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Plant compounds show promise in skin cancer prevention
Researchers at The University of Texas Health Science Center San Antonio reported this year in the journal Cancer Prevention Research the finding of protective effects for combinations of resveratrol, grape seed extract, D-glucarate and ellagic acid against the development of skin cancer.
Using rats bred to develop skin carcinoma, Zbigniew Walaszek, PhD of the University’s Health Science Center and his colleagues topically applied the carcinogen DMBA, which elicits genetic mutations, over a four week period. The animals concomitantly received diets containing combinations of the phytochemicals and topical resveratrol or grape seed extract.
At the end of the treatment period, the researchers found that combinations of low dose compounds provided protection against skin thickening, oncogene mutation and inflammation, while individually administered compounds offered less benefit. The reason for this effect is that each of the compounds works in a different way, and contributes to an additive or synergistic benefit when combined. "The combined inhibitory effects of different plant chemicals are expected to be particularly beneficial to, for example, smokers, former smokers or individuals with heavily tanned skin, who carry thousands of cells already initiated for malignant transformation," commented report coauthor and research associate professor of pharmacology Margaret Hanausek.
First author Magdalena Kowalczyk, PhD concurred, remarking that "Described combinations may be very useful in the prevention of skin cancer and other epithelial cancers in humans, achieving a high efficacy and potency with reduced side effects."
"On the basis of our research, supplements and creams or sunscreens may be developed, tested in humans and then used to prevent skin cancer," Dr Walaszek predicted. "Our next step is to go to an ultraviolet B light model of skin cancer initiation and confirm our results."
Broccoli fiber combats Crohn’s disease
An article published online on August 25, 2010 in the journal Gut reveals that fibers found in broccoli and plantain block a stage in the development of the Crohn's disease, an inflammatory bowel disease. The stage involves a process known as translocation, which is the invasion of microfold cells (M-cells) lining the colon by bacteria, particularly E. Coli, which tend to adhere to one another.
Crohn’s disease is uncommon in countries whose citizens regularly consume fibrous fruits and vegetables, while the incidence of the disease has increased in Japan with the rise of Westernized dietary habits. Additionally, some enteral feeds have been shown to result in clinical remission. “It is therefore a plausible hypothesis that dietary factors may have either harmful or protective roles in Crohn’s pathogenesis as a consequence of their effects on the interaction between the host epithelia and intestinal microbiota,” the authors write.
Dr Barry J. Campbell of the University of Liverpool and his associates tested the effects of soluble fiber from leeks, apples, broccoli and plantain in cultured human M-cells. Concentrations of 5 and 50 milligrams per milliliter plantain fiber, and broccoli fiber concentration of greater than 0.5 milligrams per milliliter helped inhibit E. Coli translocation. While apple and leek failed to show an inhibitory effect, translocation of E. Coli was enhanced by the fat emulsifier polysorbate 80, which is included in some enteral feed solutions administered to Crohn’s disease patients and is a common dietary additive. The results were confirmed in epithelial tissue samples derived from humans who underwent surgery for colon cancer or colonoscopy.
“These studies show that different dietary components may have powerful and contrasting effects on bacterial translocation across intestinal M-cells,” the authors conclude. “These effects may be relevant to the role of environmental factors in the pathogenesis of Crohn’s disease and suggest possible novel therapeutic approaches.”
Research confirms cranberry juice’s effectiveness in preventing urinary infection
At the 240th National Meeting of the American Chemical Society, held during the week of August 23 in Chicago, Terri Anne Camesano, PhD of Worcester Polytechnic Institute reported that cranberry juice helps prevent bacterial adhesion, thereby protecting against urinary tract infection. The infections occur frequently in women and cause severe pain and urinary urgency.
Urinary tract infections are most often caused by E. coli, a strain of bacteria that exists in the lower digestive tract. The bacteria enter the urethra, which is the opening through which urine is excreted, and migrate upward into the bladder and, in some cases, the kidneys. E. coli adheres to other bacteria of its kind, forming what is known as a biofilm. Biofilms enable bacteria to survive and multiply and resist eradication.
Dr Camesano and her colleagues tested the ability of E. Coli to form biofilms in the urine of healthy volunteers before and 0, 2, 8, 24, 48 hours after consuming a cranberry juice cocktail beverage. They found that cranberry juice’s beneficial metabolites reach the urinary tract to prevent adhesion within 8 hours after the drink is consumed.
"A number of controlled clinical trials -- these are carefully designed and conducted scientific studies done in humans -- have concluded that cranberry juice really is effective for preventing urinary tract infections," commented Dr Camesano. "That has important implications, considering the size of the problem and the health care costs involved."
She stressed that individuals who suspect that they have a urinary tract infection seek medical attention, because the infection can progress rapidly if untreated with antibiotics.
