Thursday, January 31, 2013

An article in the New England Journal of Medicine debunks much of what we think we know about obesity, diets, and weight gain/loss. If the authors' assertions are true, should there be a call for the dissemination of more accurate information to the public and a cessation of misleading product advertising?


Much Fiction Found in Obesity Reporting


Press reports and scientific writing on dieting, weight gain, and obesity are burdened by false or unproven claims, a literature review found.

A search of popular media and scientific literature showed seven myths and six presumptions about obesity were prevalent in text, mostly related to false or unsupported claims about caloric intake or expenditure and dieting, as well as breast feeding, environment, and types of food eaten, according to David Allison, PhD, of the University of Alabama at Birmingham, and colleagues.

Along with pervasive myths and misconceptions, the authors listed nine facts and the practical implications they have for health policy and in clinical recommendations. They published their findings online in the New England Journal of Medicine.

"When the public, mass media, government agencies, and even academic scientists espouse unsupported beliefs, the result may be ineffective policy, unhelpful or unsafe clinical and public health recommendations, and an unproductive allocation of resources," Allison and colleagues noted.

To establish what misinformation was prevalent in popular and scientific literature, the researchers gathered data from Internet searches of mass media and published studies about common myths and misconceptions related to weight gain or loss and obesity.

The authors defined myths as claims that persist despite contradicting evidence, while presumptions and misconceptions were defined as beliefs that persist without supporting scientific evidence.

Myths addressed related to weight loss included the idea that small sustained changes in energy intake or expenditure produce longer-term weight changes; that realistic goal setting leading to fewer frustrated attempted weight-losers; that rapid loss of great weight was associated with poorer long-term weight loss compared with gradual weight loss; and that diet readiness was an important element of weight-loss success.

The authors also pointed out other myths, including the usefulness of play in physical-education classes in weight loss, breast feeding as protection against obesity, and sexual activity as a 100-to-300-calorie-burning activity.

A number of presumptions about obesity included dietary misconceptions, such as the idea that eating breakfast being a protective act against obesity; that eating more fruits and vegetables encourages weight loss or decreases weight gain without other behavioral or environmental changes; and that snacking is a contributor to weight gain and obesity.

Other presumptions were based on misconceptions about activity and environment, including identifying early childhood as the point in time when individuals learn to exercise and eat for the rest of the person's life; associating yo-yo dieting -- quickly regaining weight lost after quickly losing weight -- with worse mortality outcomes; and believing that the presence or absence of parks or sidewalks and other environmental fitness outlets can help or hinder obesity.

"Many of the myths and presumptions about obesity reflect a failure to consider the diverse aspects of energy balance, especially physiological compensation for changes in intake or expenditure," the authors noted.

"The facts that we have about obesity and obesity management are those that should be heeded and really applied to day-to-day operations," Robert Eckel, MD, of the University of Colorado School of Medicine in Denver, told MedPage Today in a video interview.

Two facts that should be emphasized are "the idea of eating less as the way to lose weight, and, perhaps, the more important aspect of physical activity [being] that it should be applied once weight is lost to help sustain weight loss," said Eckel, who was not involved in the study. Eckel is past president of the American Heart Association (AHA) and a contributor to an AHA diet book, "No-Fad Diet: A Personal Plan for Health Weight Loss."

To counteract the misconceptions and myths, the study authors listed nine facts about obesity that could aid in reducing public and practice false beliefs and promote factually supported, healthier lives. These included:
  • Genes as a large contributor to obesity, but not one that cannot be overcome with sufficient environmental influence
  • The importance of dietary intake -- and accompanying lower caloric intake -- in weight management
  • Exercise as a positive factor on health
  • Exercise in sufficient doses -- and accompanying caloric expenditure -- becoming routine as a way to maintain weight loss
  • Involving parents or a home setting in weight-loss programs to help overweight children
  • Structuring meals or use of meal replacement as an aid in weight loss
  • Use of pharmaceutical agents as an effective treatment in weight reduction
  • Adoption of bariatric surgery for long-term weight loss and to decrease rates of incident diabetes and mortality
"The myths and presumptions about obesity that we have discussed are just a sampling of the numerous unsupported beliefs held by many people," they noted, adding that many myths and misconceptions likely remain pervasive because of repeated exposure to them.

