Stanford researchers develop a new way to identify bacteria in fluids

An innovative adaptation of the technology in an old inkjet printer plus AI-assisted imaging leads to a faster, cheaper way to spot bacteria in blood, wastewater, and more.

Peer-Reviewed Publication

STANFORD UNIVERSITY SCHOOL OF ENGINEERING

 

IMAGE: A DERIVATIVE OF THE STANFORD UNIVERSITY LOGO PRINTED FROM DROPLETS CONTAINING A 1:1 MIXTURE OF STAPHYLOCOCCUS EPIDERMIDIS BACTERIA AND MOUSE RED BLOOD CELLS (RBCS) ONTO A GOLD-COATED SLIDE. DROPLETS WERE PRINTED USING 147 MHZ ACOUSTIC TRANSDUCER. view more 

CREDIT: FAREEHA SAFIR

Shine a laser on a drop of blood, mucus, or wastewater, and the light reflecting back can be used to positively identify bacteria in the sample.

“We can find out not just that bacteria are present, but specifically which bacteria are in the sample – E. coli, Staphylococcus, Streptococcus, Salmonella, anthrax, and more,” said Jennifer Dionne, an associate professor of materials science and engineering and, by courtesy, of radiology at Stanford University. “Every microbe has its own unique optical fingerprint. It’s like the genetic and proteomic code scribbled in light.”

Dionne is senior author of a new study in the journal Nano Letters detailing an innovative method her team has developed that could lead to faster (almost immediate), inexpensive, and more accurate microbial assays of virtually any fluid one might want to test for microbes.

Traditional culturing methods still in use today can take hours if not days to complete. A tuberculosis culture takes 40 days, Dionne said. The new test can be done in minutes and holds the promise of better and faster diagnoses of infection, improved use of antibiotics, safer foods, enhanced environmental monitoring, and faster drug development, says the team.

Old dogs, new tricks

The breakthrough is not that bacteria display these spectral fingerprints, a fact that has been known for decades, but in how the team has been able to reveal those spectra amid the blinding array of light reflecting from each sample.

“Not only does each type of bacterium demonstrate unique patterns of light but virtually every other molecule or cell in a given sample does too,” said first author Fareeha Safir, a PhD student in Dionne’s lab. “Red blood cells, white blood cells, and other components in the sample are sending back their own signals, making it hard if not impossible to distinguish the microbial patterns from the noise of other cells.”

A milliliter of blood – about the size of a raindrop – can contain billions of cells, only a few of which might be microbes. The team had to find a way to separate and amplify the light reflecting from the bacteria alone. To do that, they ventured along several surprising scientific tangents, combining a four-decade-old technology borrowed from computing – the inkjet printer – and two cutting-edge technologies of our time – nanoparticles and artificial intelligence.

“The key to separating bacterial spectra from other signals is to isolate the cells in extremely small samples. We use the principles of inkjet printing to print thousands of tiny dots of blood instead of interrogating a single large sample,” explained co-author Butrus “Pierre” Khuri-Yakub, a professor emeritus of electrical engineering at Stanford who helped develop the original inkjet printer in the 1980s.

“But you can’t just get an off-the-shelf inkjet printer and add blood or wastewater,” Safir emphasized. To circumvent challenges in handling biological samples, the researchers modified the printer to put samples to paper using acoustic pulses. Each dot of printed blood is then just two trillionths of a liter in volume – more than a billion times smaller than a raindrop. At that scale, the droplets are so small they may hold just a few dozen cells.

In addition, the researchers infused the samples with gold nanorods that attach themselves to bacteria, if present, and act like antennas, drawing the laser light toward the bacteria and amplifying the signal some 1500 times its unenhanced strength. Appropriately isolated and amplified, the bacterial spectra stick out like scientific sore thumbs.

The final piece of the puzzle is the use of machine learning to compare the several spectra reflecting from each printed dot of fluid to spot the telltale signatures of any bacteria in the sample.

“It’s an innovative solution with the potential for life-saving impact. We are now excited for commercialization opportunities that can help redefine the standard of bacterial detection and single-cell characterization,” said senior co-author Amr Saleh, a former postdoctoral scholar in Dionne’s lab and now a professor at Cairo University.

Catalyst for collaboration

This sort of cross-disciplinary collaboration is a hallmark of the Stanford tradition in which experts from seemingly disparate fields bring their varying expertise to bear to solve longstanding challenges with societal impact.

