September 24, 2007

American Cancer Society journal finds strong evidence for diet and medication in prostate cancer prevention

A review published in the November 1, 2007 issue of the American Cancer Society journal Cancer concluded that specific medications and dietary approaches combined with a greater understanding of the molecular pathways involved in the disease may herald a new era in prostate cancer prevention.

University of Toronto researchers Dr Neil Fleshner and Dr Alexandre Zlotta reviewed the current medical literature in order to evaluate the progress in developing a preventive strategy for prostate cancer. They noted that the use of 5-alpha reductase inhibitors such as finasteride and dutasteride (which reduce the formation of dihydrotestosterone), as well as the selective estrogen receptor modifier toremifine may be of benefit to reduce the number of malignancies found upon biopsy of the prostate. Dutasteride has been shown to lower the number of cancers in men with benign prostatic hypertrophy, and a clinical trial is being held to determine whether the drug can prevent cancer in men with elevated prostate specific antigen levels and a history of negative prostate biopsies.

Additionally, adopting a low fat diet, and including such supplements as soy, selenium and green tea may be of value. Increasing selenium has been associated with a 49 percent reduction in the incidence of prostate cancer over a ten year period, and studies involving soy and vitamin D are currently underway. Vitamin E has also shown promise in prostate cancer prevention.

The authors of the review observe that although prostate cancer is usually slow growing, some studies suggest that prostate cells become malignant while men are in their twenties and thirties. “Unless we intervene with men in their early 20s, prevention in the context of prostate cancer refers to a slowing of the growth of existing prostate cancer cells so that they never harm the host,” the authors write.

—D Dye

September 21, 2007

Needle found in investigative haystack

An article published online on August 8, 2007 in the Proceedings of the National Academy of Sciences described research by Stephen Helfand and his colleagues at Brown University that decreasing the activity of a protein in just fourteen brain cells extends the lifespan of fruit flies by as much as 20 percent. The protein, p53, helps protect against the development of cancer, however reducing it has been shown to extend lifespan in fruit flies by up to 58 percent.

Dr Helfand, along with postdoctoral research fellow Johannes Bauer and associates, studied batches of flies modified to have reduced p53 activity in various small areas of their nervous systems. In each group, the flies survived their average lifespan of approximately two months. However, when a cluster of fourteen insulin-producing cells in the brains of one group of flies were altered to have lower p53 activity, the flies lived 15 to 20 percent longer than average.

No further extension of lifespan was observed when the fruit flies with altered p53 were placed on calorie restricted diets, leading the researchers to believe that p53 reduction within these brain cells is one of calorie restriction's effects.

“It’s quite surprising,” commented Dr Bauer. “In the fruit fly brain, there are tens of thousands of cells. But we found that it takes a reduction of p53 activity in only 14 of those brain cells to extend lifespan. It was like finding a needle in the haystack – a very small needle at that.” The insulin-producing cells modified in this study are the equivalent of human pancreatic beta cells. A decrease in p53 reduces insulin-responsive activity in the major metabolic organ of the fruit fly known as fat body. “Our findings suggest that lifespan regulation is linked to metabolic regulation,” Dr Helfand stated. “The findings also suggest a tight connection between aging and diabetes. And we may have a new laboratory model for studying diabetes and other metabolic diseases.”

—D Dye

September 19, 2007

High dose vitamin D found to be safe in recent study

A report appearing in the September, 2007 issue of the American Journal of Clinical Nutrition concluded that doses of up to 280,000 international units (IU) of vitamin D3 per week may be safe to administer to multiple sclerosis patients. Vitamin D has been found to be reduced in the blood of individuals suffering from the disease, and raising levels by administering the vitamin may prove to be beneficial.

Samantha M Kimball of the University of Toronto and her colleagues gave twelve men and women in the active stage of MS 1200 milligrams calcium per day and a weekly dose of vitamin D that was increased over six visits from 28,000 IU at the beginning of the study to 280,000 IU at the end of 28 weeks. Serum 25-hydroxyvitamin D, calcium, parathyroid hormone, liver enzymes and creatinine levels (which assess kidney function), as well as urinary calcium and creatinine were measured at the beginning of the study, at each patient visit , and three months after the end of the treatment period.

Although the participants' serum concentrations of 25-hydroxyvitamin D rose to double the top of the normal range by the end of the study , serum calcium levels and urinary calcium to creatinine did not increase or exceed reference values. Disease progression and activity did not appear to be affected by vitamin D treatment, yet the brain lesions that are characteristic of the disease were reduced from a mean of 1.75 per patient to 0.83.

"The widespread use of vitamin D supplements (1000 IU)/d) has been advised as a simple way to improve many aspects of public health," the authors conclude. "The present study provides an objective confirmation that the recent proposal by Hathcock et al is appropriate—ie, a upper limit of 250 micrograms/day (10 000 IU/d) for vitamin D intake can be justified."