Continued research and elimination of "the distortions of scientific information" would cut down on the spread of these fallacies, the authors concluded.

The study was supported by the NIH.
Dr. Allison served as an unpaid board member for the International Life Sciences Institute of North America; received payments from Kraft Foods; received consulting fees from Vivus, Ulmer and Berne, Paul, Weiss, Rifkind, Wharton, Garrison, Chandler Chicco, Arena Pharmaceuticals, Pfizer, National Cattlemen's Association, Mead Johnson Nutrition, Frontiers Foundation, Orexigen Therapeutics, and Jason Pharmaceuticals; received lecture fees from Porter Novelli and the Almond Board of California; received payment for manuscript preparation from Vivus; received travel reimbursement from International Life Sciences Institute of North America; received other support from the United Soybean Board and the Northarvest Bean Growers Association; received grant support through his institution from Wrigley, Kraft Foods, Coca-Cola, Vivus, Jason Pharmaceuticals, Aetna Foundation, and McNeil Nutritionals; and received other funding through his institution from the Coca-Cola Foundation, Coca-Cola, PepsiCo, Red Bull, World Sugar Research Organisation, Archer Daniels Midland, Mars, Eli Lilly and Company, and Merck.
One co-author received payment for board membership from the Global Dairy Platform, Kraft Foods, Knowledge Institute for Beer, McDonald's Global Advisory Council, Arena Pharmaceuticals, Basic Research, Novo Nordisk, Pathway Genomics, Jenny Craig, and Vivus; received lecture fees from the Global Dairy Platform, Novo Nordisk, Danish Brewers Association, GlaxoSmithKline, Danish Dairy Association, International Dairy Foundation, European Dairy Foundation, and AstraZeneca; owned stock in Mobile Fitness; held patents regarding the use of flaxseed mucilage, an alginate for the preparation of an aqueous dietary product, and a method for regulating energy balance for body-weight management.
Two co-authors received grant support from the Coca-Cola Foundation through their institution.
One co-author received grant support from Kraft Foods.
Another co-author received grant support from General Mills Bell Institute of Health and Nutrition.
Another co-author received consulting fees from Kraft Foods.
Another co-author had a licensing agreement for the Volumetrics trademark with Jenny Craig.
Another co-author received consulting fees from Jenny Craig.

Wednesday, January 23, 2013

According to a study done at the Mayo Clinic, the top three reasons patients see a physician are: skin conditions, joint pain, and back pain. With joint and back pain on the rise as the population ages, its more important than ever to choose the right doctor for your needs.

Skin, Joint, and Back Problems Prompt Most Physician Visits

Larry Hand
Jan 22, 2013

Most patients without acute conditions see their physicians not because of diabetes, heart disease, or cancer but because of skin problems, joint disorders, and back pain, according to an article published in the January issue of Mayo Clinic Proceedings.

Jennifer L. St. Sauver, PhD, MPH, from the Division of Epidemiology, Mayo Clinic Center for the Science of Health Care Delivery, Rochester, Minnesota, and colleagues analyzed the medical records of residents of Olmstead County, Minnesota, as of April 1, 2009, through the Rochester Epidemiology Project medical records linkage system.

Spurred on by healthcare reform, the researchers sought to determine how healthcare resources were being used for nonacute conditions. They examined records between January 1, 2005, and December 31, 2009, and categorized patients according to disease group and according to International Classification of Diseases, Ninth Revision (ICD-9), codes.

Of the 146,687 Olmstead residents (53% female) included in the Rochester Epidemiology Project in April 2009, 142,377 (97.1%) consented for their records to be used for research.

"Skin disorders were the most prevalent disease group in this population," the researchers write. "Almost half of the population (42.7%) had at least one ICD-9 code for a skin condition within approximately 5 years." Conditions included actinic keratosis, acne, and sebaceous cysts.

After skin disorders, the most common conditions were osteoarthritis and joint disorders (33.6%), back problems (23.9%), disorders of lipid metabolism (22.4%), and upper respiratory tract disease (22.1%).

