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What's Hot
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| October 2004
Drinking tea may help improve memory The August 2004 issue of the journal Phytotherapy Research published the findings of a team from the University of Newcastle upon Tyne that green and black tea may help improve memory and could be useful one day in the treatment of Alzheimer's disease. Green tea consists of leaves from the plant Camilla sinensis, which, when fermented, is known as black tea. Dr Ed Okello of Newcastle University's Medicinal Plant Research Centre and colleagues conducted experiments using coffee, black tea and green tea and found that black and green tea inhibited the enzyme acetylcholinesterase which breaks down the neurotransmitter acetylcholine. Acetylcholine is a compound that facilitates the transmission of impulses between nerve cells, and is reduced in people who have Alzheimer's disease. Coffee had no effect on acetylcholinesterase. The scientists also discovered that tea inhibited another enzyme known as butyrylcholinesterase found in protein deposits in the brains of Alzheimer's disease patients. Additionally, green tea inhibited the enzyme beta-secretase for one week, whereas black tea was effective for only one day. Beta-secretase is an enzyme that initiates the formation of the protein amyloid in early Alzheimer's disease. Dr Okello suggested that drinking tea could help improve memory and stated, “Although there is no cure for Alzheimer's, tea could potentially be another weapon in the armoury which is used to treat this disease and slow down its development. It would be wonderful if our work could help improve the quality of life for millions of sufferers and their carers. Our findings are particularly exciting as tea is already a very popular drink, it is inexpensive, and there do not seem to be any adverse side effects when it is consumed. Still, we expect it will be several years until we are able to produce anything marketable.” —D Dye Iron key to restless legs Restless legs syndrome (RLS) is a condition in which afflicted individuals experience an irresistible urge to move the legs and arms, particularly at night. At the annual meeting of the Society for Neuroscience held this month in San Diego, Xinsheng Wang MD of Penn State College of Medicine reported that mixed central nervous system signals caused by an iron deficiency are at the root of the problem. In a series of experiments, Dr James R Connor PhD of Penn State Milton S. Hershey Medical Center and colleagues found that individuals with restless legs syndrome have elevated active levels of an enzyme called tyrosine hydroxylase (TH) produced in an area of the middle brain called the substantia nigra. Active TH regulates dopamine, but the regulation of dopamine production also needs adequate levels of iron. Dr Connor explained, "We think the 'active form' has lost its feedback mechanism. The cell is getting a signal that more dopamine is needed so TH is made and shifted to the active form, but the activity is compromised because less iron is available. If the iron was present in sufficient amounts, the feedback process would signal the cells to stop or slow TH production." Dr Connor's team found that exposure to a substance that removes iron increased the expression of TH in cultured dopamine-producing cells. In another experiment, which compared brain tissue from individuals who had restless legs syndrome to that of healthy individuals, iron-deficient middle brain cells from the individuals with RLS expressed higher levels of TH than tissue derived from individuals without the condition. Dr Connor stated, “Our next steps are to continue investigations of treatment strategies for RLS involving iron supplementation and dopamine agents to attempt to reach the normal balance between iron and dopamine in the brain.” —D Dye Vitamin C helps prevent contrast-mediated nephropathy A study published early online on October 18 2004 in the American Heart Association journal Circulation showed that oral administration of vitamin C aids in the prevention of contrast-mediated nephropathy in men and women with impaired kidney function. Contrast-mediated nephropathy is a decrease in kidney function diagnosed by an increase in serum creatinine which results from contrast agents used in radiographic procedures such as coronary angiography. Individuals with diabetes or preexisting kidney impairment are at greater risk of developing the condition. Researchers in Greece randomized 231 patients with impaired kidney function to receive a placebo or 3 grams ascorbic acid at least 2 hours prior to scheduled coronary angiography or intervention in addition to 2 grams the night and morning after the procedure. Serum creatinine was measured at the beginning of the study and two to five days following the procedure. The increase in serum creatinine levels was significantly greater in the group who received the placebo compared to those who received vitamin C. Creatinine clearance, an estimation of the kidney's filtering capabilities, underwent a greater decline in the group who received the placebo compared to those who received vitamin C. Contrast-mediated nephropathy was determined to have occurred in 9 percent of the ascorbic acid group and 20 percent of those who did not receive the vitamin. The reduction in kidney function caused by contrast media may be due to the generation of free-radicals. In previous research the antioxidant amino acid N-acetyl- cysteine was found to be helpful in preventing the condition. The current study shows that another widely available and safe antioxidant nutrient can also help protect the kidneys from radiographic contrast agents and adds evidence to the belief that contrast-mediated nephropathy is caused by oxidative stress. —D Dye Mothers' multivitamin use before pregnancy associated with fewer preterm births A study published in the November 2004 issue of the American Journal