This particular approach was hatched during a lunchtime meeting at a café on campus and, in 2017, was among the first recipients of a series of $3 million grants distributed by Stanford’s Catalyst for Collaborative Solutions. Catalyst grants are specifically targeted at inspiring interdisciplinary risk-taking and collaboration among Stanford researchers in high-reward fields such as health care, the environment, autonomy, and security.

While this technique was created and perfected using samples of blood, Dionne is equally confident that it can be applied to other sorts of fluids and target cells beyond bacteria, like testing drinking water for purity or perhaps spotting viruses faster, more accurately, and at lower cost than present methods.

Additional Stanford co-authors include former PhD student Loza Tadesse; research staff Kamyar Firouzi; Niaz Banaei, professor of pathology and of medicine at the School of Medicine; and Stefanie Jeffrey, the John and Marva Warnock Professor, Emerita, in the School of Medicine. Nhat Vu from Pumpkinseed Technologies is also a co-author. Banaei, Dionne, Jeffrey, and Khuri-Yakub are also members of Stanford Bio-X. Dionne is also senior associate vice provost of research platforms/shared facilities, a member of the Cardiovascular Institute and the Wu Tsai Neurosciences Institute, and an affiliate of the Precourt Institute for Energy. Jeffrey is also a member of the Stanford Cancer Institute. Khuri-Yakub is also a member of the Cardiovascular Institute, the Stanford Cancer Institute, and the Wu Tsai Neurosciences Institute.

This research was funded by the Stanford Catalyst for Collaborative Solutions, the Chan Zuckerberg Biohub Investigator Program, the NIH-NCATS-CTSA, the Gates Foundation, the National Science Foundation, the NIH New Innovator Award, and from seed funds from the Stanford Center for Innovation in Global Health. Part of this work was performed at the Stanford Nano Shared Facilities (SNSF) and the Soft & Hybrid Materials Facility (SMF), which are supported by the National Science Foundation and National Nanotechnology Coordinated Infrastructure.

Details of the printed dots on a gold-coated slide (a) where false coloring in the close-up of a single dot shows red blood calls in red and Staphylococcus epidermidis bacteria in blue. The researchers also printed onto an agar-coated slide (b) to show how the dots fare under incubation.

CREDIT

Fareeha Safir

JOURNAL

Nano Letters

DOI

10.1021/acs.nanolett.2c03015 

ARTICLE TITLE

Combining Acoustic Bioprinting with AI-Assisted Raman Spectroscopy for High-Throughput Identification of Bacteria in Blood

ARTICLE PUBLICATION DATE

1-Mar-2023

Integrating humans with AI in structural design

A process that seeks feedback from human specialists proves more effective at optimization that automated systems working alone.

Peer-Reviewed Publication

MASSACHUSETTS INSTITUTE OF TECHNOLOGY                                          

 

IMAGE: THIS SEQUENCE SHOWS AN EXAMPLE OF THE ITERATIVE DESIGN PROCESS IN ACTION. ON TOP, YOU CAN SEE THE AI-DESIGNED INITIAL VERSION OF A SUPPORT BEAM. IN THE SECOND AND THIRD IMAGES, A HUMAN OPERATOR HIGHLIGHTS TWO SUPPORT SEGMENTS AS UNNECESSARY. THE BOTTOM IMAGE SHOWS HOW THE AI SYSTEM INCORPORATES THAT INPUT BY ELIMINATING THOSE SEGMENTS AND STRENGTHENING OTHERS TO COMPENSATE. view more 

CREDIT: COURTESY OF DAT HA AND JOSEPHINE CARSTENSEN; EDITED BY MIT NEWS

Modern fabrication tools such as 3D printers can make structural materials in shapes that would have been difficult or impossible using conventional tools. Meanwhile, new generative design systems can take great advantage of this flexibility to create innovative designs for parts of a new building, car, or virtually any other device.

But such “black box” automated systems often fall short of producing designs that are fully optimized for their purpose, such as providing the greatest strength in proportion to weight or minimizing the amount of material needed to support a given load. Fully manual design, on the other hand, is time-consuming and labor-intensive.

Now, researchers at MIT have found a way to achieve some of the best of both of these approaches. They used an automated design system but stopped the process periodically to allow human engineers to evaluate the work in progress and make tweaks or adjustments before letting the computer resume its design process. Introducing a few of these iterations produced results that performed better than those designed by the automated system alone, and the process was completed more quickly compared to the fully manual approach.