The top 10 disease groups varied in prevalence by age and ethnicity. For instance, 0- to 18-year-olds experienced the highest prevalence of skin disorders, whereas patients aged 65 years and older experienced the highest prevalence of hypertension. Blacks had a higher prevalence of back problems and headaches than whites, whites had higher prevalence of skin disorders than blacks and Asians, and Asians had a higher prevalence of diabetes than whites.

"Much research already has focused on chronic conditions, which account for the majority of health care utilization and costs in middle-aged and older adults," Dr. St. Sauver said in a Mayo Clinic news release. "We were interested in finding out about other types of conditions that may affect large segments of the population across all age groups."

Limitations of the study include the inability to validate ICD-9 codes that may have been assigned in error or the possibility that some patients were missed who should have had a code. However, the researchers point out that their prevalence estimates for 10 chronic conditions are similar to published US population estimates.

The researchers write that although skin disorders are not major drivers of disability or death, they may be "important determinants of health care utilization and cost." They recommend that newer models of dermatological care, including teledermatology, should be considered as possible ways to increase care efficiency.

"Finding that skin and back problems are major drivers of health care utilization affirms the importance of moving beyond the commonly recognized health care priorities such as diabetes, heart disease, or cancer," the researchers conclude. "Our findings highlight opportunities to improve health care and decrease costs related to common nonacute conditions as we move forward through the changing health care landscape."

This research was supported by a grant from the Rochester Epidemiology Project and by the Mayo Clinic Center for Translational Science Activities. The authors have disclosed no relevant financial relationships.
 
Mayo Clin Proc. 2013;88:56-67. Full text

Tuesday, January 15, 2013

Once again it seems prevention is a great remedy and now there is good news for women: A new study shows impressive response for natural remedy of eating berries to ward off myocardial infarction.

Berries Ward Off MI in Women

 
By Nancy Walsh, Staff Writer, MedPage Today
Young and middle-age women whose diet included high levels of anthocyanins -- the flavonoids present in red and blue fruits such as strawberries and blueberries -- had a significantly reduced risk for myocardial infarction (MI), a large prospective study found.

Women whose anthocyanin intake was in the highest quintile had a 32% decrease in risk of MI during 18 years of follow-up (HR 0.68, 95% CI 0.49 to 0.96, P=0.03), according to Eric B. Rimm, ScD, of Harvard University, and colleagues.

And in a food-based analysis, women who consumed more than three servings of strawberries or blueberries each week showed a trend towards a lower MI risk, with a 34% decrease (HR 0.66, 95% CI 0.40 to 1.08, P=0.09) compared with women who rarely included these fruits in their diet, the researchers reported online in Circulation.

"Growing evidence supports the beneficial effects of dietary flavonoids on endothelial function and blood pressure, suggesting that flavonoids might be more likely than other dietary factors to lower the risk of [coronary heart disease] in predominantly young women," they observed.

A number of preclinical experiments have demonstrated cardioprotective effects of anthocyanins, including anti-inflammatory effects, plaque stabilization, and inhibition of the expression of growth factors.

While studies have suggested that MI risk is increased in young and middle-age women who smoke or use oral contraceptives, little is known about the influence of diet in this population, whose risk may differ from that in older women.

The younger women may have a greater likelihood of endothelial dysfunction and coronary vasospasm and less obstructive disease.

Because dietary flavonoids -- found in vegetables, fruits, wine, and tea -- are recognized as benefiting endothelial function, the researchers looked at outcomes for 93,600 women enrolled in the Nurses' Health Study II who reported their consumption of various foods and their lifestyle factors every 4 years.

At the time of enrollment, beginning in 1991, participants were ages 25 to 42.

During almost 2 decades of follow-up, there were 405 cases of MI, occurring at a median age of 48.9 years.

Review of the food frequency and lifestyle questionnaires revealed that women who consumed high levels of anthocyanins were less likely to smoke, were more physically active, and had lower fat and higher fiber intake.

The 32% reduction in MI risk was seen after adjustment for multiple factors including body mass index, physical activity, saturated fat intake, use of caffeine and alcohol, and family history of MI.

"This inverse association was independent of established dietary and nondietary [cardiovascular disease] risk," the researchers noted.

