Chapter 9. Homeostasis: Active Regulation of the Internal Environment

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By Richard Klasco, M.D. A. The theory of the “sugar high” has been debunked, yet the myth persists. The notion that sugar might make children behave badly first appeared in the medical literature in 1922. But the idea did not capture the public’s imagination until Dr. Ben Feingold’s best-selling book, “Why Your Child Is Hyperactive,” was published in 1975. In his book, Dr. Feingold describes the case of a boy who might well be “patient zero” for the putative connection between sugar and hyperactivity: [The mother’s] fair-haired, wiry son loved soft drinks, candy and cake — not exactly abnormal for any healthy child. He also seemed to go completely wild after birthday parties and during family gatherings around holidays. In the mid-’70s, stimulant drugs such as Ritalin and amphetamine were becoming popular for the treatment of attention deficit hyperactivity disorder. For parents who were concerned about drug side effects, the possibility of controlling hyperactivity by eliminating sugar proved to be an enticing, almost irresistible, prospect. Some studies supported the theory. They suggested that high sugar diets caused spikes in insulin secretion, which triggered adrenaline production and hyperactivity. But the data were weak and were soon questioned by other scientists. An extraordinarily rigorous study settled the question in 1994. Writing in the New England Journal of Medicine, a group of scientists tested normal preschoolers and children whose parents described them as being sensitive to sugar. Neither the parents, the children nor the research staff knew which of the children were getting sugary foods and which were getting a diet sweetened with aspartame and other artificial sweeteners. Urine was tested to verify compliance with the diets. Nine different measures of cognitive and behavioral performance were assessed, with measurements taken at five-second intervals. © 2020 The New York Times Company

Keyword: ADHD; Obesity
Link ID: 27060 - Posted: 02.21.2020

Ian Sample Science editor Consuming a western diet for as little as one week can subtly impair brain function and encourage slim and otherwise healthy young people to overeat, scientists claim. Researchers found that after seven days on a high fat, high added sugar diet, volunteers in their 20s scored worse on memory tests and found junk food more desirable immediately after they had finished a meal. The finding suggests that a western diet makes it harder for people to regulate their appetite, and points to disruption in a brain region called the hippocampus as the possible cause. “After a week on a western-style diet, palatable food such as snacks and chocolate becomes more desirable when you are full,” said Richard Stevenson, a professor of psychology at Macquarie University in Sydney. “This will make it harder to resist, leading you to eat more, which in turn generates more damage to the hippocampus and a vicious cycle of overeating.” Previous work in animals has shown that junk food impairs the hippocampus, a brain region involved in memory and appetite control. It is unclear why, but one idea is that the hippocampus normally blocks or weakens memories about food when we are full, so looking at a cake does not flood the mind with memories of how nice cake can be. “When the hippocampus functions less efficiently, you do get this flood of memories, and so food is more appealing,” Stevenson said. To investigate how the western diet affects humans, the scientists recruited 110 lean and healthy students, aged 20 to 23, who generally ate a good diet. Half were randomly assigned to a control group who ate their normal diet for a week. The other half were put on a high energy western-style diet, which featured a generous intake of Belgian waffles and fast food. © 2020 Guardian News & Media Limited

Keyword: Learning & Memory; Obesity
Link ID: 27050 - Posted: 02.19.2020

By Jane E. Brody I’ve long thought the human body was not meant to run on empty, that fasting was done primarily for religious reasons or political protest. Otherwise we needed a reliably renewed source of fuel to function optimally, mentally and emotionally as well as physically. Personal experience reinforced that concept; I’m not pleasant to be around when I’m hungry. There’s even an official name for that state of mind, confirmed by research: Hangry! But prompted by recent enthusiasm for fasting among people concerned about their health, weight or longevity, I looked into the evidence for possible benefits — and risks — of what researchers call intermittent fasting. Popular regimens range from ingesting few if any calories all day every other day or several times a week to fasting for 16 hours or more every day. A man I know in his early 50s said he had lost 12 pounds in about two months on what he calls the 7-11 diet: He eats nothing from 7 p.m. until 11 a.m. the next morning, every day. I was skeptical, but it turns out there is something to be said for practicing a rather prolonged diurnal fast, preferably one lasting at least 16 hours. Mark P. Mattson, neuroscientist at the National Institute on Aging and Johns Hopkins University School of Medicine, explained that the liver stores glucose, which the body uses preferentially for energy before it turns to burning body fat. “It takes 10 to 12 hours to use up the calories in the liver before a metabolic shift occurs to using stored fat,” Dr. Mattson told me. After meals, glucose is used for energy and fat is stored in fat tissue, but during fasts, once glucose is depleted, fat is broken down and used for energy. Most people trying to lose weight should strive for 16 calorie-free hours, he said, adding that “the easiest way to do this is to stop eating by 8 p.m., skip breakfast the next morning and then eat again at noon the next day.” (Caffeine-dependent people can have sugar- free black coffee or tea before lunch.) But don’t expect to see results immediately; it can take up to four weeks to notice an effect, he said. © 2020 The New York Times Company

