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What's Hot

December 2001

What's Hot Archive


December 21, 2001

Lycopene prevents DNA damage in prostate cancer patients

Because the accumulation of oxidative DNA damage to the prostate may play a role in the development cancer in this gland, the antioxidant action of lycopene, a carotenoid found in high levels in tomatoes, may help prevent it.

The December 19 2001 issue of the Journal of the National Cancer Institute featured a study conducted at the University of Illinois at Chicago which provided further evidence of lycopene's benefit in prostate cancer. Lycopene intake has been associated with a lower incidence of the disease. In this study, thirty-two patients with localized cancer of the prostate who were scheduled for prostatectomies were given one tomato sauce-based food daily for three weeks, providing them with a total of 30 milligrams lycopene per day from three-fourth's cup sauce. Prior to and following the study, the participants serum and prostate lycopene levels, PSA and leukocyte DNA oxidative damage were assessed. After three weeks, and following the scheduled prostatectomies, serum and prostate concentrations of lycopene were found to have increased while leukocyte oxidative DNA damage was signficantly reduced to levels 21.3% lower than pretrial levels. Additionally, DNA damage to the prostate gland was found to be 28.3% lower than that of a randomly selected group of post-prostatectomy patients. Serum PSA levels that averaged 10.9 nanograms per milliliter declined to 8.7 nanograms per milliliter, a drop of 17.5%, at the conclusion of the study.

A clinical trial is now ongoing which is testing lycopene's ability to lower PSA against a placebo, and the researchers note that the findings in the current study warrant futher testing with a larger group of patients.

December 19, 2001

CLA helps prevent cancer through apoptosis

A study published in the November 2001 issue of British Journal of Nutrition revealed that conjugated linoleic acid, or CLA, induced programmed cell death, known as apoptosis, in the colon walls of rats who were fed carcinogens. The researchers, from Seoul and Chinju, Korea, state that this may be why CLA has demonstrated anticancer properties in several studies.

In one experiement, colon cancer was induced in six week old rats by injecting them with the carcinogen DMH. The rats were fed a diet containing 1% CLA, or a control ad libitum diet for thirty weeks. The group receiving CLA experienced a significantly decreased incidence of colon tumors. In order to determine whether apoptosis in the colon mucosa of the carcinogen treated rats was affected by the amount CLA consumed, the researchers conducted another experiment in which rats injected with DMH received a diet containing 0.5%, 1%, 1.5% or no CLA. No differences in food intake or growth characteristics between the animals were observed. The colon mucosa of the rats was examined after fourteen weeks. While animals who did not receive CLA had none of the substance detected in the colon mucosa, in the animals fed the 0.5% CLA diet, CLA detection in the mucosa corresponded with a rise in the apoptotic index and a decline in 1,2-diacylglycerol. The rats receiving 1.0% and 1.5% CLA experienced an increase in apoptotic index equal to the 0.5% CLA group, while mucosal levels of prostaglandin E2, thormboxane B2 and arachidonic acid, which are involved in the development of colon cancer, all decreased dose-dependently. The authors conclude that the increased apoptosis induced by CLA may be attributable to changes in arachidonic acid metabolism.

December 17, 2001

Fish oil supplements may cut breast cancer risk

In research conducted at the University of California Los Angeles Jonsson Comprehensive Cancer Center, a team has discovered that a three month low omega-6 fat diet containing soy products, fish oil capsules and vegetables can change the ratio of omega-3 to omega-6 polyunsaturated fatty acids in women's breast tissue to that of countries with low breast cancer rates. Studies have shown that omega-3 polyunsaturated fatty acids are metabolized into prostaglandins that can inhibit cancer growth, whereas omega-6 polyunsaturated fatty acids can metabolize into other types of prostaglandins that promote the growth of cancer. Omega-6 polyunsaturated fatty acids are found in vegetable oils, shortening or other foods containing corn oil. An analysis of the study has shown that the fish oil component of the diet, with its high omega-3 fatty acid content, is responsible for the change in breast tissue composition.

Although an association between fat intake and breast cancer has long been observed, some studies have failed to confirm the relationship. Nutritionist and study colleague Dr Dilprit Bagga, speculating that the range of rat intake examined has been too narrow, commented, "If we looked at a population in the U.S. with a fat intake as low as the Japanese have, then maybe we would see a difference."

The Japanese typically consume less than half the amount of fat found in the diet of most Americans.

Research team leader and UCLA Oncology Center Director, Dr John Glaspy summarized, "My colleagues and I have shown that at least one aspect of human breast composition in American women can be altered to approximate the breast composition of women in certain Asian and European countries. In those countries, the incidence of breast cancer is much lower than it is here."

