Another reason for women to take calcium and vitamin D
In addition to protecting themselves from an increased risk of osteoporosis, women who consume relatively high amounts of calcium and vitamin D may also be reducing the risk of premenopausal breast cancer.
In research was published in the the May 28, 2007 issue of Archives of Internal Medicine, Jennifer Lin, PhD and colleagues at Brigham and Women's Hospital and Harvard Medical School utilized data from 10,578 premenopausal and 20,909 postmenopausal participants in the Women's Health Study. Medical history and lifestyle questionnaires were completed by the subjects upon enrollment, and dietary questionnaires provided information concerning calcium and vitamin D intake. Subsequent breast cancer diagnoses were reported in yearly follow-up questionnaires.
Over the ten year follow-up period there were 276 premenopausal and 743 postmenopausal women diagnosed with breast cancer. A greater intake of calcium and vitamin D had a protective association against breast cancer in premenopausal, but not postmenopausal women. Premenopausal women whose intake of calcium was in the top one-fifth of participants experienced a 39 percent lower risk of developing breast cancer than women whose intake was in the lowest fifth. For vitamin D, the risk was 35 percent lower for women whose intake was in the top group. The protective association appeared to be greater for more aggressive tumors.
In their commentary concerning the findings, the authors suggest that it is "possible that the protective effects of calcium and vitamin D against postmenopausal breast cancer occur only when intakes of both nutrients are substantially high, as inadequacy of both nutrients is very common in postmenopausal women."
"Further investigation is warranted to study the potential utility of calcium and vitamin D intake in reducing the risk of breast cancer," they conclude.
More evidence for COX-2 inhibition as protective mechanism against colorectal cancer
A report published in the May 24, 2007 issue of the New England Journal of Medicine, revealed the finding of researchers from Massachusetts General Hospital, Dana-Farber Cancer Institute, and Brigham and Women’s Hospital that inhibition of cyclooxygenase-2 (COX-2) is the mechanism by which aspirin reduces colorectal cancer risk. Numerous studies have found an association between aspirin use and a reduction in colorectal cancer, yet how the drug works had yet to be confirmed.
"We knew that aspirin can block COX-2 function and that COX-2 is present in the vast majority of colorectal tumors but not in normal colon tissue," lead author Andrew Chan, MD, MPH, of Massachusetts General commented. "Therefore we hypothesized that, if blocking the COX-2 pathway was the mechanism underlying aspirin-associated risk reduction, it should preferentially reduce the incidence of those tumors that rely on COX-2."
Dr Chan and his associates utilized data from 83,000 participants in the ongoing Nurses Health Study and 47,000 men participating in the Health Professionals Follow-Up Study, which collect data concerning diet and disease incidence every two years. Both studies had previously found an association between a lower risk of colorectal cancer and aspirin intake. For the current study, 636 pathology specimens from participants with confirmed colorectal cancer were analyzed for COX-2 expression.
Use of two or more standard aspirin tablets per week was found to reduce the risk of colorectal cancer by 25 percent, yet this reduction only applied to tumors that expressed COX-2. COX-2-negative tumor incidence was found to be the same among aspirin users and nonusers.
Senior author Charles Fuchs, MD, MPH, noted, "These results will allow us to test another hypothesis: that in patients who have had colorectal cancer or polyps in the past, expression of COX-2 in the earlier lesion might indicate those for whom aspirin could reduce the risk of recurrence. Answering that will be our next target."
Exercise really is rejuvenating
Simon Melov, PhD of the Buck institute and Mark Tarnopolsky, MD, PhD, of McMaster University Medical Center in Hamilton, Ontario conducted gene expression profiles on muscle tissue obtained from 25 healthy older men and women before and after six months of twice weekly resistance training, and compared them with tissue from men and women aged 20 to 35. Although gene expression prior to exercise showed a decline in mitochondrial function compared with the younger adults, exercise reversed the changes back to younger levels. Additionally, strength improved by 50 percent following six months of training, from a level that was 59 percent weaker than the young men and women to only 38 percent lower.
"We were very surprised by the results of the study," Dr Melov commented. "We expected to see gene expressions that stayed fairly steady in the older adults. The fact that their 'genetic fingerprints' so dramatically reversed course gives credence to the value of exercise, not only as a means of improving health, but of reversing the aging process itself, which is an additional incentive to exercise as you get older."
"The vast majority of aging studies are done in worms, fruit flies and mice; this study was done in humans," Dr Melov observed. "It's particularly rewarding to be able to scientifically validate something practical that people can do now to improve their health and the quality of their lives, as well as knowing that they are doing something which is actually reversing aspects of the aging process."
Apples, fish consumed by mothers reduce their children's risk of asthma and allergy
The results of a study presented at the American Thoracic Society 2007 International Conference on Sunday, May 20, 2007 concluded that women who eat more fish and apples during their pregnancies are less likely to have children who develop asthma or eczema, an allergic skin disease.