Keyword: Obesity
Link ID: 27045 - Posted: 02.18.2020

By Jane E. Brody Climate change is not the only source of dire projections for the coming decade. Perhaps just as terrifying from both a health and an economic perspective is a predicted continued rise in obesity, including severe obesity, among American adults. A prestigious team of medical scientists has projected that by 2030, nearly one in two adults will be obese, and nearly one in four will be severely obese. The estimates are thought to be particularly reliable, as the team corrected for current underestimates of weight given by individuals in national surveys. In as many as 29 states, the prevalence of obesity will exceed 50 percent, with no state having less than 35 percent of residents who are obese, they predicted. Likewise, the team projected, in 25 states the prevalence of severe obesity will be higher than one adult in four, and severe obesity will become the most common weight category among women, non-Hispanic black adults and low-income adults nationally. Given the role obesity plays in fostering many chronic, disabling and often fatal diseases, these are dire predictions indeed. Yet, as with climate change, the powers that be in this country are doing very little to head off the potentially disastrous results of expanding obesity, obesity specialists say. Well-intentioned efforts like limiting access to huge portions of sugar-sweetened soda, the scientists note, are effectively thwarted by well-heeled industries able to dwarf the impact of educational efforts by health departments that have minuscule budgets by comparison. With rare exceptions, the sugar and beverage industries have blocked nearly every attempt to add an excise tax to sugar-sweetened beverages. Claims that such a tax is regressive and unfairly targets low-income people is shortsighted, according to Zachary J. Ward, public health specialist at Harvard and the lead author of the new report, published in The New England Journal of Medicine in December. © 2020 The New York Times Company

Keyword: Obesity
Link ID: 27028 - Posted: 02.10.2020

By Nicholas Bakalar Flavonols, a large class of compounds found in most fruits and vegetables, may be associated with a reduced risk for Alzheimer’s disease. Flavonols are known to have antioxidant and anti-inflammatory effects, and animal studies have suggested they may improve memory and learning. A study in Neurology involved 921 men and women, average age 81 and free of dementia, who reported their diet using well-validated food questionnaires. During an average follow-up of six years, 220 developed Alzheimer’s disease. People with the highest levels of flavonol intake tended to have higher levels of education and were more physically active. But after controlling for these factors plus age, sex, the Apo E4 gene (which increases the risk for dementia) and late-life cognitive activity, the scientists found that compared with those in the lowest one-fifth for flavonol intake, those in the highest one-fifth had a 48 percent reduced risk for Alzheimer’s disease. The study covered four types of flavonols: kaempferol, quercetin, isorhamnetin and myricetin. All except quercetin showed a strong association with Alzheimer’s risk reduction. These flavonols are available as supplements, but the lead author, Dr. Thomas M. Holland, a professor of medicine at Rush Medical College in Chicago, said that foods are a better source. “You get a broader intake of vitamins, minerals and bioactives in food than in the supplements,” he said. © 2020 The New York Times Company

