High homocysteine correlates with lowered cognitive function after age 60
Pomegranate extract kills cancer cells in vivo and in vitro
Green tea compound helps protect brain
The September 21 2005 issue of the Journal of Neuroscience published the findings of researchers at the University of South Florida (USF) in Tampa that a compound found in green tea may help protect the brain from Alzheimer’s disease (AD).
Jun Tan, MD, PhD and colleagues gave daily injections of epigallocatechin-3-gallate (EGCG), an antioxidant component of green tea associated with many of its benefits, to mice bred to develop neurodegenerative disease. After two months, the team observed a decrease in beta-amyloid containing plaques of up to 54 percent. Experimentation with mouse neuronal cell cultures produced similar findings.
Dr Tan, who is the director of the Neuroimmunology Laboratory at the Silver Child Development Center, at USF;s Department of Psychiatry, stated, "The findings suggest that a concentrated component of green tea can decrease brain beta-amyloid plaque formation. If beta-amyloid pathology in this Alzheimer's mouse model is representative of Alzheimer's disease pathology in humans, EGCG dietary supplementation may be effective in preventing and treating the disease."
Although other flavonoids in green tea help protect against free radical damage, in this study they were actually found to oppose the action of EGCG in preventing amyloid build-up. Report coauthor Doug Shytle explained, "This finding suggests that green tea extract selectively concentrating EGCG would be needed to override the counteractive effect of other flavonoids found in green tea. A new generation of dietary supplements containing pure EGCG may lead to the greatest benefit for treating Alzheimer's disease."
Dr Tan added that humans would need 1500 to 1600 milligrams EGCG to mimic the dose found to benefit the mice in the current study. This dosage has already been found to be safe in human studies. The authors conclude, "These data raise the possibility that EGCG dietary supplementation may provide effective prophylaxis for AD."
High folate helps prevent cognitive decline
In another study to demonstrate the benefits of consuming enough folate, a report published in the September 2005 issue of the American Journal of Clinical Nutrition, revealed that a higher intake of folate is associated with a reduced rate cognitive decline in older individuals. Leafy vegetables (foliage) are a good food source of folate, the natural form of the B vitamin folic acid.
Katherine L. Tucker, PhD and colleagues at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University analyzed data obtained from 321 men aged 50 to 85 who participated in the Veterans Affairs Normative Aging Study. A previous study involving the group had found that high levels of homocysteine were associated with lower scores on cognitive tests. In the current study, dietary questionnaires were administered to the participants to determine nutrient intake, and blood samples were analyzed for B vitamin and homocysteine levels. A series of tests were administered at the beginning of the study and three years to evaluate cognitive function.
After adjustment for other vitamins and for plasma homocysteine, it was found that both dietary and plasma folate levels were independently protective against a decline in spatial copying and verbal fluency, two measures of cognitive function. Although the findings were independent of folate's known influence on homocysteine, having a high level of homocysteine was associated with a greater decline in recall memory compared to men whose levels were lower.
Dr Tucker, who is the director and professor of the Nutritional Epidemiology Program at the Friedman School of Nutrition Science and Policy at Tufts, noted, "Unlike our prior work with this population, in which we observed an association between low folate levels and lower cognitive test scores at one point in time, this study looks at the effects of these nutrients over time. That is an important step in establishing causality."
Compound occurring in beans and nuts inhibits tumor growth
The September 15 2005 issue of the journal Cancer Research (http://cancerres.aacrjournals.org/) published the findings of researchers at University College London that a compound found beans, nuts and grains inhibits an enzyme involved in tumor growth. The compound, known as inositol pentakisphosphate, inhibits phosphoinositide 3-kinase, which is involved in angiogenesis, the formation of new blood vessels by a tumor that facilitates their development and progression. Researchers have attempted to find a way to block the enzyme but have experienced challenges with the stability and toxicity of inhibitors that have been developed.
