Tag: obesity

How sucrose, the ‘real’ sugar commonly found in sodas, can disrupt your appetite

Sugar-sweetened drinks interfere with the hunger-suppressing hormones that signal a sense of feeling full, a new USC study finds.

(photo/Pexels)

Sugary drinks interfere with hormones that tell the body “I feel full,” potentially contributing to obesity and undermining weight loss efforts, a new USC study shows.

The findings, which appear Thursday in the Journal of Clinical Endocrinology and Metabolism, strengthen the case against sugar-sweetened beverages, a significant driver of obesity. Sugary drinks are the single largest source of calories from added sugar for American adults.

“Our study found that when young adults consumed drinks containing sucrose, they produced lower levels of appetite-regulating hormones than when they consumed drinks containing glucose — the main type of sugar that circulates in the bloodstream,” said Kathleen Page, an associate professor of medicine specializing in diabetes and childhood obesity at the Keck School of Medicine of USC.

The impact on hormone signaling was even greater among women who were already obese, as well as men, regardless of whether they were obese or not.

Sugar-sweetened foods, beverages can lead to lower amounts of appetite-regulating hormones

The study included 69 young adults ages 18 to 35 who participated in two study visits where they consumed drinks containing either sucrose or glucose. Sucrose, a combination of glucose and fructose, comes from sugar cane or sugar beets. Glucose is found in honey, grapes, figs and plums.

Participants gave blood samples at 10, 35 and 120 minutes after drinking the drinks. Researchers found that when the participants consumed drinks containing sucrose, they produced lower amounts of hormones that suppress hunger compared to when they consumed drinks containing an equal dose of glucose.

They also found that individual characteristics, including body weight and sex, affected the hormone responses to the different sugars. For example, people with obesity and those with lower insulin sensitivity had a smaller rise in hunger-suppressing hormones after consuming drinks sweetened with sucrose compared to glucose.

Page, who leads the Diabetes & Obesity Research Institute at USC, said the takeaway for the general public isn’t to switch from one sweet drink to another but to try to reduce added sugar altogether.

“The majority of sucrose that people consume in the American diet comes from sugar-sweetened foods and beverages, whereas glucose is found naturally in most carbohydrate-containing foods, including fruits and whole-grain breads,” she said. “I would advise reducing the consumption of sugar-sweetened foods and beverages and instead trying to eat more whole foods, like fruits.”

— Leigh Hopper


Other authors of the study include Alexandra G. Yunker, Sabrina Jones, Brendan Angelo, Alexis DeFendis, Trevor A. Pickering, Shan Luo, Hilary M. Dorton and Jasmin M. Alves, all of the Keck School of Medicine; and John R. Monterosso, of the USC Dornsife College of Letters, Arts and Sciences.

The study was supported by grants from the National Institute of Diabetes and Digestive and Kidney Diseases, part of the National Institutes of Health (R01DK102794), and the Southern California Clinical and Translational Science Institute (NIH UL1TR001855).

Overweight children are excluded from friendships and disliked by peers

Negative social interactions can increase the kids’ risk of loneliness, depression, poor eating habits and illness.

Overweight children are more likely to struggle with friendships, according to a USC study. (Photo/iStock)

Overweight children have more unreciprocated friendships and frenemies than their thinner counterparts, a Keck School of Medicine of USC study finds.

In a survey of 504 preteens in the Netherlands, researchers found that overweight children are excluded from friendships, call classmates friends when the feeling is not mutual and are disliked by peers. And overweight children dislike more classmates than their thinner peers.

These heightened negative relationships take a mental, social and physical toll, said Kayla de la Haye, lead author of the new study and an assistant preventive medicine professor at the Keck School of Medicine.

“Our finding is alarming because if we continue to have social environments where fat shaming is the norm, these kids will continue to be ostracized,” de la Haye said. “Those adverse interactions increase the risk of loneliness, depression, poor eating habits and illness.”

Although overweight children, on average, listed as many people in the friend category as children with healthy weight, they were 1.7 times more likely to be disliked and 1.2 times more likely to dislike their peers. These combined tendencies indicate that overweight children are generally involved in more unreciprocated friendships and mutual frenemy relationships, de la Haye said.

The study, published on June 7 in PLOS ONE, included 714 students, 210 of whom were nominated as friends but did not take the survey.