Keyword: Alzheimers
Link ID: 27015 - Posted: 02.04.2020

By Gretchen Reynolds In a world that encourages inactivity, even our babies may be moving too little, according to an innovative new study of physical activity patterns during a child’s first year of life. The study, which used tiny activity trackers to monitor babies’ movements, found associations between infants’ squirming, kicking, crawling or stillness and the levels of fat around their middles, raising provocative questions about just how early any links between inactivity and obesity might begin. We already have considerable evidence, of course, that children in the Western world tend to be sedentary. According to recent estimates, most school-age children in the United States sit for more than eight hours a day, while children as young as 2 or 3 years of age can be sedentary for 90 percent or more of their waking hours. These statistics are concerning, because other studies suggest that inactive children face much higher risks of becoming overweight or obese than children who move more often. But little has been known about how much — or little — tiny babies move and if there might be correlations between their activities and their rotundity, and if such correlations matter. So, for the new study, which was published this month in Obesity, a group of researchers from Johns Hopkins University and other institutions decided to fit baby-size trackers to infants’ ankles and watch how they wiggled. They began by turning to new mothers already participating in a large, ongoing study of the health of mothers and newborns and asking if they could now track their babies’ activities. The researchers wound up recruiting 506 young boys and girls from various socioeconomic levels, more than half of them African-American. The researchers visited these infants in their homes when the babies were 3, 6, 9 and 12 months old, weighing and measuring the children, gently checking their body fat with calipers and fitting them with tiny accelerometers. © 2020 The New York Times Company

Keyword: Obesity; Development of the Brain
Link ID: 26978 - Posted: 01.22.2020

By Aaron E. Carroll Childhood obesity is a major public health problem, and has been for some time. Almost 20 percent of American children are affected by obesity, as well as about 40 percent of adults. Over all, this costs the United States around $150 billion in health care spending each year. Pediatricians like me, and many other health professionals, know it’s a problem, and yet we’ve been relatively unsuccessful in tackling it. About six years ago, some reports seemed to show that rates had stabilized in children and even decreased in those ages 2 to 5. Later studies showed this trend to be an illusion. If anything, things have gotten worse. Efforts to help can backfire. People on diets often gain weight. Although individual studies have pointed to potential interventions and solutions, these have not yet translated into actual improvements. Part of the problem may be flawed research. A recent paper in Pediatric Obesity provided a guide on how to do better. Its suggestions fall into five general themes. 1) When things look better, it’s critical to ask “compared to what?” In short, you need a control group. Over time, changes in behaviors or measurements often follow a pattern known as regression toward the mean. Outliers (in this case those who are more overweight) tend to move toward the average. Thus, interventions might look as if they’re working when they’re not. Control groups — participants who don’t receive the intervention — can help ensure that we’re seeing real effectiveness. Even then, things can get tricky. In a randomized controlled trial, it’s important to keep the comparisons directly between the intervention and control groups. A common mistake is comparing each group after the intervention with the same group before the intervention. In other words, people could compare a dieting group to itself, before and after, and compare the control group to itself, before and after, to see if the © 2020 The New York Times Company

Keyword: Obesity
Link ID: 26972 - Posted: 01.20.2020

By Philippa Roxby Health reporter A sleep disorder that can leave people gasping for breath at night could be linked to the amount of fat on their tongues, a study suggests. When sleep apnoea patients lost weight, it was the reduction in tongue fat that lay behind the resulting improvements, researchers said. Larger and fattier tongues are more common among obese patients. But the Pennsylvania team said other people with fatty tongues may also be at risk of the sleep disorder. The researchers now plan to work out which low-fat diets are particularly good at slimming down the tongue. Tongue tied "You talk, eat and breathe with your tongue - so why is fat deposited there?" said study author Dr Richard Schwab, of Perelman School of Medicine, Philadelphia. "It's not clear why - it could be genetic or environmental - but the less fat there is, the less likely the tongue is to collapse during sleep." Sleep apnoea is a common disorder that can cause loud snoring, noisy breathing and jerky movements when asleep. It can also cause sleepiness during the day, which can affect quality of life. The most common type is obstructive sleep apnoea, in which the upper airway gets partly or completely blocked during sleep. Those who are overweight or who have a large neck or tonsils are more likely to have the condition. Researchers at the Perelman School of Medicine, University of Pennsylvania, scanned 67 people with obstructive sleep apnoea who were obese and had lost 10% of their body weight, improving their symptoms improved by 30%. © 2020 BBC.

