower among men and women with higher vitamin D levels
A report published in the December 20, 2006 issue of the Journal of the American Medical Association concluded that having a higher serum level of vitamin D is associated with a lower risk of multiple sclerosis (MS) among white, but not black or Hispanic, men and women. The finding adds to those of previous studies that suggest that the vitamin may have a protective effect against the disease.
Alberto Ascherio, MD, DrPH of the Harvard School of Public Health, Boston, and colleagues compared 257 individuals diagnosed with multiple sclerosis between 1992 and 2004 with two age, gender and ethnicity matched controls selected from over 7 million U.S. military personnel whose serum samples were stored in the Department of Defense Serum Repository.
The team determined that for every 50 nanomole per liter increase in serum 25-hydroxyvitamin D among white participants there was a 41 percent decrease in the risk of MS. Whites in the top one-fifth of serum vitamin D concentrations had the lowest risk of the disease, and those in the lowest fifth had the greatest risk. Those with the highest vitamin D levels experienced a 62 percent lower risk of MS than those among the lowest fifth. No associations between MS and vitamin D were found among black and Hispanic participants.
"Although the results of this study are quite encouraging, reasonable certainty of a protective effect of vitamin D supplements requires direct experimental evidence in a large trial," concluded Dr Ascherio, who is an associate professor of nutrition and epidemiology at Harvard School of Public Health. "Meanwhile, we are planning to expand our study to obtain more accurate data on the importance of age and of the vitamin D levels that need to be achieved for optimal protection."
Curtailing fat lowers breast cancer recurrence
The December 20, 2006 issue the Journal of the National Cancer Institute published the finding of Rowan T. Chlebowski, MD, PhD, of the Harbor-UCLA Medical Center in Torrance, California, and colleagues that reducing the amount of fat in the diet helps prevent the recurrence of breast cancer.
The investigation included 2,437 participants in the Women’s Intervention Nutrition Study who had received treatment for early-stage breast cancer. Forty percent of the participants were assigned to receive a diet in which fat was reduced to 15 percent of total calories, and 60 percent served as controls. Women assigned to the low fat group received counseling sessions to learn about low-fat eating, and recorded their fat intake. Fat consumption by both groups amounted to about 30 percent of total calories at the beginning of the study. This amount was reduced to 20.3 percent among women in the dietary intervention group by the end of one year, and was maintained throughout the average five year follow-up period. At the study's conclusion, women on the reduced fat diet weighed an average of six pounds less than those in the control group.
By the end of October, 2003, 9.8 percent of the women who adopted a reduced fat diet had experienced some form of relapse, compared with 12 percent of the control group. This resulted in a 24 percent lower risk of relapse among women on the modified diet.
An accompanying editorial by authors at the National Cancer Institute notes the controversial findings concerning the relationship between fat intake and breast cancer, and remarks that the weight loss experienced by women in the treatment group may have contributed to their lower rate of relapse.
The report's authors conclude that "A lifestyle intervention reducing dietary fat intake, with modest influence on body weight, may improve relapse-free survival of breast cancer patients receiving conventional cancer management."
A report published in the December 13, 2006 issue of the Journal of the American Medical Association concluded that older men who were treated for localized prostate cancer lived significantly longer than men with the disease who not untreated. Observation, or "watchful waiting" is frequently recommended over aggressive therapy for men in this age group because patients more frequently die of other causes before these slow growing tumors spread.
Yu-Ning Wong, MD, of the University of Pennsylvania in Philadelphia and colleagues utilized information from the Surveillance, Epidemiology, and End Results (SEER) Medicare database, which includes approximately 14 percent of the U.S. population, to compare the effects of active treatment and observation on the survival of men with localized prostate cancer. The current analysis included 44,630 men between the ages of 65 and 80 diagnosed with prostate cancer between 1991 and 1999. Active treatment was defined as radical prostatectomy or radiation within six months following diagnosis. The men were followed until their death or the conclusion of the study at the end of 2002.
Over the course of the study, 23.8 percent of the 32,022 men who received treatment died, compared with 37 percent of the 12,608 men who underwent observation. The researchers determined that active treatment for prostate cancer reduced the risk of death by 31 percent.
"In summary, even though prostate cancer commonly is considered an indolent disease, this observational study suggests a reduced risk of mortality associated with active treatment for low- and intermediate-risk prostate cancer in the elderly Medicare population examined," the authors write. "Because observational data can never be free of concerns about selection bias and confounding, these results must be validated by rigorous randomized controlled trials of elderly men with localized prostate cancer before the findings can be used to inform treatment decisions."
