What's Hot Archive
December 30, 2005
Increased magnesium linked with stronger bones
A report published in the published in the November 2005 issue of the Journal of the American Geriatrics Society revealed that individuals who consumed more dietary and supplemental magnesium had greater bone mineral density (BMD) than those whose intake of the mineral was lower.
Kathryn M. Ryder, MD, of the University of Tennessee Health Science Center and colleagues analyzed data from 2,038 men and women aged 70 to 79 enrolled in the Health, Aging and Body Composition study. Magnesium intake was calculated via the use of food frequency questionnaires and medication inventories, and whole body bone mineral density was determined for all subjects.
Dr Ryder's team discovered that less than 26 percent of the subjects met the recommended daily allowance for magnesium, which is 320 milligrams per day for women and 420 milligrams per day for men of this age group. Bone mineral density was found to be greater in African-American men and women than among Caucasians. Magnesium intake was positively associated with bone mineral density only for Caucasian men and women. Among Caucasian men and women whose magnesium intake was in the top one-fifth of participants, bone mineral density was 0.02 and 0.04 grams per cubic centimeters greater than the BMD of those whose intake was lowest. For each 100 milligram daily increase in magnesium intake, there was a one percent gain in bone density, an effect similar to that of calcium. Dr Ryder commented, "Although this seems small, increases across a population may have large public health impact."
The authors suggest that magnesium could benefit bone mineral density via calciotropic hormones or by buffering the acidity produced by the typical Western diet. They conclude, "Higher magnesium intake through dietary change of supplementation may provide an additional strategy for the prevention of osteoporosis."
December 23, 2005
NAC cuts cocaine cravings
The American College of Neuropsychopharmacology's annual conference held in Hawaii from December 11-15, 2005, was the site of a presentation by Peter Kalivas, PhD, Professor and Chair of the department of neurosciences at the Medical University of South Carolina (MUSC) concerning the ability of N-acetylcysteine (NAC) to reduce cravings associated with cocaine addiction. N-acetylcysteine is a popular dietary supplement available over the counter that has antioxidant and other benefits. Its metabolic pathway in the brain affects one of the same proteins that is affected by cocaine.
In research funded by the National Institutes of Health, Dr Kalivas and his colleagues established cocaine dependency in rats and treated some of the animals with NAC. Unlike those who did not receive the amino acid, rats who received NAC ceased actively seeking cocaine and showed normal food-seeking behaviors.
In a second experiment, conducted by MUSC's department of psychiatry, Dr Robert Malcolm and his team members tested N-acetylcysteine on fifteen cocaine-dependent inpatients. Participants treated with NAC spent less time looking at cocaine-related pictures when various pictures were shown to them and reported reduced craving for the drug. Functional magnetic resonance imaging showed a reduction in activity in the prefrontal cortex (an area activated during cocaine craving) among those who received NAC, compared to patients who did not receive it.
Dr Kalivas commented, "The potential to use NAC for the treatment of individuals addicted to cocaine is a major finding. For those individuals who have the desire to end their addictive habit, a NAC supplement might help to control their cravings."
A clinical trial involving 282 individuals with cocaine addiction has been initiated to help clarify how NAC works in the brain to reduce craving for the drug.
December 21, 2005
Study confirms melatonin's role in breast cancer prevention
The December 1 2005 issue of the journal Cancer Research http://cancerres.aacrjournals.org/ published a report by researchers at the Bassett Research Institute of the Mary Imogene Bassett Hospital in Cooperstown, New York and Thomas Jefferson University in Philadelphia that adds further evidence to the theory that the pineal hormone melatonin help prevents breast cancer, while a deficiency contributes to the disease.
Rats with liver tumors or with implanted human breast cancers were exposed to varying intensities of light during twelve hour dark phases and were found to have levels of melatonin suppression that were dependent upon the dose of light received. The researchers then took blood samples from 12 women during daylight, at night after 2 hours of complete darkness, or during nighttime after exposure to 90 minutes of bright fluorescent light, and pumped the blood samples directly into the developing tumors.
While tumors perfused with blood collected at night after complete darkness showed a significant reduction in growth, blood collected at night after light exposure was associated with a growth-stimulating effect similar to that of daytime-collected blood. Lead author David Blask, MD, PhD, who is a neuroendocrinologist with the Bassett Research Institute, concluded, "These results are due to a direct effect of the melatonin on the cancer cells. The melatonin is clearly suppressing tumor development and growth."
