Kamis, 20 September 2012
Yogurt Fights High Blood Pressure
Adding more yogurt to your diet without increasing the number of calories you eat may help lower your risk of high blood pressure, according to new research presented at the American Heart Association's High Blood Pressure Research 2012 Scientific Sessions.
A recent study found long-term yogurt-eaters were less likely to develop high blood pressure and on average had lower systolic blood pressure than those who didn't eat yogurt. Systolic blood pressure is the top number in a blood pressure reading. It measures the force of blood against the walls of your arteries when your heart is beating.
During the 15 year study, researchers followed more than 2,000 volunteers who did not have high blood pressure at the start of the study. Yogurt consumption was measured by questionnaires filled out by the volunteers at three intervals over the study period. Study participants were 31 percent less likely to develop high blood pressure if at least 2 percent of their daily calories came from yogurt, which would be like eating at least one six-ounce cup of low-fat yogurt every three days. In addition, their systolic blood pressure increased less than that of people who didn't eat yogurt.
Rabu, 19 September 2012
Exercise too much and you won't lose weight!
The amount of weight loss induced by exercise is often disappointing. A diet-induced negative energy balance triggers compensatory mechanisms, e.g., lower metabolic rate and increased appetite. However, knowledge about potential compensatory mechanisms triggered by increased aerobic exercise is limited. A randomized controlled trial was performed in healthy, sedentary, moderately overweight young men to examine the effects of increasing doses of aerobic exercise on body composition, accumulated energy balance, and the degree of compensation.
A moderate dose of exercise induced a markedly greater weight loss, than a higher dose.
No statistically significant changes were found in energy intake or nonexercise physical activity that could explain the different compensatory responses associated with 30 vs. 60 min of daily aerobic exercise. In conclusion, a similar body fat loss was obtained regardless of exercise dose.
Related article
Selasa, 18 September 2012
Scientists conclude high fructose corn syrup should not be blamed for obesity
A new article published today in International Journal of Obesity found there is no evidence to suggest the current obesity epidemic in the United States can be specifically blamed on consumption of high fructose corn syrup (HFCS).
The commentary concludes that after an extensive review of all available HFCS research, there is overwhelming evidence showing HFCS is nutritionally equivalent to sugar. This opinion is in-line with the American Medical Association and the Academy of Nutrition and Dietetics, both of which concluded that HFCS is not a unique cause of obesity.
The authors state that while there has been a large amount of debate in the media about the impact of HFCS on obesity levels, the fact is "Sucrose (sugar) and HFCS are very similar in composition….and are absorbed identically in the human GI tract."
"The public discussion about HFCS will likely continue to rage on and more studies will be conducted," said James M. Rippe, M.D., Founder and Director of the Rippe Lifestyle Institute, and Professor of Biomedical Sciences at the University of Central Florida, one of the article's authors. "However, at this point there is simply no evidence to suggest that the use of HFCS alone is directly responsible for increased obesity rates or other health concerns."
The article goes on to discuss a number of research trials that have been conducted on the issue of HFCS and obesity, and concludes that at this time the evidence shows no short-term health differences between the use of HFCS or sugar could be detected in humans. Weight gain, glucose levels, insulin and appetite were not adversely affected by the use HFCS over sugar.
The commentary was co-authored with Dr. Rippe by David M. Klurfeld, Ph.D. of the USDA Agricultural Research Service, John Foreyt, Ph.D. of Baylor College of Medicine, and Theodore J. Angelopoulos, Ph.D., MPH Professor and Director, Laboratory of Applied Physiology Department of Health Professions at University of Central Florida.
HFCS was developed in the mid-1960's as a more flexible alternative to sugar and was widely embraced by the food industry. The use of HFCS grew rapidly from 1970-1999 where usage peaked. Since 1999, the use of HFCS has declined while obesity rates have continued to rise. Sucrose is still the dominant sweetener worldwide with over nine times the consumption of HFCS.
Jumat, 14 September 2012
Geneticists verify cholesterol-cancer link
University of Rochester Medical Center scientists discovered new genetic evidence linking cholesterol and cancer, raising the possibility that cholesterol medications could be useful in the future for cancer prevention or to augment existing cancer treatment.
The data, published in the online journal Cell Reports, support several recent population-based studies that suggest individuals who take cholesterol-lowering drugs may have a reduced risk of cancer, and, conversely that individuals with the highest levels of cholesterol seem to have an elevated risk of cancer.