The results are reported this week in the journal Structural and Multidisciplinary Optimization, in a paper by MIT doctoral student Dat Ha and assistant professor of civil and environmental engineering Josephine Carstensen.

The basic approach can be applied to a broad range of scales and applications, Carstensen explains, for the design of everything from biomedical devices to nanoscale materials to structural support members of a skyscraper. Already, automated design systems have found many applications. “If we can make things in a better way, if we can make whatever we want, why not make it better?” she asks.

“It’s a way to take advantage of how we can make things in much more complex ways than we could in the past,” says Ha, adding that automated design systems have already begun to be widely used over the last decade in automotive and aerospace industries, where reducing weight while maintaining structural strength is a key need.

“You can take a lot of weight out of components, and in these two industries, everything is driven by weight,” he says. In some cases, such as internal components that aren’t visible, appearance is irrelevant, but for other structures aesthetics may be important as well. The new system makes it possible to optimize designs for visual as well as mechanical properties, and in such decisions the human touch is essential.

As a demonstration of their process in action, the researchers designed a number of structural load-bearing beams, such as might be used in a building or a bridge. In their iterations, they saw that the design has an area that could fail prematurely, so they selected that feature and required the program to address it. The computer system then revised the design accordingly, removing the highlighted strut and strengthening some other struts to compensate, and leading to an improved final design.

The process, which they call Human-Informed Topology Optimization, begins by setting out the needed specifications — for example, a beam needs to be this length, supported on two points at its ends, and must support this much of a load. “As we’re seeing the structure evolve” on the computer screen in response to initial specification, Carstensen says, “we interrupt the design and ask the user to judge it. The user can select, say, ‘I’m not a fan of this region, I’d like you to beef up or beef down this feature size requirement.’ And then the algorithm takes into account the user input.”

While the result is not as ideal as what might be produced by a fully rigorous yet significantly slower design algorithm that considers the underlying physics, she says it can be much better than a result generated by a rapid automated design system alone. “You don’t get something that’s quite as good, but that was not necessarily the goal. What we can show is that instead of using several hours to get something, we can use 10 minutes and get something much better than where we started off.”

The system can be used to optimize a design based on any desired properties, not just strength and weight. For example, it can be used to minimize fracture or buckling, or to reduce stresses in the material by softening corners.

Carstensen says, “We’re not looking to replace the seven-hour solution. If you have all the time and all the resources in the world, obviously you can run these and it’s going to give you the best solution.” But for many situations, such as designing replacement parts for equipment in a war zone or a disaster-relief area with limited computational power available, “then this kind of solution that catered directly to your needs would prevail.”

Similarly, for smaller companies manufacturing equipment in essentially “mom and pop” businesses, such a simplified system might be just the ticket. The new system they developed is not only simple and efficient to run on smaller computers, but it also requires far less training to produce useful results, Carstensen says. A basic two-dimensional version of the software, suitable for designing basic beams and structural parts, is freely available now online, she says, as the team continues to develop a full 3D version.

“By integrating engineering ‘intuition’ (or engineering ‘judgement’) into a rigorous yet computationally efficient topology optimization process, the human engineer is offered the possibility of guiding the creation of optimal structural configurations in a way that was not available to us before,” he adds. “Her findings have the potential to change the way engineers tackle ‘day-to-day’ design tasks.”

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Written by David Chandler, MIT News Office

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JOURNAL

Structural and Multidisciplinary Optimization

DOI

10.1007/s00158-023-03512-0 

ARTICLE TITLE

“Human-Informed Topology Optimization: interactive application of feature size controls”                                                          

Smithsonian science backs Caribbean Ocean conservation: Panama will protect 54% of its oceans

Business Announcement

SMITHSONIAN TROPICAL RESEARCH INSTITUTE

 

VIDEO: PANAMA, PIONERO AZUL, A SHORT VIDEO DESCRIBING HOW SMITHSONIAN SCIENCE HAS SUPPORTED PANAMA'S CREATION OF NEW MARINE PROTECTED AREAS. view more 

CREDIT: STRI (SMITHSONIAN TROPICAL RESEARCH INSTITUTE)

Within the framework of the Our Ocean Conference on Mar. 2-3, 2023 in Panama City, Panama’s President Laurentino Cortizo and Minister of Environment Milciades Concepción added 36,058 square miles to the Banco Volcán marine protected area in the Caribbean. During the last two decades, researchers at the Smithsonian Tropical Research Institute (STRI) along with local and international collaborators have offered much of the science backing Panama’s successful proposals to create the MPA’s bringing more than 50% of its ocean waters under some form of management or protection.