Even adding conditions such as hypertension, dyslipidemia, and diabetes to the analytical model did not significantly change the risk estimate (HR 0.70, 95% CI 0.50 to 0.97).

Comparison of risk among women in the highest and lowest 10% of anthocyanin intake showed a relative risk of 0.53 (95% CI 0.33 to 0.86) for the high-intake group, which suggested the presence of a dose-response relationship.

Intake of other types of flavonoids did not significantly lower the risk of MI. The researchers had hypothesized that high intake of flavan-3-ol also would be important, because they had previously identified cardiovascular benefits for one type of flavan-3-ol compound in a meta-analysis.

The lack of effect in the current analysis may have reflected the fact that in the early 1990s, when the study began, most food frequency questionnaires did not include dark chocolate, which is a primary source for flavan-3-ol, they noted.

Adjustment for additional dietary factors such as total fruit and vegetable consumption also did not alter the risk, which suggests "that the benefits are specific to a food constituent in anthocyanin-rich foods (including blueberries, strawberries, eggplants, blackberries, blackcurrants) and not necessarily to nonspecific benefits among participants who consume high intakes of fruits and vegetables."

However, the results of this study do not support the use of flavonoid dietary supplements, according to Michael Rinaldi, MD, of the Carolinas HealthCare System's Sanger Heart and Vascular Institute in Charlotte, N.C.

The study does suggest that a healthy diet that includes fruits and vegetables can be healthy, said Rinaldi, who was not involved in the study.

"On the other hand, if you're going to say that these flavonoid substances in the berries should be taken as supplements, that's not what the study has the power to say," he told MedPage Today in an interview.

Limitations of the study included a lack of information about the results of cardiac catheterization and the possibility of additional unmeasured confounding factors.

In addition, while the model adjusted for intake of a number of other potentially beneficial food components, there may have been other unidentified compounds in fruits that contribute to cardioprotection.

"In a population-based study like ours, it is impossible to disentangle the relative influence of all the constituents of fruits and vegetables," the researchers wrote.

Further research will be needed to identify cardiac biomarkers that could help explain mechanisms of action, to explore dose responses, and to evaluate longer-term clinical endpoints.

The study was funded by the National Institutes of Health, the Department of Health and Human Services, and the U.K. Biotechnology and Biological Sciences Research Council.
The authors reported no financial disclosures.

Friday, January 11, 2013

Has too much "spin" crept into study reports? Well according to the Annals of Oncology: One third of breast cancer studies flawed with bias in reporting efficacy and safety.


A third of randomized clinical trials (RCTs) in breast cancer had published results that showed bias in the reporting of endpoints, and two-thirds showed bias in reporting toxicity, authors of a literature review concluded.

Of 164 studies included in the review, 54 (32.9%) had positive results that were not based on the primary endpoint, which was not statistically different. Authors of the reports "used spin in an attempt to conceal bias," according to an article published online in Annals of Oncology.

The frequency of biased reporting increased to 59% when the analysis was limited to 92 studies that produced nonsignificant differences in primary endpoints.

"Bias in the reporting of efficacy and toxicity remains prevalent," Ian F. Tannock, MD, of the University of Toronto, and co-authors wrote in conclusion. "Clinicians, reviewers, journal editors, and regulators should apply a critical eye to trial reports and be wary of the possibility of biased reporting. Guidelines are necessary to improve the reporting of both efficacy and toxicity."

Because RCTs represent the gold standard for evaluation of a new therapy's efficacy and toxicity, appropriate trial design and objective reporting of results are essential. Bias in reporting can create false impressions about a therapy's safety and efficacy, and clinical decisions may be influenced by the reports, the authors noted in their introduction.

Spin (considered a form of bias) involves use of reporting strategies that emphasize the benefits of an experimental treatment, even when the primary outcome is nonsignificant. Spin might also be used to distract readers from nonsignificant results, the authors continued.

To evaluate the occurrence of bias and spin in breast cancer studies, investigators searched for articles published from 1995 to 2011. They defined bias as inappropriate reporting of the primary endpoint and toxicity, particularly in an article's abstract. Spin was defined as use of terminology in the abstract to suggest that a negative trial was positive, as based on outcomes other than the primary endpoint.

