What makes someone healthy? Certainly exercise and diet. But what about a college degree? Or say, a higher salary? A new study found that the more income and education people have, the less likely they are to have colds, headaches, flu and chronic physical pain.

The study, published in March by The Archives of Internal Medicine, asked 350,000 participants to remember their symptoms the day before. People who did not finish high school were nearly twice as likely to report having a cold, a headache or pain than those with a college degree. Among those earning less than $12,000 a year, 46 percent report feeling physical pain on any given day, double that of the average American. This was true even when factors such as age, access to health care and medical history were considered.

What researchers are trying to understand is why? Health differences across socioeconomic gradients have been looked at in many studies before, but most have focused on chronic conditions: obesity, heart disease, etc, and others have looked at access to health care and physical environment. It’s no secret that poor living conditions can affect health. Buildings without heat or air cooling; rooms with layers of peeling lead paint; rats and roaches and other vermin that carry disease-all conspire to compromise health in impoverished areas. The high incidence of asthma in poor urban areas is just one indicator. But the study signifies that education and psychological stress may be just as important markers of disease and pain as poor environment.

“Everyone thought it was going to be access to health care-you know, people with more money or education would have better access to health care, and hence they would do better,” says Dr. Arthur Stone, who led the study. “But that doesn’t seem to be the case from the research that’s out there. So it really is a puzzle as to why this is. It may be that people with lower levels of resources-educational and financial-are under higher levels of stress, which then has an impact on a variety of things.”

Health Inequality

The authors of the study run though possible explanations: Crowded living conditions and greater use of public transportation could mean increased exposure to infection. Increased headaches and pain could be related to differences in noise exposure, working environments, posture, or increased muscle tone from chronic stress.

One of the first to tackle the subject of health inequality along socioeconomic lines, was a London professor Sir Michael Marmot in 1985 with the Whitehall studies. He was surprised to find that people in high status jobs-meaning more responsibility and stress-actually had a lower risk of heart disease than lower-tier employees.

“Autonomy, control, empowerment, turn out to be crucial influences on health and disease,” said Sir Marmot in a PBS documentary on his research called Unnatural Causes: Is Inequality Making Us Sick? He found that not only do the poor live on average six years less than the rich, but those in the middle class will die two years sooner than rich, and this continues all the way down the socioeconomic pyramid.

Only recently have studies begun to address everyday health. Dr. Nancy Adler, a health psychology professor at University of California, San Francisco, collaborated on a study where participants rated themselves on where they stood on the socioeconomic ladder, and were then exposed to a flu virus. Those who rated themselves low on the ladder were more likely to develop a cold. “The best way to think about this is it’s a ripple effect, which is, being of low status, living in poor areas just subjects you to a whole lot more challenges to the body, both psychological and physical,” she says.

Other Findings

In fact, stress, the psychological effects of low income, and poor living conditions have been looked at as a determinant of health in many studies, particularly at the MacArthur Research Network on SES & Health. Researchers there have found that stress from financial insecurity or conflict can take a toll on many systems in the body including cardiovascular, immune, metabolic and nervous systems. This, on top of poor diet and exercise, fewer healthy food options in poor neighborhoods, and increased exposure to infection, one can see how it starts to add up.

Of course, access to health care also plays a part, as many supporters of the health care bill will point out. But according to Dr. Adler, it’s not as much of an issue in this case. “We’ve quite explicitly not looked at the role of health care for three reasons: One is it’s really well studied, it’s the first thing everyone thinks of. The second is access to health care tends not to be as helpful in avoiding the onset of diseases, in part because our health system is not very good in prevention. The other thing is that we find these SES gradients in insured populations, we find it in countries that have universal access to care, so it just doesn’t look like much of the action is in health care.”

As the health care debate continues and the new bill is implemented, the pervading health inequalities in America should not be overlooked. As one congressman, Rep. Pete Stark (D-CA) said when calling for an amendment to the Constitution to guarantee health care for all, “The health of every American is vital to their unalienable rights of ‘life, liberty, and the pursuit of happiness.'”