Links for Keyword: Obesity

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Artificial Sweeteners Don't Help People Lose Weight, Review Finds

Katherine Hobson The theory behind artificial sweeteners is simple: If you use them instead of sugar, you get the joy of sweet-tasting beverages and foods without the downer of extra calories, potential weight gain and related health issues. In practice, it's not so simple, as a review of the scientific evidence on non-nutritive sweeteners published Monday shows. After looking at two types of scientific research, the authors conclude that there is no solid evidence that sweeteners like aspartame and sucralose help people manage their weight. And observational data suggest that the people who regularly consume these sweeteners are also more likely to develop future health problems, though those studies can't say those problems are caused by the sweeteners. The health effects of artificial sweeteners are important to study, because so many people use them. Another study published earlier this year found that a quarter of U.S. children and 41 percent of adults reported consuming them, most of them once per day. Even more people may be consuming them unwittingly in products such as granola bars or yogurt. "We were really interested in the everyday person who is consuming these products not to lose weight, but because they think it's the healthier choice, for many years on end," says Meghan Azad, lead author of the review and a research scientist at the University of Manitoba. While more research needs to be done, from what we know now, "there is no clear benefit for weight loss, and there's a potential association with increased weight gain, diabetes and other negative cardiovascular outcomes," says Azad. © 2017 npr

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 23845 - Posted: 07.18.2017

Drinking sugary beverages in pregnancy linked to kids’ later weight gain

Aimee Cunningham An expectant mom might want to think twice about quenching her thirst with soda. The more sugary beverages a mom drank during mid-pregnancy, the heavier her kids were in elementary school compared with kids whose mothers consumed less of the drinks, a new study finds. At age 8, boys and girls weighed approximately 0.25 kilograms more — about half a pound — with each serving mom added per day while pregnant, researchers report online July 10 in Pediatrics. “What happens in early development really has a long-term impact,” says Meghan Azad, an epidemiologist at the University of Manitoba in Canada, who was not involved in the study. A fetus’s metabolism develops in response to the surrounding environment, including the maternal diet, she says. The new findings come out of a larger project that studies the impact of pregnant moms’ diets on their kids’ health. “We know that what mothers eat during pregnancy may affect their children’s health and later obesity,” says biostatistician Sheryl Rifas-Shiman of Harvard Medical School and Harvard Pilgrim Health Care Institute in Boston. “We decided to look at sugar-sweetened beverages as one of these factors.” Sugary drinks are associated with excessive weight gain and obesity in studies of adults and children. Rifas-Shiman and colleagues included 1,078 mother-child pairs in the study. Moms filled out a questionnaire in the first and second trimesters of their pregnancy about what they were drinking — soda, fruit drinks, 100 percent fruit juice, diet soda or water — and how often. Soda and fruit drinks were considered sugar-sweetened beverages. A serving was defined as a can, glass or bottle of a beverage. |© Society for Science & the Public 2000 - 2017

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 13: Memory, Learning, and Development
Link ID: 23820 - Posted: 07.11.2017

Microglia Tied to Weight Gain in Mice

By Aggie Mika Microglia—the brain’s own macrophages—can prompt excess eating and subsequent weight gain in mice fed high-fat diets, according to a study published today (July 5) in Cell Metabolism. The researchers demonstrate that an appetite-promoting inflammatory cascade driven by these immune cells occurs within the mediobasal region of the hypothalamus, a structure that, according to a news release, “contains key groups of neurons that regulate food intake and energy expenditure.” Prior studies have demonstrated that when mice are fed a diet high in saturated fat, they consume more while expending fewer calories, leading them to gain weight, the news release states. Additionally, previous work in both obese mice and humans has also shown that microglia within the hypothalamus increase following high-fat feeding, prompting inflammation, the authors write in their report. In the current study, the researchers examined whether microglial activity in the mediobasal hypothalamus had anything to do with the increased food consumption and weight gain observed in mice consuming diets high in fat. First, they used a drug to wipe out microglia in this region brain and found that microglia-lacking, high-fat consuming mice gained less weight than their non-drugged, high-fat counterparts. They then genetically manipulated mice so that their microglia weren’t capable of mounting an inflammatory response, and these mice also ate less and gained less weight than normal mice on the high-fat diets. © 1986-2017 The Scientist

