Soy consumption associated with lower endometrial cancer risk
Consumption of soy appears to be protective against breast and prostate cancer, and now Chinese researchers have uncovered a positive association between soy intake and the risk of endometrial cancer (cancer of the uterine lining). Asian countries consume high levels of soy foods and have a lower incidence of these reproductive cancers. The average rate of endometrial cancer is China is one-fifth to one-third of that of western countries.
In a study published in the May 29 2004 issue of the British Medical Journal, 832 Chinese women with endometrial cancer diagnosed between 1997 and 2001 were compared to 846 healthy controls. Food frequency questionnaires provided information on soy and soy components such as isoflavones over a five year period.
They found a dose-response inverse relationship between regular consumption of soy foods and the risk of developing endometrial cancer. Women in the highest one-fourth of soy consumption experienced a 33 percent lower risk of developing endometrial cancer than women in the highest group. The association was particularly strong among women who were overweight.
Soy isoflavones have both weak estrogenic and antiestrogenic effects and appear to offer protection against some hormonally driven cancers. The researchers believe that the effect of soy on endometrial cancer was probably underestimated in this study.
Green tea catechin may prevent life-threatening cardiac arrhythmias
A study presented at the Heart Rhythm Society's 25th Annual Scientific Sessions, held in San Francisco May 19-22, 2004, found that the epigallocatechin-3-gallate (EGCG) could help prevent the dangerous alterations in heart rhythms known as ventricular arrhythmias, that can follow a heart attack. Ventricular arrhythmias include ventricular tachycardia and ventricular fibrillation, which are commonly associated with heart attacks or with the scarring of the heart muscle that occurred during the event.
Tea drinkers have been known to have a lower rate of death following a heart attack than those who do not drink tea. A team from the University of Heidelberg, in Heidelberg, Germany, sought to find out why.
By studying frog egg cells, the researchers found that EGCG inhibited HERG potassium channels, which are involved in cardiac repolarization . The HERG potassium channel is present in Long QT syndrome, a cardiac electrical disorder that can be inherited or caused by taking certain medications. Individuals with the disorder are susceptible to ventricular fibrillation. HERG potassium channels are also overexpressed in extracardiac tumors.
Heart Rhythm Society president said Michael E. Cain, MD, commented, "This is an interesting development in the battle against these serious and life-threatening disorders. While this is a preventive action that may be beneficial, it is important to continue with your current medications and health regimen."
New findings on resveratrol's mechanism against cancer
In research funded in part by the National Cancer Institute, scientists at the University of Virginia Health System have uncovered more information on how resveratrol works to combat cancer. University of Virginia assistant professor of biochemistry and molecular genetics, Marty Mayo and colleagues found that resveratrol inhibits nuclear factor-kappa B (NF- kB ) found in cell nuclei, which activates genes that control cell survival. Resveratrol is an antioxidant compound found in grapes and other plants, which has been found to have anticancer, and perhaps, antiaging effects. The report was published on May 20 2004 in the online edition of the Journal of the European Molecular Biology Organization (http://embojournal.npgjournals.com).
When the research team administered resveratrol to cancer cells, the cells became sensitive to tumor necrosis factor alpha ( TNFa ) through a loss of nuclear factor-kappa B gene expression, which induced apoptosis (programmed cell death). Dr Mayo stated, “We used physiologically-relevant doses of resveratrol and found dramatic effects on human cancer cells. Researchers are always looking for ways to improve cancer therapy. Current studies are using compounds similar to TNFa in conjunction with resveratrol to kill cancer cells.”
Dr Mayo stated that the amount of resveratrol consumed by drinking a glass of wine three to four times per week is enough to block NF- kB from encouraging cancer growth, but drinking greater amounts of alcohol could arrest the effect and lead to a higher cancer risk.
Nuclear factor-kappa B, which can control inflammatory responses, may be involved in other disorders that have been found to be combated by resveratrol , such as atherosclerosis, heart disease, arthritis, and autoimmune disorders. Clinical trials using combining reseveratrol with TNFa -like compounds are showing encouraging results.
