Researchers employed imaging techniques to examine and analyze brain anatomical differences between 55 female IBS patients and 48 female control subjects. Patients had moderate IBS severity, with disease duration from one to 34 years (average 11 years). The average age of the participants was 31.
Investigators found both increases and decreases of brain grey matter in specific cortical brain regions.
Even after accounting for additional factors such as anxiety and depression, researchers still discovered differences between IBS patients and control subjects in areas of the brain involved in cognitive and evaluative functions, including the prefrontal and posterior parietal cortices, and in the posterior insula, which represents the primary viscerosensory cortex receiving sensory information from the gastrointestinal tract.
“The grey-matter changes in the posterior insula are particularly interesting since they may play a role in central pain amplification for IBS patients,” said study author David A. Seminowicz, Ph.D., of the Alan Edwards Centre for Research on Pain at McGill University. “This particular finding may point to a specific brain difference or abnormality that plays a role in heightening pain signals that reach the brain from the gut.”
Decreases in grey matter in IBS patients occurred in several regions involved in attentional brain processes, which decide what the body should pay attention to. The thalamus and midbrain also showed reductions, including a region – the periaqueductal grey – that plays a major role in suppressing pain.
“Reductions of grey matter in these key areas may demonstrate an inability of the brain to effectively inhibit pain responses,” Seminowicz said.
The observed decreases in brain grey matter were consistent across IBS patient sub-groups, such as those experiencing more diarrhea-like symptoms than constipation.
“We noticed that the structural brain changes varied between patients who characterized their symptoms primarily as pain, rather than non-painful discomfort,” said Mayer, director of the UCLA Center for Neurobiology of Stress. “In contrast, the length of time a patient has had IBS was not related to these structural brain changes.”
Mayer added that the next steps in the research will include exploring whether genes can be identified that are related to these structural brain changes. In addition, there is a need to increase the study sample size to address male-female differences and to determine if these brain changes are a cause or consequence of having IBS.
The study was funded by the National Institutes of Health.
Additional authors include M. Catherine Bushnell, Ph.D., of McGill University, and Jennifer B. Labus, Joshua A. Bueller, Kirsten Tillisch and Bruce D. Naliboff, Ph.D., all of UCLA.
Researchers have long speculated that the diet may help explain why nations in the Mediterranean region have historically had lower rates of heart disease and some cancers, including breast cancer, compared with other European countries and the U.S.
Until now, only two other studies have looked at the relationship between Mediterranean-style eating and the risk of breast cancer, both done in the U.S. Each found a connection between the diet and lower breast cancer risk, although in one the link was limited to breast cancers that lack receptors for the hormone estrogen — which account for about one-quarter of breast tumors.
The current study focused on women in Greece, as it is the “cradle” of the Mediterranean diet, and a large segment of the population still adheres to it, Dr. Dimitrios Trichopoulos, the senior researcher on the work, told Reuters Health by email.
At the outset, the study participants completed detailed dietary questionnaires and gave information on their lifestyle habits and demographics. Each woman was given a Mediterranean diet score, ranging from 0 to 9, based on how often they consumed vegetables, legumes, fruit and nuts, whole grains, fish and olive oil or other sources of monounsaturated fats; they also won points by limiting meat and dairy.
Of the 14,800 women included, 240 were diagnosed with breast cancer over an average follow-up of 10 years.
Overall, postmenopausal women whose Mediterranean diet scores were in the 6-to-9 range were 22 percent less likely to develop breast cancer than their counterparts with scores between 0 and 3. That was with factors such as age, education, smoking history, weight and exercise habits taken into account.
The findings show an association between Mediterranean eating and lower breast cancer risk, but do not prove cause-and-effect, according to Trichopoulos, who is with the Harvard School of Public Health in Boston and the Bureau of Epidemiologic Research at the Academy of Athens in Greece.
Further studies are needed to confirm the results, he said.
However, other evidence suggests ways the Mediterranean diet might curb cancer risk.