Mice shed weight when they can’t smell—but not because they stop eating

By Mitch Leslie When you have a stuffy nose, a slice of freshly baked apple pie tastes like mush. But not being able to smell your food could have a surprising effect on your metabolism, potentially helping you remain thin even when you eat fatty foods, a new study in mice suggests. “This is a very exciting study, and the outcome is quite compelling,” says neuroendocrinologist Tamas Horvath of Yale School of Medicine, who wasn’t connected to the research. To conduct the study, molecular biologist Andrew Dillin of the University of California, Berkeley, and colleagues turned to a variety of genetically altered mice. The scientists gave them regular doses of the diphtheria toxin—which causes a temporary loss of odor-sensing neurons—to suppress their sense of smell. They then fed the rodents either a normal diet or fatty foods—the mouse equivalent of cheesecake and pizza—that usually induce obesity. After more than 3 months of noshing on regular chow, the odor-deprived rodents weighed slightly less than mice whose sense of smell was intact. In the group on the high-fat diet, however, the mice that couldn’t smell weighed 16% less than animals that could, which became obese. Losing the ability to smell also caused a different group of already-obese mice to lose weight, the researchers reveal today in Cell Metabolism. © 2017 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 23810 - Posted: 07.06.2017

Losing Fat, Gaining Brain Power, on the Playground

By GRETCHEN REYNOLDS Better grades might be found on the playground. A new study of elementary-age children shows that those who were not part of an after-school exercise program tended to pack on a particular type of body fat that can have deleterious impacts on brain health and thinking. But prevention and treatment could be as simple as playing more games of tag. Most children do not meet the federal health guidelines for exercise, which call for at least an hour of it a day for anyone under the age of 18. Physical inactivity can result in weight gain, especially around the midsection — including visceral fat, a type of tissue deep inside the abdomen that is known to increase inflammation throughout the body. It is also linked to heightened risks for diabetes and cardiovascular complications, even in children, and may contribute to declining brain function: Obese adults often perform worse than people of normal weight on tests of thinking skills. But little has been known about visceral fat and brain health in children. For a soon-to-be-published study, researchers from Northeastern University in Boston and the University of Illinois at Urbana-Champaign tracked hundreds of 8-to-10-year-old children in a nine-month after-school exercise program in Urbana. Every day, one group of children played tag and other active games for about 70 minutes. The subjects in a control group continued with their normal lives, with the promise that they could join the program the following year. All the children completed tests of fitness, body composition and cognitive skills at the start and end of the program. The researchers did not ask the children to change their diets. © 2017 The New York Times Company

More Than 10 Percent of World’s Population Is Obese

By MATT RICHTEL More than 10 percent of the world’s population is now obese, a marked rise over the last 30 years that is leading to widespread health problems and millions of premature deaths, according to a new study, the most comprehensive research done on the subject. Published Monday in The New England Journal of Medicine, the study showed that the problem had swept the globe, including regions that have historically had food shortages, like Africa. The study, compiled by the Institute for Health Metrics and Evaluation at the University of Washington and funded by the Gates Foundation, looked at 195 countries, essentially the world’s population, finding that rates of obesity at least doubled in 73 countries — including Turkey, Venezuela and Bhutan — from 1980 to 2015, and “continuously increased in most other countries.” Analyzing some 1,800 data sets from around the world, researchers found that excess weight played a role in four million deaths in 2015, from heart disease, diabetes, kidney disease and other factors. The per capita death rate was up 28 percent since 1990 and, notably, 40 percent of the deaths were among people who were overweight but not heavy enough to be classified as obese. The study defined obese as a body mass index of 30 or higher and overweight as a B.M.I. from 25 to 29. By those measures, nearly 604 million adults worldwide are obese and 108 million children, the authors reported. Obesity rates among children are rising faster in many countries than among adults. In the United States, 12.5 percent of children were obese, up from 5 percent in 1980. Combining children and adults, the United States had the dubious distinction of having the largest increase in percentile points of any country, a jump of 16 percentage points to 26.5 percent of the overall population. © 2017 The New York Times Company

