California magazine

A new report by a Berkeley public health professor is the largest of its kind to refute the longstanding assumption that greater income leads to better health.

In her study, Professor Lia Fernald, MBA '00, and her UC San Francisco colleague examined the relationship between systolic blood pressure—a leading health indicator—and various measures of socio-economic status in 9,000 women living in poor villages across Mexico. She found that, contrary to expectations, women who had greater household income and higher self-perceived status also tended to have higher blood pressure. Income was not the whole story, however; factor in educational attainment and the correlation reversed.

The study challenges the widely held belief among public health professionals that greater income always fosters improvements in health. Fernald says that idea is based on studies conducted in wealthy nations and was never adequately tested in developing countries or among low-income populations.

Fernald speculates that access to processed foods is a major contributor to the positive correlation between income and blood pressure. "Increased income among very poor populations," she writes, may "be used to purchase 'unnecessary' calories," like soda and potato chips. Another factor could be the stress that comes along with increased workloads and having more resources than one's neighbors. Such stress is a known precursor to hypertension but education can mitigate the effect.

Fernald says the research reinforces the importance of investing in education, which is "the thing that's protecting people, whereas income and assets are associated with worse outcomes."