Thirty years: difference in life expectancy between the world's rich and poor peoples

Life expectancy in the richest countries of the world now exceeds the poorest by more than 30 years, figures show. The gap is widening across the world, with Western countries and the growing economies of Latin America and the Far East advancing more rapidly than Africa and the countries of the former Soviet Union.

Average life expectancy in Britain and similar countries of the OECD was 78.8 in 2000-05, an increase of more than seven years since 1970-75 and almost 30 years over the past century. In sub-Saharan Africa, life expectancy has increased by just four months since 1970, to 46.1 years.

Narrowing this "health gap" will involve going beyond the immediate causes of disease – poverty, poor sanitation and infection – to tackle the "causes of the causes" – the social hierarchies in which people live, the Global Commission on the Social Determinants of Health says in a report.

Professor Sir Michael Marmot, chairman of the commission established by the World Health Organisation in 2005, who first coined the term "status syndrome", said social status was the key to tackling health inequalities worldwide.

In the 1980s, in a series of ground-breaking studies among Whitehall civil servants, Professor Marmot showed that the risk of death among those on the lower rungs of the career ladder was four times higher than those at the top, and that the difference was linked with the degree of control the individuals had over their lives.

He said yesterday that the same rule applied in poorer countries. If people increased their status and gained more control over their lives they improved their health because they were less vulnerable to the economic and environmental threats.

"When people think about those in poor countries they tend to think about poverty, lack of housing, sanitation and exposure to infectious disease. But there is another issue, the social gradient in health which I called status syndrome. It is not just those at the bottom of the hierarchy who have worse health; it is all the way along the scale. Those second from the bottom have worse health than those above them but better health than those below."

The interim report of the commission, in the online edition of The Lancet, says the effects of status syndrome extend from the bottom to the top of the hierarchy, with Swedish adults holding a PhD having a lower death rate than those with a master's degree. The study says: "The gradient is a worldwide occurrence, seen in low-income, middle-income and high-income countries. It means we are all implicated."

The result is that even within rich countries such as Britain there are striking inequalities in life expectancy. The poorest men in Glasgow have a life expectancy of 54, lower than the average in India. The answer, the report says, is empowerment, of individuals, communities and whole countries. "Technical and medical solutions such as medical care are without doubt necessary. But they are insufficient."

Professor Marmot said: "We talk about three kinds of empowerment. If people don't have the material necessities – food to eat, clothes for their children – they cannot be empowered. The second kind is psycho-social empowerment: more control over their lives. The third is political empowerment: having a voice."

The commission's final report, to be published next May, will identify the ill effects of low status and make recommendations for how they can be tackled.

In Britain a century ago, infant mortality among the rich was about 100 per 1,000 live births compared with 250 per 1,000 among the poor, a rate similar to that in Sierra Leone

Infant mortality is still twice as high among the poor in Britain, but the rates have come down dramatically to 7 per 1,000 among the poor and 3.5 among the rich. Professor Marmot said: "We have made dramatic progress, but this is not about abolishing the rankings – there will always be hierarchies – but by identifying the ill effects of hierarchies we can make huge improvements."

A ray of hope from the street vendors of Ahmedabad

The women street vendors of Ahmedabad, India, have peddled their wares for generations, rising at dawn to buy flowers, fruit and vegetables from wholesalers in the markets before fanning out across the city. They frequently needed to borrow money, faced punitive rates of interest and were routinely harassed and evicted from their vending sites by local authorities.

They were a typical example of disempowered women, prey to the evils of debt, loss of livelihood and ill health, until they campaigned to improve their status.

With help from the Self-Employed Women's Association of India (Sewa), the vegetable sellers and growers set up their own wholesale vegetable shop, cutting out the middlemen who had exploited them. They also organised childcare, set up a bank for credit and petitioned for slum upgrading.

To overcome possible health crises, when poor women frequently had to sell their possessions to raise money for treatment, Sewa set up a health insurance scheme for them.

Emboldened by their links with Sewa, the vegetable sellers campaigned for the local authority to recognise them formally and strengthen their status by issuing street vending licences and identity cards, giving them security of employment. The campaign started in Gujarat and went all the way to the Supreme Court, attracting international attention.