By Catherine Clabby

Frequent exposure to intense stress in childhood increases risks for several grave health problems throughout life; heart disease, diabetes, substance abuse, and depression are among the unwelcome outcomes.

But trouble from so-called “toxic stress” may start even earlier: in the womb, says Cathrine  Hoyo, a genetic epidemiologist at N.C. State University.

headshot of an African American woman.
Catherine Hoyo wants to make invisible effects from stress on human genes visible. Photo courtesy of North Carolina State University

With complex lab studies and questionnaires, Hoyo is probing why women who endure substantial stress while pregnant are more likely to have children who become obese.

Genetic changes that stressed mothers pass on to developing fetuses, may be in play, Hoyo says.

If she is correct, Hoyo hopes to help uncover a DNA fingerprint to identify children vulnerable to obesity, opening new doors to early preventative care by clinicians and families.

“If we’re going to intervene, we need to screen. To screen, you need to know what you are looking for,” Hoyo said.

Not just fast food and inactivity

In North Carolina, 13.5 percent of children ages 2 to 4 years enrolled in a federal nutrition supplement program were obese in 2016; 14 percent were overweight, according to the Centers for Disease Control and Prevention. Among those aged 10 to 17, 30.9 percent were overweight or obese, a slight dip from the 33.9 percent recorded in 2004.

chart shows prevalance of obesity among youth aged 2-19.
African American and Latino children are more likely to be obese in the United States. Source: Centers for Disease Control and Prevention.

Those tallies sound public health alarms because obese children are more likely to suffer breathing problems, including asthma, joint disorders and type 2 diabetes. They are also at heightened risk of becoming obese adults, who live with an elevated risk of developing heart disease, cancer and, with age, diabetes.

Not only is it expensive to treat such disorders, the illnesses often diminish a person’s quality of life.

“Obese children essentially have a permanent noose around their necks in terms of their future,” said Mary Jo Deck, a long-time child advocate who works with the obesity-prevention program ShapeNC at Buncombe Partnership for Children.

ShapeNC is among the programs in this state using science-based strategies to reduce excess weight in children by encouraging increased physical activity and switching from high-calorie processed foods to nutritious whole foods, including fruits and vegetables.

Hoyo, however, focuses on what most people could never see: biological alterations in miniscule stretches of the six feet of microscopic DNA tightly coiled inside human cells.

DNA carries the genetic code that children inherit from their parents; it’s the playbook that directs the specialized biochemical activities of our many specialized cells.

Hoyo studies epigenetics, the research field focused on how environmental triggers alter the activity of genes. Rather than rewriting DNA the way genetic mutations do, epigenetic gene regulation uses chemicals and proteins to activate or shut down genes or, sometimes, to blunt or rev up their activity.

Sustained and extreme stress are now recognized as environmental cues that can prompt epigenetic adjustments.

Surveys and sequencers

This summer, the National Institute of Minority Health and Health Disparities funded multiple research projects exploring the impact of “social epigenetics,” including an $800,000 annual award for five years to Hoyo. Such research is being pursued because some people, often poor people living in stressful environments, encounter more negative environmental triggers than others.

“Living in disadvantaged neighborhoods with exposure to chemical stressors, violence, discrimination, residential segregation and psychosocial stress, and limited access to healthy foods, can affect a person’s ability to stay healthy, becoming barriers to health,” the NIH announcement read.

NC Statistics show 30.9 percent of 10-17 year olds are obese in 2016, NC ranks 25th among states.
North Carolina childhood obesity figures. Source: The State of Obesity, by the Trust for America’s Health and the Robert Wood Johnson Foundation.

Hoyo’s laboratory team and research partners at Johns Hopkins University are recruiting hundreds of pregnant black, Latino and white women in North Carolina and Florida for their study.

They’ll ask the women detailed questions regarding the degrees of difficulties they live with. Queries will cover a woman’s use of drugs, physical activity habits and exposure to violence. They’ll ask whether family members throw things during arguments or strike one another, whether the women’s homes are in good or poor condition, and whether the water they consume is safe.

Eventually, they will study cells within their babies’ umbilical cords to see if they have been altered by high blood pressure and other physical responses to prolonged stress. They will also decode, or sequence in scientific language, regions of their babies’ DNA to look for epigenetic effects linked to high stress and obesity.

Through much of human history, the genetic regulation Hoyo wants to map could have been very useful. Having a child feel compelled to eat when not hungry could increase her chances of survival in places when food was scarce, for instance.

But that trait can be highly unhealthy today in the United States and other affluent countries among families when stress is abundant, and low-cost high-calorie food is only a fast-food drive-up window away, Hoyo said.

“The uterus is supposed to be preparing you for the outside world, but probably not the world we have now,” Hoyo said.

Eager for help

Ongoing efforts to change the quality of food available in day care centers and to encourage children to be more active have had positive impacts in North Carolina, Deck said.


Centers across the state participating in ShapeNC, for instance, have recorded gradual improvements in the weight of the children they care for along with more physical activity, more fruit and vegetables consumed and more outdoor learning.

The insight that a scientist such as Hoyo develops may help indicate which kids need special attention due to a physical predisposition to be obese and could help expand prevention. And prevention is always better than treatment.

“We’re picking up the pieces but we’re always behind,” Deck said. “Prevention puts us ahead.”

Creative Commons License

Republish our articles for free, online or in print, under a Creative Commons license.

Rose Hoban is the founder and editor of NC Health News, as well as being the state government reporter. Hoban has been a registered nurse since 1992, but transitioned to journalism after earning degrees...