of Epidemiology (volume 160, number 9) found that the use of multivitamin supplements by women prior to becoming pregnant was associated with fewer preterm deliveries. Preterm birth is defined as birth at less than 37 weeks of gestation and is associated with a lower rate of infant survival during the first year of life. Researchers at the University of North Carolina at Chapel Hill utilized data from the Pregnancy, Infection and Nutrition Study which recruited 2,010 women during their 24 th to 29 th week of pregnancy. Telephone interviews and food frequency questionnaires provided information on vitamin supplement use. The current study compared the incidence of preterm delivery among women who took multivitamins prior to conception, before conception and during pregnancy, during pregnancy only, or not at all. The team found that women who took a multivitamin supplement before conception had half the risk of early and late preterm delivery than those who took no vitamins. Women used multivitamins before and during pregnancy or during pregnancy only had approximately the same amount of preterm births than women who took none at all. The authors note that the women who took vitamins prior to conception, but discontinued taking them during pregnancy may have done so because of nausea, and that nausea and vomiting during early pregnancy has been associated with a lower risk of preterm delivery. A lower intake of nutrients during these months may modify the mother's hormones in a manner that benefits her offspring, possibly explaining the lack of benefit for multivitamins in women who took them both before and after conception. This study reinforces the concern that waiting until pregnancy is diagnosed may be too late for nutritional intervention to benefit pregnancy outcomes. —D Dye Primate study finds soy does not negatively impact fertility Research presented on October 19 2004 at the annual meeting of the American Society for Reproductive Medicine held in Philadelphia has found no validity for the concern that high soy diets impair fertility. Asian women, who consume a greater amount of soy compared to western women, have a lower risk of breast cancer. Researchers have sought to explain this phenomenon by hypothesizing that the plant estrogens in soy known as isoflavones could reduce a woman's own estrogen production or increase menstrual cycle length, lowering a woman's lifetime exposure to estrogen. Although less estrogen exposure could lower breast cancer risk, a concern has been raised that it could affect the ability to conceive. Researchers from Wake Forest University Baptist Medical Center and Emory University School of Medicine used monkeys for the current study because they have menstrual cycles similar to those of women. They fed half of the animals a diet high in soy for one year, and provided the remainder of the monkeys with a diet that contained protein of animal origin. The monkeys were observed for any changes in menstrual cycle or ovarian hormone levels. Lead researcher Jay Kaplan PhD of Wake Forest University explained the findings: "Our study was designed to determine whether a soy supplement containing twice the level of plant estrogen consumed by Asian women would alter any aspect of the menstrual cycle or ovarian function in monkeys. Soy treatment did not change any characteristics of the menstrual cycle, including length, amount of bleeding or hormone levels. This suggests that any protection that soy may provide against breast cancer does not come from changes in the menstrual cycle.” Dr Kaplan noted that although soy does not appear to affect ovarian hormones, high stress levels were confirmed to have this effect in the current study. —D Dye High fiber diet associated with reduced estrogen levels The American Association for Cancer Research's third annual International Conference on Frontiers in Cancer Prevention Research was the site of a presentation on October 17 2004 of the findings of researchers from the University of Southern California and colleagues that a greater intake of fiber is associated with a reduction in circulating estrogen levels. High estrogen levels have been associated with the development of breast cancer, which could make increasing dietary fiber an important measure in preventing the disease. The research team used data obtained in the Multiethnic Cohort Study of Diet and Cancer, which provided information on the fiber intake and estrogen levels of 252 Mexican-American women, a population that has a higher intake of fiber than other groups. They found that as fiber levels increased, levels of two estrogens, estrone and estradiol, declined. It was also discovered that the hormones increased with a greater intake of dietary fat, but when both fat and fiber were included in the statistical model, only fiber remained significant as a predictor of hormone levels. Lead author and postdoctoral fellow at the USC Keck School of Medicine, Kristine Monroe, PhD, noted, "There's been so much research on this subject, and yet the jury's still out. Latinas enrolled in the Multiethnic Cohort Study have lower breast cancer rates than any major racial/ethnic group in the U.S. Even after adjusting for known risk factors, their incidence rate is still 20 percent less than white women, who have been the focus of the majority of earlier research and whose dietary fiber intake is generally not that high." Although no direct cause and effect relationship between fiber intake and breast cancer has been confirmed, the researchers believe that fiber has the potential of providing a dietary means of lowering breast cancer risk. —D Dye Good nutrition before and after obesity surgery helps prevent neuropathy A study presented on October 14 2004 at the American Medical Association's 23rd Annual Science Reporters Conference held in Washington DC has found that good nutrition can help prevent peripheral neuropathy (PN) after surgery for obesity. The study will appear in the October 26 