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Artificial sweeteners may do more than sweeten, and protein needs change by age

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Researchers at the Washington University School of Medicine in St. Louis have found that a popular artificial sweetener can modify how the body handles sugar. The study and/or its abstract, "Sucraolse affects glycemic and hormonal response to an oral glucose load," is available online since April 30, 2013, appearing in the journal Diabetes Care.

In a small study, the researchers analyzed the sweetener sucralose (Splenda®) in 17 severely obese people who do not have diabetes and don't use artificial sweeteners regularly. You also may wish to check out an audio podcast from Washington University BioMed Radio.

Artificial sweeteners are thought to make foods and drinks taste sweet without any of the other consequences that come from sugar. But now studying people who are obese, nutrition researchers at Washington University School of Medicine in St. Louis have found that at least one artificial sweetener does, indeed, affect how the body secretes insulin in response to blood glucose, Jim Dryden reports.

"Our results indicate that this artificial sweetener is not inert — it does have an effect," said first author M. Yanina Pepino, PhD, according to the April 29, 2013 news release, "Artificial sweeteners may do more than sweeten." Pepino is a research assistant professor of medicine. "And we need to do more studies to determine whether this observation means long-term use could be harmful."

Pepino's team studied people with an average body mass index (BMI) of just over 42; a person is considered obese when BMI reaches 30. The researchers gave subjects either water or sucralose to drink before they consumed a glucose challenge test. The glucose dosage is very similar to what a person might receive as part of a glucose-tolerance test. The researchers wanted to learn whether the combination of sucralose and glucose would affect insulin and blood sugar levels.

"We wanted to study this population because these sweeteners frequently are recommended to them as a way to make their diets healthier by limiting calorie intake," Pepino said, according to the news release.

Every participant was tested twice. Those who drank water followed by glucose in one visit drank sucralose followed by glucose in the next. In this way, each subject served as his or her own control group.

"When study participants drank sucralose, their blood sugar peaked at a higher level than when they drank only water before consuming glucose," Pepino explained in the news release. "Insulin levels also rose about 20 percent higher. So the artificial sweetener was related to an enhanced blood insulin and glucose response."

The elevated insulin response could be a good thing, she pointed out, because it shows the person is able to make enough insulin to deal with spiking glucose levels. But it also might be bad because when people routinely secrete more insulin, they can become resistant to its effects, a path that leads to type 2 diabetes.

It has been thought that artificial sweeteners, such as sucralose, don't have an effect on metabolism. They are used in such small quantities that they don't increase calorie intake.

Rather, the sweeteners react with receptors on the tongue to give people the sensation of tasting something sweet without the calories associated with natural sweeteners, such as table sugar. But recent findings in animal studies suggest that some sweeteners may be doing more than just making foods and drinks taste sweeter.

Some sweeteners may be doing more than just making foods and drinks taste sweeter

One finding indicates that the gastrointestinal tract and the pancreas can detect sweet foods and drinks with receptors that are virtually identical to those in the mouth. That causes an increased release of hormones, such as insulin. Some animal studies also have found that when receptors in the gut are activated by artificial sweeteners, the absorption of glucose also increases.

Pepino, who is part of Washington University's Center for Human Nutrition, said those studies could help explain how sweeteners may affect metabolism, even at very low doses. But most human studies involving artificial sweeteners haven't found comparable changes.

"Most of the studies of artificial sweeteners have been conducted in healthy, lean individuals," Pepino said. "In many of these studies, the artificial sweetener is given by itself. But in real life, people rarely consume a sweetener by itself. They use it in their coffee or on breakfast cereal or when they want to sweeten some other food they are eating or drinking."

Just how sucralose influences glucose and insulin levels in people who are obese is still somewhat of a mystery

"Although we found that sucralose affects the glucose and insulin response to glucose ingestion, we don't know the mechanism responsible," said Pepino, according to the news release. "We have shown that sucralose is having an effect. In obese people without diabetes, we have shown sucralose is more than just something sweet that you put into your mouth with no other consequences."

She said further studies are needed to learn more about the mechanism through which sucralose may influence glucose and insulin levels, as well as whether those changes are harmful. A 20 percent increase in insulin may or may not be clinically significant, she added, according to the news release. "What these all mean for daily life scenarios is still unknown, but our findings are stressing the need for more studies," she said in the news release. "Whether these acute effects of sucralose will influence how our bodies handle sugar in the long term is something we need to know."

Funding for this research comes from a National Center for Advancing Translational Sciences (NCATS) Clinical and Translational Sciences Award and subaward and from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) of the National Institutes of Health (NIH). Tate & Lyle provided the sucralose. NIH grant numbers: UL1 R000448, KL2 TR000450, DK0088126, DK37948 and DK56341. Authors of this study are Pepino MY, Tiemann CD, Patterson BW, and Wice BM, Klein S.

