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The fragile health of adolescents

Two national studies warn of elevated levels of excess weight, hypertension, total cholesterol and sedentariness



The overall picture of young people reflects the antiquated view that chubby children are healthier

The overall picture of young people reflects the antiquated view that chubby children are healthier

Adolescents go through so many changes that even potential health problems can be viewed as temporary. Some changes during this phase are normal, but not everything can be easily resolved later.  Two wide-ranging national surveys – one involving 75,000 and the other 100,000 adolescents across Brazil – have painted a disturbing picture of the health of Brazilian youth.  One out of every four adolescents presented excess weight (was overweight or obese) and one out of every 10 had high blood pressure.  According to blood tests conducted in one of the studies, one out of every five presented total cholesterol levels higher than recommended.  These metabolic changes increase the risk of death due to heart attack and promote the development of cardiovascular diseases and diabetes.  Obesity, physical inactivity and smoking, also found among young people at levels experts find alarming, can contribute to the development of some types of cancer.  Excess fat circulating in the body can even impair functioning of the hypothalamus, the region of the central nervous system that, among other things, controls appetite (see table).

One of the surveys, the Study of Cardiovascular Risks in Adolescents (ERICA), mobilized nearly 500 researchers from 30 Brazilian universities.  In 2013 and 2014, interviewers collected information about 75,000 adolescents between the ages of 12 and 17 at 1,247 public and private schools in 124 Brazilian cities.  According to this study, financed by the Ministry of Health (MS), sedentariness, a factor that can lead to continuous weight gain, is high.  Most of the adolescents assessed (54.3%) do not engage in regular physical activity beyond physical education classes at school, and thus fail to complete the five hours of exercise per week that is recommended for this age group.

Most (66.6%) also spend two or more hours a day in front of the television, which is where they prefer to eat at whatever time suits them.  Half of the study participants reported habitually eating breakfast and meals with their parents, but the other half, mainly public school students, have no regular meal schedule or family company and maintain unbalanced, unwholesome diets, featuring many calorie-laden processed foods, high in salt and fat.

Most prefer processed foods and very few snack on fruit

Most prefer processed foods and very few snack on fruit

“We have to concern ourselves with adolescent health problems and habits, such as sedentariness, consumption of alcoholic beverages and smoking that are hard to change later,” notes physician Katia Vergetti Bloch, professor of epidemiology at the Institute of Public Health Studies of the Federal University of Rio de Janeiro (UFRJ) and national coordinator of the ERICA. Its findings were described in 13 articles published in the February issue of the Revista de Saúde Pública. “Today’s adolescents run a very high risk of becoming adults with chronic health problems.”

Many of the ERICA findings are similar to those reported in the 2015 National School Health Survey (PeNSE) conducted by the Brazilian Institute of Geography and Statistics (IBGE) and the Ministry of Health based on information about 109,104 adolescents between the ages of 13 and 17 collected in 2015 from 2,842 schools throughout Brazil. Published in August 2016 on the IBGE website, PeNSE reported a 23.7% prevalence of overweight individuals, which corresponds to an estimated total of 3 million students; the previous version of the study (conducted in 2012) placed that figure at 20%.  Despite some differences – the PeNSE provided a detailed analysis of access to school playing fields, for example –, both surveys show that adolescents from Brazilian states in the South and Southeast presented higher rates of excess weight and hypertension, while those from states in the North and Northeast, showed lower rates (see tables).

The root of the problem
“The health of adolescents reflects serious problems that begin in childhood, with the mistaken view that a chubby child is healthier,” says Elizabeth Fujimori, a professor of nursing and public health at the School of Nursing of the University of São Paulo (EE-USP) and one of the ERICA coordinators in the state of São Paulo. A study published in the Journal of Pediatric Nursing examined maternal weight perception of toddlers up to age three treated at health care facilities in a city in inland São Paulo.  “More than half of the mothers wanted their children to weigh more, even if they were already overweight,” says Luciane Duarte, doctoral candidate at EE-USP who conducted the study under Fujimori’s supervision. “If the mother does not perceive that the child is overweight, she is not going to seek help.”