Created in 2015, with 5,487 square miles, the “Banco Volcán Managed Resources Area” is an area with unique natural resources, such as deep mountain ranges and high biodiversity that includes various migratory species and protected and endangered species, all important for the health of the oceans. The proposal to expand its limits was made in response to a request from the Ministry of the Environment last year, after a review of the protected area by STRI scientist Héctor Guzmán and considering the ecological integrity of the region.

The expansion of the Banco Volcán Marine Protected Area in 2023 has not only led Panama to protect more than 54% of its territorial waters, but will also buffer climate change, protect Panama's deep-sea mountain environments, and help safeguard fauna from human interventions, including several fish and invertebrate species of high commercial value, such as the Caribbean spiny lobster (Panulirus argus). Therefore, this action will have a direct impact on the protection of an important sustainable resource for the indigenous and Afro-Caribbean coastal communities of Panama. In addition, it could maintain the connectivity of migratory routes for oceanic and marine-coastal species in the area that extends along the Caribbean coasts of Jamaica, Colombia, Honduras, Nicaragua, Costa Rica, and Panama.

“With the protection of more than half of its seas, including extensive ocean reserves on both sides of the isthmus, Panama is not only ensuring the conservation of its marine biodiversity and the livelihoods of the people who depend on these ecosystems in the long-term, but is also positioned to lead a much more ambitious regional effort,” said STRI marine biologist and MigraMar co-founder Héctor Guzmán.

STRI has accompanied the Panamanian government with the scientific bases for the creation of new marine protected areas for almost two decades, starting with the Coiba National Park in 2004 and followed by the Las Perlas archipelago in 2007, both in coastal areas of the Pacific Ocean. In 2015, STRI led the design and scientific justification for the creation of the first two oceanic marine protected areas: Banco Volcán in the Caribbean and Cordillera de Coiba in the Pacific, helping Panama to protect 13% of its oceans. With this, the country surpassed the international Aichi target for biological diversity.

A few years later, in 2021, STRI once again supported the Panamanian government with the scientific data for the expansion of the Cordillera de Coiba marine protected area. With this action, Panama achieved a total of 37,926 square miles of marine protected areas throughout the country and met the goal of the United Nations 30x30 Initiative to protect at least 30% of its marine surface by the year 2030.

“The expansion of Banco Volcan is an essential first step for large-scale regional protection of marine biodiversity,” said STRI Director Joshua Tewksbury. “A lot more science by us and by others will be required to ensure that we do the monitoring of this massive area and ensure that specific policy interventions actually create the sustainable ecosystems we all want.”

The Smithsonian Tropical Research Institute, headquartered in Panama City, Panama, is part of the Smithsonian Institution. The Institute furthers the understanding of tropical nature and its importance to human welfare, trains students to conduct research in the tropics and promotes conservation by increasing public awareness of the beauty and importance of tropical ecosystems.      

Map of Panama's extended Marine Protected Areas

 

                

Experiencing racism increases black women’s heart disease risk, BU research finds

New study shows perceived racism in employment, housing, and interactions with the police associated with 26% higher risk of coronary heart disease.

Reports and Proceedings

BOSTON UNIVERSITY

 

IMAGE: BU EPIDEMIOLOGIST SHANSHAN SHEEHY SAYS THE STUDY PROVIDES THE “FIRST LONGITUDINAL EVIDENCE THAT PERCEIVED RACISM IS ASSOCIATED WITH INCREASED RISK OF CORONARY HEART DISEASE.” view more 

CREDIT: PHOTO BY DAVID KEOUGH, CHOBANIAN & AVEDISIAN SCHOOL OF MEDICINE.

More than half of Black women in America aged 20 and older have cardiovascular diseases, according to the American Heart Association, and every year, 50,000 will die as a result. Some researchers have tied Black women’s increased risk of heart disease to genetics, others to higher rates of obesity and diabetes. A new Boston University-led study points to another key factor: experiences of racism.

A team of researchers who followed more than 48,000 Black women over 22 years found those who reported experiencing interpersonal racism in employment, housing, and in interactions with the police had a 26 percent higher risk of coronary heart disease than those who did not. The women were participants in BU’s Black Women’s Health Study, a more than 25-year effort to track the health of 59,000 women in the United States.