Keyword: Sleep; Obesity
Link ID: 26946 - Posted: 01.10.2020

By Nicholas Bakalar The right diet might help you sleep better. In a study of 77,860 postmenopausal women, researchers found that consuming foods that had a low glycemic index is associated with a reduced risk for insomnia. Foods with low glycemic indexes — for example, vegetables, nuts and whole grain breads — have carbohydrates that are slowly absorbed and cause lower, and slower, rises in blood glucose and insulin levels after being consumed. For this study, in the American Journal of Clinical Nutrition, participants completed lengthy questionnaires about what foods they ate and how often. They also reported their degree of insomnia at the start of the study and after three years of follow-up. Compared with the one-fifth of participants whose diet had the lowest glycemic index, those with the highest were 11 percent more likely to have insomnia. Some low-glycemic index foods — whole grains and dairy foods, for example — were not associated with reduced insomnia. But people who ate the most fruits and vegetables were about 14 percent less likely to have insomnia, and the largest consumers of fiber were 13 percent less likely. In contrast, women who ate the most refined grains had a 16 percent higher risk of insomnia than those who ate the least. Although the study controlled for many health and behavioral characteristics, the study showed only an association and could not prove cause and effect. “Randomized controlled trials examining dietary patterns in relation to insomnia are needed to clarify these findings,” the authors write. © 2019 The New York Times Company

Keyword: Sleep; Obesity
Link ID: 26917 - Posted: 12.27.2019

New results from the largest long-term study of brain development and children's health raise provocative questions about obesity and brain function. Does excess body weight somehow reduce brain regions that regulate planning and impulse control? Is obesity a result of that brain difference? Or are eating habits, lifestyle, family circumstances and genetics to blame? Previous studies in children and adults have had conflicting results. The new research doesn't settle the matter and outside experts cautioned that misinterpreting it could unfairly perpetuate weight stigma. But an editorial published with the study Monday in JAMA Pediatrics called it an important addition to mounting evidence of a link between weight, brain structure and mental function. If follow-up research confirms the findings, it could lead to new ways to prevent obesity that target improved brain function. "We don't know which direction these relationships go nor do they suggest that people with obesity are not as smart as people at a healthy weight,"said Dr. Eliana Perrin, a Duke University pediatrics professor who co-wrote the editorial. The federally-funded study involved 3,190 U.S. children aged 9 and 10. They had height and weight measurements, MRI brain scans and computer-based tests of mental function including memory, language, reasoning and impulse control. Nearly 1,000 kids — almost 1 in 3 —were overweight or obese, similar to national statistics. Inflammatory changes early in life ©2019 CBC/Radio-Canada

Keyword: Obesity
Link ID: 26888 - Posted: 12.11.2019

By Laura Sanders Bulging stomachs often take the blame for ending holiday indulging. But bulging guts might be the real appetite killer, a study in mice suggests. The results, published November 14 in Cell, could point out new ways to treat obesity, or even help explain how gastric bypass surgeries limit eating. Those procedures result in food moving faster through the stomach into the intestines, stretching the gut in a way that might signal fullness, the authors speculate. Zachary Knight, a neuroscientist at the University of California, San Francisco, and colleagues identified and studied nerve cells in mice’s intestines that sense mechanical stretching. To simulate full intestines, the team activated these nerve cells with light and chemicals. As a result, the mice ate less food. Physically stretching the mice’s intestines with a salty liquid or a diuretic also caused the mice to eat less. Different stretch-sensing cells in the stomach also curbed mice’s appetites, but to a lesser extent, the researchers found. These nerve cell endings relay messages up the vagus nerve (SN: 11/13/15), which then zips signals to the brain. These messages about intestinal stretching help influence the eat-or-not decision, researchers suspect. L. Bai et al. Genetic identification of vagal sensory neurons that control feeding. Cell. Vol. 179, November 14, 2019, p. 1129. doi: 10.1016/j.cell.2019.10.031 © Society for Science & the Public 2000–2019.

Keyword: Obesity
Link ID: 26834 - Posted: 11.20.2019

By David S. Ludwig and Steven B. Heymsfield Most diet trials in the best journals fail even the most basic of quality control measures. That’s the finding of a study by us to be published today in JAMA Network Open. Investigators receiving funding for any clinical trial from the National Institutes of Health must register in advance what they plan to test, among other design features, to ensure that the data are fairly analyzed. Comparing the original registries with the final published studies, we found that diet trials in the past decade were about four times as likely as drug trials to have a discrepancy in the main outcome or measurement — raising concern for bias. This quality-control problem of diet trials in comparison to ones on pharmaceuticals leads to a bigger issue: underinvestment in nutrition research and in how we tackle the mysteries of a healthy diet. Although the problems with observational studies have received much attention (“Association doesn’t prove causation,” as scientists say), clinical trials can suffer from equally important limitations. In a clinical trial, investigators assign volunteers to receive different treatments — such as a a low-carbohydrate versus low-fat diet — ideally in random order. Beyond registry issues, trials may provide misleading results for many reasons, including small size, short duration and weak interventions (they lack power to actually make the intended change in behavior). These failures are disturbing because epidemics of diet-related disease will shorten life expectancy and impose huge economic costs on the United States in coming years. We continue to lack effective dietary prevention, in part because clinical trials have been too poorly designed and conducted to reach definitive conclusions. We’re still debating questions that have raged for decades: Should we focus on reducing carbs or fat? Is red meat harmful? Is sugar toxic? What about artificially sweetened beverages or moderate amounts of alcohol? © 2019 The New York Times Company