The cancer-cholesterol question has been debated since the early 20th century, and along with it doctors and scientists have observed various trends and associations. However, until now genetic evidence directly linking cholesterol and malignancy has been lacking, said senior author Hartmut (Hucky) Land, Ph.D., Robert and Dorothy Markin Professor and chair, Department of Biomedical Genetics, and director of research and co-director of the James P. Wilmot Cancer Center at URMC.
"Scientifically it is very satisfying to have data that support longstanding ideas about cholesterol in the context of cancer," Land said. "Our paper provides a rationale for cholesterol targeting as a potentially fruitful approach to cancer intervention or prevention strategies."
Cholesterol is a fat-like substance supplied in foods and made in cells throughout the body. Too much cholesterol is bad for the heart and vascular system. It is typically measured as serum cholesterol by routine blood tests.
Unlike serum cholesterol that is bound to proteins, however, cholesterol also hides inside cells. While locked inside cell membranes before it is eventually exported, cholesterol has an impact on cell growth and survival. A gene, known as ABCA1, is at the crossroads of the process that shuttles intracellular cholesterol outbound.
Several years ago while conducting unrelated experiments that were published in the journal Nature, Land and colleagues first noticed the importance of ABCA1. At that time, they identified a network of approximately 100 so-called "cooperation response genes" that mediate the action of cancer genes. ABCA1 was found among these genes and is frequently turned off in presence of other mutant cancer genes.
In the latest investigation, Land and co-author Bradley Smith, Ph.D., a post-doctoral fellow in the Land lab, wanted to further understand the role of ABCA1 and cholesterol in cancer. They found that defective cholesterol exportation appears to be a key component in a variety of cancers.
The proper function of ABCA1, in fact, is critical for sensing of cell stress. If ABCA1 function is lost in cancer cells, cholesterol is allowed to build up in the cells' mitochondria, or energy centers, making their membranes more rigid. This in turn inhibits the function of cell-death triggers that normally become activated in response to cell stresses, as for example cancer gene activation. Therefore, when functioning properly ABCA1 has anti-cancer activity – in the sense that by keeping mitochondrial cholesterol low it protects the functioning of cellular stress response systems and acts as a barrier to tumor formation and progression.
Smith and Land also demonstrated that some of the relatively rare ABCA1 mutations found in human colon cancers by other investigators disabled the gene's ability to export cholesterol. And by re-establishing the cholesterol export function in human colon cancer cells, they inhibited the cells' ability to grow as cancers when grafted onto mice.
The URMC study, therefore, is the first to directly show how ABCA1 loss-of-function and cholesterol may play a role in cancer.
Millions of Americans take cholesterol-lowering drugs or statins, as prescribed by physicians. The drugs work by blocking the action of key enzymes in the liver, which synthesizes cholesterol. Clinical trials also are evaluating statins as a tool against cancer, and some previous studies suggest that when used in combination with chemotherapy, statins might make chemotherapy more effective by sensitizing certain cancer cells to chemotherapy-induced cell death.
Land, however, urges caution and further study. Doctors do not know the appropriate statin dose for cancer prevention or treatment of cancer-related conditions. Side effects cannot be ignored either, and little research has distinguished between the responses among people who take statins.
"The link between cholesterol and cancer is clear," Land said, "but it's premature to say that statins are the answer."
Exercise May Protect Against Future Emotional Stress
Moderate exercise may help people cope with anxiety and stress for an extended period of time post-workout, according to a study by kinesiology researchers in the University of Maryland School of Public Health published in the journal Medicine and Science in Sports and Exercise.
"While it is well-known that exercise improves mood, among other benefits, not as much is known about the potency of exercise's impact on emotional state and whether these positive effects endure when we're faced with everyday stressors once we leave the gym," explains J. Carson Smith, assistant professor in the Department of Kinesiology. "We found that exercise helps to buffer the effects of emotional exposure. If you exercise, you'll not only reduce your anxiety, but you'll be better able to maintain that reduced anxiety when confronted with emotional events."
Smith, whose research explores how exercise and physical activity affect brain function, aging and mental health, compared how moderate intensity cycling versus a period of quiet rest (both for 30 minutes) affected anxiety levels in a group of healthy college students. He assessed their anxiety state before the period of activity (or rest), shortly afterward (15 minutes after) and finally after exposing them to a variety of highly arousing pleasant and unpleasant photographs, as well as neutral images. At each point, study participants answered 20 questions from the State-Trait Anxiety inventory, which is designed to assess different symptoms of anxiety. All participants were put through both the exercise and the rest states (on different days) and tested for anxiety levels pre-exercise, post-exercise, and post-picture viewing.