“Research by others has shown people who chronically feel isolated, lonely or socially disconnected experience greater inflammation and reduced viral suppression,” de la Haye added. “We’re not sure if that’s at play here, but a consistent body of research shows that negative social relationships can go under the skin and affect health.”

Childhood obesity rises

Worldwide, childhood obesity increased by 31 percent in a little over two decades with about 42 million overweight or obese children in 2013, according to the World Health Organization.

In the United States, the number of obese children has more than tripled since the 1970s. About 1 in 5 school-aged children is obese — about 17 percent of all children in America, according to the Centers for Disease Control and Prevention.

The prevalence of childhood obesity is higher among Latinos (22 percent) and blacks (20 percent) than among whites (15 percent), according to the CDC.

Isolation can create a vicious cycle for overweight children

The study is based on questionnaires that 504 preteens answered in the Netherlands when they were aged 10 to 12. Participants in 28 classes listed their best friends and their enemies. On average, 26 students participated per classroom.

Children were assigned weight categories based on their body mass index, a measure of body fat. About 16 percent of the participants were overweight.

Researchers controlled for gender because it can steer friendships and omitted children who had skipped a grade or who were held back a grade.

On average, children were listed as a friend by five of their classmates and as an enemy by two. However, overweight kids typically were considered a friend by just four classmates and were disliked by three.

“This social environment characterized by fewer friendships and more antipathies is likely to put overweight youth at increased risk for psychosocial maladjustment,” the study stated. “The resulting social isolation may also promote unhealthy behaviors, such as excessive food intake and decreased participation in sports and physical activities, which can lead to further weight gain and thus a cycle of poor physical and social outcomes.”

Unfortunately, it seems overweight children tend to have fewer friends and be friends with less popular kids who also tend to be overweight, de la Haye said.

“We want to reduce the stigma of being overweight,” she said. “We have anti-bullying campaigns based on sexual identity, race and ethnicity. We should do more to integrate obesity in our anti-bullying repertoire.”

Boosting health

The study used data from the Tracking Adolescents’ Individual Lives Survey, an ongoing research on the psychological, social and physical development of adolescents and young adults.

USC researchers are working across disciplines to improve children’s physical and mental health, boosting health across the life span. They have studied how “secondhand sugars” found in breast milk might negatively affect a baby’s future body weight, how a concussion might interrupt a child’s normal brain development and how teens in military families are at higher risk of depression and suicidal thoughts.

“Childhood obesity is a major focus area on both USC campuses,” Keck School of Medicine Dean Rohit Varma said, referring to the University Park and Health Sciences campuses. “USC-led research shows that children with asthma are more likely to become obese and little bribes spark better eating habits. Through continuous, multidisciplinary research across USC, we hope to bring about the decline of childhood obesity and its impact on children.”

— By Zen Vuong

From mother to baby: ‘Secondhand sugars’ can pass through breast milk

Even a small amount of fructose in breast milk is associated with increases in a baby’s body weight

Selection of food high in sugar, written sugar

Add breast milk to the list of foods and beverages that contain fructose, a sweetener linked to health issues ranging from obesity to diabetes.

A new study by researchers at the Keck School of Medicine of USC indicates that a sugar called fructose is passed from mother to infant through breast milk. The proof-of-concept study involving 25 mothers and infants provides preliminary evidence that even fructose equivalent to the weight of a grain of rice in a full day’s serving of breast milk is associated with increased body weight, muscle and bone mineral content.

Found in fruit, processed food and soda, fructose is not a natural component of breast milk, which is still considered the gold standard diet for babies. The “secondhand sugar” is derived from a mom’s diet, said Michael Goran, lead author of the new study published in February in the journal Nutrients.

Exposing infants and children to higher amounts of sugar during growth and development can produce problems with cognitive development and learning as well as create lifelong risk for obesity, diabetes, fatty liver disease and heart disease, said Goran, founding director of the Childhood Obesity Research Center at the Keck School of Medicine.

Frappuccinos, energy drinks, cranberry juice cocktails and fructose are examples of sources of secondhand sugars. Healthy, naturally occurring sugars in breast milk include lactose, which is beneficial to infant growth and development.

“Lactose is the main source of carbohydrate energy and breast milk is very beneficial, but it’s possible that you can lose some of that beneficial effect depending on maternal diet and how that may affect the composition of breast milk,” Goran said. “Other studies have shown that fructose and artificial sweeteners are particularly damaging during critical periods of growth and development in children. We are beginning to see that any amount of fructose in breast milk is risky.”

