Chapter 13. Homeostasis: Active Regulation of the Internal Environment

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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.

Keyword: Obesity
Link ID: 23670 - Posted: 05.29.2017

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.

Keyword: Obesity
Link ID: 23664 - Posted: 05.26.2017

Claude Messier, Alexandria Béland-Millar, The short answer is yes: certain brain regions do indeed consume more energy when engaged in particular tasks. Yet the specific regions involved and the amount of energy each consumes depend on the person’s experiences as well as each brain’s individual properties. Before we delve into the answer, it is important to understand how we measure a brain’s energy expenditure. Picture the colorful brain images researchers use to display neural activity. The colors typically represent the amount of oxygen or glucose various brain regions use during a task. Our brain is always active on some level—even when we are not engaged in a task—but it requires more energy to accomplish something that demands concentration such as moving, seeing or thinking. A simple example is that our primary visual cortex lights up more in brain scans—consuming more energy—when our eyes are open than when they are closed. Similarly, our primary motor cortex uses more energy if we move our hands than if we keep them still. Say you are learning a new skill—how to juggle or speak Spanish. Neuroscientists have made the fascinating observation that when we do something completely novel, a broad range of brain areas becomes active. As we become more skilled at the task, however, our brain becomes more focused: we require only the essential brain regions and need increasingly less energy to perform that task. Once we have mastered a skill—we become fluent in Spanish—only the brain areas directly involved remain active. Thus, learning a new skill requires more brainpower than a well-practiced activity. © 2017 Scientific American

Keyword: Brain imaging
Link ID: 23647 - Posted: 05.23.2017

By Catherine Caruso If you give a mouse a beer, he is going to want a cookie—and another, and another. If you give a person enough beer, she might find herself wolfing down a plate of greasy nachos or some other caloric snack. A study published in January in Nature Communications helps to explain why binge drinking, in both mice and humans, so often leads to binge eating even though alcohol is, itself, high in calories. In the first part of the study, neuroscientists Craig Blomeley and Sarah Cains, both at the Francis Crick Institute Mill Hill Laboratory in London, injected mice with the equivalent of roughly two bottles of wine once a day for three consecutive days, mimicking a weekend of heavy drinking. Sure enough, the inebriated mice ate far more than sober mice in a control group. To figure out why, the researchers then exposed thin-sliced postmortem mouse brains to alcohol and measured the resulting neural activity using fluorescent tags and electrodes. They found that ethanol exposure alters calcium exchange in the cells, causing specialized nerve cells called agouti-related protein (AgRP) neurons to fire more frequently and easily. These neurons normally fire when our body needs calories, and research has shown that activating them artificially will cause mice to chow down even when they are full. The study results suggest that alcohol activates AgRP neurons in the brain, giving drunk mice the munchies. The same is likely true for humans because this brain circuitry has been highly conserved across mammal species, Cains says: “I don't doubt that AgRP neurons are activated in humans, and that's why you see this effect.” © 2017 Scientific American

Keyword: Drug Abuse; Obesity
Link ID: 23645 - Posted: 05.22.2017

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.

Keyword: Obesity; Attention
Link ID: 23639 - Posted: 05.20.2017

By: Ted Dinan, M.D., Ph.D, and John F. Cryan, Ph.D. O ver the past few years, the gut microbiota has been implicated in developmental disorders such as schizophrenia and autism, neurodegenerative disorders such as Alzheimer’s disease and Parkinson’s disease, mood disorders such as depression, and even addiction disorders. It now seems strange that for so many decades we viewed the gut microbiota as bacteria that did us no harm but were of little benefit. This erroneous view has been radically transformed into the belief that the gut microbiota is, in effect, a virtual organ of immense importance. What we’ve learned is that what is commonly referred to as “the brain-gut-microbiota axis” is a bidirectional system that enables gut microbes to communicate with the brain and the brain to communicate back to the gut. It may be hard to believe that the microbes in the gut collectively weigh around three pounds—the approximate weight of the adult human brain—and contain ten times the number of cells in our bodies and over 100 times as many genes as our genome. 1 If the essential microbial genes were to be incorporated into our genomes, it is likely that our cells would not be large enough for the extra DNA. Many of those genes in our microbiota are important for brain development and function; they enable gut bacteria to synthesize numerous neurotransmitters and neuromodulators such as γ-aminobutyric acid (GABA), serotonin, dopamine, and short-chain fatty acids. While some of these compounds act locally in the gut, many products of the microbiota are transported widely and are necessary for the proper functioning of diverse organs. This is a two-way interaction: gut microbes are dependent on us for their nourishment. Any pathological process that reduces or increases food intake has implications for our microbes. © 2017 The Dana Foundation. All Rights Reserved.