December 14, 2001

Saw palmetto shown to alleviate urinary symptoms in men

In a six month long study published in the December 2001 issue of the journal Urology, researchers from University of Chicago and the Dekalb Clinic in Dekalb, Illinois, demonstrated that the herb serenoa repens, or saw palmetto, was able to reduce lower urinary tract symptoms in men complaining of urinary retention. Although there have been several smaller trials confirming saw palmetto's ability to improve urinary symptoms, some members of the medical community had remained unconvinced.

Ninety-four men who experienced urinary retention, frequently caused by interference from an enlarged prostate gland, were enrolled in the trial. All participants received a placebo twice per day for the first month, after which any subjects reporting improvement were removed from participation. Eighty-five remaining participants were then randomized to receive either saw palmetto or a placebo for the remainder of the trial. At this time, and at two, four and six months, the men completed questionnaires concerning their urinary symptoms, sexual function and quality of life, and urinary flow rates were measured.

At six months, the group receiving saw palmeto reported a signficiant improvement in their urinary symptom score compared to the placebo group, although there were no differences in other measurements.

Study director and associate professor of surgery at the University of Chicago, Glen Gerber MD, summarized, "Our study provides the best evidence to date that saw palmetto can have a beneficial effect. Saw palmetto clearly offers symptomatic benefit as compared with placebo controls. We can tell patients that this appears to be a safe, well-tolerated substance that can produce short-term improvement of urinary symptoms."

December 12, 2001

Lifespan switch identified

In research published in Current Biology, volume 11, number 24, researchers at University of Colorado, Boulder have identified the switch that controls lifespan in the roundworm, C elegans. The switch is a protein known as DAF-16 which is part of a signaling pathway involving insulin and glucose. In food-rich conditions DAF-16 is prevented from entering the cell nucleus and remains in the surrounding cytoplasm, considered the "off" mode. When the cell seeks more food, or in conditions of heat or stress, DAF-16 penetrates cell nucleii, initiating a cascade of events that appears to lengthen the lives of the worms. It is probable that humans possess a similar protein.

Study coauthor and University of Colorado Institute for Behavioral Genetics, Professor Thomas Johnson, explained, "If DAF-16 is 'on,' it triggers less reproduction, more efficient cell repair and longer lives. On the other hand, if DAF-16 is 'off,' the result is more reproduction, worse cell repair and a shortened lifespan . . . The longer lived species of C. elegans have a higher resistance to free radicals and environmental stress."

Professor Johnson's observation confirms the trade-off observed in biology between devotion of resources to increased growth/ reproduction, and improved cell repair resulting in longer lifespan. Johnson was the first scientist to confirm that genetic mutation could increase lifespan, via a study published in Science magazine in 1990 in which the lifespan of roundworms was doubled by a single mutation.

The longer lifespan achieved in the worm appears to be due to greater protection against oxidative stress. The researchers speculate that a drug could be developed that would cause DAf-16 to move into the nucleus, thereby lengthening the lifespan of animals, including humans.

December 10, 2001

Folate supplements associated with lower childhood cancer risk

Researchers at the Cancer Foundation of West Australia, in West Perth, Australia, have discovered that children of women who take folate (folic acid) supplements during pregnancy experience a reduced risk of acute lymphoblastic leukemia, the most prevalent childhood cancer in developed countries. Little is known regarding how to prevent the disease. In order to investigate possible risk factors, the researchers conducted a population-based case-control study of children up to fourteen years of age in Western Australia from 1984 to 1992. Eighty-three children with the disease were referred by a pediatric cancer center, and 166 age and sex-matched controls were randomly recruited through a postal survey. Mothers of eligible children were interviewed by the researchers in regard to lifestyle, supplement intake or medication use. Fathers completed a questionnaire which featured lifestyle-related questions such as smoking history during the mother's pregnancy.

Folate taken with iron supplements taken during pregnancy was associated with a 60% lower risk of developing acute lymphoblastic leukemia in the children born to these mothers compared to those who did not take supplements. The protective effect of the supplements appears to be independent of when they were first used or how long they were taken. In women who took iron alone, the children experienced a 25% lower incidence of the disease, demonstrating a greater protective benefit with the addition of folic acid.

The findings, described as "unexpected" by the authors, indicate that prevention of this cancer may occur in the fetus due to improved ability of DNA to repair itself when folic acid intake is adequate. The study appeared in the December 8 2001 issue of the medical journal, The Lancet.

December 07, 2001

Energy restriction helps protect rats bred to develop estrogen-dependent breast cancer

A study published in the November 2001 issue of the Journal of Nutrition showed that rats bred to develop mammary tumors treated with a naturally occurring form of estrogen known as 17beta-estradiol, receive some protection from developing the disease when the amount of energy in their diets was restricted to 40% less than that of controls. Because of the strong link between estrogen and breast cancer in humans, the rat model, known as the ACI rat, is valuable in testing methods that may prevent the disease. Chronic administration of 17beta-estradiol to these rats causes atypical epithelial hyperplasia of the breast, and eventually cancer.

