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August 2002

What's Hot Archive

August 30, 2002

Protein supplements maintain muscles

The National Space Biomedical Research Institute recently sponsored a study conducted at the University of Texas Medical Branch at Galveston to determine if consuming an amino acid supplement would decrease the muscle shrinkage, or atrophy, that occurs during space travel, or with bed confinement or immobility. Amino acids are the building blocks of protein and are necessary to grow and maintain muscle mass. Astronauts' lack of muscular activity is one of the main causes of muscular atrophy, but stress-induced cortisol elevation plays a role in the breakdown of muscle protein as well.


The study, led by Dr. Robert Wolfe, enrolled healthy subjects and consigned them to bed for 28 days. Participants were allowed to get up only for nearby bathroom visits and were required to eat and bathe from their beds. One group received an amino acid supplement three times per day, while a control group received a placebo drink.


The researchers compared protein synthesis and breakdown rates and muscle mass at the study's onset and conclusion. Protein synthesis and breakdown rates were determined by attaching a tracer to certain amino acids and measuring the amount that enter and exit the leg by testing blood samples.


Research team member, and professor of surgery at University of Texas Medical Branch, Dr Amy Ferrando, summarized, "When muscles are inactive, as they are in space, they don't make new proteins. If muscle breakdown rates are the same, that means you lose muscle . . . Early results suggest that the amino acid supplement is able to maintain synthesis rates and body mass. Muscle atrophy is common in many populations: the elderly, kids with burns, patients in intensive care or people who have had major operations. We're looking at this phenomenon in terms of space flight, but the study has many other implications."

August 28, 2002

Flavonoids lower chronic disease risk

Research published in the September 2002 issue of the American Journal of Clinical Nutrition has revealed an association between the intake of plant flavonoids such as quercetin and hesperetin, and the incidence of some chronic diseases. Bioflavonoids are found in plants, and have free radical scavenging and metal ion chelation properties. Antibacterial, antithrombotic, vasodilatory, antiinflammatory and anticarcinogenic properties are also associated with flavonoid compounds.

The Finnish researchers examined the total dietary intakes of 10,054 men and women who were interviewed concerning their food consumption. Study participants were asked to estimate amounts consumed of over one hundred food items during the year prior to the interview. Intake levels of the flavonoids quercetin, kaempferol, myricetin and hesperetin were calculated from this data.

During the twenty-eight year follow-up period, information on deaths and the development of diseases was obtained from government-provided data. The researchers examined in this study those chronic diseases associated with oxidative stress etiology.

Individuals with a higher flavonoid intake were found to have experienced lowered mortality rates. Quercetin was associated with lower mortality from ischemic heart disease, kaemperfol, naringenin and hesperetin with lower cerebrovascular disease risk; and quercetin, naringenin and hesperetin with a lower incidence of asthma. Greater quercetin and myricetin intakes were associated with a trend toward diabetes type 2 reduction. For men, an inverse relationship was observed between quercetin intake and lung cancer, and high myricetin intake with a lowered incidence of prostate cancer. No association between bioflavonoid intake and other cancers was determined.

These findings support the hypothesis that flavonones and flavonols help protect against several major chronic diseases. The researchers comment that although their "finding was independent of the intake of antioxidant vitamins, the potential importance of other biologically active compounds in fruit and vegetables . . . cannot be excluded." (Kneckt P, "Flavonoid intake and risk of chronic diseases, AJCN vol 76 no 3 560-568)

August 26, 2002

Early stage age-related macular degeneration may be slowed by lutein

The annual meeting of the Association for Research in Vision and Ophthalmology held in Florida this year featured a presentation by Dr Ian Murray of Department of Optometry and Neurosciences at the University of Manchester that provided the latest findings on the protective benefits of lutein against age-related macular degeneration (AMD), the leading cause of irreversible blindness in older individuals.

The macular pigment, located in a small portion of the retina of the eye, is composed of the plant pigments lutein and zeaxanthin. Lutein and zeaxanthin are found in spinach and other vegetables, and are also available as dietary supplements. Previous research findings have shown that individuals with low macular pigment density are at higher risk of developing age-related macular degeneration.

Dr Murray's team demonstrated that eight patients with early stage macular degeneration had lower pigment density than an age matched control group without signs of the disease. Six of these patients were recruited into a second study along with two others with early stage disease, and were administered a daily lutein supplement over an eighteen week period. Eight normal patients also received the supplement. Although the study has not been completed, at twelve weeks both groups showed an increase in macular pigment density. In the group with macular degeneration, both the effected and normal eye responded equally well. The researchers concluded that the presence of early stage AMD does not does not prevent lutein from being deposited in the retina, and that dietary intervention may help protect those with the condition or those at risk.