Saskia Willers, MSc of Utrecht University in the Netherlands evaluated data provided by 1212 mothers and their children participating in the SEATON study conducted at the University of Aberdeen in Scotland. Dietary questionnaires were completed by the mothers during their pregnancies, and questionnaires concerning their children's respiratory symptoms, allergies and food consumptions were filled out when the children were five years of age. In addition, the children underwent lung function and allergy tests.
Children of mothers who consumed the most apples during pregnancy experienced a lower risk of having ever wheezed or having been diagnosed with asthma compared to those of mothers whose intake was lowest. Eating fish at least once per week appeared to protect children from eczema, when compared with the children of mothers who did not consume fish.
Noting that previous studies of this group of children found evidence for the protective effects against wheeze and asthma of vitamins D and E, and zinc taken during pregnancy by their mothers, Ms Willers suggests that if the newest findings are confirmed, "recommendations on dietary modification during pregnancy may help to prevent childhood asthma and allergy."
"Other studies have looked at individual nutrients’ effect on asthma in pregnancy, but our study looked at specific foods during pregnancy and the subsequent development of childhood asthma and allergies, which is quite new," she observed. "Foods contain mixtures of nutrients that may contribute more than the sum of their parts."
Omega-3 fatty acids protective against advanced age-related macular degeneration
Having a greater intake of omega-3 fatty acids and fish was found to be associated with a reduced risk of advanced age-related macular degeneration (AMD) in a report published in the the May, 2007 issue of the American Medical Association journal Archives of Ophthalmology. Age-related macular degeneration occurs when the macula at the back of the eyes' retina deteriorates, which can lead to central vision loss.
In a study conducted by The Age-Related Eye Disease Study Research Group, 4,519 individuals aged 60 to 80 upon enrollment completed questionnaires concerning the previous year's dietary intake and underwent retinal photography to assess the presence and stage of macular degeneration.
While 1,115 participants were free of AMD symptoms, 2,746 were classified in intermediate stages, and 658 were found to have advanced (neovascular) age-related macular degeneration. The research team determined that a greater intake of omega-3 fatty acids, as well as fish, which is a source of the omega-3s, was associated with a reduced risk of advanced disease. When fish intake was examined, consuming more than two servings per week provided the greatest protection.
"Dietary total omega-3 long-chain polyunsaturated fatty acid intake was inversely associated with neovascular AMD, as was docosahexaenoic acid," the authors write. "Higher fish consumption, both total and broiled/baked, was also inversely associated with neovascular AMD."
Omega-3 fatty acids docosahexaenoic acid and eicosapentaenoic acid may protect the retina by influencing gene expression, retinal cell differentiation, and survival. Other properties of the fatty acids may also be involved, including their ability to reduce inflammation.
The authors conclude, "These results and those from other observational analytic investigations suggest that modifying diet to include more foods rich in omega-3 long-chain polyunsaturated fatty acids could result in a reduction in the risk of having neovascular age-related macular degeneration."
Fiber and magnesium independently reduce diabetes risk
In a study and meta-analysis published in the May 14, 2007 issue of the Archives of Internal Medicine , researchers at the German Institute of Human Nutrition Potsdam-Rehbruecke in Nuthetal found that a higher intake of magnesium and cereal fiber could separately reduce the risk of developing type 2 diabetes.
Matthias B. Schulze, DrPH and colleagues analyzed data obtained from 9,702 men and 15,365 women between the ages of 35 to 65 years enrolled in the European Prospective Investigation Into Cancer and Nutrition (EPIC)-Potsdam study. Participants completed food dietary questionnaires upon enrollment and were observed for the development of diabetes for an average of seven years. Over the follow-up period, 844 cases of type 2 diabetes were diagnosed.
For the meta-analyses, 9 studies of fiber and 8 concerning magnesium and diabetes risk were selected.
Although fiber from fruit and vegetables did not appear to significantly impact diabetes risk in the EPIC study, when the participants' cereal fiber intake was analyzed, those in the top one-fifth of subjects who consumed an average of 17 grams of fiber per day had a 28 percent lower risk of developing the disease than subjects in the lowest fifth whose intake averaged 7 grams. Meta-analysis of the fiber studies found a 33 percent lower risk when participants whose intake was highest were compared with those that were lowest. In EPIC, magnesium intake was not related to diabetes risk, however, the meta-analysis concluded that subjects whose magnesium intake was high experienced a 23 percent lower risk than those with a lower intake.
"In conclusion, the evidence from our study and previous studies, summarized by means of meta-analysis, strongly supports that higher cereal fiber and magnesium intake may decrease diabetes risk," the authors write. "Whole-grain foods are therefore important in diabetes prevention."