New research links vitamin D to hundreds of genes
A report published online on August 23, 2010 in the journal Genome Research reveals the results of a genome-wide mapping of the vitamin D receptor, which was found to exist on 2,776 binding sites. The researchers responsible for the finding also demonstrated that vitamin D directly affects the activity of 229 genes, including a gene associated with multiple sclerosis, and PTPN2, which is associated with Crohn's disease and type 1 diabetes.
Vitamin D affects genes via the vitamin D receptor, a protein that binds to particular genome locations to influence gene expression of proteins. Dr Sreeram Ramagopalan of the Wellcome Trust Centre for Human Genetics at Oxford University and colleagues found that binding sites were concentrated near genes associated with susceptibility to autoimmune conditions such as multiple sclerosis (MS), and cancers including chronic lymphocytic leukemia and colorectal cancer, which are diseases to which vitamin D deficiency has been linked. "Considerations of vitamin D supplementation as a preventative measure for these diseases are strongly warranted," Dr Ramagopalan observed.
"There is now evidence supporting a role for vitamin D in susceptibility to a host of diseases,” he added. “Vitamin D supplements during pregnancy and the early years could have a beneficial effect on a child's health in later life. Some countries such as France have instituted this as a routine public health measure."
"Vitamin D status is potentially one of the most powerful selective pressures on the genome in relatively recent times," noted Action Medical Research Professor of Clinical Neurology George Ebers, who is one of the article’s senior authors. "Our study appears to support this interpretation and it may be we have not had enough time to make all the adaptations we have needed to cope with our northern circumstances."
Leafy vegetables may help protect against diabetes
In their introduction to the article, Patrice Carter and her colleagues at the University of Leicester in England remark that fruit and vegetables supply antioxidants and phytochemicals that combat free radicals, which are associated with the early phases of the development of several chronic diseases. High intake of fruit and vegetables has been linked with a reduction in cardiovascular disease, and diabetes is a risk factor for cardiovascular disease’s development. At this point in time, there is no scientific consensus concerning whether increased intake of fruit and vegetables decreases the risk of diabetes itself.
For their review, Dr Carter and her associates selected 6 studies that provided data on type 2 diabetes incidence and measured the intake of fruits and vegetables for a total of 223,512 participants, aged 30 to 74. The studies’ follow-up periods ranged from 4.6 to 23 years.
The reviewers found a significant association between increased leafy green vegetable intake and decreased type 2 diabetes risk. An increase of 1.15 servings green leafy vegetables per day was associated with a 14 percent reduction in the risk of developing type 2 diabetes.
“Results from our meta-analysis support recommendations to promote the consumption of green leafy vegetables in the diet for reducing the risk of type 2 diabetes,” the authors conclude. “The results support the growing body of evidence that lifestyle modification is an important factor in the prevention of type 2 diabetes. The potential for tailored advice on increasing intake of green leafy vegetables to reduce the risk of type 2 diabetes should be investigated further.”
Mediterranean diet protective against ultraviolet-light-induced skin damage
The diet consisting of foods consumed in the sunny area surrounding the Mediterranean Sea may help protect the residents of those countries from developing melanoma, a skin cancer that is increasingly common and potentially fatal.
In an article published this year in Nutrition Reviews, Dr Niva Shapira of Tel Aviv University's School of Health Professions observes that the incidence of skin cancer is on the rise, despite the use of sunscreens. Concurrently, studies are revealing that dietary antioxidant vitamins, minerals, phytochemicals, omega-3 polyunsaturated fatty acids and omega-9 monounsaturated fatty acids have cancer-protective properties.
Ultraviolet rays damage the skin by promoting oxidation. Dr Shapira, along with Professor Bodo Kuklinksi of Rostock University, divided a group of subjects who spent 5 to 6 hours in the sun per day to receive a high antioxidant drink or commonly consumed beverages such as sodas for 2 weeks. At the end of the treatment period, blood samples from those who received the antioxidant-containing beverage were found to have half the oxidation products such as malondialdehyde compared to the group that did not receive antioxidants. The antioxidant compounds, particularly carotenoids, were shown to accumulate in skin and delay sun damage that can lead to skin cancer.
"My theory was that if you prepared the body with sufficient and relevant antioxidants, damage could be reduced," Dr Shapira stated. She noted that the finding was particularly valuable in light of increasing temperatures which aggravate the damaging effect of ultraviolet rays. Ultraviolet light also impairs the immune system, which decreases the body's ability to repair damaged skin.
Dr Shapira cautions that a few natural foods, including parsley, celery, dill, cilantro and figs, contain psoralen, which increases sensitivity to the sun, and should be avoided by those planning to spend a significant amount of time out of doors.
