Social class is simply the best predictor of health. If you could know only one thing about a person and predict that person’s health and longevity, you’d ask about social class. It’s even more important than family history.

In cases where someone has bothered asking poor people about their health, research confirms the trend: the poorer you are, the less healthy you’re likely to feel. That’s the finding of a recent Columbia University study. And results of the United States Centers for Disease Control and Prevention’s National Health Interview Survey make the case even stronger. In 2006, nearly nine times as many lower-income adults reported being in fair or poor health as affluent adults. Wealth and health go hand in hand.

Here’s epidemiologist and author of The Status Syndrome Dr Michael Marmot’s way of thinking about it: our society is a gigantic Titanic. First-class passengers on that ship disproportionately survived. In second class, fewer did. Third-class passengers… yikes. Many died before their time. And many of their modern counterparts still do.

The connections between status and health are hugely complex and only partly understood. No matter where you are, money and status make it easier for you to live in a restful place, go out for a Saturday morning jog and buy lean protein instead of fast food. It’s more likely you’ll enjoy a wide circle of friends, more job opportunities and more control over your schedule. And there’s more social pressure to stay away from blood-sucking vices like alcohol, tobacco and drugs.

If socio-economic status tells us so much about health, why didn’t we know this? In the past, many researchers felt obliged to avoid questions about socio-economic status when they designed public-health surveys. As a result, they had very little data until about a decade ago. Then the field exploded.

Adler recalls the study that got her hooked. It was one of Marmot’s, a landmark British study that scientists refer to by its shorthand, Whitehall I. Whitehall is the wide street in London where many key government departments are located, and the name is synonymous with the British civil service. In 1967, Marmot’s team began a huge survey of 18 000 male civil servants. The men were grouped into quadrants based on office hierarchy, with administrators who set policy at the top, followed by executives, clerical workers and finally office messengers at the bottom. All the workers had safe office jobs and high job security. The most surprising finding of the study was that not much about the disparity in health outcomes could be explained away by nasty habits or access to care. And in a follow-up study 25 years later in the Nineties, the men at the bottom were found to be not only unhealthier as a group, but three times as likely to die an early death as the men at the top. health and social care