Research has found, for instance, that women who closely follow the diet tend to have lower levels of estrogen, which fuels the growth of the majority of breast cancers, than other women do. Other studies in the lab suggest that the fats found in the Mediterranean diet — both olive oil and the omega-3 fats in oily fish — may slow the growth of cancer cells.
The diet is also typically rich in antioxidants, which protect body cells from damage that can eventually lead to disease, including cancer. Trichopoulos said that if the Mediterranean diet does have a protective effect against cancer, it is “likely” to involve that antioxidant component.
It also makes sense, said the researcher, that the diet could affect the risk of postmenopausal, but not premenopausal, breast cancer.
Younger women who develop breast cancer, he explained, often have a genetic vulnerability to the disease, whereas in older women, lifestyle and environmental exposures may be relatively more important contributors to risk.
Based on their findings, Trichopoulos and his colleagues write, the association between the Mediterranean diet and breast cancer is of “modest, but not negligible, strength.”
In the U.S., a woman's chance of being diagnosed with breast cancer rises from about a half a percent, or one in 233, during her 30s, to about four percent, or one in 27, during her 60s.
Established risk factors for breast cancer include older age and having had a first-degree relative diagnosed with the disease. Research has also linked obesity, sedentary lifestyle, use of hormone replacement therapy and high alcohol intake to an increased risk.
SOURCE: Journal of Clinical Nutrition
The new data come from an ongoing National Institutes of Health-AARP study and involved more than 300,000 participants. Researchers found that those study participants who reported eating the most processed meat had about a 30 percent greater risk of bladder cancer than those who ate the least.
What's more, those whose diets were highest in nitrites and nitrates (from processed meat as well as other sources) were about 33 percent more likely to develop bladder cancer than those whose diets contained the smallest amounts of these compounds.
Bladder cancer is currently the 10th most common cancer in the US, with over 70,000 cases diagnosed each year.
Link to Bladder Cancer Needs Confirmation; Link to Colorectal Cancer Convincing
The evidence that consumption of processed meat is linked to colorectal cancer was judged convincing by the independent expert panel behind the major AICR/WCRF report, Food, Nutrition, Physical Activity and the Prevention of Cancer: A Global Perspective.
This same report, published in 2007, found the evidence linking red and processed meat to bladder cancer too sparse to make a judgment. Although this new study's findings need to be confirmed, it represents a major contribution to the scientific literature on diet's role in bladder cancer.
Higginbotham noted that the AICR/WCRF report's findings are continually updated; data from this and other studies will be added to AICR/WCRF's database and are scheduled to be reassessed by independent experts in the future.
Until that time, AICR reiterates that for people who are concerned about cancer, there is already good reason to limit consumption of red meat and avoid processed meat.
Source: American Institute for Cancer Research
Using a UK database of electronic medical records, he and his colleagues identified 367 children and adults diagnosed with Crohn's disease and 591 diagnosed with ulcerative colitis between 2005 and 2008. The researchers matched each of those people to five IBD-free individuals the same age and sex.
They then used air-quality data from government monitors to assess the average yearly levels of three air pollutants in the study subjects' residential areas.
The pollutants included nitrogen dioxide, which is produced largely by vehicles and is highest in urban, high-traffic areas; sulfur dioxide, which is produced through industrial processes, including the burning of coal and oil; and particulate matter, fine particles emitted via car exhaust, as well as power plants and other industrial sources.
Overall, Kaplan's team found no association between IBD and the three air pollutants across the study group as a whole.
However, young people — those age 23 or younger — were about twice as likely to be diagnosed with Crohn's disease if they lived in a region in the top 60 percent of nitrogen dioxide levels, versus the bottom 20 percent.
Similarly, people age 25 or younger were twice as likely to have ulcerative colitis if they lived in areas with higher sulfur dioxide levels. However, there was no evidence of a “dose-response” relationship — that is, the risk of ulcerative colitis climbing steadily as sulfur dioxide levels rose.