Pregnancy diet high in refined grains could increase child obesity risk by age 7

Children born to women with gestational diabetes whose diet included high proportions of refined grains may have a higher risk of obesity by age 7, compared to children born to women with gestational diabetes who ate low proportions of refined grains, according to results from a National Institutes of Health study. These findings, which appear online in the American Journal of Clinical Nutrition, were part of the Diabetes & Women’s Health Study, a research project led by NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). Gestational diabetes, or high blood sugar during pregnancy, affects about 5 percent of all pregnancies in the United States and may lead to health problems for mothers and newborns. The authors noted that previous studies have linked diets high in refined grains — such as white rice — to obesity, type 2 diabetes and heart disease. The researchers compared records from 918 mother-child pairs who took part in the Danish National Birth Cohort, a study that followed the pregnancies of more than 91,000 women in Denmark. They found that children born to women with gestational diabetes who consumed the most refined grain (more than 156 grams per day) were twice as likely to be obese at age 7, compared to children born to women with gestational diabetes who ate the least amount of refined grain (less than 37 grams per day). The link between maternal grain consumption during pregnancy and obesity by age 7 still persisted when the researchers controlled for factors that could potentially influence the children’s weight — such as physical activity level and consumption of vegetables, fruit and sweets. The authors called for additional studies to confirm their results and to follow children through later childhood, adolescence and adulthood to see if the obesity risk persists later in life.

Drinking diet beverages during pregnancy linked to child obesity

Children born to women who had gestational diabetes and drank at least one artificially sweetened beverage per day during pregnancy were more likely to be overweight or obese at age 7, compared to children born to women who had gestational diabetes and drank water instead of artificially sweetened beverages, according to a study led by researchers at the National Institutes of Health. Childhood obesity is known to increase the risk for certain health problems later in life, such as diabetes, heart disease, stroke and some cancers. The study appears online in the International Journal of Epidemiology. According to the study authors, as the volume of amniotic fluid increases, pregnant women tend to increase their consumption of fluids. To avoid extra calories, many pregnant women replace sugar-sweetened soft drinks and juices with beverages containing artificial sweeteners. Citing prior research implicating artificially sweetened beverages in weight gain, the study authors sought to determine if diet beverage consumption during pregnancy could influence the weight of children. “Our findings suggest that artificially sweetened beverages during pregnancy are not likely to be any better at reducing the risk for later childhood obesity than sugar-sweetened beverages,” said the study’s senior author, Cuilin Zhang, Ph.D., in the Epidemiology Branch at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). “Not surprisingly, we also observed that children born to women who drank water instead of sweetened beverages were less likely to be obese by age 7.”

The Weight Loss Trap: Why Your Diet Isn't Working

Alexandra Sifferlin Like most people, Kevin Hall used to think the reason people get fat is simple. "Why don't they just eat less and exercise more?" he remembers thinking. Trained as a physicist, the calories-in-vs.-calories-burned equation for weight loss always made sense to him. But then his own research--and the contestants on a smash reality-TV show--proved him wrong. Hall, a scientist at the National Institutes of Health (NIH), started watching The Biggest Loser a few years ago on the recommendation of a friend. "I saw these folks stepping on scales, and they lost 20 lb. in a week," he says. On the one hand, it tracked with widespread beliefs about weight loss: the workouts were punishing and the diets restrictive, so it stood to reason the men and women on the show would slim down. Still, 20 lb. in a week was a lot. To understand how they were doing it, he decided to study 14 of the contestants for a scientific paper. Hall quickly learned that in reality-TV-land, a week doesn't always translate into a precise seven days, but no matter: the weight being lost was real, speedy and huge. Over the course of the season, the contestants lost an average of 127 lb. each and about 64% of their body fat. If his study could uncover what was happening in their bodies on a physiological level, he thought, maybe he'd be able to help the staggering 71% of American adults who are overweight. © 2017 Time Inc.