Green tea blocks the formation of new arterial plaque
The May 25 2004 issue of the American Heart Association journal Circulation presented the results of research which revealed that green tea prevents the formation of new plaque in the arteries but does not remove pre-existing plaque.
A team at Cedars-Sinai Medical Center Atherosclerosis Research Center fed a high cholesterol diet to mice bred to rapidly develop atherosclerotic plaque. Injury to the right carotid artery was carried out at twenty-eight weeks of age to induce the formation of new plaque so that the researchers could examine the effect of a purified form of the green tea catechin epigallocatechin-3-gallate (EGCG) on both new and established plaque. The compound was injected five days per week following arterial injury, and the arteries of mice who received EGCG as well as control groups who did not receive the compound were examined after three, twenty-one and forty-two days.
Mice treated with EGCG were found to have significantly reduced new plaque formation at the injury site compared to the control mice, but there was no benefit for the compound on established plaque. Lead author Kuang-Yuh Chyu , MD, PhD, of UCLA, explained, "Most animal experiments evaluating the effects of antioxidants are started when the animals are young, while randomized clinical trials typically enroll adult patients with varying stages of plaques. This discrepancy supports speculation that antioxidant treatment affects early but not later stages of plaque development. EGCG treatment was started late, when atherosclerotic lesions in the aortic sinus were already at an advanced stage. Our observations that EGCG reduced the progression of evolving carotid plaques but had no effect on the mature plaques in the aorta reinforce the theory that intervention is effective in early but not late stages of atherosclerotic development. It appears that antioxidant therapy would have therapeutic benefits only if initiated during a critical window very early in the formation of plaque."
Nonanemic women with tissue iron deficiency benefit from supplements
Anemia is condition defined by a reduced number of red blood cells or hemoglobin, which can occur in individuals who are iron deficient. In a study published in the March 2004 issue of the American Journal of Clinical Nutrition, Cornell University nutritionists have shown for the first time that women who have low body iron but do not have anemia benefit from iron supplements only when tissue iron, as opposed to liver iron stores are low. Up to twelve percent of women in the U.S. have iron deficiency without anemia. When individuals become iron-deficient they initially deplete liver iron stores before becoming anemic due to the consequent inability to produce new red blood cells.
Previous research conducted by the Cornell researchers demonstrated that mild iron deficiency reduces endurance and that supplementation with iron improves exercise training. In the current double blind trial, they assigned forty-one iron-depleted, nonanemic women to receive either 100 mg ferrous sulfate or a placebo for 6 six weeks. Tissue iron status was measured by a test called serum transferrin receptor concentration. During the last four weeks of the study, participants trained on cycle ergometers for five days per week. Endurance capacity was tested at the beginning and end of the study period.
At the study's conclusion, only women with low tissue iron who did not take iron supplements failed to experience improved endurance.
First author and Cornell doctoral candidate in nutritional sciences. Thomas Brownlie, suggested, "It would be useful for women who test low for iron but who are not yet anemic to have this test. Women found to be tissue-iron deficient will find exercise exceedingly difficult without improving their iron status -- which could be achieved by increasing consumption of iron-rich foods or iron supplementation."
Mechanism found for green tea's anticancer effect in Barrett's associated esophageal adenocarcinoma
A study presented at the Digestive Disease Week convention, held in New Orleans May 15-20, 2004, has found a mechanism for green tea in inhibiting esophageal cancer associated with Barrett's esophagus. Barrett's esophagus is a precancerous condition which results from chronic irritation of the esophagus that occurs with gastroesophageal reflux disorder. Tea drinking has been linked with a lower risk of several cancers of the gastrointestinal tract, and the esophagus may be exposed to high levels of green tea polyphenols, such as epigallocatechin gallate (EGCG), when green tea is consumed.