Keyword: Parkinsons
Link ID: 23636 - Posted: 05.19.2017

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

Keyword: Obesity
Link ID: 23634 - Posted: 05.19.2017

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.

Keyword: Obesity
Link ID: 23629 - Posted: 05.18.2017

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”.

Keyword: Obesity
Link ID: 23623 - Posted: 05.17.2017

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

Keyword: Obesity; Genes & Behavior
Link ID: 23619 - Posted: 05.16.2017

By GINA KOLATA Researchers have traced the cause of a baffling brain disorder to a surprising source: a particular type of bacteria living in the gut. Scientists increasingly suspect that the body’s vast community of bacteria — the microbiome — may play a role in the development of a wide variety of diseases, from obesity to perhaps even autism. The new study, published on Wednesday in Nature, is among the first to suggest convincingly that these bacteria may initiate disease in seemingly unrelated organs, and in completely unexpected ways. Researchers “need to be thinking more broadly about the indirect role of the microbiome” in influencing even diseases that have no obvious link to the gut, said Dr. David Relman, professor of microbiology and immunology at Stanford. The researchers studied hereditary cerebral cavernous malformations — blood-filled bubbles that protrude from veins in the brain and can leak blood or burst at any time. The findings do not point to a cure, but they do suggest a way to prevent these brain defects in children who inherit a mutated gene that can cause them. Researchers warned, though, that it is too soon to say whether the potential treatment — antibiotics, followed by a fecal transplant — will work. “Caution, caution, caution,” urged Dr. Mark Ginsberg, a professor of medicine at the University of California, San Diego, who was not involved in the new study. Still, he added, “The findings are very convincing.” When Dr. Mark Kahn, professor of cardiovascular medicine at the University of Pennsylvania’s Perelman School of Medicine, began this work, the microbiome was the last thing on his mind. © 2017 The New York Times Company

Keyword: Stroke; Epilepsy
Link ID: 23603 - Posted: 05.11.2017

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.

Keyword: Obesity
Link ID: 23601 - Posted: 05.11.2017

A law in France banning the use of unhealthily thin fashion models has come into effect. Models will need to provide a doctor's certificate attesting to their overall physical health, with special regard to their body mass index (BMI) - a measure of weight in relation to height. The health ministry says the aim is to fight eating disorders and inaccessible ideals of beauty. Digitally altered photos will also have to be labelled from 1 October. Images where a model's appearance has been manipulated will need to be marked photographie retouchée (English: retouched photograph). A previous version of the bill had suggested a minimum BMI for models, prompting protests from modelling agencies in France. Image copyright Getty Images Image caption Models must now provide a doctor's note when applying for jobs But the final version, backed by MPs 2015, allows doctors to decide whether a model is too thin by taking into account their weight, age, and body shape. Employers breaking the law could face fines of up to 75,000 euros (£63,500; $82,000) and up to six months in jail. "Exposing young people to normative and unrealistic images of bodies leads to a sense of self-depreciation and poor self-esteem that can impact health-related behaviour," said France's Minister of Social Affairs and Health, Marisol Touraine, in a statement on Friday, French media report. France is not the first country to legislate on underweight models - Italy, Spain and Israel have all done so. Anorexia affects between 30,000 to 40,000 people in France, 90% of whom are women. © 2017 BBC