Dr Murray stated, "I have seen many patients who are suffering from the disabling effects of AMD. Of course we are excited by the prospect that a simple addition to the diet may impede the progress of the disease and prevent others who are at risk from experiencing such problems. Right now, dietary intervention is the only hope for most of them."

August 23, 2002

National Institutes of Health to sponsor tocotrienol study

The National Institute of Health's National Institutes of Neurological Disorders and Stroke has awarded over a million dollars in funding to a project which will investigate how alpha-tocotrienol helps to protect against brain cell death. Alpha, beta, delta and gamma tocotrienol are four of eight forms of vitamin E, the other four being the more commonly known tocopherols. Tocotrienols have been found to have stronger antioxidant properties than the tocopherols. The study, the first its kind funded by the National Institutes of Health, will utilize Tocomin brand alpha-tocotrienol derived from palm oil. Previous investigation of tocotrienols has revealed that the compounds cross the blood-brain barrier to protect brain cells, or neurons, against death due to stroke or other neurodegenerative conditions.

Vice chairman of surgery and director of the Laboratory of Molecular Medicine at The Ohio State University Medical Center, Professor Chandan K Sen, will head the current project. Dr Sen's earlier work found that alpha-tocotrienol prevented neuron death caused by glutamine, a major contributor to abnormal nervous system cell death. The current project will study alpha-tocotrienol's neuroprotective mechanism of action.

Dr Sen commented, "Eighty years after the discovery of vitamin E in 1922, it is long overdue to closely examine all naturally occurring forms of vitamin E side by side. Attention to the naturally occurring tocotrienols, especially to their neuroprotective properties, could well provide us with a powerful tool to combat neurodegeneration by safe dietary means."

August 21, 2002

Synthetic broccoli compound developed as cancer preventive

The 224th national meeting of the largest scientific society in the world, the American Chemical Society, was the site of the announcement of the synthesis of a compound that provides the cancer prevention benefits of sulforaphane, found in broccoli and other cruciferous vegetables, without its potential for toxicity in high doses. The compound, named oxomate, boosts phase II enzyme production, which detoxifies cancer-causing chemicals. It is also easier and less expensive than sulforaphane to produce.

Investigative team member and research assistant professor at the University of Illinois at Chicago, Jerry Kosmeder, PhD, stated, "It may be easier to take a cancer-prevention pill once a day rather than rely on massive quantities of fruits and vegetables. Oxomate would give you a definitive benefit; you'd know exactly how much you're getting everyday, its exact benefit and risk."

In tests conducted on cultured liver cells, oxomate had seven times less toxicity than sulforaphane. By removing certain chemical compounds from sulforaphane, the researchers were able to create a compound less toxic to healthy cells.

Dr Kosmeder reported that female rats exposed to carcinogens experienced a 50 percent reduction in breast tumors when fed oxomate compared to rats who did not receive it. He stated that oxomate could be combined with other nutrients and drugs that have a cancer preventive effect in order to maximize their benefits. He also noted that an oxomate drug would be effective whether a tumor was estrogen-dependent or nonestrogen-dependent. If further testing shows that oxomate is effective for cancers other than breast cancer, the compound may be able to help protect anyone who has been exposed to carcinogens and has an increased risk of developing cancer. However, Dr Kosmeder continues to urge people to consume healthy amounts of fruits and vegetables, and to reduce exposure to factors known to increase the risk of cancer.

August 19, 2002

High phytoestrogen intake linked with low aortic stiffness in women

It has been observed that the risk of cardiovascular events for premenopausal women is lower than that of men, but that the risk rises after menopause to make heart disease women's number one threat. In an article published in the August 2002 issue of Arteriosclerosis, Thrombosis and Vascular Biology, a journal of the American Heart Association, researchers from the Netherlands found that postmenopausal women who consume higher than usual amounts of phytoestrogens in their diets have less aortic stiffness, a sign of developing coronary heart disease. Phytoestrogens are naturally occurring compounds found in plants such as soy, that have a mild estrogenic effect when consumed in adequate quantities.

The investigators recruited 403 subjects from the PROSPECT study, which enrolled healthy women in the Netherlands aged 49 to 70, between 1993 and 1997. Upon enrollment in PROSPECT the women completed food-frequency questionnaires that estimated the intake of 178 food items during the previous year. For the current study, aortic stiffness was measured for each patient as well as blood pressure and heart rate, and blood samples were analyzed for various factors.