Goran and his colleagues did not collect mothers’ dietary data for this study, so they were unable to determine if the trace amounts of fructose found in breast milk is positively associated with habitual consumption of fructose-rich foods and drinks.

“We know very little about why some children eventually become overweight or obese,” Goran said. “It’s important that we study what may be taking place in the earliest times of their development to determine whether anything could be done just after birth to lower their risks.”

How much is too much?

The first year of life is a critical period for building brain networks and for cementing the foundation for the metabolic system. Minute amounts of fructose may have detrimental effects on infant metabolism, said Tanya Alderete, co-author of the study and a postdoctoral research scholar at the Keck School of Medicine. Ingestion of fructose could coach pre-fat storage cells to become fat cells, raising the baby’s risk of one day becoming overweight or obese.

“Early life is a period of rapid development and early nutrition is strongly linked to long-term health outcomes,” Alderete said. “We know that the decision to breastfeed or bottle feed may have impacts on later health. Results from this work suggest that the composition of breast milk may be another important factor to consider in regard to infant health.”

Looking at the study data, Alderete said the average breastfeeding 1-month-old baby could consume just 10 milligrams (about a grain of rice) of fructose from breast milk a day, yet he would see adverse changes in body composition during growth.

A single microgram of fructose per milliliter of breast milk — that’s 1,000 times lower than the amount of lactose found in breast milk — is associated with a 5 to 10 percent increase in body weight and body fat for infants at six months of age, Goran said.

Still, Alderete emphasized that breastfeeding is the ideal form of infant nutrition and mothers should continue to breastfeed for as long as possible or up to one year.

Baby fat

Twenty-five mothers brought their infants to the Oklahoma Health Sciences Center when the babies were 1 month old and again when they were 6 months old. The mothers fasted for at least three hours prior to the visit.

The infants were fed breast milk, consumed less than 8 ounces of formula a week and had no solid foods, according to their mothers.

Researchers took a breast milk sample from each mom and scanned it for sugars such as lactose, glucose and fructose. They measured each baby’s fat mass, muscle mass and bone mass.

Infant growth was not related to mothers’ pre-pregnancy body mass index, a measure of body fat, or to any of the other breast milk components, scientists found. The researchers adjusted their results for the sex of the infant and the baby’s weight at 1 month.

Researchers at the Childhood Obesity Research Center at USC are looking at how maternal food intake affects fructose levels in breast milk as well as how specific elements in breast milk can alter a baby’s developing gut bacteria, which neutralizes toxic byproducts of digestion. This “gut microbiome” impacts infant growth and metabolism. Based on early study results, Goran offers some advice to pregnant women and new mothers.

“New moms can prevent passing secondhand sugars to their children by eating and drinking less sugars while pregnant or breastfeeding,” Goran said. “Caregivers can shield babies and children from harmful effects of sugars by carefully choosing infant formula, baby foods and snacks without added sugars or sweeteners.”

The study was supported by Mead Johnson Nutrition, the Harold Hamm Diabetes Center at the University of Oklahoma Health Sciences Center and National Institutes of Health grants awarded to the Washington University Diabetic Cardiovascular Disease Center.

— By Zen Vuong

USC, Mexico make strides in public health research

Jonathan Samet has partnered with many Mexican agencies on studies involving public health issues.

For more than 20 years, Jonathan Samet has developed strategies to prevent smoking in Mexico, with help from scientists and leaders at the country’s National Institute of Public Health (INSP).

The USC Distinguished Professor teams with several of Mexico’s 12 institutes of health, which aim to improve public health through research, policy and care. The INSP’s research centers and school of public health examine tobacco, obesity and other issues that contribute to health problems.

Samet assisted in the development of the institute’s Center for Tobacco Control Research and co-founded the Summer Program in Public Health, one of the largest of its kind in Latin America, with INSP Director Mauricio Hernández-Ávila. Samet has taught in the program every year since it began 22 years ago and has arranged for Trojans to teach there as well.

Building momentum

Since 2008, the year of Samet’s arrival at USC, the Department of Preventive Medicine has gained momentum in its research and scholarly exchanges with Mexico. Samet’s ties to INSP have enabled USC researchers to collaborate on various public health projects in the country and among Mexican and immigrant populations.