Obscure brain region linked to feeding frenzy in mice

Laura Sanders Nerve cells in a poorly understood part of the brain have the power to prompt voracious eating in already well-fed mice. Two to three seconds after blue light activated cells in the zona incerta, a patch of neurons just underneath the thalamus and above the hypothalamus, mice dropped everything and began shoveling food into their mouths. This dramatic response, described May 26 in Science, suggests a role in eating behavior for a part of the brain that hasn’t received much scrutiny. Scientists have previously proposed a range of jobs for the zona incerta, linking it to attention, movement and even posture. The new study suggests another job — controlling eating behavior, perhaps even in humans. “Being able to include the zona incerta in models of feeding is going to help us understand it better,” says study coauthor Anthony van den Pol, a neuroscientist at Yale University. The new results may also help explain why a small number of Parkinson’s disease patients develop binge-eating behavior when electrodes are implanted in their brains to ease their symptoms. Those electrodes may be stimulating zona incerta nerve cells, van den Pol suspects. He and his collaborator Xiaobing Zhang, also of Yale, studied the mice with a technique called optogenetics. Mice were engineered so that some nerve cells in the zona incerta fired off signals when hit with blue light. When the light activated these cells, the mice immediately found the food and began eating, the researchers reported. “It’s really quick,” van den Pol says. |© Society for Science & the Public 2000 - 2017.

Want to lose weight? Eat in a crinkly plate

Sarah Boseley in Porto A crinkly plate, designed with ridges that cunningly reduce the amount of food it holds, may be heading for the market to help people concerned about their weight to eat less. The plate is the brainchild of a Latvian graphic designer, Nauris Cinovics, from the Art Academy of Latvia, who is working with a Latvian government agency to develop the idea and hopes to trial it soon. It may look like just another arty designer plate, but it is intended to play tricks with the mind. “My idea is to make food appear bigger than it is. If you make the plate three-dimensional [with the ridges and troughs] it actually looks like there is the same amount of food as on a normal plate – but there is less of it,” said Cinovics. “You are tricking the brain into thinking you are eating more.” The plate will be made of clear glass and could turn eating dinner into a more complex and longer process than it is usually for most of us. Negotiating the folds in the glass where pieces of fish or stray carrots may lurk will slow down the speed with which people get through their meal. Cinovics has also designed heavy cutlery, with the idea of making eating more of a labour – that therefore lasts longer. His knife, fork and spoon weigh 1.3kg each. “We tested this and it took 11 minutes to finish a meal with this cutlery rather than seven minutes,” he said.

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 14: Attention and Consciousness
Link ID: 23639 - Posted: 05.20.2017

How Much Weight Do I Need to Lose to Prevent Diabetes?

By RONI CARYN RABIN Q. How can a blood test determine if I have prediabetes? How much weight do I need to lose to bring my numbers down? A. Doctors typically perform one of three blood tests to diagnose prediabetes, a condition marked by blood sugar (glucose) levels that are higher than normal but not high enough to qualify as diabetes. While prediabetes often leads to full-fledged Type 2 diabetes, many people can hold the condition in check if they lose a relatively small amount of weight and increase their physical activity, said Dr. Rhonda Bentley-Lewis, an assistant professor of medicine at Harvard Medical School. “I stress to my patients that we’re not talking about a huge amount of weight,” she said, “just 5 to 7 percent of one’s body weight” — or 10 to 14 pounds for someone who weighs 200 pounds. Two of the tests require fasting, which helps prevent results being distorted by a prior meal and provides “an even baseline,” Dr. Bentley-Lewis said. One, the fasting plasma glucose test, checks blood glucose levels after an 8 to 10 hour fast; results of 100 to 125 milligrams per deciliter indicate prediabetes. The other, the oral glucose tolerance test, is the most sensitive. It checks blood glucose levels after fasting and then two hours after you consume a sweetened drink; levels of 140 to 199 after the drink indicate prediabetes. A third test, the A1C test, may be the most convenient because it doesn’t require fasting. It measures your average blood glucose levels over the past two to three months; results of 5.7 percent to 6.4 percent, which indicate the percentage of red blood cells that have glucose attached to them, indicate prediabetes. Though doctors often repeat a test to confirm a diabetes diagnosis, they do not always do so for a prediabetes diagnosis, Dr. Bentley-Lewis said. Doctors can treat prediabetes with medication, but many patients prefer to try weight loss and exercise first, Dr. Bentley-Lewis said. Among thousands of people with prediabetes who participated in a national study called the Diabetes Prevention Program, 58 percent of those who adopted lifestyle changes, like losing a modest amount of weight, stepping up physical activity and reducing the amount of fat and calories in their diets, were able to prevent progression to full-blown diabetes. © 2017 The New York Times Company

