Poverty's harsh effects on health start before babies are born and pile up throughout their adult lives. With stressed-filled homes, shaky nutrition, toxic environments and health-care gaps of every kind, kids in very low-income families may never catch up when it comes to their health. Below, experts spell out the strong link between poverty and illness and discuss efforts to lift people to better health.

Between 10 and nearly 15 years – that's the difference in life expectancy between the poorest and richest people in the United States, according to findings just published online in the medical journal JAMA. In the huge, long-term study encompassing 1.4 billion Americans, researchers matched income levels and mortality data between 1999 and 2014 to reach their conclusion. And low income has long been linked to lower birth weight, which increases the risk of a host of health and educational problems.

Gaps like this come as no surprise to Dr. James Duffee, who's been a community pediatrician in Springfield, Ohio, for more than 20 years, serving mostly low-income children and families. "Poverty is a negative, independent factor that influences lifelong health," he says. "Through the science of toxic stress, we understand that early childhood adversity and poverty is a factor that affects not only brain architecture and [neurologic and endocrine] function, but affects the probability of lifelong illness, including cardiac disease and diabetes."

The insidious role of stress starts early. "If a child is exposed to constant stress in childhood, essentially their stress mechanism is never turned off," Duffee says. "So it resets at a higher level, a higher heart rate, higher blood pressure." Adults living in poverty, among other stresses, are much more likely to have inflammatory diseases, he says, with an increased risk for heart attack and stroke.

"Many, many adult illnesses have thdepressioneir foundation in early childhood," Duffee says. People living in poverty are more likely to smoke, he points out, putting them at higher risk for lung cancer and respiratory conditions.

Injuries and Low Income

"People are often surprised at the increase in accidents and actual deaths that happen to poor children," says Dr. Benard Dreyer, president of the American Academy of Pediatrics. But it's not really that hard to understand.

"They live in more dangerous environments," he says. "Their parents are stressed out, often working multiple jobs. They live in substandard housing. They live in dangerous neighborhoods where they can be shot or injured."

Food on the Table?

It seems like a paradox: increased hunger yet more obesity among poor people. "The answer is pretty simple," says Dreyer, who is also the director of developmental-behavioral pediatrics at the New York University School of Medicine. "The cheapest food you can buy is usually empty calories – high-calorie, high-fat food."

People may live in food deserts, Dreyer says – neighborhoods with nowhere to get fresh vegetables but plenty of access to fast food. With this combination, he says, "people are hungry, and when they get food, they're going to try to eat a lot of it."

Sometimes there just isn't enough to eat. When that happens, Duffee says, "The truth of the matter is, most of the time parents are forgoing their meals to feed the kids."

Emotional Health Suffers

Almost half of children who live in poverty have mothers with at least some symptoms of depression, because of the stresses of raising a family in these circumstances, Duffee says.

"Mothers who are depressed interact with their children very differently," he says. "Those interactions – the lack of stimulation and socio-emotional connections, what we call attachment – also have long-term effects, if not lifelong effects, on children."

Duffee recalls a recent situation. "I saw a family with two children and the parents and an older adult child in the room," he says. "And the identified patient was a 9-year-old boy who was very upset. The father said to me, 'Why doesn't he follow any instructions I give him? I don't understand why he's so disrespectful, and he's always hateful to me.'"

There was more to the story, Duffee learned. "Halfway through the interview, the mother turned to me and said, 'There's something you probably need to know: We're homeless and living in one room in a hotel.' So I said to [the father], 'Can we understand that this boy is extremely upset because you live in a hotel room and don't have a home, and all five of you live in the same room? And how would you expect him to follow directions or not respond to that?'"

Kids respond to that kind of adversity in two ways, Duffee says: either with outward behavior or becoming depressed and internalizing their reaction. "This boy was expressing his distress by becoming oppositional," Duffee says.

Toxic Infrastructures

Lead-contaminated water used to be a widespread health hazard, Duffee says, although it has been less so in the past few decades. But the threat remains. "Because of the lack of infrastructure in cities, lead is becoming more of a concern," he says. "As the infrastructure deteriorates, lead is released in some of the older pipes."

Duffee points to the Flint, Michigan, water crisis as a recent example. "There's no safe level of lead exposure," he says. "Exposure to lead in the first couple of years can cause lifelong, irreparable damage" to the brain, he says. "It doesn't always, but it can."

Dental and Vision Disparities

Pediatricians are starting to take more interest in early oral-health promotion, Duffee says. Applying fluoride varnish during well-child visits significantly reduces childhood dental cavities, he says. Also, he adds, educating mothers to not prop bottles of milk during feeding helps prevent rotting front teeth.

Vision health, although covered by Medicaid, can still be a problem. Kids often break their glasses, Duffee notes. "And so they walk around without any glasses because they've broken them, and there's not enough money to replace them." When kids can't see properly, that "absolutely" has an educational impact, he says.

Two-Way Street

Inadequate dental coverage helps perpetuate the poverty cycle, says Barbara Wolfe, a professor who specializes in health economics at the University of Wisconsin–Madison. "If an individual hasn't gotten appropriate oral health care, as a child or an adolescent, and then loses teeth, it makes it really hard to get a job," she says.

The tie between poverty and health most likely goes in both directions, Wolfe says, with an adult in poor health more likely to have lower earnings.

On the other hand, a boost in income can boost health. In research Wolfe conducted involving Native American tribes included in reservation gaming compacts, her group found mental-health improvements for depression and anxiety. Other studies of groups with an influx of income have found small improvements in blood pressure among people with hypertension, she says, and needed eyesight corrections being made.

Maternal Health Focus

Narrowing the health-care gap starts at the beginning of life. "We have gone a long way to provide health care, mainly through Medicaid, to low-income women," Wolfe says. "We do have policies in this country that are targeted on trying to reduce outcomes that could be prevented just by prenatal care."

The Affordable Care Act appears to be helping, she says, not only through earlier access to prenatal care, but also in terms of providing greater services to young women from low-income families in the first few months of a child's life. "That focus on intensive services in those early months is an effort to educate parents," she says. That includes raising their awareness of children's health and teaching them about kids' nutritional needs.

Programs That Help

"Without government programs, instead of one out of five children living in poverty, it would be one in three children living in poverty," Dreyer says. "So they really do help keep children out of poverty. The problem is, we need to expand and enhance them rather than fight just to keep them alive." The good news, he says, is programs such as the Supplemental Nutrition Assistance Program (or food stamps), WIC and school-lunch programs and certain tax credits that are permanently in place.

Community health centers are improving access, Wolfe says. "We have spread these health care centers to many more areas that did not have adequate providers," she says.