Dr Marco Falasca of the University College London's Sackler Institute and his colleagues tested inositol pentakisphosphate in mice and on ovarian and lung cancer cell cultures. They found that inositol pentakisphosphate inhibited tumor growth in the animals as well as enhanced the action of cytotoxic drugs on the ovarian and lung cancer cell cultures, indicating that the compound could help sensitize cancer cells to the drugs. Unlike chemotherapeutic drugs, inositol pentakisphosphate was found to be non-toxic, even at higher concentrations than those determined to be effective in the experiments.
Dr Falasca summarized, "Our study suggests the importance of a diet enriched in food such as beans, nuts and cereals which could help prevent cancer. Our work will now focus on establishing whether the phosphate inhibitor can be developed into an anticancer agent for human therapy. We believe that inositol pentakisphosphate is a promising anticancer tool and we hope to bring it to clinical testing soon."
Fat cells link inflammation and cardiovascular disease
In a letter published in the September 20 2005 issue of the Journal of the American College of Cardiology (http://www.sciencedirect.com/science/journal/07351097), researchers at The University of Texas M. D. Anderson Cancer Center and the University of Texas Health Science Center at Houston showed that inflammatory cytokines in fat cells produce the C-reactive protein (CRP), a marker of inflammation which is associated with an increased risk of heart disease and stroke. C-reactive protein production had previously only been identified in the liver and blood vessel walls.
Edward T. H. Yeh, MD, who is chairman of the Department of Cardiology at M. D. Anderson, and colleagues stimulated human fat cell cultures under various conditions to make their observations. They also found that resistin, a hormone involved in insulin resistance and the development type 2 diabetes, can stimulate C-reactive protein. Interestingly, resistin is also made by fat cells. The findings provide an explanation concerning why overweight individuals have higher CRP levels than normal weight people, and may help explain why they have a greater incidence of cardiovascular disease.
When the researchers exposed the cells to aspirin, troglitazone and statin drugs, which are known to lower CRP, they found that their production of the protein decined, demonstrating how the drugs work to help reduce inflammation.
Dr Yeh announced, "This study is the first to show how body fat participates in the inflammatory process that leads to cardiovascular disease, but also demonstrates that this process can be blocked by drugs now on the market."
"Inflammation is a very complicated phenomenon, but at least we now have a few more clues as to what it does and how the damage it produces can be prevented," he added.
Eating vegetables and fruit associated with reduced risk of pancreatic cancer
A report published in the September 2005 issue of the journal Cancer, Epidemiology, Biomarkers and Prevention (http://cebp.aacrjournals.org/) revealed the finding of researchers at the University of California, San Francisco (UCSF) that consuming a lot of vegetables and fruits is associated with half the chance of developing pancreatic cancer than that experienced by people whose intake is low. The study is one of the largest of its kind to date.
The research team analzyed the results of interviews with 532 patients with pancreatic cancer and 1,700 age and gender-matched control subjects. Participants in the study were queried concerning diet, smoking, and other factors.
When participants who consumed five or more servings per day of a group of protective vegetables or vegetables and fruits were compared to those who consumed two or fewer servings per day, they were found to have half the risk of pancreatic cancer. Consuming nine servings of vegetables and fruit per day was also associated with a 50 percent lower risk of pancreatic cancer compared to an intake of fewer than five servings.
Onions, garlic, beans, yellow vegetables, dark leafy vegetables and cruciferous vegetables (broccoli, cauliflower, Brussels sprouts) were vegetables associated with the greatest amount of protection against pancreatic cancer risk. Although eating fruit was associated with a lesser degree of risk reduction, citrus fruits offered more protection than other fruits.
Senior author and UCSF professor of epidemiology and biostatistics Elizabeth A. Holly, PhD, commented, "Pancreatic cancer is not nearly as common as breast or lung cancer, but its diagnosis and treatment are particularly difficult. Finding strong confirmation that simple life choices can provide significant protection from pancreatic cancer may be one of the most practical ways to reduce the incidence of this dreadful disease."