“This is the first longitudinal evidence that perceived racism is associated with increased risk of coronary heart disease,” says Shanshan Sheehy, a BU Chobanian & Avedisian School of Medicine assistant professor. “Racism has a real impact on the heart health of Black women.” Sheehy presented the findings at the American Heart Association’s Epidemiology, Prevention, Lifestyle & Cardiometabolic Health Scientific Sessions 2023.

The research kicked off in 1997, when participants—then with a mean age of 40.5—answered a series of questions about their experiences of racism. The first set of questions aimed to get at instances of perceived discrimination and unfair treatment while job hunting or at work, when trying to rent or buy a home, or during a law enforcement stop or search. Another set looked at experiences of interpersonal racism in everyday life: whether the women felt they’d received poorer restaurant service, been looked down upon, or treated as unintelligent, dishonest, or as a threat. Throughout the next 22 years, researchers tracked the women’s wellbeing with biennial mailed and online health questionnaires. All started the study with apparently healthy hearts; by 2019, 1,947 had developed coronary heart disease.

Although the research team discovered an association between a higher probability of heart disease and self-reported experiences of racism in employment, housing, and interactions with the police, they found that racism in everyday life—at a store, in a restaurant—was not linked with an increased risk. Sheehy suspects that’s because while the different types of racism are pernicious and damaging, their relative consequences are varied. Someone discriminated against in a store, she says, may be able to draw on coping mechanisms—like talking with a friend—but missing out on a promotion or a mortgage is much harder to tune out.

“When we think about how racism impacts our health, it’s a psychosocial stressor,” says Sheehy, who’s also affiliated with the BU Slone Epidemiology Center. “It increases your blood pressure, your level of inflammation—all of these biological mechanisms increase your risk of coronary heart disease.”

In past papers, Black Women’s Health Study researchers have also shown a connection between perceived experiences of racism and obesity, reduced cognitive function, insomnia, preterm birth, and many other afflictions. Sheehy and her colleagues say one next step for the coronary heart disease research is to take a deeper dive into the impact of structural racism.

“Structural racism is real—on the job, in educational circumstances, and in interactions with the criminal justice system,” says coauthor Michelle A. Albert, American Heart Association president and a University of California at San Francisco professor of medicine. “Now, we have hard data linking it to cardiovascular outcomes, which means that we as a society need to work on the things that create the barriers that perpetuate structural racism.”

 

This research was funded by the National Institutes of Health. Other study coauthors are Julie R. Palmer, BU Slone Epidemiology Center director and Karin Grunebaum Cancer Research Professor, Medicine; Yvette C. Cozier, a BU School of Public Health associate professor of epidemiology; Lynn Rosenberg, an SPH professor of epidemiology; and Max Brock, a Cook County Health cardiologist.

Pregnant patients with anxiety have altered immune systems

Peer-Reviewed Publication

WEILL CORNELL MEDICINE

The immune system of pregnant women with anxiety is biologically different from that of pregnant women without anxiety, according to new research from Weill Cornell Medicine, Johns Hopkins University School of Medicine and Columbia University Irving Medical Center investigators.

The study, published Sept. 14 in Brain, Behavior and Immunity, demonstrates that pregnant women with anxiety have higher levels of certain immune cells known as cytotoxic T cells; these cells attack infected or otherwise compromised cells within the body. Women with anxiety also showed differences in the activity of immune markers that circulate in the blood. This is the first known study to evaluate the relationship of anxiety to the trajectory of immune changes over the course of pregnancy and the postpartum period.

“Women with anxiety appear to have an immune system that behaves differently from that of healthy women during pregnancy and after delivery,” said principal investigator Dr. Lauren M. Osborne, vice chair for clinical research for the Department of Obstetrics and Gynecology at Weill Cornell Medicine, who conducted the research while on Johns Hopkins University School of Medicine’s faculty. “During pregnancy, a delicate dance is supposed to occur, in which the immune system changes so that it does not reject the fetus but is still strong enough to keep out foreign pathogens.”

This study could encourage better treatment of anxiety in pregnant patients, said Dr. Osborne, who is also a reproductive psychiatrist at NewYork-Presbyterian/Weill Cornell Medical Center. As a clinician, she finds that women with anxiety may resist taking antianxiety medications because they fear the drugs will hurt the baby, despite evidence that they are compatible with pregnancy.