Olive oil may account for Southern Europe's lower rate of cancer
A study scheduled to be published in the January, 2007 issue of The Journal of the Federation of American Societies for Experimental Biology (FASEB) reports the finding of researchers from five European countries that the greater intake of olive oil in Southern European countries may be responsible for the lower rate of cancer observed among individuals living there, in comparison with their Northern European neighbors.
Investigators led by Henrik E. Poulsen, MD of Rigshospitalet, Denmark gave volunteers from Denmark, Finland, Germany, Italy, and Spain 25 milliliters olive oil daily for three weeks. Urine samples were analyzed for levels of the waste by-products of cellular oxidative damage, which is a precursor of cancer. While the by-products were higher among Northern European participants at the beginning of the trial, a significant reduction was observed by the study's end.
"Determining the health benefits of any particular food is challenging because of it involves relatively large numbers of people over significant periods of time," Dr Poulsen stated. "In our study, we overcame these challenges by measuring how olive oil affected the oxidation of our genes, which is closely linked to development of disease. This approach allows us to determine if olive oil or any other food makes a difference. Our findings must be confirmed, but every piece of evidence so far points to olive oil being a healthy food. By the way, it also tastes great."
"Every New Year people make resolutions that involve eating less fat to improve their health," FASEB Journal editor-in-chief Gerald Weissmann, MD, commented. "This academically sound, practically useful study shows that what you eat is just as important as how much you eat. No wonder Plato taught wisdom in an olive grove called Academe."
alpha-Tocopheryl succinate fights treatment-resistant breast cancer tumors
In a study scheduled to be presented at the the Gold Coast Health and Medical Research Conference, which will be held December 14-15, 2006 in Gold Coast, Australia, Associate Professor Jiri Neuzil and colleagues at Australia's Griffith University’s School of Medical Science found that alpha-tocopheryl succinate, a precursor of vitamin E, helps induce the death of breast cancer cell lines which over-express human epidermal growth factor receptor (HER2). HER2, which is overexpressed in approximately 30 percent of breast cancers, is associated with treatment resistance, including resistance to chemotherapy.
In the current study, mice bred to develop breast cancers with high levels of HER2 were treated for three weeks with alpha-tocopheryl succinate. Tumor volume was monitored by ultrasound imaging every three days. The research team found that while the compound was effective alone, its delivery was enhanced when it was given in a conjugate form with a targeting peptide. "Tumor volume reduced more than 50% when animals were treated with the conjugate rather than free alpha-tocopheryl succinate," Professor Neuzil observed.
"Alpha-tocopheryl succinate has already shown promise as a potent anticancer agent in diseases such as colon cancer and mesothelioma," Dr Neuzil noted. "It induces controlled cell death or apoptosis in tumor cells."
One of the compound's benefits in cancer therapy is that it is metabolized in the liver to vitamin E, and is not likely to cause significant adverse effects.
alpha-Tocopheryl succinate has the potential to be a safe, selective and inexpensive therapy for treatment-resistant breast cancers, Dr Neuzil concluded.
Lower protein diets may reduce cancer risk
The December, 2006 issue of the American Journal of Clinical Nutrition published the finding of researchers at Washington University School of Medicine in St Louis that consuming a diet that is lower in protein than the standard Western diet reduces insulin-like growth factor 1 (IGF-1), which promotes cell proliferation and has been linked with several cancers when elevated. Animal studies have also found an association between low IGF-1 levels and increased lifespan.
Washington University assistant professor of medicine Luigi Fontana, MD, PhD and colleagues studied 21 lean men and women on a low-protein, low-calorie, raw vegetarian diet, 21 lean runners who consumed a standard Western diet that included sugars, refined grains and animal products, and 21 sedentary individuals who also consumed a Western diet. The vegetarians' daily intake of protein averaged 0.73 grams per kilogram body weight, the runners' intake averaged 1.6 grams, and the sedentary group averaged 1.23 grams.
Dr Fontana's team found that the group with the least protein intake had significantly lower blood levels of plasma IGF-1 than the other two groups whose protein intake was well above the recommended daily allowance of 0.8 grams per kilogram. Higher IGF-1 levels have been associated with an increased risk of prostate, colon, and premenopausal breast cancer.
"It's interesting to us that both the runners and especially the sedentary people consumed about 50 percent more protein than recommended," Dr Fontana observed. "We know that if we consume 50 percent more calories than recommended, we will become obese. But there is not a lot of research on whether chronic over-consumption of protein also has harmful effects."
"Our findings show that in normal weight people IGF-1 levels are related to protein intake, independent of body weight and fat mass," Dr Fontana stated. "I believe our findings suggest that protein intake may be very important in regulating cancer risk."