The authors trimmed an initial list of 568 articles to 164, consisting of 148 RCTs of systemic therapy in breast cancer, 11 evaluating radiation therapy, and five involving surgery. The trials were almost equally divided between the adjuvant and metastatic settings.

In 27 trials, overall survival was the primary endpoint, whereas disease-free or progression-free survival was the primary outcome of interest in the remaining 137 studies. In 30 cases, trials were identified as being included in ClinicalTrials.gov, and investigators in seven of those trials changed the primary endpoint in the final report.

Results showed that 72 (43.9%) trials yielded statistically significant differences in the primary endpoint in favor of the experimental arm. The remaining studies showed no difference between the experimental and control arms.

More than 90% of the studies were published in medium- or high-impact journals (median impact factor of 19). Date of publication did not influence bias or spin in reporting, according to the authors.

Limiting their analysis to 92 trials with nonsignificant endpoints, the authors found that almost 54 of the studies exhibited bias in reporting. Authors of negative studies were significantly more likely to exclude the primary endpoint in the concluding statement of the abstract (27% versus 7%, OR 5.15, P=0.001). The probability of bias did not differ between trials in the adjuvant versus metastatic setting.

Examination of toxicity reporting revealed bias in 110 of 164 trials. The authors found a significant association between biased reporting of toxicity and a statistically significant difference in the primary endpoint (OR 2.00, P=0.044). They found no association between bias in reporting toxicity and bias in reporting efficacy.

Biased reporting of toxicity was significantly associated with trials that had overall survival as the primary endpoint (OR 3.30, P=0.028). The journal impact factor and trial setting (adjuvant versus metastatic) did not influence bias in reporting toxicity.

About two-thirds (103) of the RCTs were industry funded. The authors found that the source of funding did not influence the likelihood of bias in reporting efficacy or toxicity.

Acknowledging limitations of the study, the authors noted that they studied only RCTs of breast cancer, excluded trials involving fewer than 200 patients, used subjective measures (bias and spin), used scales based on investigator interpretation of characteristics associated with bias, most of the trials were not included in ClinicalTrials.gov, and they did not search European Clinical Trials Registries.

The authors had no relevant disclosures.

Wednesday, January 9, 2013

Not only is there evidence that soda and other sweetened drinks cause weight gain (including diet drinks as the biggest culprits), but now a new study indicates that the drinks can also cause depression in the elderly.

Sweetened Drinks Hike Depression in Seniors


SAN DIEGO -- Older adults who drink sweetened beverages, and artificially sweetened diet drinks in particular, are at increased risk for depression, a large prospective study suggested.

Individuals ages 50 to 70 who consumed four cans or cups of sweetened soft drinks each day had a 30% increase in risk of developing depression (odds ratio 1.30, 95% CI 1.17 to 1.44, P<0.0001) compared with those who avoided such beverages, according to Honglei Chen, MD, PhD, of the National Institutes of Health in Research Triangle Park, N.C., and colleagues.

The increased risk with diet soda was 31% (OR 1.31, 95% CI 1.16 to 1.47) while that for regular soda was 22% (OR 1.22, 95% CI 1.03 to 1.45), the researchers reported online in advance of presentation at the March annual meeting of the American Academy of Neurology.

In contrast, drinking four cups of coffee daily was associated with an almost 10% lower risk for depression (OR 0.91, 95% CI 0.84 to 0.98, P<0.0001).

"Our research suggests that cutting out or down on sweetened diet drinks or replacing them with unsweetened coffee may naturally help lower your depression risk," Chen said in a statement.

Sweetened drinks and coffee are popular worldwide, and interest has been growing in recent years about the possible health consequences of this consumption.

To explore the possibility that beverage consumption could influence risk for depression, Chen and colleagues enrolled 263,925 older adults and reviewed their beverage intake from 1995 to 1996. A decade later, they asked the participants if they had been diagnosed with depression since 2000.

A total of 11,311 participants reported having had such a diagnosis.