Anxiety during pregnancy, which is self-reported by more than 20 percent of people, according to the researchers, is already known to be detrimental to the parent and child. For example, it can increase the risk of preterm birth and a lower newborn birth weight.

For this study, Dr. Osborne and her colleagues assessed a group of 107 pregnant women, 56 with anxiety and 51 without anxiety, during their second and third trimesters and at six weeks postpartum. The researchers evaluated blood samples for immune activity and conducted psychological evaluations to detect clinical anxiety.

They found that in the women with anxiety, levels of cytotoxic T cells were elevated during pregnancy and then decreased in the weeks following childbirth. In women without anxiety, the activity of these cells declined in pregnancy and continued to decline after birth.

The researchers also observed that the activity of largely pro-inflammatory cytokines, or substances secreted by cells as part of the immune system response, was suppressed during pregnancy in women with anxiety and then rose after childbirth, while healthy women exhibited the opposite pattern. 

“The takeaway is that this is the first clear evidence that immune activity differs for pregnant women depending on their anxiety status.  Knowing that there is immune system involvement is a first step toward understanding the biological factors related to anxiety in pregnancy, and a first step toward developing new treatments,” said Dr. Osborne. “We know that anxiety needs to be treated to ensure healthy outcomes for both mother and child.”

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JOURNAL

Brain Behavior and Immunity

More evidence that sugary drinks cause weight gain

Peer-Reviewed Publication

UNIVERSITY OF TORONTO

 

IMAGE: PROFESSOR VASANTI MALIK view more 

CREDIT: PHOTO COURTESY OF UNIVERSITY OF TORONTO

A review of dozens of studies from the last decade, led by researchers at the University of Toronto and Harvard University, recently found that sugar-sweetened beverages promote weight gain in children and adults.

The review, published in the American Journal of Clinical Nutrition, is the largest and most thorough analysis to date of research on sweetened drinks, and overweight and obesity — both of which heighten risks for diabetes, heart disease, some cancers and other diseases.

Vasanti Malik led the study, with colleagues in Toronto and Boston. Malik is an assistant professor of nutritional sciences at U of T’s Temerty Faculty of Medicine and the Joannah & Brian Lawson Centre for Child Nutrition. She spoke with writer Jim Oldfield about the findings, and take-aways for public policy and personal health.

Why do this study now?

Our last meta-analysis on this topic was 2013. You want to update a meta-analysis every five to 10 years anyway, but especially in this area because there has been so much new research the last decade. Evidence has continued to accumulate showing associations among sugar-sweetened beverages, or SSBs as we call them, and weight and chronic disease. And it’s very important to have an updated synthesis of that evidence, especially for public policy. The Canada Food Guide is clear on the need to limit SSBs and recommends water as the drink of choice, and added sugar intake including SSBs has declined in Canada, in part due to public policies. But levels here are still too high. As well, the USDA Dietary Guidelines for Americans are arguably not as strong, and with U.S. policymakers coming together soon to discuss the 2025 guidelines, our study will be an important piece of evidence to inform their work. 

What did your study show?

We expected to find a positive association between SSBs and weight gain, among adults and children, and in cohort studies and randomized clinical trials. And that was exactly what we found. We analyzed 85 studies, which totalled over half a million participants. In cohort studies, which follow people over long periods of time, each serving-per-day increase in SSBs was associated with a 0.42-kg (almost one-pound) higher body weight in adults. In children, we saw a 0.07-unit higher body-mass index (just under one-twelfth of a BMI unit). Perhaps most striking, findings from our dose-response analysis showed that weight gain increases with increasing levels of SSB intake, in both children and adults. A dose-response relationship provides strongevidence for a cause-and-effect relationship.  

How much weight gain might one drink a day lead to over time?

Well, we estimated that associated change in body weight over a one-year period. For adults, one additional 12-ounce serving a day was linked to a 0.20-kg higher body weight (about half a pound) in one year. Over 10 years, that could be about five pounds. In children, we observed a 0.03-unit higher BMI for each additional daily serving of SSBs over a one-year period. Although these results may seem modest, weight gain is a gradual process, with adults averaging about one pound (0.45 kg) of weight gain per year. So, limiting SSB consumption could be an effective way to prevent age-related weight gain. Limiting SSB intake among children is also an important strategy to help them develop healthy lifestyle habits and weight trajectories.

How common is excess consumption of these drinks?