In the ERICA, Duarte, as one of the 12 supervisors tasked with collecting data at the 122 schools selected for assessment in the greater São Paulo metropolitan area, made the initial contacts with principals and students to explain the study objectives and schedule the dates for interviews, physicals and blood sample collections. Then the field team took over.  In 2014, Renata Gonçalves, one of the field supervisors on Fujimori’s team, would get up at four o’clock in the morning, gather up the portable monitors on which the kids would respond to the questionnaire about their eating and health habits, scales and other devices for measuring blood pressure, height, and abdominal size, and set out to schools in the capital and nearby cities having a population of more than 100,000.  The interviews, measurements and blood sample collections began at 7 a.m.

Play ball and sweat more to stay in shape: 20% of hypertensive adolescents could regulate their blood pressure if they were not obese

Play ball and sweat more to stay in shape: 20% of hypertensive adolescents could regulate their blood pressure if they were not obese

As soon as they had the results of the blood tests analyzing levels of glucose, insulin, cholesterol and triglycerides as well as anthropometric data and blood pressure, the supervisors returned to the schools, presented a general report to the principals, and delivered sealed envelopes containing exam results to every adolescent who had participated in the study.  “Some asked what cholesterol was, many were interested in changing their habits, but some said ‘I’m fine the way I am’, even though they were not,” noted Duarte. The researchers referred more serious cases for healthcare services, recommending that they soon begin treatment to control blood pressure, elevated glycemia or excess weight.  Nationwide, 25,787 adolescents, equivalent to 30.2% of those evaluated and found to have some parameters above normal, were referred for healthcare services.

The studies published in the Revista de Saúde Pública also present data about adolescent behavior regarding alcoholic beverages and sex.  Of all the teens interviewed, half (54%) had already experimented with some sort of alcoholic beverage and 24.1% had done so for the first time before the age of 12.  Most heavily consumed were beer and mixed drinks made with vodka. “Understanding this preference by adolescents could help plan prevention strategies,” notes Bloch.  In the PeNSE, where this topic was studied for the first time, 26% of the teens had consumed some type of alcoholic beverage and 21% had experienced some level of intoxication in the 30 days leading up to the survey.

Among those interviewed for the ERICA, 28% had begun to be sexually active, a proportion that increased with age, and by age 17, more than half of those interviewed reported being sexually active.  Most (82%) had used some method of contraception during their most recent sexual relations, mainly condoms (69%). “This percentage could be higher,” says Ana Luiza Vilela Borges, professor at EE-USP who analyzed the data.  The result that intrigued her was the sharp contrast among regions in the use of birth control pills.  In the South, 27% of teens reported using this method while only 3% in the North reported doing so.  According to Borges, one explanation for this difference may be difficulty in access because teenage girls can get birth control pills only after undergoing a check-up at a physician’s office.

CREN nutritionist asks which child has “the biggest mustache”...

CREN nutritionist asks which child has “the biggest mustache”…

What can be done?
“We don’t need to go so far as to say that teenagers in Porto Alegre need to stop having family barbeques, but we can suggest that they eat more fruit, vegetables and other less processed foods,” says Bloch. According to several studies, most adolescents have a diet based on traditional foods such as rice, beans and meat, but consume sugary drinks and ultra-processed products in excess, in addition to sodium above the recommended limits, all of which contribute to hypertension and excess weight.

“Since teenagers are by nature antagonistic and do just the opposite of what adults suggest, in order to change eating habits, we have to resort to other strategies for intervention that take into consideration the behavior of the group,” Bloch says. “The group a teenager belongs to has to think it’s cool to participate in sports instead of always going out and eating French fries and drinking.” An article published in July 2016 in the journal PNAS by researchers at the Universities of Chicago and Texas corroborate Bloch’s suggestion: a double-blind study of 536 high school students showed that a change in eating habits can be more effective when teens have autonomy in making the healthiest choices and see the act of eating better as an attitude of rebellion against junk food.

The researchers emphasize that today’s young people need to sweat a little more. They estimate that 20% of hypertensive teenagers – equivalent to 200,000 Brazilians in this age group – could regulate their blood pressure if they were no longer obese, indicating that some of the effects of sedentariness and inadequate nutrition could be reversed.  “Two weekly classes of physical education in primary and high school, at 50 minutes a pop, are not enough to make the adolescents active enough, considering international recommendations call for 60 minutes a day,” says physical education teacher Dilson Belfort, professor at the Federal University of Amapá (Unifap) and one of the coordinators of Fujimori’s team in that state.  Through an extension project, Belfort offers lessons in track to nearly 40 students from the university and the surrounding communities at the university sports center three times a week, from 7 to 8 in the morning.