Swallowable gastric balloon could help the obese lose weight without surgery

Sarah Boseley in Porto A balloon that can be swallowed and then filled with water while in the stomach can help obese people to lose large amounts of weight without invasive surgery, a new study has shown. Bariatric surgery to reduce the size of the stomach is highly effective, but anaesthesia for somebody who is very overweight can be risky. Those who want to undergo the surgery must also undergo a long period of preparation to ready them physically and psychologically. It is expensive, and there is a long waiting list in the UK, even though NHS guidance recommends it be considered. The balloon is swallowed like a pill, but with a long thin tube attached. Ultrasound is used to determine when the balloon is in place in the stomach, and it is then filled with water through the tube. The tube then detaches and is pulled back up the throat and out. Unlike gastric surgery, the balloon is a temporary measure. After 16 weeks, it bursts in the stomach, the water is released and the balloon itself is excreted. A small study presented at the European Congress on Obesity in Porto, Portugal, showed that the 38 patients enrolled in the trial had lost a mean 15.2kg (33.5 lbs) by the end of the 16 weeks, which amounted to about a third (mean 31%) of their excess weight.

No such thing as 'fat but fit', major study finds

Sarah Boseley People who are obese run an increased risk of heart failure and stroke even if they appear healthy, without the obvious warning signs such as high blood pressure or diabetes, according to a major new study. The findings, presented at the European Congress on Obesity in Porto, Portugal, may be the final death knell for the claim that it is possible to be obese but still metabolically healthy – or “fat but fit” – say scientists. Several studies in the past have suggested that the idea of “metabolically healthy” obese individuals is an illusion, but they have been smaller than this one. The new study, from the University of Birmingham, involved 3.5 million people, approximately 61,000 of whom developed coronary heart disease. Is it possible to be healthy and obese? The issue has been controversial. Obesity is usually measured by body mass index (BMI) – a ratio of weight against height. It is generally agreed to be imperfect because athletes and very fit people with dense muscle can have the same BMI as somebody who is obese. The scientists examined electronic health records from 1995 to 2015 in the Health Improvement Network – a large UK general practice database. They found records for 3.5 million people who were free of coronary heart disease at the starting point of the study and divided them into groups according to their BMI and whether they had diabetes, high blood pressure [hypertension], and abnormal blood fats [hyperlipidemia], which are all classed as metabolic abnormalities. Anyone who had none of those was classed as “metabolically healthy obese”.

