According to research to be published in the journal Circulation, blood could be repository of clues as to why people with lower incomes and education tend to have higher blood levels of two inflammatory chemicals.
The study by researchers of the University of Michigan; Nalini Ranjit, Ph.D., and colleagues, shows that high levels of these chemicals - interleukin-6 (IL-6) and C-reactive protein (CRP) - have been associated with heart disease.
Yet scientists caution that there is no suggestion that a person's salary or schooling determines his health. Still education and income often seen to sync up with a person's opportunities, access to medical care, and other factors.
The study looked at levels of IL-6 and CRP levels in around 6,800 U.S. men and women aged 45-84.
Data surveyed included that of the participants' education, income, BMI (body mass index, which relates height to weight), waist circumference, smoking, drinking, physical activity, diabetes, and medications.
Participants were also asked to rate their depression, hostility, chronic stress, and depression.
In all of the groups studied - white, African-American, Chinese, and Hispanic, it was noted that lower incomes were linked to higher levels of IL-6.
In whites and African-Americans, lower levels of education were associated with higher levels of IL-6.
The patterns were quite the same for CRP, Rangit's team concluded.
It was also seen that being overweight was the most common link between education, income, and higher levels of IL-6 and CRP.
"Diet is well known to affect other risk markers for cardiovascular disease, notably blood cholesterol levels, but levels of the inflammatory molecules are more sensitive markers than serum [blood] cholesterol," Ranjit said.
Hostility and smoking were also seen to matter. According to the study, there could be multiple factors that connect increased inflammation and lower income.
"Our results suggest that persons of lower socioeconomic position have greater inflammatory burden than those of higher socioeconomic position because of the cumulative effects of multiple behavioral, psychological and metabolic characteristics", Rangit was quoted.
"If the role of inflammation in the origin of multiple chronic diseases is confirmed, inflammation may represent a common element through which socioeconomic position is related to cardiovascular disease and other chronic disease common in aging", she added.