Eating protein while young is handled differently by the body than eating it while older

If you're over age 66, when it comes to how your body handles protein, your stage in life matters. A new paper explores the role of dietary protein from the cellular level to the population level. And it doesn't make a difference if the protein comes from vegan sources or meat, if you're over age 66. But for young and middle-aged people, the study explained that the source of the protein mattered. For those young and middle-aged people (in the study) whose sources of protein were heavily plant-based — nuts and legumes — the increased risk of dying of cancer declined and the increased risk of all-cause mortality disappeared altogether.

If you're over age 66, the source of proteins was less important, according to the study. As people age and muscles weaken or turn to fat, in order to reduce the frailty that advances with age, by eating a certain amount of protein could help reduce the loss of weight and muscle mass numerous seniors experience if the older adults have a higher intake of a nutrient that helps sustain and build muscles and maintains a healthy weight.

You may want to check out a March 4, 2014 Los Angeles Times article by Melissa Healy, "High-protein diets: Bad for the middle-aged, good for the elderly," that emphasized how the body's use and need of certain amounts of protein changes between middle age and the years beyond 65. According to a recent study, there's a need for a lesser amount of protein in the diet during the middle-age years, but due to changes with age, a need after age 66, more of a need for dietary protein as people grow older, in order to keep muscle wasting from advancing too fast.

You might want to check out the abstract of the original study online that shows how in older age, fortifying one’s diet with more protein-rich foods appears to be a formula for extending life. The article, "Low Protein Intake Is Associated with a Major Reduction in IGF-1, Cancer, and Overall Mortality in the 65 and Younger but Not Older Population," is published since March 4, 2014 in the journal Cell Metabolism.

The recent study explained that during an 18-year study period, middle-aged Americans who had the highest consumption of protein were more than four times as likely to die of cancer or diabetes, and twice as likely to die of any cause, than those whose diets were lowest in protein

Researchers in the study turned to a database of 6,381 Americans’ health and nutrition behaviors. And what the research team uncovered regarding individuals in the database between the ages of 50 and 65 revealed that following a diet in which protein accounted for 20% or more of daily calories consumed increased the risk of death during the 18-year study period to levels comparable to the effect of smoking cigarettes.

On the other hand, from age 66 and beyond, it's a different story. A certain amount of protein in the diet helped to slow down the advance of muscle wasting and weight loss that leads to frailty in so many older adults.

For Americans over the age of 66, those whose diets were highest in protein were 60% less likely to die of cancer and 28% less likely to die of any cause than were those whose protein intake was lowest

As you age beyond 66, a high-protein diet becomes more beneficial, if taken in moderation. In the study, Americans studied who were over age 66 and who ate higher protein diets had the opposite effect, a group of Americans and Italian researchers found. Now, that's one study. If you eat too much protein, it could affect your eyes. There's been another study on excess protein powders and a possible link to glaucoma, which tends to run in families.

In the recent study on protein intake published March 4, 2014 in Cell Metabolism, researchers found that these associations were either abolished or attenuated if the proteins were plant derived. That means proteins could come from plants, fish, or animals.

The researchers in that new study found, conversely, high protein intake was associated with reduced cancer and overall mortality in respondents over 65, but a 5-fold increase in diabetes mortality across all ages.

High protein intake signals progression of tumors in young and middle aged, but low-protein intake in older age (after age 66) may optimize longevity and healthspan, says the study

Mouse studies confirmed the effect of high protein intake and GHR-IGF-1 signaling on the incidence and progression of breast and melanoma tumors, but also the detrimental effects of a low protein diet in the very old. These results suggest that low protein intake during middle age followed by moderate to high protein consumption in old adults may optimize healthspan and longevity.

The study explains the similarity between mice and humans when it applies to growth hormone. Mice and humans with growth hormone receptor IGF-1 deficiencies display major reductions in age-related diseases. IGF is an abbreviation for insulin growth factor.

The main point of the study, according to its abstract found the following associations or links:

  • High protein intake is linked to increased cancer, diabetes, and overall mortality
  • High IGF-1 levels increased the relationship between mortality and high protein
  • Higher protein consumption may be protective for older adults
  • Plant-derived proteins are associated with lower mortality than animal-derived proteins

Ever-so-slight delay improves decision-making accuracy, say researchers in another study

In another study by different researchers, new findings could improve understanding of ADHD, schizophrenia, and other neuropsychiatric diseases, according to a new study which you can check out (the abstract of the paper) online, "Humans optimize decision-making by delaying decision onset."

Columbia University Medical Center (CUMC) researchers have found that decision-making accuracy can be improved by postponing the onset of a decision by a mere fraction of a second. The results could further our understanding of neuropsychiatric conditions characterized by abnormalities in cognitive function and lead to new training strategies to improve decision-making in high-stake environments. You can check out the abstract of the study, "Humans Optimize Decision-Making by Delaying Decision Onset," published online in the March 5, 2014 issue of the journal PLoS One.