In the classroom, Belfort uses the ERICA results to motivate students to move more and eat better.  O Guia alimentar para a população Brasileira [Food guide for Brazilians], published in 2014, has become a reference in this field by proposing that people gather to eat together, value in natura (fresh) or minimally processed foods, limit the consumption of processed foods such as tomato paste, dried meat, bacon, fruit in syrup or in crystallized form, and avoid highly processed foods such as filled cookies, prepackaged snacks, soft drinks, instant noodles,  sausages and other stuffed meats that offer little nutrition, are high in calories and tend to be consumed in excess.  Preparing one’s own meals also promotes healthy eating.

...after preparing and trying a fruit smoothie

…after preparing and trying a fruit smoothie

Changing eating habits
“With adolescents, we have to tread very carefully, listen more and plan with them what we can do together,” says pediatrician Maria Paula Albuquerque, clinical director of the Center for Nutritional Recovery and Education (CREN), established in 1994 as an extension project of the Federal University of São Paulo (Unifesp) and now funded by national and international organizations. For 10 years, the CREN outpatient clinic has treated overweight children, seeing weight loss in 70% of the cases, expanding the experience of nearly 30 years of treating malnourished and obese children.

On any given day at the day-hospital’s two care facilities, nutritionists, psychologists, social workers, nurses, teachers and physicians care for 144 children under the age of five, identified in collaboration with public health services in pockets of extreme poverty in the city of São Paulo.  With their family’s consent, children who show signs of malnutrition begin to frequent CREN where they spend the day, receiving five meals a day – including unsweetened milk, natural juices and, when necessary, vitamin supplements – and try green vegetables, legumes and fruit in an environment of educational activities.  The team tries to encourage mothers to cook more using natural ingredients, promote family meals and revive old recipes.  “Comfort food that easily satisfies is generally ultra-processed food, high in salt, fat and sugar.  Real comfort food refers to the emotional connections, to mom’s cooking,” says Albuquerque, while at her side, walks an 18-month old baby weighing 8 kilograms, monitored by a nutritionist. “Malnutrition is still a problem in Brazil and unlike obesity, it is easily overlooked because most of the children are just shorter than others of the same age.”

Treated for a period of two years, the children generally grow in stature and muscle mass as a result of their new eating habits, which appear to persist over the years, this according to a 2006 study in the Journal of Nutrition. “The children continue to live in the favelas but eat better than other children their age because of changes in their family habits,” Albuquerque says. In recent years, the proportion of obese children has surpassed that of children with malnutrition, reflecting the increased supply and reduced price of foods, and at the same time, the change in people’s eating habits around the world.

Health of adolescents“Obesity became a public health problem back in the 1980s when processed food producers discovered how to better preserve and expand the distribution of their products, first in the United States and Great Britain, but later in other countries,” says biologist Ana Lydia Sawaya, Unifesp professor and one of the founders of CREN, which she ran until 2006. “Obesity rates are falling among the most affluent classes due to recognition of its causes, but it continues to grow among the lower classes.  As a result, we are now seeing children who at age 12 have type 2 diabetes, which is the result of excess sugar in the blood, and hepatic steatosis, which is the accumulation of fat in the liver.  In 30 years, I’ve never seen such cases,” she says, referring to initial examinations performed under a new CREN project to treat 930 obese children between the ages of 10 and 12, most of whom are students in public schools.

“It is neither hard nor expensive to eliminate malnutrition and obesity as public health problems,” says Sawaya.  “The government already has a structure in place to communicate messages about proper eating in a persuasive, understandable and suitable manner, using campaigns at health clinics and training healthcare service program teams in nutrition.”  Sawaya believes the sale of ultra-processed foods at schools and to children under age 18 should be prohibited, just as cigarettes are. “Appropriate legislation would have an immediate impact on millions of people.”  According to PeNSE, half of all public school students can buy candy, soft drinks and processed snacks at school and eat treats nearly every day.