Age-standardized death rates lower
Ahmedin Jemal, DVM., PhD, and colleagues at the American Cancer Society in Atlanta analyzed American death rates for heart disease, stroke cancer, chronic obstructive pulmonary disease, accidents and diabetes. They found that the age-standardized death rate per 100,000 people per year decreased from 1,242 in 1970 to 845 in 2002. The stroke death rate fell by 63 percent, while that of heart disease and accidents were down 54 and 41 percent. Although the death rate from cancer climbed from 1970 to 1990, it was followed by a decrease between 1990 and 2002, resulting in a decline of only 2.7 percent. At the same time, the rate for chronic obstructive pulmonary disease doubled, and for diabetes it increased by 45 percent.
The authors note that "Several important insights are suggested by these temporal trends in the death rates and number of deaths at various ages. First, the decrease in the age-standardized death rate for 4 of the 6 leading causes of death in the United States represents progress toward one of the fundamental goals of disease prevention by extending the number of years of potentially healthy life. This progress has been greater for cardiovascular disease and for accidental deaths than for cancer, yet even for cancer the age-standardized death rate has been decreasing by 1.1 percent per year since 1993. Less favorable developments are the slowing of the decline in age-standardized mortality rates from stroke and accidents since the early 1990s, and the increase in death rates from COPD and diabetes."
Diets high in soy associated with reduced fracture risk
A study published in the September 12 2005 issue of the American Medical Association journal Archives of Internal Medicine http://archinte.ama-assn.org/ found that postmenopausal women whose dietary intake of soy was high experienced a lower risk of bone fracture than women whose intake was comparatively low.
Researchers at Vanderbilt University School of Medicine in Nashville utilized data from women who took part in the Shanghai Women's Health study, which included approximately 75,000 Chinese women aged 40 to 70. The current study analyzed dietary information provided at the beginning of the study and during the follow up from 24,403 postmenopausal participants whose age averaged 60 years.
There were 1,770 fractures reported during the four and one half year follow up period. The researchers, led by Xianglan Zhang, MD, MPH, determined that women whose soy intake was in the top one-fifth of the group at 13.27 grams or more per day had a 37 percent lower risk of fracture than those whose soy intake was in the lowest fifth, at less than 4.98 grams per day. When isoflavones from soy were separately analyzed, they were found to provide a similar protective benefit. For those whose intake of isoflavones was in the top fifth, there was a 35 percent reduced risk of fracture compared to the risk experienced by women whose intake was the lowest.
In their commentary, the authors write that soy isoflavones stimulate the production osteoprotegerin, which inhibits the activation of osteoclasts that break down bone. They conclude, "In this prospective cohort study of postmenopausal women, we found that soy food consumption was associated with a significantly lower risk of fracture, particularly among women in the early years following menopause. The potential impact of timing on the skeletal effects of soy needs to be further addressed in future studies."
Soy protein protects liver from diabetes-related condition
The September 2005 issue of the American Society for Biochemistry and Molecular Biology's Journal of Lipid Research (http://www.jlr.org/) published the findings of researchers at the Instituto Nacional de Ciencias Medicas y Nutricion in Mexico that a diet rich in soy protein helps protect against hepatic steatosis (fatty liver). Fatty liver disease is characterized by an increased production of fatty acids in the liver, which results in the accumulation of lipid filled compartments within the liver's cells. The condition is associated with the development of insulin resistance, and can result in liver enlargement and chronic liver disease. There is currently no treatment for this potentially fatal condition.
Acting on previous findings concerning soy's ability to help prevent insulin resistance and lower lipid production, Dr Nimbe Torres, who is a member of the Instituto's department of nutritional physiology, and colleagues fed soy protein diets to rats bred to develop diabetes and fatty liver. Although the rats developed their characteristic obesity and hyperinsulinemia, they failed to exhibit an accumulation of cholesterol and triglycerides in their livers after 160 days on the diet. Dr Torres explained, "We also observed that the effects of soy protein were due to a low expression of genes involved in the synthesis of fatty acids and triglycerides in the liver. These changes were due to a reduction in the transcription factors that control the expression of genes involved in lipid production."