That lack of a dose-response, Kaplan told Reuters Health, “makes us a little more cautious about that finding.”
Indeed, he urged caution in interpreting the findings as a whole. While he and his colleagues tried to account for other factors — such as study subjects' smoking habits and socioeconomic status — they cannot rule out the possibility that something other than air pollution itself accounts for their findings.
“This is an interesting association,” Kaplan said. But, he added, the findings do not prove cause-and-effect.
As for why air pollution would affect IBD risk, Kaplan said he could only speculate, based on research into other health conditions, including heart and lung disease. Studies indicate that air pollutants can trigger inflammation in the body; that, Kaplan explained, raises the possibility that in genetically predisposed people, air pollution may trigger an inflammatory response in the intestines that leads to IBD.
Since the current study found a relationship between pollutants and IBD only in young people, the findings also raise the question of whether children and teenagers are particularly susceptible to any effects of air pollution on the risk of the digestive disorders.
Much more research is needed, Kaplan said — both larger population studies and research in animals to see how exposure to various air pollutants might affect intestinal health.
He added that no one is proposing that air pollution is the environmental cause of IBD; if it does turn out to be a factor, he said, it will likely be one of many players.
But if air pollution is confirmed as a risk factor, there would be important implications, Kaplan said, since air quality is something that can be modified.
Beetroot juice, a source of high nitrate levels, may help prevent high blood pressure, according to a study published in Hypertension. Nitrate is a compound that increases the amount of gas nitric oxide that circulates through the blood.In an effort to determine if beetroot juice contains enough nitrate to lower blood pressure, researchers had two groups of individuals either drink the juice or take nitrate capsules.
The results of the study showed that within 24 hours, the supplements and the juice had lowered the blood pressure of people in both groups. Furthermore, the investigators discovered that about 250 mL of beetroot juice was all that was needed to have the same effects on one's blood pressure as the nitrate capsules.
These findings showed that “beetroot and nitrate capsules are equally effective in lowering blood pressure, indicating that it is the nitrate content of beetroot juice that underlies its potential to reduce blood pressure,” said Amrita Ahluwalia, lead researcher of the study.
The paper directly compared findings from two separate studies: 'The Diets of British Schoolchildren' conducted by the Department of health (DH) in 1983 (Department of Health 1989); and the National Diet and Nutrition Survey (NDNS) from 1997 (Gregory & Lowe, 2000).
Gibson's analysis found that total sugar intake averaged at 115g/day in 1983, compared with 113g/day in 1997. Allowing for exclusions of low and high energy reporters, intake levels were 122g/day (1983) and 127g/day (1997), showing a marginal and insignificant increase over the study period. Contrastingly, mean body weight increased significantly during the period of the DH and NDNS surveys, showing a rise of 1.9kg for 10-11 year olds and 3.4kg among 14-15 year olds. BMI increased from 17.9 to 18.6 units in the younger group, and 20.2 to 21.3 units in the older group. According to these calculations, the prevalence of being overweight (plus obesity), as defined by the International Obesity Taskforce (IOTF) cut-offs (91st percentile) rose from 13% to 21-22% between surveys. Gibson concluded that the slight increase in consumption of total sugars did not account for the significant increase in BMI, equivalent to 2-3 kg over the review period.
During the same period, Gibson found that mean energy intake (EI) was 3% lower in 1997 than in 1983, mainly as a result of lower fat intake. This change in overall energy consumption meant that sugars represented a higher proportion of daily energy intake in 1997 (23.6% versus 22.3%), despite total sugar consumption remaining relatively static in comparison. The review surmises that the most likely cause for the increased BMI is a decline in energy expenditure.
In addition, Gibson's paper found that basal metabolic rate (BMR) increased by approximately 3% between surveys as a result of higher body weights, and it is estimated that EI in relation to basal requirements was even lower at 6%. Gibson found that the paradox of rising BMI, despite a 2-3% rise in BMR and an EI that is static or falling, pointed to declining energy expenditure as an important factor in the change.