Howard Y Chang, MD and colleagues at Harvard Medical School and the Veterans Administration Boston Healthcare System administered varying concentrations of EGCG to cultured human Barrett's esophagus-associated adenocarcinoma cells and compared them to untreated cells. They found that cell growth was inhibited in a dose dependent manner within 72 hours of exposure to EGCG. The team concluded that EGCG induces the programmed cell death known as apoptosis, which occurred as early as 24 hours in the cells exposed to the compound. Further research found an elevation of caspase 3 (an enzyme involved in apoptosis) in the treated cells compared to untreated cells, as well as increased cleaved PARP protein levels, another indicator of apoptosis.
Dr Chang summarized, "Research suggests that drinking green tea may be both a valuable chemopreventive therapy as well as a treatment for esophageal adenocarcinoma. Our results suggest that extracts in green tea may help to lower the prevalence of esophageal adenocarcinoma, one of the fastest growing cancers in western countries."
Vitamin supplements lower diabetic retinopathy risk
In research published in the may 2004 issue of the American Journal of Clinical Nutrition ( http://www.ajcn.org/ ), the use of vitamin C and E supplements was found to be associated with a lower risk of diabetic retinopathy, yet vitamin C and E from food alone or food and supplements combined was not found to be preventive.
The study examined participants in the Atherosclerosis Risk in Communities Study, which enrolled 15,792 men and women in 1987 and which sought to investigate the etiology of atherosclerosis. The current study examined data from 1,353 subjects with type 2 diabetes diagnosed from 1993 to 1995 or earlier. Food frequency questionnaires administered from 1987 to 1989 and 1993 to 1995 provided information on nutrient intake, including supplement use. Fundus photographs taken between 1993 and 1995 revealed the development of diabetic retinopathy in 224 individuals.
Analysis of the data revealed no association of retinopathy with vitamins C and E from food alone or from food and supplements, but a decreased risk was found among those who reported long term vitamin C or E or multinutrient supplement use. Compared to those who did not report supplement use, long term supplement users experienced a two fold reduction in the risk of developing diabetic retinopathy.
The authors comment that the large body of evidence from in vitro investigations, animals studies, and short term trials of supplementation suggest that vitamin C and E may help prevent retinopathy, but epidemiologic data have not found a protective effect of dietary micronutrient intake against the condition. They note the protective effect associated with vitamin C and vitamin E in supplement form that emerged in this study, which warrants further investigation.
Homocysteine levels linked to fracture risk
Two studies published in the May 13 2004 issue of the New England Journal of Medicine ( http://content.nejm.org/ ) have established a link between homocysteine and osteoporotic fracture. However, in an accompanying editorial, Lawrence G Raisz MD asks whether homocysteine is a culprit in the disease or a bystander.
In a study conducted by researchers in the Netherlands, two population-based studies (the Rotterdam Study and the Longitudinal Aging Study Amsterdam) were analyzed that included a total of 2,406 men and women aged 55 and older. During the studies follow-up periods, 191 osteoporotic fractures occurred among the participants. The team found that participants whose homocysteine levels were in the top fourth had a risk of nonvertebral osteoporotic fractures that was double that of those whose homocysteine levels were in the lower three-fourths.
In another study, Boston researchers analyzed data obtained from the Framingham study, which was begun in 1948 to evaluate risk factors for heart disease. The current study examined 1174 women and 825 men, aged 59 to 91. Frozen blood samples obtained between 1979 and 1982 were analyzed for total homocysteine levels. During the follow-up period, the female participants experienced 146 hip fractures and 41 occurred among the men. Women in the highest one-fourth of total homocysteine were found to have nearly twice the risk of hip fracture than those in the lowest fourth, and for men in the top fourth the risk was nearly four times as high.
Although it is not yet known whether having elevated homocysteine contributes to the development of osteoporosis or merely reflects other factors that play a role in the disease, such as estrogen deficiency or poor nutrition, what is clear is that elevated homocysteine can now be added to the list of risk factors for fractures, which will improve the ability of health care providers to predict the possibility of their occurrence.