Researchers at the Eppley Institute for Research in Cancer at the University of Nebraska Medical Center in Omaha, Nebraska randomized ACI rats to receive a control diet or a diet containing 40% less total energy from fat and carbohydrate than that of the control diet, without a reduction in essential nutrients. After seventeen days on the diet, rats from each group were administered 17beta-estradiol, following which they were examined twice per week for the presence of tumors. The hormone rapidly induced breast cancer in the ACI rats who received the control diet, with the first tumor in this group appearing only 69 days after hormone treatment was begun, contrasted with the group who received the restricted diet in which the first tumor was observed after 104 days. After 216 days of treatment, all rats on the control diet had at least one tumor, compared to 59% of the energy-restricted rats at 207 days. The number and size of tumors was also smaller in rats whose diets were restricted.

To determine the mechanism of action by which dietary restriction inhibits tumor formation, cell proliferation within the mammary epithelium of the rats was examined 84 days after the initiation of 17beta-estradiol. Mammary epithelial cell proliferation induced by 17beta-estradiol was found to be lower in the energy-restricted rats. Both groups treated with the hormone had a similar number of regions of atypical epithelial hyperplasia which can develop into cancer, suggesting that dietary energy restriction exerts its effect after the development of these lesions, preventing their progression to carcinoma. Because progesterone was found to be reduced in the restricted rats, this may be part of the how the diet exerts its protection.

December 05, 2001

Antioxidants enhance statin's antitumor action

In a study conducted by researchers at the Center for Vitamins and Cancer Research at the University of Colorado Health Sciences Center, published in the December 2001 Journal of the American College of Nutrition, the ability of closed-ring statin drugs to combat tumor cells was found to be enhanced by the addition of vitamin E, 13-cis-retinoic acid or polar carotenoids. Statins are cholesterol-lowering drugs that have a closed-ring or open-ring molecular structure. Closed-ring statins, such as lovastatin, simvastatin and mevastatin, have also been found to inhibit tumor growth, while those with an open-ring such as pravastatin and fluvastatin may not be effective.

The researchers treated cultures of mouse neuroblastoma cells and rat immortalized dopamine neurons, equivalent to premalignant lesions, with the drug mevastatin alone or combined with alpha-tocopherol succinate, retinoic acid and polar carotenoids. Mevastatin and pravastatin were also separately administered to mouse neuroblastoma cells to compare their potential efficacy. Each experiment was repeated three times with three samples per treatment. Viability in control and experimental groups was determined at three days after treatment.

Mevastatin was confirmed as having an inhibitory effect on the growth of neuroblastoma cells, while pravastatin proved to be ineffective. Mevastatin combined with antioxidants was shown to be more effective at inhibiting cell growth in both cultures than any of the separate agents. The authors conclude that, "A combination of a statin having a closed-ring structure with alpha-tocopherol succinate, retinoic acid and polar carotenoids may be one of the potentially useful anti-cancer agents for prevention and treatment strategies." (Kumar B, Cole WC and Prasad, KN, "Alpha Tocopheryl Succinate, Retinoic Acid and Polar Carotenoids Enhanced the Growth-Inhibitory Effect of a Cholesterol-Lowering Drug on Immortalized and Transformed Nerve Cells in Culture," Journal of the American College of Nutrition, Volume 20, Number 6, December 2001)

December 03, 2001

Bifidobacteria probiotic helps restore age-related decline in immune function

In research published in the American Journal of Clinical Nutrition http://www.ajcn.org/, New Zealand researchers discovered that the probiotic enhanced cellular immune function in older subjects. Immune function is associated with a decline in cellular immunity, therefore elderly individuals experience impairment of immunity. The most well known change involves the thymic, or T lymphocytes.

Thirty volunteers ages 63 to 84 received milk supplemented with Bifidobacterium lactis HN019 in a typical dose consisting of fifty billion organisms, or a low dose consisting of five billion organisms for three weeks. This was preceded by three weeks of unsupplemented low fat milk twice daily and followed by three weeks of the same. Blood samples were analyzed for the relative proportions of white blood cell, or lymphocyte types, and the tumor-cell killing activity and ability of white blood cells to consume infectious or otherwise unwanted cells known as phagocytosis, was measured in vitro, before and after administration of the probiotic.

Study participants were found to have an increase in proportions of total, helper or CD4, and activated, or CD25+ T lymphocytes, as well as natural killer cells. The ability of the lymphocytes to kill tumor cells as well phagocytotic activity were also found to be elevated when subsets of these cells were examined outside the body. Test subjects who exhibited the poorest pretreatment immune responses experienced the greatest changes in immune function. There were no adverse reactions experienced by any of the participants.

The typical dose and low dose of Bifidobacterium lactis HN019 proved equally effective in this study. The findings led the researchers to conclude that the beneficial bacteria "may therefore be a safe dietary supplement for enhancing innate cellular immune function and combating some of the deleterious effects of immunosenescence."

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