Additionally, the team found that a transcription factor involved the genetic control of fatty acid breakdown was increased, which further lowers the amount of fatty acid in the liver.
Dr Torres believes that eating soy protein can help lower insulin resistance and its consequent damage to the liver and kidneys, although further research is recommended.
Pomegranate extract helps protect against arthritis
The September 2005 Journal of Nutrition (http://www.nutrition.org/) published the findings of Case Western Reserve University School of Medicine researchers that an extract derived from pomegranate fruit can block enzymes that contribute to osteoarthritis. The study is the first to show the ability of the fruit to slow cartilage deterioration.
Professor of medicine Tariq M Haqqi PhD and colleagues examined the effect of a pomegranate extract on interleukin-1b in arthritis-afflicted cartilage samples. Interleukin-1b is a protein that causes an overproduction of inflammatory molecules that include matrix metalloproteinases (MMP), enzymes that have been implicated in cartilage resorption.
The research team found that treating cartilage tissue samples with pomegranate extract prior to stimulating the cells with interleukin-1b prevented the expression of matrix metalloproteinases. The finding demonstrates that pomegranate may be able to protect cartilage in addition to its other recently discovered properties, such as its antioxidant benefits.
Dr Haqqui stated that "Arthritis is one of the foremost diseases for which patients seek herbal or traditional medicine treatments . . . Careful use of supplements and herbal medicines during early stages of disease or treatment may be made to limit the disease progression."
He added that pomegranate "has been revered through the ages for its medicinal properties. Studies in animal models of cancer suggest that pomegranate fruit extract consumption may be anticarcinogenic, whereas studies in mice and humans indicate that it may also have a potential therapeutic and chemopreventive adjuvant effect in cardiovascular disorders."
The authors conclude that in addition to helping to prevent osteoarthritis from worsening, pomegranate "may also be a useful nutritive supplement for maintaining joint integrity and function." Plans are being made to test pomegranate in an animal model of osteoarthritis and to find if the fruit is also effective against rheumatoid arthritis.
Olive oil compound acts like nonsteroidal anti-inflammatory drug
Acting on the observation that both extra-virgin olive oil and ibuprofen elicit a signature sting to the back of the throat, Gary Beauchamp, PhD of the Monell Chemical Senses Center in Philadelphia and colleagues discovered that an olive oil compound has the ibuprofen-like effect of inhibiting cyclo-oxygenase 1 (COX-1) and 2 enzymes. The research was summarized in a letter published in the September 1 2005 issue of Nature (http://www.nature.com).
The team evaluated a compound in extra-virgin olive oil that was believed to cause throat irritation and confirmed that the degree of irritation conferred by the oil was in direct proportion to the concentration of the compound, which they named oleocanthal. Similar to ibuprofen, oleocanthal was demonstrated to inhibit both COX-1 and COX-2, but it did not inhibit lipoxygenase, another enzyme involved in the inflammation pathways derived from arachidonic acid.
The authors write that their discovery "raise[s] the possibility that long-term consumption of oleocanthal may help to protect against some disease by virtue of its ibuprofen-like COX-inhibiting activity."
Coauthor Paul Breslin, PhD, also of Monell, commented, "The Mediterranean diet, of which olive oil is a central component, has long been associated with numerous health benefits, including decreased risk of stroke, heart disease, breast cancer, lung cancer, and some dementias. Similar benefits are associated with certain NSAIDs, such as aspirin and ibuprofen. Now that we know of oleocanthal's anti-inflammatory properties, it seems plausible that oleocanthal plays a causal role in the health benefits associated with diets where olive oil is the principal source of fat." He added, "This study is the first to make the case for pharmacological activity based on irritation and furthers the idea originally proposed decades ago by Fischer that a compound's orosensory qualities might reflect its pharmacological potency."