“The U.S. and Mexico share more than a border,” said Samet, holder of the Flora L. Thornton Chair in the Department of Preventive Medicine at the Keck School of Medicine of USC. “We share health challenges but also the expertise to combat them.”

In 2015, preventive medicine professors Lourdes Baezconde-Garbanati and Mary Ann Pentz founded the Center for Health Equity in the Americas to advance health equity in the region through research, training and partnerships. Using findings from an international summit in October, the group is working with INSP on a cervical cancer prevention report to be published in INSP’s journal, Salud Pública de Mexico, later this year.

Other centers in the department, including the Institute for Global Health, the Program on Global Health & Human Rights and the Immigrant Health Initiative, have hosted Mexican researchers and collaborators for talks, seminars and training on subjects, including sexually transmitted infectionsobesity, H1N1premature mortality and cervical cancer prevention.

Institute for Global Health Associate Director Heather Wipfli collaborated with INSP in 2016 to survey Mexican corporations about how health and wellness are integrated into their workplaces. The project is helping to inform the global cancer prevention programs begun by the American Cancer Society.

Another recent project, led by USC neurologist John Ringman and Mellissa Withers, assistant professor of clinical in the Department of Preventive Medicine, examined knowledge and attitudes regarding Alzheimer’s disease, genetics and participation in research among populations at-risk for a rare form of early onset familial Alzheimer’s disease in Mexico.

Fair exchange

In 2015, the Department of Preventive Medicine welcomed INSP postdoctoral fellow Katia Gallegos as part of an initiative with Mexico’s National Council of Science and Technology, in which USC provides scholars from Mexico with residencies in fields related to science, technology and innovation.

Gallegos is working with large binational data sets to determine the impact of acculturation in patterns of physical activity and sedentary behavior, as well as its association with body mass index observed in Mexicans, Mexican immigrants and Mexican-Americans. In addition, she is teaming with U.S. tobacco-use databases to study young people with mental illness who use multiple tobacco products.

Department researchers have also examined Mexico’s indoor smoking bancigarette sales tax, drug reform and teenagers’ smoking habits, as well as mental health risks and lower colorectal cancer susceptibility among Mexicans who migrated to the United States.

Along with Mexican and other U.S. scientists, USC researchers in 2013 discovered a genetic link associated with higher Type 2 diabetes risk among Mexican populations. Most recently, a study found that Latino children living in areas with higher levels of air pollution have a greater risk of developing Type 2 diabetes.

Career dedicated to public health

JonSametINSP-hw.jpg

Jonathan Samet accepts an honorary degree awarded by Mexico’s National Institute of Public Health. (Photo/Heather Wipfli)

Now celebrating its 30th anniversary, the INSP gave Samet an honorary doctorate recognizing his contributions to public health on Jan. 27.

At that event, Hernández-Ávila cited Samet’s scientific and professional achievements, among them his 27 books, 127 chapters and more than 350 scientific articles. “This Honoris Causa is awarded to recognize Dr. Samet’s work for global public health — for the health of all people,” he said.

A graduate of the University of Rochester School of Medicine and Dentistry, Samet has participated since the 1980s in the reports of the U.S. surgeon general on smoking and health, and he served as senior scientific editor for the 50-year anniversary edition in 2014. Most recently, he contributed to the 2016 surgeon general report on e-cigarettes and youth, the first of its kind.

His work has contributed to national legislation to control tobacco use, air pollution and radiation both in the United States and Mexico.

“I’m honored to be a part of this celebration to mark INSP’s decades-long commitment to public health in Mexico and to receive this very high recognition,” Samet said. “I look forward to continuing our partnership for many years to come.