Some states are organizing to change the situation.  On the evening of September 13, 2016, SPTV, Rede Globo TV news in São Paulo, televised the start of debates in the São Paulo Legislative Assembly that could lead to a ban on the sale of candy, soft drinks and other high calorie foods in the state’s public schools. “I’m on the right track,” said Solange Tagliapietra, principal of Colégio Pietra, a private school in São Paulo’s north zone that took part in ERICA, upon hearing the news.  For years, she has banned these products from her school’s snack-bar, a spot that continues to sell fried salty snacks, which she also wanted to do away with.  On a break between classes on this day, seated in groups on the stadium bleachers, teens were chatting and enjoying their snacks. Most filled their bellies with packages of cookies or potato chips and sodas – a few munched on fruit and sandwiches made with whole grain bread.

Sugar response
The hypothalamus of obese adolescents reacts more slowly than that of thin adolescents to the intake of a super-concentrated glucose solution

Researchers at the School of Medical Sciences of the University of Campinas (FCM-Unicamp) have identified changes – purportedly reversible – in the structure and functioning of the hypothalamus of obese children and adolescents.  The hypothalamus, located in an area deep within the brain, controls, among other things, the production of hormones that regulate appetite.

The changes were detected using magnetic resonance imaging studies of the hypothalamus of children and adolescents aged 9 to 17, divided into two groups:  12 participants were overweight and 11 were of normal weight.  Participants whose weight was above the recommended level presented a phenomenon known as gliosis, characterized by the proliferation and inflammation of the glial cells which, like neurons, make up the nervous system. Glial cells form a type of scar in response to lesions, likely caused by excessive lipids (fats) circulating in the body, and stop functioning as they did before.  Gliosis is one of the signs of mental disorders like Alzheimer’s disease, frequently seen among the elderly.

Excess fat can damage the cells of the hypothalamus (in green above), which controls the production of appetite-regulating hormones.

Excess fat can damage the cells of the hypothalamus (in green above), which controls the production of appetite-regulating hormones.

“Inflammation of the glial cells and functional changes of the hypothalamus explain some of the day-to-day phenomena commonly experienced by overweight people, such as binge eating,” says pediatrician Leticia Sewaybricker, who conducted the study as part of her doctoral research completed in September 2016, advised by Unicamp pediatrician Gil Guerra Junior. She also determined that the hypothalamus of overweight children and adolescents showed no reaction after ingestion of a concentrated solution of glucose.  In comparison, the hypothalamus of normal weight participants responded and “the brain quickly sent satiety signals,” she noted (see graph). In addition, the hypothalamus of the overweight group presented fewer connections with the brain and other regions of the central nervous system than did that of the other group.

“The inflammatory stimulus that causes the gliosis persists as long as one continues to eat a lot of saturated fats,” says Lício Velloso, professor at FCM-Unicamp and one of the coordinators of the study associated with the Obesity and Comorbidities Research Center (OCRC), one of the Research, Innovation and Dissemination Centers (RIDCs) supported by FAPESP. “As a result, overweight adolescents will have even more trouble controlling their appetite, regulated by the hypothalamus, and will continue to eat more than they really need to.”

Perhaps this condition can be reversed, at least in part. Studies using mice indicated that reduced inflammation of glial cells leads to weight loss, and unsaturated fatty acids like Omega 3, could reverse the damage caused by excess saturated fats like that found in red meat, and help restore the neurons (see Pesquisa FAPESP Issue nº 240).  In addition, the hypothalamus of obese people resumed the desired normal function after the patients underwent bariatric surgery.  Based on these observations, researchers believe that changes in diet, with decreased consumption of saturated fats and reduced glucose levels could possibly reverse these changes observed in the hypothalamus of overweight children and adolescents.

Scientific articles
BLOCH, K. V. et al. Erica: Prevalências de hipertensão arterial e obesidade em adolescentes brasileiros. Revista de Saúde Pública. V. 50, p. 1s-13s. 2016.
DUARTE, L. S. et al. Brazilian maternal weight perception and satisfaction with toddler body size: A study in primary health care. Journal of Pediatric Nursing. V. 31, p. 490-7. 2016.
BRYAN, C. J. et al. Harnessing adolescent values to motivate healthier eating. PNAS. V. 113, n. 39. 2016.
DAS NEVES, J. et al. Malnourished children treated in day-hospitals or outpatient clinics exhibit linear catch-up and normal body composition. Journal of Nutrition. V. 136, n. 3, p. 648-55. 2006.

Ministry of Health. Guia alimentar para a população Brazileira. 2a ed., Brasília: MS, 2014.
Brazilian Institute of Geography and Statistics. National School Health Survey 2015. Rio de Janeiro: IBGE, 2016.

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