Keyword: Obesity
Link ID: 26820 - Posted: 11.14.2019

By Veronique Greenwood When a bird preens its feathers, it uses a little of nature’s own pomade: an oil made by glands just above the tail. This oil helps clean and protect the bird’s plumage, but also contains a delicate bouquet of scents. To other birds — potential mates or would-be rivals — these smells carry many messages, not unlike the birdsongs and fancy feathers that are more obvious to human observers. These scents may signal that a bird would be dangerous to encounter or might be ready to mate, or any number of other cues. However, new research using dark-eyed juncos, a common North American bird, suggests that these odoriferous messages may not be entirely of the bird’s own making. In a study published last month in the Journal of Experimental Biology, biologists reported that microbes living peacefully on the birds’ oil glands may play an important role in making the scent molecules involved. That implies that the birds’ microbiomes may influence both the smell and the behavior it provokes in other birds. Birds’ scented messages are the focus of the research of Danielle Whittaker, managing director of the Beacon Center for the Study of Evolution in Action at Michigan State University and an author of the paper. Some years ago, after she gave a talk, Kevin Theis, a colleague who studied scent-producing bacteria living on hyenas and who is a co-author of the new paper, asked her whether she had ever looked at the birds’ microbes. “I had never thought about bacteria at all,” said Dr. Whittaker. “But all the compounds I was describing were known byproducts of bacterial metabolism.” Dr. Whittaker took samples of bacteria living on the oil glands of 10 captive dark-eyed juncos and then injected the glands with an antibiotic. When she compared the microbes before and after the treatment, the results seemed to show that two groups of bacteria in particular had taken a hit from the treatment. Furthermore, when she compared the scent molecules in the oil before and after the treatment, there were significant differences. © 2019 The New York Times Company

Keyword: Chemical Senses (Smell & Taste)
Link ID: 26812 - Posted: 11.11.2019

By Nicholas Bakalar A healthy diet may help relieve the symptoms of depression. There is good evidence from observational studies that diet can affect mood, and now a randomized controlled trial suggests that healthy eating can modestly improve clinical levels of depression. The study, in PLOS One, randomized 76 college students with poor diet and depression symptoms to two groups. One group was put on a Mediterranean-style diet high in fruits, vegetables, fish, olive oil, nuts and seeds, and low in refined carbohydrates, sugar and saturated fat. The other continued their usual eating habits. At the beginning and end of the three-week trial, all participants were assessed with well-validated scales measuring depression, anxiety, current mood, memory and self-efficacy (confidence in one’s ability to exert control over behavior). Symptoms of depression improved, on average, in the diet group, shifting from the moderate severity range to the normal range. Depressive symptoms among the controls, meanwhile, remained stable, staying within the moderate severity range. On tests of anxiety and stress, the diet group had significantly lower scores than the controls, after controlling for levels of anxiety and stress at the start of the study. There were no differences between the two groups in memory or self-efficacy scores. The study controlled for smoking, physical activity, B.M.I. and other factors. © 2019 The New York Times Company