The Genetics of Pooched-Out Pooches

By ROXANNE KHAMSI What lengths will a dog go to for a bite of sausage? Last November, scientists at the University of Cambridge in Britain persuaded several dozen pet owners to bring their Labrador retrievers to its veterinary school for a true test of will. Inside a mostly empty white room, a research associate let each dog sniff a hot dog before demonstratively placing it inside a small plastic hamster cage on the floor and sealing it shut with black duct tape. Some of the Labs showed only passing interest in the trapped sausage and spent more time exploring the rest of the room. But others stayed laser-focused on the treat. One in particular, a black Labrador named Ash, went into a tizzy, banging the cage around and not giving up until he pried the tape loose with his teeth and ate the hot dog. As it turns out, Ash has more than just determination and a precise tooth grip. He also has a gene mutation linked to obesity. Ash is not overweight, perhaps because his owner keeps him on a rigid diet. But Eleanor Raffan, the researcher who designed the study, suspects his underlying gene mutation and his food-induced frenzy in the experiment are linked. She hasn’t yet analyzed all the data from this latest study, but it has become a mission of hers to understand what makes some canines so voracious. Raffan’s curiosity about this traces back 15 years, to when she became a veterinary surgeon and saw firsthand that certain breeds are more likely than others to put on extra weight. Shortly afterward, when scientists published the first complete dog genome, Raffan decided she wanted to search for DNA mutations that might contribute to heaviness. She got a doctorate in genetics and in 2013 began the GOdogs Project — short for the genetics of obesity in dogs — at Cambridge. She notes that because of the way people have bred dogs, there’s a small gene pool within each breed, making the animals simpler to study: “The way the jiggery-pokery of genetics works means that it’s remarkably easy to get to map the sites where disease-causing genes are in dogs,” Raffan says. © 2017 The New York Times Company

Study beefs up support for brain cells that control protein hunger

Have you ever found yourself craving a steak or a burger? The brain controls our feelings of hunger and also determines the types of nutrients we should be seeking out. Not much is understood about the brain’s regulation of nutrient-specific hunger, but in a new study published in Science, researchers identified the brain cells in fruit flies that regulate protein hunger and were able to control those cells, affecting what the animals ate. The study, was funded by the National Institute of Neurological Disorders and Stroke (NINDS), part of the National Institutes of Health. To study protein hunger, a team of researchers led by Mark Wu, M.D., Ph.D., associate professor of neurology at Johns Hopkins University in Baltimore, starved flies of yeast (the animal’s protein source) for one week. Afterwards, they discovered that the flies ate more yeast and less sugar than flies that ate a control diet. “Flies have been a great model system for brain research so we can learn a lot about how our own brain circuits work by peeking inside the heads of flies,” said Janet He, Ph.D., program director at the NINDS. “A better understanding of the basic mechanisms that regulate the consumption of different nutrients may help to provide clues to addressing the obesity epidemic.” Using novel genetic tools, Dr. Wu’s team identified a specific circuit, a set of brain cells that communicate with one another, which controls protein-seeking behavior. When the circuit was stimulated, flies ate more yeast than normal. In contrast, when the researchers turned off the circuit, the flies ate less yeast. The cells in the circuit were more active, which was demonstrated by increased firing activity, when the flies were starved of yeast. Turning the circuit on or off did not affect the animals’ general hunger or thirst.

Fast or feast? Study shows alternate-day dieting too difficult to sustain

Nicola Davis From Beyoncé to Benedict Cumberbatch, celebrities have flocked to diets based on intermittent fasting, but it turns out such regimes might be less effective than previously thought. Among the diets experiencing a boom in popularity is the alternate-day fasting diet – a regime many experts believed would be more palatable than daily calorie counting for those hoping to lose weight. But a new study suggests it is tougher to stick to than expected, making it no better than a traditional diet in helping people to shed the pounds. “We thought that it would be easier to stick to alternate-day fasting, just because you get that day off every [other] day where you don’t have to diet,” said Krista Varady, co-author of the research from the University of Illinois at Chicago. “We were really just expecting the traditional [daily diet] group to cheat a lot more.” Writing in the journal JAMA Internal Medicine, Varady and colleagues from four US institutions described how they recruited 100 overweight or obese participants, 86% of whom were women, and randomly allocated them to one of three regimes: eating as normal, daily calorie counting and an alternate-day fasting diet. For the first month all participants ate as normal, after which they spent six months on their allocated diet. In the fasting diet, participants consumed 25% of their normal daily calorie intake on the “fast” day, and 125% the following “feast” day, while the calorie-restricted group consumed 75% of their normal calorie intake every day. The third group made no changes to their typical diet.