—D Dye

September 17, 2007

Don't gamble with NAC

The September 15, 2007 issue of the journal Biological Psychiatry published the results of a pilot study conducted by Jon E. Grant, MD and colleagues at the University of Minnesota, Minneapolis that consuming the amino acid N-acetyl cysteine (NAC) reduces the urge to gamble in individuals with gambling addictions, and may help reduce other addictions.

Fifteen men and twelve women treated for pathological gambling as determined by the Yale Brown Obsessive Compulsive Scale Modified for Pathological Gambling (PG-YBOCS) were given increasing doses of N-acetyl cysteine for eight weeks. At the end of the treatment period, average test scores had improved, with 16 of the participants classified as responders to the therapy. While three of the responders did not wish to risk discontinuing NAC, 13 entered a double-blind phase of the research, in which one group of subjects received N-acetyl-cysteine and the remainder received a placebo for six weeks. Eighty-three percent of those who received NAC responded favorably, compared with only 28.6 of those assigned to the placebo.

N-acetyl cysteine's effect on glutamate, which is frequently associated in the brain with reward, is likely to be the amino acid's mechanism of action in helping to control addiction. Similar studies with NAC have found positive effects against drug addictions in animals.

“It looks very promising,” stated Dr Grant, who is an associate professor of psychiatry at the University of Minnesota School of Medicine. “We were able to reduce people’s urges to gamble.”

Dr Grant is currently investigating NAC in methamphetamine users. “This research could be encouraging for a lot of addictions,” he said.

—D Dye

September 14, 2007

Mediterranean diet improves survival of Alzheimer’s disease patients

The September 11, 2007, issue of the journal Neurology® published a report by Columbia University Medical Center researchers that described the positive survival benefit of a Mediterranean diet in men and women with Alzheimer's disease. The Mediterranean diet, which has been previously associated with a decreased risk of developing the disease, is characterized by a high intake of vegetables, legumes, fruits, cereals, fish, monounsaturated fatty acids; a mild to moderate amount of alcohol, and a reduced intake of saturated fatty acids, dairy products, poultry and meat.

For the current study, American Academy of Neurology member Nikos Scarmeas, MD and his associates followed 192 Alzheimer's disease patients every 1.5 years for a 4.4 year average, during which there were 85 deaths. The participants' food intake was scored for adherence to the Mediterranean diet on a 0 to 9 point scale.

Higher adherence scores were found to be associated with a lower risk of dying over the follow up period. Alzheimer's patients whose adherence to the diet was greatest were 76 percent less likely to die than those whose adherence was least. “The more closely people followed the Mediterranean diet, the more they reduced their mortality,” Dr Scarmeas observed. “For example, Alzheimer’s patients who adhered to the diet to a moderate degree lived an average 1.3 years longer than those people who least adhered to the diet. And those Alzheimer’s patients who followed the diet very religiously lived an average four years longer.”

“New benefits of this diet keep coming out,” he noted. “We need to do more research to determine whether eating a Mediterranean diet also helps Alzheimer’s patients have slower rates of cognitive decline, maintain their daily living skills, and have a better quality of life.”

"Adherence to the Mediterranean diet may affect not only risk for Alzheimer disease but also subsequent disease course," the authors conclude.

—D Dye

September 12, 2007

Study confirms lutein and zeaxanthin's link with macular degeneration risk reduction

A report published in the September, 2007 issue of the American Medical Association journal Archives of Ophthalmology added more evidence to previous research which found a protective effect for the carotenoids zeaxanthin and lutein against age-related macular degeneration. The disease occurs when the area at the back of the eye's retina known as the macula deteriorates, leading to visual impairment and blindness.

Members of the Age-Related Eye Disease Study (AREDS) Research Group evaluated the diets of 4,519 AREDS participants. The current analysis did not include participants younger than 60 years of age Retinal photographs were used to divide the subjects into five categories of macular disease severity, from individuals with little or no evidence of macular degeneration, who served as the control group, to severe, neovascular disease . Dietary questionnaires were analyzed for lutein, zeaxanthin, beta-carotene, lycopene, and other nutrient levels.

Participants whose intake of lutein and zeaxanthin were greatest had a significantly lower risk of age related macular degeneration than those whose intake was least, and were less likely to have large or numerous intermediate drusen, the deposits on the retina or optic nerve that characterize the disease. No risk reductions were associated with the other nutrients examined in this study.

“Lutein and zeaxanthin have the capacity to filter short-wavelength light associated both with photochemical damage and the generation of reactive oxygen species that attack cellular lipids, proteins and nuclear material; these carotenoids also have the capacity to reduce the potency of nascent reactive oxygen species,” the authors write. “If these cross-sectional results can be confirmed in prospective samples and experimental studies, lutein and zeaxanthin may be considered as useful agents in food or supplement-based interventions designed to reduce the risk of AMD,” they conclude.

—D Dye

September 10, 2007

Pregnant women deficient in vitamin D risk preeclampsia

A report published in the Journal of Clinical Endocrinology and Metabolism described the discovery of researchers at the University of Pittsburgh Schools of the Health Sciences that a deficiency of vitamin D during pregnancy is associated with five times the risk of preeclampsia as that experienced by nondeficient women. Preeclampsia is a complication of pregnancy characterized by hypertension and swelling of the extremities, and is the leading cause of maternal and fetal death.