Participants' intake of total phytoestrogens, isoflavones and lignans were calculated, and the relationship between these levels and aortic stiffness determined. It was found that a high dietary intake of isoflavones was significantly associated with less aortic stiffness than those whose intake of isoflavones was in the lowest group. Increased intake of lignans was associated with decreased aortic stiffness as well. The results were more pronounced in older women who had been postmenopausal longer. The authors conclude, "the present study found that phytoestrogens may have a protective effect on the risk of atherosclerosis and arterial degeneration through an effect on arterial walls, especially among older women." (van der Schouw YT, et al, ATAVB, 2002;22:1316-1322)

August 16, 2002

Activity of enzyme associated with high HDL related to increase in antioxidant vitamins

In the journal Arteriosclerosis, Thrombosis and Vascular Biology's August 2002 issue (http://atvb.ahajournals.org/), researchers from the University of Washington and the Puget Sound Veterans Affairs Health Care Systems in Seattle, Washington, have found an association between vitamin C and E intake and the activity of paraoxonase (PON1), an enzyme associated with high density lipoprotein (HDL) that inhibits low density lipoprotein, or LDL, while also inhibiting the oxidation of beneficial HDL. The activity of PON1 is under genetic and environmental regulation, and studies have found that its activity is lower in individuals with myocardial infarction, carotid artery disease and coronary heart disease.

The participants were 189 white male veterans aged 48 to 88 with varying percentages of carotid stenosis or lower extremity vascular disease without carotid stenosis. The participants completed food frequency questionnaires which provided information concerning the frequency of intake of 131 foods as well as vitamin supplements, including multivitamins, vitamin C and vitamin E. Questionnaires were validated against two one-week long diet records compiled by the participants approximately six months apart. Smoking status and statin drug use were also ascertained.

The researchers determined that increased intakes of vitamins C or E were associated with an elevation of PON1 activity. Smoking was found to depress one of the two aspects of PON1 activity, that of hydrolysis of paraoxon, while statin drug used elevated the enzyme's activity. Additionally, variation in the PON1 gene is predictive of PON1 activity. In their discussion, the authors point out that "any reduction in oxidative stress related to vitamin C and E activity may preserve PON1 activity."

August 14, 2002

Birth defects associated with febrile illness decrease with multivitamin use

Illnesses accompanied by fever, such as influenza, are believed to be a risk factor for birth defects that develop during early pregnancy according to evidence provided by epidemiolgic and experimental studies. A report published in the July 2002 issue of the journal Epidemiology, showed that multivitamin use by pregnant women during the periconception period was linked with a lower risk of birth defects associated with febrile illness, compared to the risk experienced by nonusers with febrile illness. The Centers for Disease Control researchers analyzed data from 548 infants with birth defects obtained from the Atlanta Birth Defects Case-Control Study, conducted from 1982 to 1983. The study enrolled infants born from 1968 through 1980, and their parents. A control group utilized 1,540 infants without birth defects born during the same period.

Birth defects examined included neural tube defects, cleft lip, cleft palate, cardiac outflow tract defects, omphalocele, limb deficiencies and heart defects. Use of multivitamin supplements during the periconception period was defined as consistent supplement use from three months prior to conception through the third month of pregnancy.

The researchers found that the risk estimates for birth defects associated with febrile illness were increased in the group using no multivitamin supplements and lower in the supplement-taking group, suggesting that taking multivitamin supplements in the periconception period might decrease febrile-illness associated risk. The authors speculate that vitamins may act antagonistically on vascular disruption and apoptosis caused by hyperthermia injury, and note that depletion of folate can increase cell apoptosis. However, they add that febrile illness and multivitamins likely affect multiple developmental processes.

August 12, 2002

Low potassium linked with stroke increase

The August 13 2002 issue of the journal Neurology, published the results of an observational study of 5600 men and women aged sixty-five and older that found those with the lowest levels of dietary potassium (less than 2.4 grams per day) were one and a half times more likely to experience a stroke than those with the highest amounts (over four grams per day). The participants were part of the Cardiovascular Health Study, which enrolled 5,888 people from four U.S. communities. Subjects had no history of stroke at the study's onset, and type and number of strokes experienced were tracked for a four to eight year follow-up period.

The study also examined diuretic use, which can deplete the body's potassium levels. It was found that individuals taking diuretic drugs who had the lowest levels of serum potassium had two and one half times the risk of stroke than diuretic users with the highest levels. Among diuretic users with atrial fibrillation, a type of heart arrhythmia that increases stroke risk, those with low serum potassium had ten times the stroke risk of diuretic users with high potassium who did not have atrial fibrillation.

These data, however, do not implicate diuretic use in elevated stroke risk. Study author and neurologist Deborah M. Green, MD, of the Neuroscience Institute at The Queen's Medical Center in Honolulu, Hawaii, explained, "Diuretics clearly help prevent stroke by controlling high blood pressure, but we wanted to see whether their effect on potassium levels would affect the risk of stroke . . . The question is whether diuretics would be even more effective with adequate potassium intake."