Increased vitamin D could reduce allergic reaction
Allergic reaction to the common mold Aspergillus fumigates, which often negatively impacts individuals with asthma or cystic fibrosis (CF), could be reduced by increasing one’s vitamin D, according to a report published online on August 16, 2010 in the Journal of Clinical Investigation.
Professor and Chair of Genetics at Louisiana State University Health Sciences Center Dr Jay Kolls and colleagues compared cystic fibrosis patients with a condition known as allergic bronchopulmonary aspergillosis to CF patients who were also colonized with the mold but did not have the allergic response. Bronchopulmonary aspergillosis affects approximately 15 percent of CF patients, and the researchers sought to determine the factors involved in which patients develop it.
Patients that did not have allergic bronchopulmonary aspergillosis were discovered to have higher levels of the proteins FoxP3 and TGF-beta in immune system cells known as CD4+T cells, which are essential in the development of tolerance to allergens. Greater reactivity of Th2 cells, which are the hormonal messengers of T helper cells that elicit the allergic response, was found to be controlled by the protein OX40L and was associated with a lower blood level of vitamin D. "We found that adding vitamin D not only substantially reduced the production of the protein driving an allergic response, but it also increased production of the proteins that promote tolerance," Dr Kolls noted.
"Our study provides further evidence that vitamin D appears to be broadly associated with human health," he remarked. "The next step in our research is to conduct a clinical trial to see if vitamin D can be used to treat or prevent this complication of asthma and cystic fibrosis."
Greater antioxidant intake associated with lower esophageal cancer risk
In an article published online on August 11, 2010 in the Journal of Nutrition, researchers from Ireland report the association of a reduced risk of esophageal cancer among men and women who consumed higher amounts of antioxidants, compared to those with a lower intake. Esophageal cancer can develop in individuals with Barrett’s esophagus, a condition in which the mucosa of the esophagus undergoes changes incurred by gastroesophageal reflux. Reflux esophagitis, a condition characterized by esophageal inflammation, is believed to precede Barrett’s esophagus and esophageal cancer.
The study included men and women who participated in the Factors Influencing the Barrett’s Adenocarcinoma Relationship study. Seamus J. Murphy of Queen’s University Belfast and colleagues compared 219 individuals with reflux esophagitis, 220 with Barrett’s esophagus and 224 with esophageal cancer to 256 gender and age-matched controls who did not have the diseases. Dietary questionnaire responses were analyzed for the intake of vitamin C, vitamin E, total carotenoids, zinc, copper, and selenium.
Overall antioxidant index was associated with a lower risk of esophageal cancer. Those in the top one-third had a 43 percent lower adjusted risk of esophageal cancer compared to those whose antioxidant index was lowest. Among individual antioxidants, participants in the top third of vitamin C intake had a 63 percent lower risk of esophageal cancer and a 52 percent lower risk of reflux esophagitis compared to those in the lowest third.
“This is the largest case control study to examine the association between dietary intake of antioxidant vitamins and minerals in humans and the risk of reflex esophagitis, Barrett’s esophagus, and esophageal adenocarcinoma utilizing the same control group,” the authors write. “These results suggest that antioxidants may play a role in the pathogenesis of reflux esophagitis and esophageal adenocarcinoma and may be more important in terms of progression rather than initiation of the disease process.”
Greater magnesium intake linked to lower rate of type 2 diabetes
Researchers from Japan report in the April, 2010 issue of the Journal of the American College of Nutrition an association of a higher intake of the mineral magnesium and a lower risk of developing type 2 diabetes.
Hiroyasu Iso, MD of Osaka University Graduate School of Medicine and his colleagues evaluated data from 17,592 men and women aged 40 to 79 who took part in the Japan Collaborative Cohort Study for Evaluation of Cancer Risk established between 1988 and 1990. Three-day dietary records and responses to questionnaires administered upon enrollment were analyzed for total magnesium intake. Primary food sources for the mineral included cereals, vegetables, beans and fish.
At the 5-year follow-up, 459 new cases of diabetes were reported. Those whose intake of magnesium was among the top 25 percent of male participants had a 36 percent lower adjusted risk of developing diabetes than men whose intake was lowest, and for women, the risk experienced by the highest 25 percent was 32 percent lower.
“To our knowledge, no study has examined the association between magnesium intake and the risk of diabetes in Japanese living in Japan,” the authors announce. They note that magnesium is a cofactor for several enzymes involved in carbohydrate metabolism, and a deficiency of the mineral may increase peripheral insulin resistance and impair glucose utilization. Previous research has found a benefit for magnesium supplements on fasting glucose level in diabetics and nondiabetics. With the increased prevalence of diabetes in Asian countries, the study’s findings are important for the development of national health policies to help prevent and control this potentially devastating disease.
