The more you earn, the healthier you’ll be: that’s the message of a new study by researchers at the Urban Institute and Viriginia Commonwealth University.

To some extent, these are obvious findings. We’re all aware that people who live in poverty are more likely to be affected by various diseases than people who don’t. But the relationship turns out to be more nuanced than that. It’s not just a poverty/not-poverty binary – very rich people tend to be healthier than somewhat rich people. As the authors put it, health and income are “connected step-wise at every level of the economic ladder.”

How did the researchers discover this?

To assess the relationship between income and health, the researchers examined 12 health problems and their prevalence according to income. They found that the rich were consistently less likely to develop the health problems.

In most cases, the disparity was significant. Look at chronic arthritis, for example: people who earn less than $35,000 a year had a type 2 diabetes risk of just under 35 per cent; people who earn more than $100,000 a year had a risk of just under 25 per cent.

A ten per cent gap between the richest group and the poorest (the study used five income categories: less than $35k; $35-50k; $50-75k; $75-100k; $100k or more) might be expected. But there is roughly a five per cent gap between people who earn between $75,000 and $100,000 a year and people who earn more than $100,000 a year. Why would there be such a significant gap between the rich and the very rich?

This trend continues for almost every one of the 12 diseases. Type 2 diabetes is one of the few exceptions, with people earning $75-100k slightly less likely to develop the disease than people earning more than $100k.

But then, people who earn $50-75k a year were three per cent more likely to develop type 2 diabetes than people earning between $75-100k. Both groups make enough to eat healthily, making the disparity difficult to explain.

Unsurprisingly, the findings extend to life expectancy. The more you earn, the longer you live.

Income and happiness

The report also examined the relationship between wealth and happiness. And the findings were just as stark.

6.4 per cent of people who earned less than $35,000 reported feeling sad “most of the time.” For people on more than $100,000 a year, this figure was 1.2 per cent.

1.3 per cent of people earning between $75,000 and $100,000 felt sad most of the time. For people who earned $50k-75k, the figure was 2.3 per cent. Once again, there are significant differences between wealth and wellbeing between people who only have slight disparities in their earnings.

Diabetes and income: Why is this the case?

Well, there’s the obvious reason: people with lots of money can afford things that protect your health, like more expensive healthy foods. Poor people can’t. This can have a big influence on the development of type 2 diabetes. In March, for example, a study found that over 60 per cent of calories come from highly processed foods, which are usually eaten in greater quantities by people from lower income backgrounds.

Previous studies have suggested that people with diabetes from more affluent backgrounds have better blood glucose control.[1] Why? Again, it’s horribly complicated. Is it to do with education? Or is it to do with stress? According to the chart above, poorer people are more likely to report feelings of hopelessness. This, in combination with the difficulties of diabetes management, might increase the risk of diabetic burnout. What’s clear is that a whole host of factors are playing their part. It’s impossible to pick just one that might be a direct cause.

Their jobs are also better in this respect, offering paid leave, health insurance, and fewer occupational hazards. Generally speaking, at least.

The relationship may also work the other way round, with unhealthy people less likely to get good jobs.

Other than that, the relationship between income and health is a fundamentally complex one. Education, family structure, and culture – all of these things are affected by money, both in straightforward and oblique ways.

What the report does tell us is that the economic debates in the US echo in the fundamental aspect of our lives: health.

[1] http://epirev.oxfordjournals.org/content/26/1/63.long