"We know that many tumors are largely dependent on a nutrient called linoleic acid, an essential fatty acid, in order to grow," Dr Blask explained, "Melatonin interferes with the tumor's ability to use linoleic acid as a growth signal, which causes tumor metabolism and growth activity to shut down."
The authors conclude, "These mechanistic studies are the first to provide a rational biological explanation for the increased breast cancer risk in female night shift workers."
December 19, 2005
Fish oil protects against pollution-induced reduction in heart rate variability
A report published in the December 15 2005 issue of the American Journal of Respiratory and Critical Care Medicine revealed that consuming fish oil capsules helped prevent the decline in heart rate variability associated with airborne particulate matter. Heart rate variability is a measure of autonomic nervous system regulation of the heart. Greater variability between beats reduces the chance of arrhythmia, heart attack and sudden death.
Fernando Holguin, MD, of the Centers for Disease Control and Prevention in Atlanta, and his associates provided 26 Mexico City nursing home residents over the age of 60 with daily supplements containing two grams fish oil, while 24 residents received two grams soy oil per day for five months. The subjects, who spent 92 percent of their time indoors, were found to be exposed to indoor airborne particles measuring 2.5 microns or less. All participants had a low omega-3 fatty acid intake prior to the beginning of the study. Heart rate variability was assessed on alternative weekdays beginning one month before treatment period through the end of the supplementation period.
Dr Holguin explained the findings: "In this randomized controlled trial, fish oil supplementation prevented the reduction in heart rate variability associated with the same-day exposure to indoor particulate matter. In contrast, soy oil, our comparison supplementation of plant-derived polyunsaturated fatty acids, was associated with a marginal, nonsignificant protection from the effects of particulate matter on heart rate variability."
"Fish oil as a source of omega-3 polyunsaturated fatty acids could be considered as a potential form of preventive measure to reduce the risk of arrhythmia and sudden death in elderly subjects exposed to ambient air pollution," he added.
December 16, 2005
Green tea compound may help leukemia patients
Acting on published findings by Mayo Clinic researchers that epigallocatechin gallate (EGCG), a compound that occurs in green tea, kills leukemic B-cells derived from patients with chronic lymphocytic leukemia (CLL), a number of patients with the disease as well as individuals with other low grade lymphomas began to try over the counter green tea extract products, despite evidence of clinical benefit against the disease or information on optimal dosing. In a case study published online on December 1 2005 in Leukemia Research, Tait Shanafelt MD, who coauthored the earlier article, and colleagues report on improvements in four of these patients, three of whom met the criteria used to define a partial response in clinical trials. Chronic lymphocytic leukemia currently has no cure, and spontaneous remission or regression is rare.
The previous research, published in the August 2004 issue of the American Hematology Society journal Blood, revealed that EGCG killed leukemic cells by interrupting communication signals needed for survival.
The patients discussed in the current case study had documented clinical and/or laboratory evidence of steady progression of CLL prior to starting green tea products, and all experienced objective responses shortly after initiating the therapy. Dr Shanafelt, who is a hematologist at the Mayo Clinic, commented on the findings: "The experience of these individuals provides some suggestion that our previously published laboratory findings may actually translate into clinical effects for patients with this disease."
Dr Shanafelt is currently the lead research in an NCI sponsored clinical trial that is examining the benefit of pharmacologic doses of green tea extract for early stage CLL patients. "Green tea has long been thought to have cancer-prevention capabilities," he added. "It is exciting that research is now demonstrating this agent may provide new hope for CLL patients."
December 14, 2005
Omega-3 fatty acids help COPD patients
A study reported in the December 2005 issue of Chest, the journal of the American College of Chest Physicians, found that diets supplemented with omega-3 fatty acids reduced inflammatory markers and improve breathing and exercise capacity in patients with chronic obstructive pulmonary disease (COPD). Omega-3 fatty acids are found in fish, walnuts and canola oil, and have been found to lower inflammation and improve symptoms in a number of disorders.
Researchers at Kagoshima University Hospital in Kagoshima, Japan enrolled sixty-four patients with COPD for the current study. Participants were provided with an omega-3 polyunsaturated fatty acid-rich dietary supplement, or a polyunsaturated fatty acid supplement containing the same amount of calories that was not rich in omega-3 fatty acids, to be taken daily for two years. Inflammatory mediators in blood serum and in sputum, exercise capacity, and dyspnea scores, which assess breathing difficulty, were evaluated before and after the study.