University of Pittsburgh Graduate School of Public Health assistant professor of epidemiology Lisa M. Bodnar, PhD, MPH and her associates analyzed data from 1,198 women participating in the Pregnancy Exposures and Preeclampsia Prevention Study, a survey that sought to determine factors contributing to preeclampsia. 25-hydroxyvitamin D levels were measured in blood samples obtained before 22 weeks of pregnancy and prior to delivery, as well as in the newborns' umbilical cord blood.

“Low vitamin D early in pregnancy was associated with a five-fold increase in the odds of preeclampsia,” Dr. Bodnar stated. "Data showed this increase risk persisted even after adjusting for other known risk factors such as race, ethnicity and pre-pregnancy body weight. Also troubling was the fact that many of the women reported taking prenatal vitamins, which typically contain 200 to 400 International Units of vitamin D.”

“Even a small decline in vitamin D concentration more than doubled the risk of preeclampsia,” added senior author James M. Roberts, MD. “And since newborn’s vitamin D stores are completely reliant on vitamin D from the mother, low vitamin levels also were observed in the umbilical cord blood of newborns from mothers with preeclampsia.”

The authors conclude that "Vitamin D supplementation in early pregnancy should be explored as a safe and effective means of preventing preeclampsia and promoting neonatal well-being."

—D Dye

September 7, 2007

Meta-analysis finds high dose folic acid improves endothelial function

A meta-analysis of 14 randomized, double-blind placebo controlled trials conducted by researchers in the Netherlands found a dose-dependent benefit for folic acid supplementation in improved endothelial function. Endothelial function, measured by flow-mediated dilatation of the brachial artery, is an indicator of early cardiovascular disease risk when decreased. Folic acid, along with vitamin B6 and vitamin B12, lower homocysteine levels, which in turn reduces the risk of cardiovascular events. The analysis was published in the September, 2007 issue of the American Journal of Clinical Nutrition.

The fourteen studies that met the researchers criteria provided data on 732 subjects. Trials were conducted for a median of eight weeks. All studies measured percent change in brachial artery flow -mediated dilatation after a period of supplementation with folic acid compared with that following administration of a placebo.

Overall, folic acid was found to improve flow-mediated dilatation by 1.08 percentage points compared with participants that received a placebo. When dosage was analyzed, higher doses appeared more effective. Doses of 5,000 micrograms per day were associated with an improvement of 1.37 percentage points, and 10,000 micrograms per day was associated with an improvement of 2.65 percentage points over the placebo. Participants at greater risk of cardiovascular disease tended to have larger improvements.

Flow-mediated dilatation values indicate the bioavailability of endothelium derived nitric oxide, which may be reduced by elevated homocysteine. Folic acid's ability to lower homocysteine could be the reason for the improvement in flow mediated dilatation suggested by this study, however, a possible antioxidant benefit, as well as the vitamin's ability to directly stimulate or regenerate the cofactor for endothelial nitric oxide are other potential mechanisms.

The authors conclude "This study indicates that high doses of folic acid improve endothelial function, which could potentially reduce the risk of cardiovascular disease."

—D Dye

September 5, 2007

Avocados fight oral cancer

A report published online on May 17, 2007 in advance of publication in the journal Seminars in Cancer Biology described the finding of Steven M. D'Ambrosio and his associates at Ohio State University that phytochemicals extracted from the popular Haas avocado were able to destroy oral cancer cells as well as prevent precancerous cells from developing into cancer.

For the current research, Dr D'Ambrosio, who is a member of the molecular carcinogenesis and chemoprevention program at OSU's Comprehensive Cancer Center, collaborated with Haiming Ding of the department of radiology, Young-Won Chin of the College of Pharmacy, and A. Douglas Kinghorn, also of the Comprehensive Cancer Center. They determined that the avocado compounds target multiple signaling pathways and increase intracellular reactive oxygen in precancerous cells to trigger programmed cell death, while leaving healthy cells unharmed.

“As far as we know, this is the first study of avocados and oral cancer,” Dr D'Ambrosio stated. “We think these phytochemicals either stop the growth of precancerous cells in the body or they kill the precancerous cells without affecting normal cells. Our study focuses on oral cancer, but the findings might have implications for other types of cancer. These are preliminary findings, and more research is needed.”

In an editorial also published online in the journal, Dr D'Ambrosio noted, “The future is ripe for identifying fruits and vegetables and individual phytonutrients with cancer preventing activity. As we identify the molecular mechanisms and targets by which individual phytonutrients prevent cancer, we may be able to improve upon nature by formulating phytonutrient cocktails for specific cancers and individual susceptibility and risk.”

Dr Ding concluded, “These studies suggest that individual and a combination of phytochemicals from the avocado fruit may offer an advantageous dietary strategy in cancer prevention."

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