Mitochondrial DNA may play important role in controlling life span
The August, 2010 issue of The American Naturalist reports the discovery of Dr Damian Dowling of Monash University in Australia and his colleagues from Lund University and Uppsala University in Sweden of a critical role for mitochondrial genes in determining life span in a species of beetle.
Mitochondrial DNA is a genome that is separate from nuclear DNA, and is inherited only from the mother. While the cell’s nuclear DNA (which contains genes from both parents and is responsible for the control of the majority of bodily functions) encodes 14,000 to 40,000 proteins, DNA that resides in the cell’s power plants known as mitochondria encodes only 13 proteins.
Dr Dowling and his associates studied the relationship of mitochondrial DNA to the life span in the beetle Callosobruchus maculates. "What we found in these beetles that some combinations of mitochondrial and nuclear genomes confer long life in virgin females, but these are not the same combinations that result in long life in females that mate once, or in females that mate many times," Dr Dowling reported.
"Clearly, the genetic determinants underlying life expectancies are complex,” he observed. “As we unravel this complexity, we draw closer to the day in which we might use the genetic information encoded in the mitochondria to assist in the development of therapies that slow the onset of ageing in humans."
"At the outset of our research program, we suspected that the evolutionary significance of the mitochondria had probably been underestimated by scientists that have come before us, but even we have been continually surprised by the magnitude and ubiquity of the effects that we have uncovered,” he added. "We suspect that this genome still harbors many more secrets awaiting discovery."
Tea drinking associated with fewer heart disease deaths over 13 year period
Tea drinkers were found to have a lower risk of dying from coronary heart disease (CHD) over a 13 year period in a study reported in the August, 2010 issue of the journal Arteriosclerosis, Thrombosis and Vascular Biology.
Researchers at University Medical Center Utrecht and the National Institute for Public Health and the Environment in the Netherlands evaluated data from 37,514 participants in the European Prospective Investigation into Cancer and Nutrition (EPIC-NL) cohort of healthy Dutch men and women. Dietary questionnaires completed upon enrollment provided information on the frequency of intake of coffee and tea. Subjects were followed for an average of 13 years, during which time any cardiovascular events or deaths were documented.
Over the follow-up period, 563 cases of stroke and 1,387 coronary heart disease events occurred. Moderate intake of coffee (2.1 to 3 cups per day) was more protective than low or high amounts against coronary heart disease events. Participants who consumed over 6 cups of tea per day had a 36 percent lower adjusted risk of heart disease compared to those whose intake was less than a cup.
Of 1,405 deaths from any cause, 70 were due to stroke and 123 to coronary heart disease. While drinking coffee insignificantly reduced the risk of coronary heart disease mortality, for those who consumed between 3 and 6 cups of tea per day, there was a 45 percent lower risk of dying of the disease. No associations were found with stroke.
“High tea consumption is associated with a reduced risk of coronary heart disease mortality,” the authors conclude. “Our results suggest a slight risk reduction for CHD mortality with moderate coffee consumption and strengthen the evidence on the lower risk of CHD with coffee and tea consumption.”
Combined vitamin C and E deficiency increases atherosclerosis in mouse model
A report published in the journal Atherosclerosis, Thrombosis and Vascular Biology describes the results of a study which found that a deficiency of vitamins C and E significantly accelerates the development of atherosclerosis in mice bred to develop the condition.
In their introduction to the article, researchers at Vanderbilt University School of Medicine in Nashville remark that the contribution of oxidative stress to the initiation of atherosclerosis has led to the hypothesis that the disease might be prevented by treatment with antioxidants, however, some research suggests that treatment may not slow the progression of established disease. “Whether antioxidant vitamins can prevent or slow early atherosclerosis may be a more relevant question that is not readily tested in humans, given the prolonged asymptomatic period of the disease,” they write.
In one experiment, mice were given a high fat diet that contained high or low amounts of vitamin C or E. After 8 weeks on the diets, the animals’ livers, brains and hearts were examined. Mice that were deficient in either or both vitamins had correspondingly lower brain and liver levels than nondeficient animals. For male mice that received diets deficient in both vitamins C and E, lipid peroxidation increased, plaque size was doubled and plaque macrophage content, which is associated with plaque instability, was greater compared to the other animals. These effects were not observed in mice that received diets deficient in only one vitamin, however, an increase in oxidative stress and atherosclerosis were observed in another experiment with mice bred to have a more severe deficiency of vitamin C.
In conclusion, the authors note that vitamin deficiencies to the extent of those produced in this study are uncommon in humans, yet it is plausible that longer-term but less severe deficiency could have similar effects in human cardiovascular disease.