Depression associated with increased CRP levels in men
The results of an investigation published in the May 10 2004 issue of the AMA journal Archives of Internal Medicine ( http://archinte.ama-assn.org/ ) found a strong link between elevations of the marker of inflammation known as C-reactive protein (CRP) and depression in men. The authors of the report, Daniel E Ford MD and Thomas P Erlinger MD of Johns Hopkins University, believe the finding may explain the greater cardiovascular disease risk observed among men with depression.
Doctors Ford and Erlinger examined data obtained from 3,154 men and 3,760 women who participated in the Third National Health and Nutrition Examination Survey (NHANES III). NHANES III was a survey of Americans conducted between 1988 and 1994 by the Centers for Disease Control. Blood samples provided C-reactive protein and other measurements, and the Diagnostic Interview Schedule was used to evaluate depression.
Lifetime major depression was present in 5.7 percent of the men and 11.7 percent of the women. There were no associations found between lifetime depression and body mass index, cholesterol or blood pressure. Elevated CRP levels, defined as greater than 0.21 milligrams per deciliter, were found in 13.7 percent of the men and 27.3 percent of the women. Men who reported severe depression during the previous year had three times the risk of elevated CRP than those who had no depression. Men who had recurrent episodes of major depression had an even greater risk of elevated CRP. These associations were not found in women, despite higher levels of both CRP and depression.
Speculating on the reason for these findings, the authors hypothesized that CRP levels might vary by the hormonal environment. They conclude, “While it is unlikely that inflammation is the only mechanism by which depression might increase risk for cardiovascular disease, future studies need to evaluate this possibility.”
Chromium plus B vitamin lower coronary risk factors
On May 6 2004, at the American Heart Association's Annual Conference on Arteriosclerosis, Thrombosis & Vascular Biology, Jeffrey Geohas MD presented the findings of a study that found that a combination of chromium picolinate and biotin (marketed under the name of Diachrome tm) improved coronary risk factors in type 2 diabetics. In the double-blind study, twenty-four individuals who had been diabetic for at least one year received 600 micrograms chromium picolinate plus 2 milligrams biotin per day or a placebo for thirty days. Participants had been using antidiabetic medications for over six months but had poorly controlled blood sugar levels. Fasting blood glucose, total, HDL and LDL cholesterol, and apolipoprotein A and B were measured before and after the treatment period.
At the study's conclusion, total cholesterol was reduced by an average of 19.1 milligrams per deciliter, LDL cholesterol was lowered by an average of 10.9 milligrams per deciliter and apolipoprotein-B was lowered by 5.3 milligrams per deciliter, while all of these lipids increased in those who received the placebo. Fasting blood glucose was reduced by an average of 26.2 milligrams per deciliter in 71 percent of the group who received chromium and biotin, while 27 percent of the placebo group experienced a decrease in blood sugar. The ratio of apolipoprotein B to apolipoprotein A and LDL to HDL cholesterol improved in the treated group, but not in the placebo group.
Dr Geohas, who is the medical director of Radiant Research in Chicago, stated, “This study emphasizes that Diachrome not only improves blood sugar levels, but decreases LDL cholesterol which will help people with diabetes meet the ATP III guidelines which is difficult for them to achieve. Diachrome should be considered as an important adjunct therapy to statins and diet in lowering LDL cholesterol.
Dietary fiber intake inversely associated with CRP levels
A report published in the May 2004 Journal of Nutrition revealed findings from the National Health and Nutrition Examination Survey (NHANES) that a higher intake of fiber is associated with lower concentrations of the inflammatory marker C-reactive protein (CRP). Elevated levels of C-reactive protein have been found to be a possible predictor of cardiovascular events in humans.