The Gibson analysis showed that the key sources of sugars in the diet have changed with a marked shift away from table sugar and smaller falls in consumption of sugars through milk, biscuits and cakes, counterbalanced by a significant increase in sugars consumed in soft drinks and, to a lesser extent, fruit juice and breakfast cereals.
A conclusion of Gibson's reanalysis of data from the DH and NDNS studies, that consumption of total sugars remained relatively static during the period, providing an estimated 22% of energy, is supported by findings from a repeated cross sectional study of children's food and drink intake, conducted in Northumberland in 1989, 1990 and 2000 which looked at trends in children's food and drink intake.
Sigrid Gibson, the paper's author, said: “There are very few studies that have assessed trends in sugar intake over time and particularly over such an extended period. The findings of the reanalysis strongly contradict widespread assumptions that sugar levels in the diet are responsible for rising obesity levels. With dietary sugar intakes relatively static, and overall energy consumption showing decline, increased BMI levels cannot be attributed to sugar consumption.”
Grains consist of three layers: the fiber- and nutrient-containing bran and germ layers and the starchy kernel layer. Refined grains, like white flour, are largely stripped of the bran and germ; whole grains — such as oatmeal, brown rice, barley and breads made from whole wheat — retain more of those components.
Studies suggest that the fiber, antioxidants and other nutrients in whole grains may help lower cholesterol, blood sugar and insulin levels, as well as improve blood vessel functioning and reduce inflammation in the circulatory system.
In the new study, Qi and his colleagues at Harvard Medical School in Boston found that among 7,800 U.S. women followed for 26 years, those with the highest bran intake were 28 percent less likely to die during the study period than those who consumed the least bran.
Similarly, they were 35 percent less likely to die of cardiovascular disease (heart disease or stroke) specifically.
The findings, published in the journal Circulation, do not prove that bran-heavy diets were the reason for the lower risks.
However, the connection was not explained by generally healthier lifestyles among the bran lovers. When the researchers accounted for other diet habits — like fat intake and total calories — as well as the women's weight, exercise levels, smoking history and drinking habits, the link between higher bran intake and lower death rates remained.
This suggests that bran intake itself may help lower diabetics' risk of premature death, according to Qi.
He suggested that women and men with diabetes try to replace refined grains in their diets with bran-rich whole grains.
That said, the researcher pointed out that the risk reductions in this study were seen across a large population — with bran lovers showing a relatively lower risk of death than those who ate little bran. That does not mean that for any one person with diabetes, boosting bran intake would have a substantial effect on longevity.
The findings are based on 7,822 women with type 2 diabetes who were part of the Nurses' Health Study, a long-term study of U.S. female nurses begun in 1976. Every two years, the women answered the questions about their lifestyle, medical history and any disease diagnoses.
Over 26 years of follow-up, 852 study participants died, including 295 women who died of heart disease or stroke.
Overall, Qi's team found, women in the top 20 percent for bran intake had a 28 percent lower risk of dying from any cause during the study period, compared with women in the lowest 20 percent. Their risk of death from cardiovascular disease was 35 percent lower.
The group with the highest bran intake typically consumed 9 grams of bran per day — about 10 times more than the lowest-intake group. In general, experts recommend that adults get at least 3 to 4 “ounce equivalents” of whole grains each day; a slice of whole-grain bread or a cup of whole-grain cereal are examples of one ounce equivalent.
SOURCE: http://circ.ahajournals.org/cgi/content/abstract/CIRCULATIONA HA.109.907360v1 Circulation, online May 10, 2010.
Over the past several decades, the food industry has reduced the amount of saturated fat in many products, and the public has reduced the amount of saturated fat in their diet. However, there has been a wide variation in the types of nutrients that have replaced this saturated fat. For example, in many products saturated fats were replaced with trans fats, which have since been determined to be detrimental; and in the overall American diet saturated fat was generally replaced with increased consumption of refined carbohydrates and grains.