"Decision making isn't always easy, and sometimes we make errors on seemingly trivial tasks, especially if multiple sources of information compete for our attention," says first author Tobias Teichert, PhD, according to the March 7, 2014 news release, "Ever-so-slight delay improves decision-making accuracy." Teichert is a postdoctoral research scientist in neuroscience at CUMC at the time of the study and now an assistant professor of psychiatry at the University of Pittsburgh. "We have identified a novel mechanism that is surprisingly effective at improving response accuracy.

The mechanism requires that decision-makers do nothing—just briefly

"Postponing the onset of the decision process by as little as 50 to 100 milliseconds enables the brain to focus attention on the most relevant information and block out irrelevant distractors," says last author Jack Grinband, PhD, in the news release. Grinband is an associate research scientist in the Taub Institute and assistant professor of clinical radiology (physics). "This way, rather than working longer or harder at making the decision, the brain simply postpones the decision onset to a more beneficial point in time."

In making decisions, the brain integrates many small pieces of potentially contradictory sensory information. "Imagine that you're coming up to a traffic light—the target—and need to decide whether the light is red or green," said Dr. Teichert. "There is typically little ambiguity, and you make the correct decision quickly, in a matter of tens of milliseconds."

The decision process itself, however, does not distinguish between relevant and irrelevant information

So, a task is made more difficult if irrelevant information—a distractor—interferes with the processing of the target. Distractors are present all the time; in this case, it might be in the form of traffic lights regulating traffic in other lanes. Though the brain is able to enhance relevant information and filter out distractions, these mechanisms take time. If the decision process starts while the brain is still processing irrelevant information, errors can occur.

Studies have shown that response accuracy can be improved by prolonging the decision process, to allow the brain time to collect more information. Because accuracy is increased at the cost of longer reaction times, this process is referred to as the "speed-accuracy trade-off." The researchers thought that a more effective way to reduce errors might be to delay the decision process so that it starts out with better information.

The research team conducted two experiments to test this hypothesis

In the first, subjects were shown what looked like a swarm of randomly moving dots (the target stimulus) on a computer monitor and were asked to judge whether the overall motion was to the left or right. A second and brighter set of moving dots (the distractor) appeared simultaneously in the same location, obscuring the motion of the target.

When the distractor dots moved in the same direction as the target dots, subjects performed with near-perfect accuracy, but when the distractor dots moved in the opposite direction, the error rate increased. The subjects were asked to perform the task either as quickly or as accurately as possible; they were free to respond at any time after the onset of the stimulus.

The second experiment was similar to the first, except that the subjects also heard regular clicks, indicating when they had to respond

The time allowed for viewing the dots varied between 17 and 500 milliseconds. This condition simulates real-life situations, such as driving, where the time to respond is beyond the driver's control. "Manipulating how long the subject viewed the stimulus before responding allowed us to determine how quickly the brain is able to block out the distractors and focus on the target dots," says Dr. Grinband, according to the news release.

"In this situation, it takes about 120 milliseconds to shift attention from one stimulus (the bright distractors) to another (the darker targets)," observes Dr. Grinband. "To our knowledge, that's something that no one has ever measured before."

The experiments also revealed that it's more beneficial to delay rather than prolong the decision process

The delay allows attention to be focused on the target stimulus and helps prevent irrelevant information from interfering with the decision process. "Basically, by delaying decision onset—simply by doing nothing—you are more likely to make a correct decision," said Dr. Teichert.

Finally, the results showed that decision onset is, to some extent, under cognitive control. "The subjects automatically used this mechanism to improve response accuracy," said Dr. Teichert. "However, we don't think that they were aware that they were doing so. The process seems to go on behind the scenes. We hope to devise training strategies to bring the mechanism under conscious control."

Justifying procrastination

"This might be the first scientific study to justify procrastination," Dr. Teichert says in the news release. "On a more serious note, our study provides important insights into fundamental brain processes and yields clues as to what might be going wrong in diseases such as ADHD and schizophrenia. It also could lead to new training strategies to improve decision making in complex high-stakes environments, such as air traffic control towers and military combat."

The other author is Vincent P. Ferrera, PhD, associate professor of neuroscience (in psychiatry) and a member of the Mortimer B. Zuckerman Mind Brain Behavior Institute at Columbia. The authors declare no financial or other conflicts of interests. The study was supported by grants from the German Research Foundation (DFG Te819/1-1) to TT and the National Institutes of Health (NIH-MH059244) to VPF.

The Taub Institute for Research on Alzheimer's Disease and the Aging Brain at Columbia University Medical Center is a multidisciplinary group that has forged links between researchers and clinicians to uncover the causes of Alzheimer's, Parkinson's, and other age-related brain diseases and to discover ways to prevent and cure these diseases.

It has partnered with the Gertrude H. Sergievsky Center at Columbia University Medical Center, which was established by an endowment in 1977 to focus on diseases of the nervous system, and with the Departments of Pathology & Cell Biology and of Neurology to allow the seamless integration of genetic analysis, molecular and cellular studies, and clinical investigation to explore all phases of diseases of the nervous system. For more information, visit The Taub Institute website.

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