As with soda, consumption of four or more cans or cups of fruit punch was associated with a 38% increase in likelihood for being diagnosed with depression (OR 1.38, 95% CI 1.15 to 1.65, P<0.0001).

Moreover, compared with no consumption of fruit punch, the risk for diet fruit punch rose by 51% (OR 1.51, 95% CI 1.18 to 1.92) while the increased risk with sugar-sweetened fruit punch was nonsignificant at only 8% (OR 0.79 to 1.46), Chen and colleagues reported.

Diet iced tea also was associated with a higher risk (OR 1.25, 95% CI 1.10 to 1.41) than sugar-sweetened iced tea (OR 0.94, 95% CI 0.83 to 1.08).

Further analysis of the specific constituents of these beverages revealed a 36% increase with high aspartame consumption (OR 1.36, 95% CI 1.29 to 1.44) and a 17% decrease with high caffeine intake (OR 0.83, 95% CI 0.78 to 0.89).

"More research is needed to confirm these findings, and people with depression should continue to take depression medications prescribed by their doctors," Chen advised in a statement.

The study was supported by the Intramural Research Programs of the National Institutes of Health, the National Institute of Environmental Health Sciences, and the National Cancer Institute.
The authors are employees of those organizations.

Primary source: American Academy of Neurology
Source reference:
Chen H, et al "Sweetened beverages, coffee, and tea in relation to depression among older U.S. adults" AAN 2013.

Tuesday, January 8, 2013

Are your kids meeting the minimum recommendations of one hour of physical activity and not more than two hours in front of a TV/computer? While the numbers are getting better, children in the U.S. are still falling short. So where do your kids fit in?

Many Kids Not Meeting Physical Activity Goals

Only two out of five U.S. children in elementary school met both the physical activity and screen-time recommendations from the federal government and the American Academy of Pediatrics, researchers found.

Although 70% of children were getting at least 60 minutes of moderate-to-vigorous exercise each day and 54% were sitting in front of a screen for no more than 2 hours a day, only 38% met both criteria, according to Tala Fakhouri, PhD, MPH, of the CDC's National Center for Health Statistics in Hyattsville, Md., and colleagues.

Remaining consistent with one recommendation did not necessarily predict meeting the other recommendation, the researchers reported online in JAMA Pediatrics.

"These findings support the distinct recommendations for screen-time viewing and physical activity by the American Academy of Pediatrics and may inform interventions designed to prevent childhood obesity, such as the First Lady Michelle Obama's program to end childhood obesity within a generation (i.e., the Let's Move! initiative)," the authors wrote.

Fakhouri and colleagues examined cross-sectional data on 1,218 children ages 6 to 11 from the 2009-2010 National Health and Nutrition Examination Survey (NHANES). A proxy, usually a parent, reported how much each child exercised and how much time each child spent watching television, playing video games, or using a computer. They also looked at demographic information, including an income measurement called the family income to poverty level ratio (FIPR).

Differences in the likelihood of meeting the physical activity recommendation were seen for several demographic categories. Those less likely to exercise for at least an hour a day included the following:
  • Girls (OR 0.68, 95% CI 0.51 to 0.92)
  • Children ages 9 to 11 versus younger children (OR 0.60, 95% CI 0.42 to 0.86)
  • Hispanics versus non-Hispanic whites (OR 0.60, 95% CI 0.38 to 0.95)
  • Children in households with an income between 130% to 349% of the FIPR versus those below 130% (OR 0.59, 95% CI 0.35 to 0.99)
  • Children in households with an income of 350% or more of the FIPR versus those below 130% (OR 0.46, 95% CI 0.26 to 0.81)
  • Obese children (OR 0.44, 95% CI 0.32 to 0.60)
There were fewer demographic differences in the likelihood of meeting the screen-time recommendation. Older children (OR 0.61, 95% CI 0.42 to 0.89), non-Hispanic blacks (OR 0.57, 95% CI 0.34 to 0.94), and obese children (OR 0.65, 95% CI 0.48 to 0.88) were less likely to have 2 or fewer hours of screen-time each day compared with their respective comparators.