Omega-3 fatty acids may help build muscle
A report published in the February, 2007 issue of the Journal of Physiology (volume 579, issue 1) described the findings of a team led by Carole Thivierge of the Université Laval in Quebec that omega-3 fatty acids benefit muscle protein metabolism.
The ability to convert nutrients from food into muscle proteins declines with age in humans and other mammals. Insulin resistance occurring in aging muscle cells may be the reason for this occurrence. Acting on the knowledge that omega-3 fatty acids improve glucose metabolism in humans and animals who demonstrate insulin resistance, the researchers added omega-3 fatty acids from fish oil, or a cottonseed and olive oil mixture that did not contain the fatty acids to the diet of steers for five weeks to evaluate the effect on protein metabolism.
At the study's conclusion, animals that received the fish oil-supplemented diet had increased insulin sensitivity resulting in twice the amount of amino acids being used by their bodies to synthesize protein, particularly in muscles.
Dr Thivierge and colleagues conducted the study in an attempt to find an alternative to the use of hormones to stimulate growth in cattle. Calves begin to be less efficient at converting food into muscle at four to six months. "Adding fish oil to their diet could prevent this decline by restoring insulin sensitivity in aging animals," Dr Thivierge stated. "In addition, it could contribute to reducing the amount of by-product emissions in the environment, since animals that are given omega-3’s spontaneously eat 10% less food to achieve the same weight gain."
Dr Thivierge suggests that omega-3 fatty acids could help prevent muscle wasting in older individuals and improve the ability of athletes to build muscle. However, she added that "For increased muscle protein metabolism to take place in people younger than 50, physical training is still required."
National Institute on Aging launches DHA trial
The Alzheimer's Disease Cooperative Study (ADCS), a group of leading researchers supported by the National Institute on Aging, which is part of the U.S. National Institutes of Health, will be conducting a nationwide clinical trial at 51 sites to test the effect of docosahexaenoic acid (DHA) on individuals age 50 and older with mild to moderate Alzheimer's disease. DHA is an omega-3 fatty acid found in oily fish and the algae they feed on. In addition to cardiovascular benefits, research suggests that increased intake of omega-3 fatty acids could lower Alzheimer's disease risk.
"The evidence to date in observational and animal studies on omega-3 fatty acids and Alzheimer's disease warrants further evaluation in a rigorous clinical trial," NIA Director Richard J. Hodes, MD commented. "This study is one of a number we are undertaking in the next few years through the ADCS to test compounds that might play a role in preventing or delaying the symptoms of this devastating disease."
The double-blind study, which will be directed by associate professor of neurology at Oregon Health and Science University Joseph Quinn, MD and coordinated by the University of California, San Diego, plans to administer 2 grams DHA to 60 percent of the participants and a placebo to the remaining subjects over an 18 month period. Participants will be monitored throughout the trial and functional and cognitive changes evaluated. The researchers will also be looking at brain atrophy and specific proteins in blood and spinal fluid to assess the physical and biological markers of the disease.
"By participating in this study, volunteers will make an invaluable contribution to Alzheimer's disease research progress," Dr Quinn acknowledged. "We are indebted to those who graciously volunteer to participate in clinical studies."
Individuals interested in participating in the trial may contact NIA's Alzheimer's Disease Education and Referral (ADEAR) Center at 1-800-438-4380, or email [email protected].
What makes the queen bee live so long?
That is the question that entomology professor Gene Robinson of the University of Illinois and his colleagues set out to answer in research that will be published this week in the online edition of the Proceedings of the National Academy of Sciences.
The queen bee reproduces throughout her life and lives ten times as long as her hives' genetically identical worker bees, yet the molecular mechanisms have not been elucidated.
“Many times the way organisms achieve longevity is via a tradeoff with reproduction,” Dr Robinson commented. “In general, life forms that postpone reproduction until later in life live longer. But the queen bee has her cake and eats it too. She’s an egg-laying machine. She lays 2,000 eggs a day and yet lives 10 times longer than individuals that stem from the same genome and yet do not reproduce.”
Dr Robinson and his associates identified three factors whose interplay is involved in the queen bees' exceptional reproduction, growth and longevity: vitellogenin, juvenile hormone, and IGF-1. Vitellogenin is a yolk protein involved in reproduction and well as worker bees' longevity. Vitellogenin expression was found to be elevated in young queens' abdomens, declining over time while increasing in the head and thorax. In worker bees, vitellogenin expression was much lower. The protein was found to scavenge free radicals, thereby reducing oxidative stress that results in aging and disease. Compared to workers, queen bees had greater oxidative stress resistance.
“There are implications here (for other species) in the sense that here is an organism that is reproductively active and long-lived,” Dr Robinson observed. “And we see novel and conserved factors that are part of a large regulatory network. The queen has her cake and eats it too. And humans want to know how that works.”
