Wealthier people are healthier and live longer. Why? One popular explanation is summarized in the documentary Unnatural Causes: Is Inequality Making us Sick?

The lives of a CEO, a lab supervisor, a janitor, and an unemployed mother illustrate how class shapes opportunities for good health. Those on the top have the most access to power, resources and opportunity – and thus the best health. Those on the bottom are faced with more stressors – unpaid bills, jobs that don’t pay enough, unsafe living conditions, exposure to environmental hazards, lack of control over work and schedule, worries over children – and the fewest resources available to help them cope. The net effect is a health-wealth gradient, in which every descending rung of the socioeconomic ladder corresponds to worse health.

If this were true, then increasing the wealth of a poor person would increase their health. That does not appear to be the case. In important new research David Cesarini, Erik Lindqvist, Robert Ostling and Bjorn Wallace look at the health of lottery winners in Sweden (75% of winnings within the range of approximately $20,000 to $800,000) and, importantly, on their children. Most effects on adults are reliably close to zero and in no case can wealth explain a large share of the wealth-health gradient:

In adults, we find no evidence that wealth impacts mortality or health care utilization, with the possible exception of a small reduction in the consumption of mental health drugs. Our estimates allow us to rule out effects on 10-year mortality one sixth as large as the crosssectional wealth-mortality gradient.

The authors also look at the health effects on the children of lottery winners. There is more uncertainty in the health estimates on children but most estimates cluster around zero and developmental effects on things like IQ can be rejected (“In all eight subsamples, we can rule out wealth effects on GPA smaller than 0.01 standard deviations”). Overall for children:

Our results suggest that in a model of child development parameterized to match conditions in Sweden, the effect of permanent income on children’s outcomes is small. With the exception of obesity risk, we estimate precise zero or negative effects in subpopulations for which theories of child development predict larger benefits of wealth. For example, though the mechanism differs, investment models (Becker and Tomes 1979) and parental stress models (Bradley and Corwyn 2002) predict larger positive effects of wealth shocks in families with low incomes. The small impact of wealth on proxies for parenting behavior may explain why the shocks to permanent income appear to have few discernible intergenerational impacts.

One point to note is that they are looking primarily at children born prelottery although they do not find any health effects in infants born postlottery.

As the authors note, Sweden is an affluent society with an extensive social safety net. Nevertheless, there is still a significant health-wealth gradient in Sweden. We might get larger causal estimates of wealth on health elsewhere but the Swedish results bound how far we can reduce the gradient.

The bottom line: Is inequality making us sick? No.

Addendum: The methodological note below was an impressive sign of how research standards at the frontier are changing, expect to see more like this in the future:

To minimize concerns about undisclosed multiple-hypothesis testing, our intergenerational analyses were prespecified in an analysis plan posted in the public domain before running any regressions of child outcomes on the treatment variable (Cesarini et al. 2014).

Addendum 2: See the comments for useful additional information from Erik Lindqvist, one of the authors.