The team found that individuals who received the omega-3 fatty acid-rich supplement had significantly decreased serum and sputum levels of the inflammatory cytokine leukotriene B4 as well as lower sputum tumor necrosis factor-alpha and interleukin-8 levels at the conclusion of the study. The group that did not receive the high omega-3 supplement experienced no change. Dyspnea scores and exercise capacity also significantly improved in the omega-3 supplemented group.
"There is an urgent need to develop new anti-inflammatory treatment because no currently available agent, including corticosteorids, can slow the chronic progressive inflammation of COPD," the authors write. They note that the dose of omega-3 fatty acids used in the current study was small and suggest that future studies using high doses of omega-3 fatty acids in COPD "might be interesting."
December 12, 2005
Drinking tea may lower ovarian cancer risk
The December 12 2005 issue of the American Medical Association journal Archives of Internal Medicine, published the finding of Swedish researchers that women who drank at least two cups of tea per day had a lower risk of ovarian cancer than those who were not tea drinkers.
Susanna C. Larsson, MSc, and Alicja Wolk, DMSc, of the Karolinska Institutet's National Institute of Environmental Medicine analyzed data obtained from 61,057 participants in the Swedish Mammography Cohort, a study of women aged 40 to 76 residing in two Swedish counties. Participants completed questionnaires upon enrollment from 1987 and 1990 that provided information on diet, education and other data. The women were followed for the incidence of cancer for an average of 15.1 years, during which time 301 women were diagnosed with invasive epithelial ovarian cancer.
Sixty-eight percent of the participants reported drinking tea at least once per month. Among these women, drinking less than one cup of tea per day was associated with an 18 percent lower risk of developing ovarian cancer than that experienced by women who drank tea less than monthly. Consuming one cup daily was associated with a 24 percent lower risk, and drinking two or more cups was linked with a 46 percent reduction.
Antioxidant polyphenols in green and black teas have been shown to inhibit the development of cancer in cell and animal studies. Inhibition of cell growth and angiogenesis and induction of apoptosis have all been proposed as mechanisms of action for tea against cancer. The antioxidant activity of polyphenols may also offer protection against the disease.
The authors conclude that tea drinking may lower the risk of ovarian cancer, but because there has only been one other prospective study to examine this relationship, the findings need confirmation by future research.
December 9, 2005
Vitamin D could help asthma patients
A report published in the December 8 2005 issue of the Journal of Clinical Investigation revealed that supplementing with vitamin D3 could help improve the response of asthma patients to steroid drugs, which are commonly prescribed for the disease. When inhalable steroids fail to elicit a response, oral steroid tablets are the only way to control the disease, however the drugs have significant side effects and do not always result in improvement, even at higher doses. This leaves some asthma patients at an increased risk of dying from the disease.
For the current study, Dr Catherine Hawrylowicz and colleagues from King's College London added vitamin D3 to T-cells derived from patients who are steroid resistant. When cultured with the steroid drug dexamethasone, T-cells from these individuals fail to produce interleukin-10, a signaling molecule that can inhibit the immune response that causes allergic and asthmatic symptoms.
They found that when vitamin D3 was added to the culture medium, the steroid-resistant cells produced interleukin-10 similarly to cells derived from steroid-responsive individuals. To test whether vitamin D3 would work in asthmatic humans, the researchers gave the vitamin to steroid-unresponsive subjects for seven days. Blood samples taken at the study's conclusion revealed an increase in the T-cells' responsiveness to dexamethasone.
Dr Hawrylowicz commented, "'The hope is that this work will lead to new ways to treat people who don't respond to steroid treatment as it currently stands, and it could also help those people who are on heavy doses of steroids to reduce the amount of medication they are taking."
"Interestingly, vitamin D3 is at present occasionally administered to patients with severe asthma to help prevent steroid-induced osteoporosis," she added. "Our studies suggest that there is an additional potential benefit to this treatment."
December 7, 2005
Fiber intake correlated with reduced cardiovascular disease risk factors
A report published in the December 2005 issue of the American Journal of Clinical Nutrition revealed the finding of French researchers that increased dietary fiber intake is associated with reduced levels of a number of cardiovascular disease risk factors. The finding adds to a growing body of evidence linking higher dietary fiber intake with a lower risk of heart disease.