Hispanics, who were less likely than non-Hispanic whites to meet the physical activity recommendation, were more likely to meet the screen-time recommendation (OR 1.69, 95% CI 1.18 to 2.43), which suggests "that screen-time viewing and physical activity may be separate constructs and that low levels of screen-time viewing do not necessarily predict higher levels of physical activity."

Indeed, the odds of meeting the physical activity recommendation did not differ between the children who did or did not meet the screen-time recommendation.

There were even fewer demographic differences in the likelihood of meeting both recommendations at the same time, which was significantly lower only in the children who were older (OR 0.57, 95% CI 0.38 to 0.85) and obese (OR 0.53, 95% CI 0.38 to 0.73).

One issue with the findings pointed out by the researchers is that in the 2009-2010 NHANES, physical activity was measured only through proxy report, which is subject to social desirability bias and can be influenced by the amount of time the parent spends with the child.

Although activity can be objectively measured with accelerometers, those too have some potential problems involving cutoff values, sampling intervals, inadequate capture of certain activities, and expense.

"Because of these measurement issues," Fakhouri and colleagues wrote, "many researchers and physical activity experts are now advocating for the use of multiple methods to assess physical activity accurately."

The authors reported that they had no conflicts of interest.

Wednesday, January 2, 2013

Did you make a New Year resolution to lose weight? If you haven't heard, avoid foods with fructose or high-fructose syrups which have now been shown on MRI to fail in turning off appetite mechanisms and may well spur over-eating.

e! Science News


Imaging study examines effect of fructose on brain regions that regulate appetite

Published: Wednesday, January 2, 2013 - 00:01 in Health & Medicine
 
In a study examining possible factors regarding the associations between fructose consumption and weight gain, brain magnetic resonance imaging of study participants indicated that ingestion of glucose but not fructose reduced cerebral blood flow and activity in brain regions that regulate appetite, and ingestion of glucose but not fructose produced increased ratings of satiety and fullness, according to a preliminary study published in the January 2 issue of JAMA. "Increases in fructose consumption have paralleled the increasing prevalence of obesity, and high-fructose diets are thought to promote weight gain and insulin resistance.

Fructose ingestion produces smaller increases in circulating satiety hormones compared with glucose ingestion, and central administration of fructose provokes feeding in rodents, whereas centrally administered glucose promotes satiety," according to background information in the article. "Thus, fructose possibly increases food-seeking behavior and increases food intake." How brain regions associated with fructose- and glucose-mediated changes in animal feeding behaviors translates to humans is not completely understood.

Kathleen A. Page, M.D., of Yale University School of Medicine, New Haven, Conn., and colleagues conducted a study to examine neurophysiological factors that might underlie associations between fructose consumption and weight gain. The study included 20 healthy adult volunteers who underwent two magnetic resonance imaging sessions in conjunction with fructose or glucose drink ingestion. The primary outcome measure for the study was the relative changes in hypothalamic (a region of the brain) regional cerebral blood flow (CBF) after glucose or fructose ingestion.

The researchers found that there was a significantly greater reduction in hypothalamic CBF after glucose vs. fructose ingestion. "Glucose but not fructose ingestion reduced the activation of the hypothalamus, insula, and striatum -- brain regions that regulate appetite, motivation, and reward processing; glucose ingestion also increased functional connections between the hypothalamic-striatal network and increased satiety."

"The disparate responses to fructose were associated with reduced systemic levels of the satiety-signaling hormone insulin and were not likely attributable to an inability of fructose to cross the blood-brain barrier into the hypothalamus or to a lack of hypothalamic expression of genes necessary for fructose metabolism."

Editorial: Fructose Ingestion and Cerebral, Metabolic, and Satiety Responses

Jonathan Q. Purnell, M.D., and Damien A. Fair, PA-C, Ph.D., of Oregon Health & Science University, Portland, write in an accompanying editorial that "these findings support the conceptual framework that when the human brain is exposed to fructose, neurobiological pathways involved in appetite regulation are modulated, thereby promoting increased food intake."

"… the implications of the study by Page et al as well as the mounting evidence from epidemiologic, metabolic feeding, and animal studies, are that the advances in food processing and economic forces leading to increased intake of added sugar and accompanying fructose in U.S. society are indeed extending the supersizing concept to the population's collective waistlines."