2004 issue of the journal Neurology (http://www.neurology.org). Associate professor of neurology James B Dyck, MD, of the Mayo Clinic College of Medicine and colleagues compared the charts of 435 people who had undergone gastric bypass or stomach stapling to 123 gall bladder surgery patients to discover whether obesity surgery was associated with a higher rate of peripheral neuropathy than abdominal surgery in general. The researchers compared a number of factors among the two groups such as age, degree of obesity, and multivitamin and calcium supplement use to determine if any were related to the development of neuropathy. They found that those who had obesity surgery were significantly more likely to have peripheral neuropathy than the gall bladder surgery patients. The most common neuropathies were sensory neuropathy and carpal tunnel syndrome. A few patients had a more severe neuropathy that sometimes becomes disabling. Dr Dyck explained his findings: “The risk factors that we found correlated with PN included very rapid weight loss, not taking vitamins and prolonged nausea and vomiting. Factors including age, gender, presurgery BMI and general health had no association. A major risk factor correlated with PN after surgery was failure to attend a nutritional clinic. The evidence was very strong that PN complications were associated with malnutrition. Our study offers a clear message that PN after bariatric surgery is largely preventable and that a multidisciplinary approach to bariatric surgery that includes good follow-up and good nutritional counseling is the key to a successful outcome.” —D Dye Lutein from supplements better absorbed A study published in the September 2004 issue of the Journal of Nutrition has found that lutein, a nutrient that occurs in some vegetables, is better absorbed from an oil based supplement than from spinach. Lutein and zeaxanthin are found in the lens and macular region of the retina, and research has found that optimal intake of these nutrients aids in the prevention of age-related macular degeneration, the leading cause of blindness in older individuals. It is believed that the prevention of free-radical damage provided by the compounds is responsible for their protective benefits. In the current study, researchers from Ohio State University in Columbus explored the absorbability of lutein, beta-carotene and zeaxanthin from a spinach puree, and lutein and zeaxanthin froma commercially available oil-based supplement in an in vitro model consisting of human intestinal cells. Uptake of lutein and zeaxanthin exceeded that of beta-carotene, and uptake of lutein provided by the supplement was greater than that available in spinach. The study showed that lutein from supplements is more bioavailable than lutein occurring in a common food source. Additionally, the study demonstrated the efficacy of an in vitro model of digestion. —D Dye Folic acid not alone in prevention of neural tube defects Dutch researcher Pascal Groenen believes that prevention of neural tube defects relies on a balanced diet. Neural tube defects, also known as spina bifida, are an abnormality of the central nervous system and were once one of the most common birth defects in the developed world. The incidence of neural tube defects has greatly declined since the implementation of food fortification with the B vitamin folic acid in the United States, Canada, and elsewhere. However, children are still born with the condition, leading researchers to pursue other possible causes. In studies with mice, Dr Gorenen discovered that myo-inostiol, a biologically active form of the B vitamin inositol which is made in the human body, prevented 70 percent of neural tube defects that would have otherwise occurred. Acting on these findings, Radboud University Nijmegen Medical Centre in the Netherlands, in cooperation with other researchers, set up a largescale clinical trial to study the role of nutrition, lifestyle and genes in the development of the defects in humans. One-hundred thirty-two families with a child born with neural tube defects and 236 families with healthy children have taken part in the study. In addition to folic acid and myo-inositol, a mother's deficiencies of zinc and vitamin B12, or having slightly elevated blood glucose can increase the risk of giving birth to a child with neural tube defects. This points to the need for a balanced diet before and during pregnancy. Further research will reveal whether pregnant women or those who wish to become pregnant should take inositol, zinc, or vitamin B12 supplements in addition to folic acid supplements that they are currently recommended. —D Dye Soy helps female hearts and bones The results of two studies reported on October 8, 2004 at the annual meeting of the North American Menopause Society, held in Washington, DC, showed that soy may benefit both the bones and hearts of premenopausal women. In the first study, conducted by Jay Kaplan, PhD and colleagues at Wake Forest University Baptist Medical Center in Winston-Salem, North Carolina, monkeys equivalent in age to 30 to 40 year old women who were fed a soy-based diet were found to have more favorable total cholesterol to high-density lipoprotein (HDL) cholesterol levels than those fed an animal protein-based diet. Animals who were at greatest risk for coronary artery disease due to the presence of impaired ovarian function that occurs with subordinate social group status experienced the most improvement. The total cholesterol to HDL ratio of these animals was 48 percent lower than monkeys on the animal protein diet, equating to a 50 percent reduction in arterial plaque. Dr Kaplan commented, "Studies have shown that heart vessel disease, or atherosclerosis, begins in the 30s and 40s in women. From our work in monkeys, we believe that the time to prevent cardiovascular disease in women is before menopause, not after. Soy seems to provide a potent protection in monkeys, in terms of cholesterol levels, which