It’s very common. Sugar-sweetened beverages include sodas, fruit drinks, sports and energy drinks, and they are the largest source of added sugar in the North American diet. Moreover, the rise in consumption of these drinks has mirrored the epidemic of overweight and obesity. In 2016, almost two billion adults were estimated as having overweight and 650 million had obesity. Even more worrying, the rate of increase in obesity in children and adolescents is now greater than in adults. The prevalence of childhood obesity has increased more than four-fold globally since the 1970s, which is truly alarming.

What are some of the health effects of SSBs?

A typical 12-ounce serving of an SSB contains over 140 calories and more than eight teaspoons of sugar. That nearly reaches the recommended daily limit for added sugar, which is no more than 10 per cent of total calories, or about 200 calories for a 2000-calorie per day diet. These drinks are sugar in liquid form. They’re usually made with table sugar, high-fructose corn syrup or other sweeteners that provide calories, and are digested rapidly, more so than sugar consumed as a solid. This bolus of glucose increases blood sugar levels, which triggers a glycemic response that over time can lead to insulin resistance and diabetes. The fructose component also floods the liver, which can cause lipogenesis (creation of fat), which puts a person on the path to fatty liver and metabolic disease. Fructose also increases uric acid, which contributes to insulin resistance and risk for cardiovascular and other diseases. Insulin spikes from the glycemic response can result in an appetite cascade and over-eating, as can excess insulin in the blood over longer periods. Some evidence shows that SSBs activate the dopaminergic reward system in the brain and encourage addictive behaviour, and that they alter the gut microbiome, but we need more research on those effects.

Are you optimistic, given these effects and the research evidence?  

Intake levels of SSBs have come down in the developed world. We’re still seeing increases in the developing world, but taxes in some of those countries are working. Thailand introduced a tax that has reduced consumption, as has Mexico and South Africa. At least 85 countries now have a tax on SSBs, which in part reflects the World Health Organization’s stand on this issue. In Canada, Newfoundland introduced a tax recently, and several U.S. regions and cities have had a tax for years, in response to public health efforts, more awareness and advocacy. The general effect of these taxes is reduced intake, and the revenues can be put toward further public health measures and health care. Other changes will help in Canada and elsewhere as well, such as limiting marketing to children, and better front-of-pack and nutrition labels. All these efforts will push intake down, but it’s important to remember that as that happens, people need access to clean, safe drinking water as an alternative. That’s an ongoing challenge globally, and in many parts of Canada, that we really need to address.

Vasanti Malik holds a Canada Research Chair in Nutrition and Chronic Disease Prevention at the University of Toronto, and an adjunct position in Nutrition at the Harvard T.H. Chan School of Public Health. Michelle Nguyen, a doctoral student at U of T, conducted the study analysis and wrote the paper.

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JOURNAL

American Journal of Clinical Nutrition

DOI

10.1016/j.ajcnut.2022.11.008 

METHOD OF RESEARCH

Meta-analysis

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Sugar-sweetened beverage consumption and weight gain in children and adults: a systematic review and meta-analysis of prospective cohort studies and randomized controlled trials

ARTICLE PUBLICATION DATE

20-Dec-2022

COI STATEMENT

Vasanti Malik has received funding from the Canada Research Chairs Program; Connaught New Researcher Award, University of Toronto; the Joannah & Brian Lawson Centre for Child Nutrition, University of Toronto; Temerty Faculty of Medicine Pathway Grant, University of Toronto; Canada Foundation for Innovation; and Ontario Research Fund and has served as a consultant for the City and County of San Francisco for litigation related to health warning labels on Sugar-sweetened beverages.

New MIT Sloan research finds Americans are more receptive to counter-partisan messages than previously thought

The study, which looked at how Democrats and Republicans react to persuasive messaging that doesn't align with their party leader’s position, challenges the view that party loyalty distorts how Americans process evidence and arguments.

Peer-Reviewed Publication

MIT SLOAN SCHOOL OF MANAGEMENT

 

IMAGE: THE STUDY, BY MIT BEHAVIORAL RESEARCHERS BEN M. TAPPIN, ADAM J. BERINSKY, AND DAVID G. RAND, WHICH LOOKED AT HOW DEMOCRATS AND REPUBLICANS REACT TO PERSUASIVE MESSAGING THAT DOESN'T ALIGN WITH THEIR PARTY LEADER’S POSITION, CHALLENGES THE VIEW THAT PARTY LOYALTY DISTORTS HOW AMERICANS PROCESS EVIDENCE AND ARGUMENTS. view more 

CREDIT: MIT SLOAN SCHOOL OF MANAGEMENT

Party loyalty and partisan motivation may interfere less with Americans’ thinking than previously believed, MIT behavioral researchers Ben M. Tappin, Adam J. Berinsky, and David G. Rand report in new research published in the journal Nature Human Behaviour.