Further research is recommended to confirm whether consuming more potassium can aid in the prevention of this devastating condition.

August 09, 2002

Government sponsored trial for chelation therapy planned

The National Institutes of Health's National Center for Complementary and Alternative Medicine (NCCAM) and the National Heart, Lung, and Blood Institute have initiated the first large-scale clinical trial of EDTA chelation therapy for coronary artery disease. The trial will last for five years and will determine efficacy and safety. The Trial to Assess Chelation Therapy will enroll 2,372 participants age fifty or over with a history of heart attack, at one hundred U.S. research sites. Patients will be randomized into groups receiving intravenous EDTA or a placebo solution. In addition, each group will be divided to receive either high dose or low dose vitamin and mineral supplementation. Nutritional supplementation is routinely provided with chelation therapy by the practitioners who administer the treatment.

Participants will receive weekly treatments with the intravenous solutions for thirty weeks, followed by every-other-week treatments. Patients will be followed until the trial's end, and benefits, side effects, coronary events or symptoms noted.

EDTA (ethylene diamine tetra-acetic acid), is given to patients intravenously to remove elements such as lead, iron, copper, and calcium from the blood by a process known as chelation. Although it is approved by the FDA for treating toxicity from heavy metals, it has not yet been approved to treat coronary artery disease, even though it is used by some practitioners for this purpose.

National Heart, Lung and Blood Institute Director Claude Lenfant, MD, stated "NCCAM's leadership in initiating and supporting this study is to be commended. It is important for heart disease patients to know whether we should add chelation therapy to the list of proven treatments for coronary artery disease. Scientific evidence is needed to resolve this issue. And only a large clinical trial can definitively answer the question of whether chelation treatment is truly safe and effective."

August 07, 2002

Green tea inhibits angiogenesis factor in breast cancer cells

The August 2002 Journal of Nutrition (www.nutrition.org) reported that the major angiogenic factor, known as vascular endothelial growth factor (VEGF), was inhibited in a dose dependent fashion by an extract of green tea as well as by its main catechin, EGCG. Angiogenesis refers to the formation of new blood vessels, a process that occurs in healthy tissue but which is also used by tumors to fuel their growth. Inhibition of angiogenesis is currently being explored by cancer researchers as a method of halting tumor growth by starving the tumor nutrients that are delivered via its blood supply.

The green tea extract and EGCG were tested on cultures of healthy human umbilical vein cells and human breast cancer cells. Both extracts were found to significantly decrease the levels of VEGF when the cells of either culture were exposed to a VEGF promoter, compared to cell cultures that did not receive the extract. The green tea extract and the EGCG did not differ significantly in their effects on the cells. In the breast cancer cells, increasing the concentration of green tea extract decreased VEGF secretion. Further experiments by the researchers revealed that the green tea extracts acted on a molecular level to inhibit VEGF transcription, although the authors noted that the inhibition of breast cancer angiogenesis by green tea probably involves several other pathways, through its inhibition of other angiogenic molecules.

The researchers write that a shortcoming with most antiangiogenic drugs is that they require longterm subcutaneous or intravenous administration. They are also difficult and expensive to produce, rendering green tea a useful alternative, if further research confirms its value in this area.

August 02, 2002

Linoleic acid helps prevent stroke

The August 2002 issue of Stroke: Journal of the American Heart Association, published a study showing that linoleic acid, the essential fatty acid found in soy, corn, sunflower oil, safflower, appears to exert a protective effect against all forms of stroke. Japanese researchers analyzed blood samples for linoleic acid levels, obtained from 7,450 men and women in Japan who had participated in cardiovascular risk surveys between 1984 and 1993. The participants, whose ages ranged from 40 to 85 years, consumed 9.5 to 13.3 grams linoleic acid per day, and experienced 122 ischemic and 75 hemorrhagic strokes. Analysis of the data revealed that a 5% increase in linoleic acid consumption was associated with a 28% reduction in the risk of having any type of stroke. Analysis by type of stroke uncovered a 19 percent reduction in hemorrhagic stroke, a 34 percent reduction in ischemic stroke, and a 37% reduction in lacunar infarction, which involve the small arteries that supply the deepest parts of the brain.

Lead author Hiroyasu Iso, M.D. Ph.D., M.P.H., professor, Department of Public Health Medicine, Institute of Community Medicine, University of Tsukuba, Ibaraki-ken, Japan, stated, "When we adjusted for other fatty acids, these associations become weak, but the association between linoleic acid and the (ischemic) stroke risk persisted."

The authors think that linoleic acid may reduce ischemic stroke risk because of its ability to lower blood pressure, decrease platelet aggregation, and improve microcirculation. They note the necessity of a clinical trial to confirm a causal relationship between linoleic acid consumption and ischemic stroke risk.

 

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