Tea soothes radiation-damaged skin
The results of a study published online on December 1, 2006 in Biomed Central Medicine showed that tea extracts applied to skin damaged by radiation treatment for cancerous tumors resulted in a reduction in inflammation. Skin toxicity experienced by cancer patients undergoing radiation can result in gaps in therapy, limiting effective treatment.
Frank Pajonk of the University of California, Los Angeles and colleagues from the University of Freiburg in Germany analyzed data from 60 patients undergoing radiotherapy for cancer of the head and neck or pelvic area who were treated three times daily with green or black tea extracts. They found that application of tea extracts reduced the duration of post-radiation skin toxicity by five to ten days. Although there was no significant difference between treatment with green and black tea extracts in the resultant duration of skin toxicity among those with head and neck cancer, green tea elicited a greater effect than black tea among patients with cancer of the pelvic region.
It was determined that tea acts on the cellular level by blocking inflammatory pathways. In an experiment with cultured human white blood cells treated with green and black tea, the researchers found that pro-inflammatory cytokines interleukin-1b, interleukin-6, interleukin-8, tumor necrosis factor alpha, and prostaglandin E2 were inhibited. The effect was greater for green than black tea extract. When mouse white blood cells were studied, a major inflammatory pathway was shown to be blocked by black and green tea extracts.
"We conclude that tea extracts are efficient means to treat radiation-induced skin toxicity," the authors write. "Understanding the underlying molecular mechanisms in the future may establish tea extracts as a cheap and broadly available treatment for skin toxicity caused by ionizing radiation in industrial as well as developing countries during clinical radiotherapy and in case of accidents involving ionizing radiation."
Percentage of disabled older Americans drops
In answer to concerns regarding the growing population of older individuals in the United States, the results of a National Institute on Aging-funded study published in the November 28, 2006 issue of the Proceedings of the National Academy of Sciences concluded that not only has the incidence of chronic disability among older Americans declined, but the rate of decline has accelerated.
Kenneth G. Manton, PhD, and colleagues at Duke University evaluated data from the National Long-Term Health Care Survey, which was last assessed in 2001. Dr Manton's team found an average 1.52 percent annual decline in disability from the survey's inception in 1982 through 2004/2005, with the rate of decline increasing from 0.6 percent in 1984 to 2.2 percent in 2004/2005. Although chronic disability rates declined among subjects over the age of 65 with both severe and less serious impairments, the greatest improvements were noted for serious disability, which may be due to decreases in the incidence and severity of disease through biomedical interventions. Individuals aged 85 and up experienced the greatest increase in the percentage of those who were disability-free, with a 32.6 rise.
The number of Medicare patients living in long-term care institutions fell from 7.5 percent to 4 percent, which is attributable to increased assisted-living options, improved rehabilitation, and changes in Medicare reimbursement. The researchers suggest that the trend will help improve the fiscal health of the Medicare and Medicaid programs. "The challenge now is to see how this trend can be maintained and accelerated especially in the face of increasing obesity," stated Richard Suzman, PhD, who is the director of National Institute on Aging's Behavioral and Social Research Program. "Doing so over the next several decades will significantly lessen the societal impact of the aging of the baby-boom generation."
Fortification of milk with micronutrients improves children's health
Fortifying milk with specific vitamins and minerals was shown to lower the incidence of diarrhea and lower respiratory disease among children living in the area surrounding New Delhi, India. The research was reported online on November 28, 2006 in the British Medical Journal.
Sunil Sazawal, MD, MPH, PhD of Johns Hopkins Bloomberg School of Public Health and colleagues at the Center for Micronutrient Research at Annamalai University in India conducted the trial among 633 children ages one to four. Three hundred-sixteen children were provided with three servings per day of milk fortified with zinc, iron, selenium, copper, vitamin, vitamin C and vitamin E, while 317 children received unfortified milk for one year.
The children's homes were visited twice weekly to collect information concerning illnesses that occurred since the last visit. At the study's conclusion, it was determined that children who consumed the fortified milk had a 15 percent reduction in the number of days in which they experienced severe illness, a 7 percent reduction in days with a high fever, an 18 percent reduction in the incidence of diarrhea, an a 26 percent lower incidence of pneumonia.
“Some micronutrients have a crucial role in generation, maintenance and amplification of immune responses in the body," stated Dr Sazawal, who is an associate professor in the Bloomberg School of Public Health’s Department of International Health. "Deficiencies in multiple micronutrients among preschool children are an important determinant of child health in developing countries."
Study coauthor said Robert E. Black, MD, MPH, who is professor and chair of the Bloomberg School’s Department of International Health, added “Together, these results suggest an improved immunity against common infections in children. There is an urgent need to develop and implement strategies to reduce the burden of micronutrient deficiencies in the developing world.”