Keyword: Anorexia & Bulimia
Link ID: 23588 - Posted: 05.08.2017

By Colleen Kimmett, Dr. Rebecca Carey admits to being a little embarrassed about what her son, Mark, eats every day. Hamburger patties for breakfast, or bacon. A pack of raisins and a cookie for lunch; a turkey and cheese sandwich “if I’m lucky,” says Carey, but it usually comes back home. His favorite dinner is fish cakes and pasta, but all vegetables remain firmly untouched. It’s the kind of diet—low in fruits and vegetables, high in carbs—that a doctor like herself might caution against. But it’s also low in milk, sugar, and artificial food additives — all things Carey believes worsen 10-year-old Mark’s attention deficit hyperactivity disorder, or ADHD, symptoms. Twice a day, in the morning at their home in Newburgh, Ind., and from the school nurse at lunch, he takes a vitamin and mineral supplement, which helps make up for the lack of veggies. It’s been six months on this diet, which Carey researched herself and tested out on Mark, and in that time he has transitioned off his ADHD medication. It wasn’t all smooth sailing; there were fights in the candy section of the grocery store, and Carey struggled to find quick, high-protein breakfasts. “But honestly, I would never go back,” she said. Carey is not the only one who’s trying this approach. Medication and therapy remain the most effective treatments for ADHD. But driven by concerns about the short- and long-term side effects of psychiatric medications on children, some parents are looking for ways to keep their kids on lower doses of the drugs, or to quit the drugs entirely. © 2017 Scientific American

Keyword: ADHD
Link ID: 23568 - Posted: 05.04.2017

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.

Keyword: Obesity
Link ID: 23560 - Posted: 05.02.2017

By NICHOLAS BAKALAR Diabetes may be bad for the brain, especially if you are overweight. Researchers studied 50 overweight and 50 normal weight people in the early stages of Type 2 diabetes. All had been given a diagnosis within the previous five years. They compared both groups with 50 healthy control subjects. The scientists performed M.R.I. examinations of their brains and psychological tests of memory, reaction time and planning. Those with diabetes scored worse than the healthy controls on tests of memory and reaction times. M.R.I. scans revealed significant differences in brain areas related to memory, planning and the visual processing of information. Compared with the controls, those with Type 2 diabetes had more severe thinning of the cortex and more white matter abnormalities. Overweight people with diabetes had more brain deterioration than diabetic people of normal weight. Are these changes reversible? Probably not, according to a co-author, Dr. Donald C. Simonson of Brigham and Women’s Hospital in Boston. “When structural changes are seen on an M.R.I. scan, the processes leading up to them have probably been going on for years,” he said. “On the positive side, patients who maintain good control of their diabetes do seem to have a slower rate of deterioration.” The findings were published in Diabetologia. © 2017 The New York Times Company

Keyword: Learning & Memory; Obesity
Link ID: 23546 - Posted: 04.28.2017

By NICHOLAS BAKALAR A new study links diet soft drinks to an increased risk for stroke and dementia. Researchers studied more than 4,000 people over 45 who had filled out food-frequency questionnaires and had periodic health examinations between 1991 and 2001. The scientists tracked their health over the next 10 years and found 97 cases of stroke and 81 cases of dementia. The study, in the journal Stroke, found that compared with those who did not drink diet soda, people who drank one to six artificially sweetened drinks a week had twice the risk of stroke. There were similar, although weaker, associations for dementia risk. The reasons for the link remain unknown. The study adjusted for age, sex, education, physical activity, diabetes, smoking and many other characteristics that might affect the risks. But the senior author, Dr. Sudha Seshadri, a professor of neurology at Boston University School of Medicine, said that there were additional variables the study could not address. For example, she said, people might have switched to diet soda because they already had cardiovascular problems. Still, she added, there are health benefits associated with some drinks, like tea or coffee, “but not with soda of any kind, either diet or not.” © 2017 The New York Times Company

Keyword: Alzheimers; Stroke
Link ID: 23542 - Posted: 04.27.2017

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,

Keyword: Obesity
Link ID: 23538 - Posted: 04.26.2017

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

Keyword: Obesity; Alzheimers
Link ID: 23535 - Posted: 04.26.2017

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.

Keyword: Obesity; Neurogenesis
Link ID: 23530 - Posted: 04.25.2017