Smith found that exercise and quiet rest were equally effective at reducing anxiety levels initially. However, once they were emotionally stimulated (by being shown 90 photographs from the International Affective Picture System, a database of photographs used in emotion research) for ~20 minutes, the anxiety levels of those who had simply rested went back up to their initial levels, whereas those who had exercised maintained their reduced anxiety levels.
"The set of photographic stimuli we used from the IAPS database was designed to simulate the range of emotional events you might experience in daily life," Smith explains. "They represent pleasant emotional events, neutral events and unpleasant events or stimuli. These vary from pictures of babies, families, puppies and appetizing food items, to very neutral things like plates, cups, furniture and city landscapes, to very unpleasant images of violence, mutilations and other gruesome things."
The study findings suggest that exercise may play an important role in helping people to better endure life's daily anxieties and stressors.
Smith plans to explore if exercise could have the same persistent beneficial effect in patients who regularly experience anxiety and depression symptoms. In collaboration with the new Maryland Neuroimaging Center, he is also exploring the addition of functional magnetic resonance imaging, or fMRI, to measure brain activity during the period of exposure to emotionally stimulating images to see how exercise may alter the brain's emotion-related neural networks.
Smith also investigates the role of exercise in preventing cognitive decline in older adults. His research has shown that physical activity promotes changes in the brain that may protect those at high risk for Alzheimer's disease.
A healthy outlook leads to a healthy lifestyle
Researchers from the Melbourne Institute of Applied Economic and Social Research analysed data on the diet, exercise and personality type of more than 7000 people.
The study found those who believe their life can be changed by their own actions ate healthier food, exercised more, smoked less and avoided binge drinking.
Professor Deborah Cobb-Clark, Director of the Melbourne Institute of Applied Economic and Social Research, said those who have a greater faith in ‘luck’ or ‘fate’ are more likely to live an unhealthy life.
“Our research shows a direct link between the type of personality a person has and a healthy lifestyle,“ she said.
Professor Cobb-Clark hoped the study would help inform public health policies on conditions such as obesity.
“The main policy response to the obesity epidemic has been the provision of better information, but information alone is insufficient to change people’s eating habits,” she said.
“Understanding the psychological underpinning of a person’s eating patterns and exercise habits is central to understanding obesity.”
The study also found men and women hold different views on the benefits of a healthy lifestyle.
Men wanted physical results from their healthy choices, while women were more receptive to the everyday enjoyment of leading a healthy lifestyle.
Professor Cobb-Clarke said the research demonstrated the need for more targeted policy responses.
“What works well for women may not work well for men,” she said.
“Gender specific policy initiatives which respond to these objectives may be particularly helpful in promoting healthy lifestyles.”
Kamis, 13 September 2012
Portion Control Program w/o Food Limits Works For Weight Loss
Effect of a Novel Food Portion Control Program (Lifesize®) on Dietary Intake and Body Weight
Study by Colorado State University
Background: Food portion sizes have increased in the U.S. which contributes to excess energy intake.
Objective: We determined the effect on body weight, energy intake, and dietary energy density of a portion control program (Lifesize(R)) that encourages free choice of foods, but limits portion sizes while allowing unlimited consumption of fruits, vegetables, and low_ fat dairy.
Methods: 22 overweight and obese subjects (n= 19 females, n=3 males; X (SD) age= 40(12); X BMI= 30.0(2.4) kg/m2) completed a 12_ week portion_control program. Participants used measuring devices to limit quantities of energy_dense foods. Body weights were recorded bi_ weekly and 3_day dietary records were collected at baseline, and weeks 1,6, and 12.
Results: Reported energy intake during the 12 weeks decreased by ~500 kcal/d compared to baseline, and mean weight loss was 2.4 kg. Relative intake of fruits and vegetables significantly increased from baseline at week 1 (X=+125.9 g/1000Kcal), week 6 (X= +80.7 g/1000Kcal), and week 12 (X= +192.6 g/1000Kcal). Despite free access to ‘favorite foods’, participants’ energy density (kcal/g food) was significantly decreased.
Conclusion: Including favorite foods while limiting portion sizes and allowing unlimited intake of fruit, vegetables and low_fat dairy may be an effective approach to lowering dietary energy density to elicit weight loss. Funded by Lifesize(R)
Related articles:
NY Times
Huffington Post