Keyword: Depression; Obesity
Link ID: 26772 - Posted: 10.31.2019

By Anahad O’Connor In recent years, hospitals and medical centers across the country have stopped selling sugar-sweetened beverages in an effort to reduce obesity and diabetes. Now a new study carried out at the University of California, San Francisco, has documented the health impact of a soda sales ban on its employees. Ten months after a sales ban went into effect, U.C.S.F. workers who tended to drink a lot of sugary beverages had cut their daily intake by about half. By the end of the study period, the group had, on average, reduced their waist sizes and belly fat, though they did not see any changes in their body mass index. Those who cut back on sugary beverages also tended to see improvements in insulin resistance, a risk factor for Type 2 diabetes. The new research, published on Monday in JAMA Internal Medicine, is the first peer-reviewed study to examine whether a workplace sales ban on sugary drinks could lead to reduced consumption of the beverages and improve employee health. At least nine other University of California campuses have said they are going to adopt similar initiatives to reduce sugary beverage sales and promote water consumption. “This was an intervention that was easy to implement,” said Elissa Epel, an author of the study and director of the Aging, Metabolism, and Emotions Center at U.C.S.F. “It’s promising because it shows that an environmental change can help people over the long run, particularly those who are consuming large-amounts of sugary beverages, and possibly even lead to a reduction in their risk of cardiometabolic disease.” In recent years, the link between sugar and obesity has drawn increasing scientific attention. Health authorities say that Americans have gotten fatter because they are consuming too many calories of all kinds. But some experts have singled out the role of added sugar consumption, which increased more than 30 percent between 1977 and 2010. © 2019 The New York Times Company

Keyword: Obesity
Link ID: 26763 - Posted: 10.29.2019

By Kim Tingley In the United States and other Western countries, diet and nutrition researchers face an urgent imperative: Figure out how to solve the crisis of obesity. About 40 percent of the adults and 19 percent of the children and adolescents in the United States have obesity, according to the Centers for Disease Control and Prevention. More and more of them face the increased risks of suffering from diabetes, cardiovascular disease and countless other negative health effects. This situation looks like a single problem from a population standpoint — one that simple guidelines for balancing calorie consumption and expenditure should be able to solve. Instead, a seeming infinitude of variables influence what each of us eats and how the body responds. That is: Obesity, like cancer, “is not one disease,” says Elizabeth Mayer-Davis, a professor of nutrition and medicine at the University of North Carolina at Chapel Hill. In order to treat it, “you really have to be thinking about biology and behavior and society and culture and policy all at the same time. Because if you miss any one of those pieces, your intervention or your diet — it’s less likely to actually work.” The same diet can affect even identical twins differently. “It’s also why there have been so many conflicting studies in nutrition,” Mayer-Davis says. “The public is very frustrated.” Indeed, just last month a paper in Annals of Internal Medicine created controversy when it argued that there’s not enough evidence to say whether red and processed meats are bad for us, despite years of guidance claiming just that. It also reignited a growing debate: How valuable can universal diet guidelines be for individuals? In recent decades, popular weight-loss plans have largely seesawed between low-fat strategies, which U.S. health agencies have also promoted, and low-carbohydrate ones. Many of them appear to work especially well for some people and not well for others; on average, however, in studies comparing the two kinds of regimens, participants lose the same moderate amount of weight. In those cases when opposing diets produce equivalent results, Kevin Hall, a researcher at the National Institutes of Health, wondered if there was, in fact, an explanation other than the nutrients. He noticed that many of those diets tended to have at least one rule in common: Avoid ultraprocessed food, the sort of packaged fare containing artificial flavorings and ingredients you wouldn’t find in your kitchen that make processed food cheap, convenient, tasty and shelf-stable — and popular. It currently accounts for 57 percent of the American diet (a proportion that is rising). Previous studies have found correlations between ultraprocessed-food consumption and obesity but no proof that it’s a cause. © 2019 The New York Times Company

Keyword: Obesity
Link ID: 26749 - Posted: 10.25.2019

By Elizabeth Pennisi The more researchers look, the more connections they find between the microbes in our intestines and those in our brain. Gut bacteria appear to influence everything from depression to autism. Now, a study on how mice overcome fear is starting to reveal more about the mysterious link between gut and mind. “This work is amazing,” says Peng Zheng, a neuroscientist at Chongqing Medical University in China who was not involved with the research. The study, he says, could provide new insight into several mental disorders. The research used a classic Pavlovian test: Shock a mouse on the foot while playing a tone and the rodent will quickly learn to associate the noise with pain, flinching whenever it hears the sound. But the association doesn’t last forever. After several sessions of hearing the tone but not getting the shock, the mouse will forget the association, and the sound will have no effect. This “forgetting” is important for people as well; it’s impaired, for example, in those with chronic anxiety and post-traumatic stress disorder. David Artis, an immunologist and microbiologist at Weill Cornell Medicine in New York City, wondered whether gut bacteria played any role in the learning and forgetting responses. He and colleagues treated mice with antibiotics to totally rid them of the bacteria in their gut, collectively known as the microbiome. They then played a tone and right after gave the mouse a mild shock, doing this multiple times. © 2019 American Association for the Advancement of Science.