How Gut Bacteria Tell Their Hosts What to Eat

By Knvul Sheikh Scientists have known for decades that what we eat can change the balance of microbes in our digestive tracts. Choosing between a BLT sandwich or a yogurt parfait for lunch can increase the populations of some types of bacteria and diminish others—and as their relative numbers change they secrete different substances, activate different genes and absorb different nutrients. And those food choices are probably a two-way street. Gut microbes have also been shown to influence diet and behavior as well as anxiety, depression, hypertension and a variety of other conditions. But exactly how these trillions of tiny guests—collectively called the microbiome—influence our decisions on which foods to stuff into our mouths has been a mystery. Now neuroscientists have found specific types of gut flora help a host animal detect which nutrients are missing in food, and then finely titrate how much of those nutrients the host really needs to eat. “What the bacteria do for appetite is kind of like optimizing how long a car can run without needing to add more petrol to the tank,” says senior author Carlos Ribeiro, who studies the eating behaviors of Drosophila melanogaster, a type of fruit fly, at Champalimaud Center for the Unknown in Lisbon. In a paper published Tuesday in PLoS Biology Ribeiro and his team demonstrated how the microbiome influences drosophila’s nutritional decisions. First, they fed one group of flies a sucrose solution containing all the necessary amino acids. Another group got a mix that had some of the amino acids needed to make protein but lacked essential amino acids that the host cannot synthesize by itself. For a third group of flies, the scientists removed essential amino acids from the food one by one to determine which was being detected by the microbiome. © 2017 Scientific American,

Sugary Drinks Tied to Accelerated Brain Aging

By NICHOLAS BAKALAR Drinking sugary beverages is associated with markers of accelerated aging and early signs of Alzheimer’s disease, a new study reports. Researchers used data on more than 4,000 people over 30, examining their brains with M.R.I. and measuring memory with psychological tests. All completed well-validated food frequency questionnaires. Sugary beverage intake is an indirect measure of how much sugar we get in our diets, which is difficult to measure precisely. The authors defined “sugary beverage” to include sodas as well as fruit juices, which may contain added sugars. The study, in Alzheimer’s & Dementia, found that on average, the more sugary drinks consumed, the lower the total brain volume and the lower the scores on memory tests. Brain shrinkage is tied to an increased risk of Alzheimer’s disease. Compared with those who drank no sugary drinks, those who drank one or two a day had a reduced brain volume equivalent to 1.6 years of normal aging, and lower memory scores equivalent to 5.8 years of aging. Those who drank more than two had decreased brain volume equivalent to two years of normal aging and lower memory scores by the equivalent of 11 years. The researchers controlled for diabetes, blood pressure, cholesterol, smoking and many other health and behavioral characteristics. “Although we can’t prove cause and effect, these data suggest that we should be cautious about drinking sugary beverages,” said the lead author, Matthew P. Pase, a senior research fellow at Boston University. “They’re empty calories that contribute to weight gain and metabolic disease.” © 2017 The New York Times Company

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 23535 - Posted: 04.26.2017

Hungry stomach hormone promotes growth of new brain cells

By Clare Wilson Could fasting boost your brainpower? A stomach hormone that stimulates appetite seems to promote the growth of new brain cells and protect them from the effects of ageing – and may explain why some people say that fasting makes them feel mentally sharper. When ghrelin was first discovered, it became known as the hunger hormone. It is made by the stomach when it gets empty, and whenever we go a few hours without food its levels rise in our blood. But there is also evidence that ghrelin can enhance cognition. Animals that have reduced-calorie diets have better mental abilities, and ghrelin might be part of the reason why. Injecting the hormone into mice improves their performance in learning and memory tests, and seems to boost the number of neuron connections in their brains. Now Jeffrey Davies at Swansea University, UK, and his team have found further evidence that ghrelin can stimulate brain cells to divide and multiply, a process called neurogenesis. When they added the hormone to mouse brain cells grown in a dish, it switched on a gene known to trigger neurogenesis, called fibroblast growth factor. If the same effect happens in animals, this could be how ghrelin exerts its effects on memory, says Davies, whose work was presented at the British Neuroscience Association conference this month. © Copyright Reed Business Information Ltd.

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