is a good marker for general cardiovascular risk. We presume the benefit would apply to premenopausal women as well." In the second study, led by Wake Forest assistant professor of comparative medicine Cynthia Lees, DVM, PhD, monkeys provided with a diet containing soy experienced increased bone mass compared to those that did not consume soy. Dr Lees stated, "The increase was small, but this is an exciting finding. Previous studies in postmenopausal monkeys and women found either no increase or bone loss." —D Dye Novel vitamin E derivative kills cancer cells Researchers at The University of Texas at Austin have found that a compound derived from vitamin E called alpha-TEA reduces tumor size and metastasis in genetically identical mice. The study appears the October 2004 issue of the journal Experimental Biology and Medicine. The researchers, led by nutrition professor Kimberly Kline of the Department of Human Ecology, injected the animals with mouse-derived breast cancer cells that normally form tumors and metastasize to the lungs. The mice were given alpha-TEA or another vitamin E compound, vitamin E succinate, administered orally or via aerosol for twenty-one days. A control group received neither compound. While vitamin E succinate was beneficial if delivered via aerosol, alpha-TEA was effective regardless of the route of administration, and reduced primary tumor mass by half. The compound also reduced metastasis to the lungs, as did aerosolized vitamin E succinate. Of ten mice treated with alpha-TEA via aerosol, only one developed visible lung tumor lesions, compared to half of the mice who received no treatment. Lung micrometastases were additionally reduced in the aerosolized alpha-TEA treated group, who had half the amount observed in the control mice. Lymph metastases were significantly reduced as well in this group. Alpha-TEA was also tested in breast cell cultures and was discovered to reduce the ability of cancer cells to multiply by 80 percent in addition to increasing the amount of programmed cell death compared to that observed in untreated cells. Dr Kline stated, "One reason that alpha-TEA is such a potent anticancer agent is that it impacts on numerous antigrowth and pro-death cellular processes in cancer cells but not normal cells. Our research is promising at this stage, but there's a lot of further investigations that have to be conducted before alpha-TEA can be cleared by the Federal Drug Administration for testing in humans." —D Dye Nonsteroidal anti-inflammatory drug use extends the lives of prostate cancer patients At the 46th Annual Meeting of the American Society for Therapeutic Radiology and Oncology in Atlanta on October 4 2004, Khanh H. Nguyen, MD of Fox Chase Cancer Center in Philadelphia reported that regular use of aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) may help men diagnosed with prostate cancer live longer. One thousand two hundred six men who had received radiation therapy for prostate cancer were followed for a four and one half year period. Two hundred thirty-two participants had used NSAIDs before being treated. Dr Nguyen, who is a radiation oncologist at Fox Chase and lead author of the study, explained the purpose of their study, " NSAIDs have been associated with reductions in the risk of developing various gastrointestinal cancers and improvement in their treatment outcomes. However, any impact NSAIDs may have on treatment for prostate cancer has been unclear. We wanted to see if patients who used these drugs regularly before their diagnosis and treatment gained any benefit." It was found that prior NSAID use was an independent predictor of survival. The researchers believe that NSAIDs may act by increasing programmed cell death and blocking the formation of new blood vessels, via the drugs' inhibition of COX-1 and COX-2 enzymes. Dr Nguyen summarized, "Pretreatment NSAID use was associated with significant delays in distant metastases, decreased rates of second cancers and improvement in overall survival. Our data suggest a potential benefit of NSAIDs in managing prostate cancer." —D Dye Low iron associated with impaired immunity in older women In a report to be presented at 4th European Congress on Nutrition and Health in the Elderly, which will be held in France next month, associate professor of nutrition Dr Namanjeet Ahluwalia and colleagues from Pennsylvania State University revealed that what may appear in women as routine old age symptoms can be caused by an iron deficiency, which is frequently associated with diminished immune function. Until now, the majority of studies on iron deficiency and immunity have focused on children in developing countries. The findings were published earlier this year in the March 2004 issue of The American Journal of Clinical Nutrition. Dr Aluwalia's team evaluated iron levels and white blood cell responses of 72 women aged 60 and older who appeared healthy, well-nourished and free of inflammation. Depleted iron stores and abnormal results on at least two other iron tests were considered diagnostic of iron deficiency. It was found that low iron impaired immunity in 28 to 50 percent of the women. "Iron deficiency in our study was associated with impairments on two measures of immunity at levels that may render older adults more vulnerable to infections,” Dr Aluwalia stated. "Older women can suffer iron deficiencies because of the effects of aging. It's best to be checked if you sense changes, such as being fatigued easily, breathlessness, attention problems, or frequent infections. It's not necessarily aging and could be a problem related to undernutrition , specifically iron deficiency. However, iron supplementation should not be started without lab work and a doctor's order,” she advised. "We are conducting a follow-up project to study the effects on immunity of correcting iron deficiency via supplements,” Dr Aluwalia announced. “We are currently recruiting women age 60 or above for that study.” —D Dye |