Subjects were selected from participants in the SU.VI.MAX study, an ongoing trial designed to evaluate the effect of antioxidants on cancer and heart disease incidence over an eight year period. Participants who provided at least six twenty-four hour dietary recalls during the first two years of the study were included in the current analysis. Height, weight, waist and hip circumference, and blood pressure were measured during the second year of follow-up. Blood samples collected during the first year were analyzed for plasma glucose, total cholesterol, triglycerides, apolipoprotein A-I and B, and lipoprotein A. Plasma homocysteine was measured in a subsample of men at the three year point.
Individuals whose intake of dietary fiber was in the top one-fifth of participants had a significantly lower risk of being overweight as well as having elevations in blood pressure, waist-to-hip ratio, plasma apoplipoprotein B, apolipoprotein B to apoplipoprotein A-I ratio, cholesterol, triglycerides and homocysteine compared to those in the lowest fifth. A similar association was observed when nonsoluble dietary fiber was examined. Increased fiber intake from vegetables and cereals was associated with lower blood pressure and homocysteine levels.
"These findings suggest that 25 grams total dietary fiber per day is the minimum intake required to achieve a significant protective effect against cardiovascular disease;" the authors write. "However, total dietary fiber intakes of 30-35 grams/day will provide an even greater protective effect."
December 5, 2005
Amino acid prevents muscle breakdown
A study published in the December 2005 issue of The Journal of Physiology reported the findings of researchers at the Human Nutrition Research Centre Clermont-Ferrand and Institut National de la Recherche Agronomique in France that adding the amino acid leucine to older individuals' diets could help prevent the muscle breakdown that occurs with aging. After age 40, humans lose 0.5 to 2 percent of their muscle tissue per year.
In the current research, Lydie Combaret and colleagues studied muscle breakdown in young and old rats. Immediately after amino acids are consumed, muscle protein degradation slows and protein synthesis increases. This process is less effective in older animals, resulting in increased breakdown and slower synthesis. While it had been demonstrated that leucine could improve protein synthesis, the amino acid's effect on breakdown had not been previously determined.
They found that the slow in degradation following a meal did not occur in the older rats, but adding leucine to the diet restored breakdown in older animals to that of younger rats. The authors believe that the problem results from a defect in the machinery that breaks down contractile muscle protein. Senior co-author Didier Attaix commented, "Preventing muscle wasting is a major socio-economic and public health issue, that we may be able to combat with a leucine-rich diet."
In an accompanying "Perspectives" article in the same issue of the journal, Michael J Rennie summarized, "When old rats are fed a diet which is supplemented with leucine, there is what amounts to a rejuvenation of the normal postprandial inhibition of muscle protein breakdown . . . This is exciting because it strengthens the idea of a co-ordinated linkage between the meal-related stimulation of protein synthesis and the inhibition of breakdown."
December 2, 2005
Higher levels of inflammatory markers linked with stroke risk
The November 28 2005 issue of the American Medical Association journal Archives of Internal Medicine reported findings obtained from the Atherosclerosis Risk in Communities (ARIC) study that elevations of two markers of inflammation are associated with an increased risk of ischemic stroke. The ARIC study enrolled 12,762 healthy middle-aged men and women between 1987 and 1989.
The current study compared 194 cases of participants who had an ischemic stroke over an approximate six year period with 766 noncases. C-reactive protein (CRP), a well-known marker of inflammation, and the proinflammatory enzyme lipoprotein-associated phospholipase A2 (Lp-PLA2), as well as plasma lipid levels and other factors, were measured at the beginning of the study.
The research team found that mean Lp-PLA2 and CRP were higher among the participants who had undergone strokes than in those who had not, while there was no significant difference in low density lipoprotein cholesterol (LDL-C) levels. Participants whose CRP levels were in the top one-third of the participants had a 2.23 times greater risk of ischemic stroke than those in the lowest third, and for Lp-PLA2, the risk was 2.7 times higher for participants in the top third.
The authors ask the question, "If LDL-C is not a major risk factor for stroke, then how can one explain the reduction of stroke observed in statin trials?" This is answered by the fact that statins reduce CRP levels by 20 to 40 percent as well as reduce Lp-PLA2 activity by 28 to 42 percent, similar to the reduction in stroke events seen with statin use. The authors conclude that "Lp-PLA2 and CRP levels may be complementary to traditional risk factors to identify middle-aged individuals at risk for stroke."
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