 

The study, which looked at how Democrats and Republicans react to persuasive messaging that doesn't align with their party leader’s position, challenges the view that party loyalty distorts how Americans process evidence and arguments.

 

“Our results are clear and unequivocal: Learning the in-party leader’s position on an issue certainly did influence partisans’ attitudes — but it did not cause the partisans to ignore or discount arguments and evidence that ran counter to the leader’s position,” said Rand, the Erwin H. Schell Professor and Professor of Management Science and Brain and Cognitive Sciences at the MIT Sloan School of Management.

 

Rather, respondents seemed to integrate the leader cues and the countervailing persuasive messages as “independent pieces of information” in determining whether they agreed or disagreed with various policy issues, he said.

 

Evidence versus cues from the left and right

 

The study was conducted in September 2021 and more than 5,000 American partisans — Republicans who voted for Donald Trump in 2020 or Democrats who voted for Joe Biden in 2020 — completed a survey spanning 24 policy issues including affirmative action, assisted suicide, the death penalty, estate tax, foreign aid, tariffs on Chinese imports and restrictions at the US border, among others.

 

In the study, respondents gave their opinions on several of the policy issues on a seven-point scale running from “strongly disagree” to “strongly agree.” Before giving their opinion, they were either shown a cue about the position of their party leader on the issue; a message with arguments and evidence that went against their leader’s position; both the cue and the message; or neither the cue nor the message.  

 

For instance, some respondents were asked whether the military should be allowed to use techniques such as waterboarding to gain information from a suspected terrorist. For those respondents who were Trump-voting Republicans and were assigned to see a persuasive message, they then read a paragraph that cited a 2014 Senate report in which the CIA concluded that such techniques rarely provided reliable intelligence or got suspects to cooperate. The message concluded, “The question then becomes: is it worth violating international law by torturing people — who are effectively innocent until proven guilty by a jury — for mainly useless information? The answer is No. America is better than that.” 

 

This particular example contradicted Trump’s position that such techniques are justified. In 2017, Trump said he believes waterboarding works, stating, "We have to fight fire with fire." Critically, informing respondents that Trump supports waterboarding did not cause them to ignore or discount the persuasive message. 

 

In fact, exposure to the message caused respondents to shift their attitudes towards the message, and this attitude change was a similar size even when they knew that their favored party leader took the opposite position. This pattern of results was consistent across a wide range of policy issues, as well as across demographic groups and different types of partisan cues.

 

“We found no evidence that countervailing cues from favored party leaders meaningfully diminished partisans’ receptivity to persuasive arguments and evidence — in contrast to what one would expect if party loyalty distorted partisans’ information processing,” said Tappin, a postdoctoral researcher at MIT Sloan and lead author on the study.

 

“These findings contrast with the notion that party loyalty overrides people’s values and interferes with, distorts, or otherwise limits their processing of counter-partisan messages,” added Rand. “If such interference and distortion does occur, our findings suggest that it is relatively minor, uncommon or may be avoided with ease.”

 

Not blinded by party loyalty

 

The authors noted that their results highlight a distinction between two key questions in political psychology: to what extent do party cues influence people’s attitudes, and why do they exert their influence? While there is relative consensus on the first question — party cues reliably influence people’s attitudes, sometimes by a great deal — the second question remains unsettled. Their new paper found that party cues are influential not because of blind loyalty to the party leader, but rather because they contain useful information (which is then weighed against countervailing information).

 

The range of issues and arguments in the latest study was larger than previous work but, by necessity, still limited; the authors write that different persuasive messages containing alternate arguments and evidence might have produced different results. They also point out that in their study the party leaders’ positions were not supported by justifications and talking points from the partisan media, as they often are in the real world. 

 

The researchers believe that the messages might have worked by appealing to people’s values and identities other than those of their party — and that party loyalty could not override the relevance of these other factors. “People have various identities and motivations that are not reducible to their party,” Tappin concluded.

 

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JOURNAL

Nature

DOI

10.1038/s41562-023-01551-7 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Partisans’ receptivity to persuasive messaging is undiminished by countervailing party leader cues

ARTICLE PUBLICATION DATE

2-Mar-2023