“The specific replacement nutrient for saturated fat may be very important,” said lead author Dariush Mozaffarian, assistant professor in the department of epidemiology at HSPH and the department of medicine at Harvard Medical School. “Our findings suggest that polyunsaturated fats would be a preferred replacement for saturated fats for better heart health.”
Results from prior individual randomized controlled trials of saturated fat reduction and heart disease events were very mixed, with most showing no significant effects. Other trials focused only on blood cholesterol levels, which are an indirect marker of risk. Large observational studies have also generally shown no relationship between saturated fat consumption and risk of heart disease events; for example, earlier this month in the American Journal of Clinical Nutrition, researchers from HSPH and Children's Hospital Oakland Research Institute performed a pooled meta-analysis of prior observational studies and found no evidence that overall consumption of saturated fat was related to risk of coronary heart disease or stroke events.
Some of these mixed findings may relate to absence of prior focus on the specific replacement nutrient for saturated fat; in other words, was saturated fat replaced primarily with carbohydrate, monounsaturated fats such as in olive oil, or polyunsaturated fats such as in most vegetable oils?
Mozaffarian and his HSPH colleagues, Renata Micha and Sarah Wallace, performed a systematic review and meta-analysis of all randomized controlled trials through June 2009 in which participants specifically increased their polyunsaturated fat consumption as a replacement for saturated fat and in which coronary heart disease events were documented. Eight trials met the inclusion criteria, totaling 13,614 participants with 1,042 coronary heart disease events.
The meta-analysis of the trials showed that increasing polyunsaturated fat consumption as a replacement for saturated fat reduced the risk of coronary heart disease events by 19%. For every 5% increase (measured as total energy) in polyunsaturated fat consumption, coronary heart disease risk was reduced by 10%. This is now just the second dietary intervention–consuming long-chain omega-3 fatty acids is the first — to show a reduction in coronary heart disease events in randomized controlled trials.
Currently, the Institute of Medicine guidelines recommend that a range of 5%-10% energy consumption come from polyunsaturated fats. In addition, some scientists and organizations have recently suggested that consumption of polyunsaturated fats (largely “omega-6” fatty acids) should actually be reduced due to theoretical concerns that such consumption could increase coronary heart disease risk.
The results from this study suggest that polyunsaturated fats from vegetable oils may be an optimal replacement for saturated fats, an important finding for dietary guidelines and for when food manufacturers and restaurants are making decisions on how to reduce saturated fat in their products. The findings also suggest that an upper limit of 10% energy consumption from polyunsaturated fats may be too low, as the participants in these trials who reduced their risk were consuming about 15% energy from polyunsaturated fats.
Support for this study was provided by the National Heart, Lung, and Blood Institute, NIH and a Searle Scholar Award from the Searle Funds at the Chicago Community Trust.
Lead researcher Dr. Jeffrey M. Lackner from the State University of New York, Buffalo said cognitive behavioral therapy was known to be a very promising treatment for IBS, with the current findings helping to identify which patients would likely maintain a positive response.
Lackner and his colleagues are conducting a larger, longer-term study, as the current study being a small one, it remains unclear how long the benefits of cognitive behavioral therapy may last i. e. do they carry over to 9 months, a year or more.
IBS symptoms include bouts of abdominal cramps, bloating and changes in bowel habits i. e. diarrhoea or constipation, or alternating episodes of both. While, no one knows the exact cause of the disorder, there are certain symptom triggers like particular foods, large meals and emotional stress.
Cognitive behavioral therapy helps IBS patients to recognize their symptom triggers and manage them. Other treatment options include general diet changes, like reducing gas-producing foods; fibre supplements, if constipation is a primary symptom; and anti-diarrhoeal medications, when diarrhoea is a primary symptom.
There are two prescription medications for specific IBS cases: Lotronex, for women with diarrhoea dominant IBS not responding to other treatments; and Amitiza, for constipation dominant IBS.
Around 20% of people have IBS symptoms, with women affected at about twice the rate of men