Ginseng, ginkgo, don't interfere with prescription drugs
In the wake of recent concern over research indicating that the popular herb St John's wort could affect the absorption and metabolism of a number of drugs, many individuals have questioned whether other herbs could act similarly. However, on May 1, University of Kansas Medical Center scientist Dr Gregory Reed reported at the Experimental Biology 2007 meeting that ginseng and ginkgo biloba, two other widely used herbs, are not likely to alter the process by which drugs are absorbed, distributed, metabolized and eliminated.
For the current study, a team led by Dr Reed along with Dr Aryeh Hurwitz enrolled 31 men and 41 women between the ages of 20 and 59 who did not smoke, or use prescription drugs or nutritional supplements. Participants were given a cocktail of five drugs selected for their ability to provide a measure of the activity of an important drug metabolism pathway, so that, taken together, the drugs provide measurements of the pathways that determine how more than 90 percent of prescription drugs are metabolized. Blood and urine samples from the participants were analyzed to determine the absorption and metabolism of each drug.
The subjects were divided to receive one of the following daily regimens: ginseng and a placebo, ginkgo biloba and a placebo, ginseng and ginkgo, or two placebos. At the end of the four week treatment period, they were again given the drug cocktail, and blood and urine samples were once more analyzed to determine any effects elicited by the herbs. The team found no significant differences in the absorption and metabolism of any of the drugs between the four groups, suggesting that neither ginseng nor ginkgo affects the pharmacokinetics of most over-the-counter or prescription drugs.
Fish oil may benefit individuals with kidney disease
Dietitian Rachel Zabel of Queensland University of Technology in Brisbane, Australia, in collaboration with researchers from the Wesley Hospital, are planning a study that will help determine the benefit of fish oil in kidney disease patients. The known anti-inflammatory effect of eicosapentaenoic acid (EPA) found in fish oil may help to alleviate the inflammation that occurs in 30 to 60 percent of patients undergoing dialysis.
"Research shows that patients with kidney disease on dialysis experience a range of complications thought to relate to chronic inflammation," Zabel stated."They can have poor nutritional status, disturbed appetite and a lower quality of life."
“Fish oils have known anti-inflammatory properties due to their high concentration of eicosapentaenoic acid," she noted. "EPA becomes incorporated into the cells of the immune system and reduces the production of pro-inflammatory substances, including cytokines such as interleukin-6 (IL-6)."
"EPA has been used successfully in other population groups with chronic inflammation including people with osteoarthritis and cancer cachexia, however the anti-inflammatory effects have not yet been applied to patients on dialysis," she added.
Zabel plans to provide dialysis patients with an EPA supplement over a twelve week period. In addition to inflammation, an area that will be evaluated is appetite, which is diminished in nearly a third of kidney dialysis patients. Loss of appetite leads to inadequate nutritional intake, more frequent hospitalizations, and reduced quality of life. Researchers believe that inflammation may contribute to appetite loss.
"The incidence of chronic kidney disease is increasing," Zabel observed. "One in seven people over the age of 25 have at least one clinical sign of chronic kidney disease and every day five Australians commence dialysis or transplantation to stay alive."
"While fish oil won't cure kidney disease, it may provide a better quality of life for sufferers."
Green tea protects against HIV-associated dementia in mouse model
The Experimental Biology 2007 conference held in Washington, DC, was the site of a presentation on May 1 by neuroscientist Brian Giunta, MD of the University of South Florida in Tampa concerning the finding that a compound derived from green tea may help prevent HIV-associated dementia, a debilitating disorder that affects 22 percent of adults infected with human immunodeficiency virus (HIV). There are no therapies currently available that specifically treat this condition.
Dr Giunta and Jun Tan, MD, PhD of the University of South Florida's Department of Psychiatry developed the animal model used in the current study by giving healthy mice doses of HIV proteins Gp120 and/or Tat, in combination with the cytokine interferon-gamma, which results in brain damage resembling that which occurs in human HIV-associated dementia.
Pretreatment of the mice with epigallocatechin-3-gallate (EGCG), an antioxidant that occurs in green tea, was found to prevent the ability of interferon-gamma to react with the HIV proteins to cause brain cell death. A similar experiment using cultured mouse neurons also found a protective effect for EGCG. "These findings suggest that EGCG, the green tea-derived compound, may represent a new and natural compound for the prevention and treatment of this devastating disease," Dr Giunta stated.
Abdul S. Rao, MD, MA, DPhil, who is the senior associate vice president for USF Health and vice dean for research and graduate affairs at the College of Medicine commented, "This is a very important finding in the prevention and treatment of HIV-related dementia, which is usually observed in the late stages of HIV disease. The neuroprotective effects of EGCG, the green-tea extract, may offer an alternative to existing mono or combination antiretroviral therapies that are known to have poor central nervous system penetration."