Analysis of NHANES data by Investigators from the Centers for Disease Control in Atlanta provided health and dietary information from which total fiber intake was calculated, and blood samples obtained from participants provided measurements of C-reactive protein. A total of 3,920 NHANES participants were included in the current analysis. Participants' CRP levels ranged from 0.1 to 140 milligrams per liter. The odds for having a high level of CRP (greater than 3.0 milligrams per liter) were reduced by almost 40 percent for those in the top fifth of dietary fiber intake compared with those in the lowest fifth. As fiber levels increased, a trend for decreasing levels of CRP was revealed. Adjusted analysis only slightly modified these results.
Increased fiber intake has been previously correlated with decreased cardiovascular disease risk. Reduction of cholesterol, blood pressure, and body weight, as well as normalization of glucose and insulin have been proposed as mechanisms of action, but the role of fiber in inflammation has not been defined. One possible way that fiber may reduce inflammation may be by lowering lipid oxidation which could decrease inflammation. The authors conclude that, “Consistent with current dietary recommendation from the AHA and the American Dietetic Association, greater consumption of dietary fiber should be recommended.”
Anemia associated with increased disability in older people
The May 2004 issue of the Journal of the American Geriatrics Society published the findings of researchers from Wake Forest University Baptist Medical Center that older individuals with anemia have more disabilities, poorer physical performance and less strength than those without the condition. Anemia is a reduction in red blood cells or hemoglobin that can be caused by a deficiency of iron or vitamin B12, and can also be due to liver disease or cancer.
In the current study, Brenda Penninx PhD and colleagues examined data obtained from the InCHIANTI study of 1,156 individuals age sixty-five and older residing in the Chianti area of Italy. Physical performance tests assessed balance, walking speed and ability to rise from a chair, and handgrip and knee extension tests assessed strength. Participants' responses to whether they needed assistance with any of six activities of daily living and eight other activities were used to evaluate disability.
Subjects who had low hemoglobin had test scores that showed reduced strength and physical performance compared to nonanemic participants. Previous research had found that poor scores on these tests predicted hospitalization, disability nursing home admission and mortality. The anemic participants also had a greater need for assistance in activities of daily living and other activities, indicating a higher level of disability.
Dr Penninx, currently of Vrije University in the Netherlands, discussed the findings: "Our results suggest that anemia is a risk factor for disability, poor physical function and low muscle strength – all which can threaten the independence of older adults. Physicians should be aware of their older patients' anemia status, even if there is no apparent disease. Our research suggests that anemia deserves more attention. We need to learn whether treatment can help restore physical function or prevent a physical decline."
Uncontrolled epilepsy linked to low omega-3 fatty acid level
The American Academy of Neurology's 56th Annual Meeting was the site of a presentation on April 28 of findings from researchers at Emory University that the omega-3 fatty acid docosahexaenoic acid (DHA) is abnormally low in individuals with uncontrolled epilepsy. DHA is essential for nervous system development in infants and for the proper brain cell membrane development and function in adults. Because the body cannot produce sufficient amounts of DHA, it must be consumed by eating foods such as fatty fish, or by taking supplements.
The researchers compared 57 healthy people with 41 individuals with a type of seizure that is resistant to antiepileptic medication. Analysis of blood samples revealed that the mean red blood cell membrane DHA level of the epileptic patients was 2.74 percent compared to 3.46 percent in the healthy group. Previous research has correlated DHA levels in red blood cell membranes with those of cerebral neuron membranes.
Associate professor of neurology at Emory University School of Medicine and director of the Emory Epilepsy Center, Thomas R. Henry, MD, explained, “We looked at prior studies of animal models of rats with epilepsy and low levels of DHA. By giving these rats more DHA, it made it more difficult for them to have seizures. We are now exploring a similar connection of low DHA levels in humans who have epilepsy."
Dr Henry added, "By determining a deficiency in the red blood cell membranes in these patients, we infer that brain cell membranes are also depleted of this normal fatty acid. This may help us link low DHA to seizures which cannot be managed by antiepileptic medications. Reasons for the reduced membrane levels are unclear at this time. Future studies are needed to determine if DHA supplementation can help control seizures in this patient population."