Keyword: Obesity
Link ID: 26747 - Posted: 10.24.2019

By Nicholas Bakalar Trans fatty acids, known to increase the risk for heart disease, stroke and diabetes, have now been linked to an increased risk for dementia. Researchers measured blood levels of elaidic acid, the most common trans fats, in 1,628 men and women 60 and older and free of dementia. Over the following 10 years, 377 developed some type of dementia. Trans fats, which are added to processed food in the form of partially hydrogenated vegetable oils, increase levels of LDL, or “bad” cholesterol. Meat and dairy products naturally contain small amounts of trans fats, but whether these fats raise bad cholesterol is unknown. After controlling for other factors, the scientists found that compared with those in the lowest one-quarter in blood levels of elaidic acid, those in the highest were 50 percent more likely to develop any form of dementia and 39 percent more likely to develop Alzheimer’s disease in particular. Elaidic acid levels were not associated with vascular dementia considered alone. The study is in Neurology. The senior author, Dr. Toshiharu Ninomiya, a professor of public health at Kyushu University in Japan, said the study is observational so cannot prove cause and effect. “It is difficult to avoid trans fats completely, and the risk of a small amount of trans fats is unclear,” he said. “But it would be better to try to avoid them as much as possible.” © 2019 The New York Times Company

Keyword: Obesity
Link ID: 26744 - Posted: 10.24.2019

/ By Elizabeth Preston On the first page of Heinz Koop’s fecal analysis test results, a bar showed where he fell on a gradient from green to red. A label above said, in German: “Overall dysbiosis.” Koop was not in the green or even the yellow regions, but a worrisome orange. It was a bad result — but, he says, “I was kind of happy.” Doctors hadn’t given him a satisfying answer about his recurring bloody diarrhea and other gut troubles. But Koop had learned on Facebook that he could test his gut microbiome — the community of bacteria and other organisms living in his gastrointestinal tract — to look for problems. Koop ordered a test from a German laboratory called Medivere. The results said his gut microbes were imbalanced, which was something he thought he could treat. Soon he would be attempting to correct this imbalance by chauffering a friend’s fresh stool samples home to implant up his own colon. Trillions of microbes living on and in our bodies, especially our guts, make up our microbiome. The bugs in our bowel are not just there to slow down our poop, as one researcher speculated in 1970, but are intricately connected to our health. Gut microbes help us digest our food, make critical vitamins, and keep pathogens out. Over the past decade or so, research into the microbiome has exploded as researchers have tried to tease apart the complex connections between our diseases and our resident microbes. Today, at least 10 percent of published microbiome papers use the term dysbiosis to describe changes in the microbiome, estimates Katarzyna Hooks, a computational biologist now at Evotec, a global biotechnology company headquartered in Germany. Some scientists say the term is useful for communicating a specific finding, though they acknowledge its limitations. Other scientists hate it. Copyright 2019 Undark

Keyword: Obesity
Link ID: 26729 - Posted: 10.22.2019

Jon Hamilton Brain scientists are offering a new reason to control blood sugar levels: It might help lower your risk of developing Alzheimer's disease. "There's many reasons to get [blood sugar] under control," says David Holtzman, chairman of neurology at Washington University in St. Louis. "But this is certainly one." Holtzman moderated a panel Sunday at the Society for Neuroscience meeting in Chicago that featured new research exploring the links between Alzheimer's and diabetes. "The risk for dementia is elevated about twofold in people who have diabetes or metabolic syndrome (a group of risk factors that often precedes diabetes)," Holtzman says. "But what's not been clear is, what's the connection?" One possibility involves the way the brain metabolizes sugar, says Liqin Zhao, an associate professor in the school of pharmacy at the University of Kansas. Zhao wanted to know why people whose bodies produce a protein called ApoE2 are less likely to get Alzheimer's. Previous research has shown that these people are less likely to develop the sticky plaques in the brain associated with the disease. But Zhao looked at how ApoE2 affects glycolysis, a part of the process that allows brain cells to turn sugar into energy. So she gave ApoE2 to mice that develop a form of Alzheimer's. And sure enough, Zhao says, the substance not only improved energy production in brain cells but made the cells healthier overall. "All of this together increased the brain's resilience against Alzheimer's disease," she says. © 2019 npr

Keyword: Alzheimers; Obesity
Link ID: 26728 - Posted: 10.22.2019