Air pollution linked to heightened diabetes risk

High levels of pollution may make insulin-creating cells become less efficient, increasing the risk for Type 2 diabetes, USC researchers say

Latino children who live in areas with higher levels of air pollution have a heightened risk of developing Type 2 diabetes, according to a new USC-led study. Scientists tracked children’s health and respective levels of residential air pollution for about 3.5 years before associating chronic unhealthy air exposure to a breakdown in beta cells, special pancreatic cells that secrete insulin and maintain the appropriate sugar level in the bloodstream. By the time the children turned 18, their insulin-creating pancreatic cells were 13 percent less efficient than normal, making these individuals more prone to eventually developing Type 2 diabetes, researchers said. “Exposure to heightened air pollution during childhood increases the risk for Hispanic children to become obese and, independent of that, to also develop Type 2 diabetes,” said Michael Goran, co-director of the Diabetes and Obesity Research Institute at the Keck School of Medicine of USC and corresponding author of the study. “Poor air quality appears to be a catalyst for obesity and diabetes in children, but the conditions probably are forged via different pathways.” Published in the journal Diabetes on Jan. 30, the study, researchers said, is the first to follow children for years to find a connection between air pollution and diabetes risk in children. These children lived in neighborhoods that, according to the U.S. Environmental Protection Agency, had excess nitrogen dioxide and tiny air pollution particles that are generated by automobiles and power plants, formally called particulate matter 2.5 (PM2.5). Researchers found that the beta cells that were still functional were overworking to compensate for the damaged cells, leading to burn out. As the cells failed to secrete insulin efficiently, regulation of sugar in the bloodstream overwhelmed the system, heightening the risk of Type 2 diabetes. Diabetes has quadrupled in the past four decades, according to the Centers for Disease Control and Prevention. If the trend continues, 1 in 3 Americans will have diabetes by 2050. Serious complications include blindness, kidney failure, limb amputation or early death. “Diabetes is occurring in epidemic proportion in the U.S. and the developed world,” said Frank Gilliland, senior author and a professor of preventive medicine at the Keck School of Medicine. “It has been the conventional wisdom that this increase in diabetes is the result of an uptick in obesity due to sedentary lifespans and calorie-dense diets. Our study shows air pollution also contributes to Type 2 diabetes risk.” 

Latino children living in polluted areas are at higher risk

 Researchers examined the data of 314 overweight and obese Latino children who were between 8 and 15 years old when they enrolled in the National Institutes of Health-funded Study of Latino Adolescents at Risk of Type 2 Diabetes (SOLAR) study, a 12-year undertaking. Scientists tracked the Los Angeles County children for an average of 3.5 years. None of them had Type 2 diabetes when they enrolled, but some may have been on the road to the disease toward the study’s end. Each year the participants fasted and then came to the Childhood Obesity Research Center at USC for a physical exam and to have their glucose and insulin levels measured over a span of two hours. When they turned 18, the participants had nearly 27 percent higher blood insulin after having fasted for 12 hours. During their two-hour glucose test, they had about 36 percent more insulin than normal, indicating that the body was becoming less responsive to insulin. This observation illustrated that increased exposure to air pollution was associated with increased risk factors for Type 2 diabetes. The researchers adjusted for body fat and socioeconomic status. In some instances, at age 18, the effect of long-term exposure to higher air pollution was larger than the effect of gaining 5 percent body weight, meaning air pollution is definitely a risk factor for diabetes, said Tanya Alderete, lead author of the study and a postdoctoral research scholar at the Keck School of Medicine. 

Steps people can take to reduce their risk

 The findings suggest that the negative effects of elevated and chronic exposure to nitrogen dioxide and tiny dirty air particles begin in early life. If other risk factors such as having an unhealthy diet persist, then risk for Type 2 diabetes is compounded, researchers said. “Air pollution is ubiquitous, especially in Los Angeles,” Alderete said. “It’s important to consider the factors that you can control — for example, being aware that morning and evening commute times might not be the best time to go for a run. Change up your schedule so that you’re not engaging in strenuous activity near sources of pollutants or during peak hours.” None of the children developed Type 2 diabetes during the study, but many showed signs that they may eventually develop it and were characterized as pre-diabetes. Some 8.1 million people in the United States have diabetes but haven’t been diagnosed, according to the CDC. That means some 28 percent of people with diabetes do not even know they have diabetes. Undiagnosed diabetes raises the risk of afflictions such as stroke, kidney damage and Alzheimer’s disease. Future studies will also include participants who are not overweight or obese and should collect data on diet and physical activity, researchers said. Findings from this study may be generalized only to overweight and obese Latino children, mostly of a lower socioeconomic status, according to the study. The research was supported by the National Institutes of Health, the National Institute on Minority Health and Health Disparities, the National Institute of Diabetes and Digestive and Kidney Diseases, the National Institute of Environmental Health Sciences, the Southern California Children’s Environmental Health Center and the U.S. Environmental Protection Agency.

— By Zen Vuong