There are now over 170 studies of income inequality in relation to various aspects of health. Life expectancy, infant mortality, low birth weight and self-rated health have repeatedly been shown to be worse in more unequal societies. These studies have been reviewed in the journal Social Science and Medicine.
Researchers sometimes disagree about the pathways leading from inequality to worse population health. The most consistent interpretation of all the evidence is that the main route hinges on the way inequality makes life more stressful. Chronic stress is known to affect the cardiovascular and immune systems and to lead to more rapid aging. Inequality makes social relations more stressful (see section on Trust and Community Life), by increasing status differences and status competition. These effects are important: Americans living in more equal states live around 4 years longer than those living in more unequal states.
This is from
The Equality Trust UK report on
the effects of inequality on physical health. They also document an increased
incidence of obesity in more unequal countries.
We found that obesity among men and women (see graph), as well as calorie intake and deaths from diabetes, are related to income inequality in rich countries. In addition, obesity in adults is also related to inequality in the 50 US states; and the percentage of children who are overweight is related to inequality both internationally and in the USA.