Today is World Food Day. It might, if one heeds the words of Ban Ki-moon, be more suitably designated Global Lack of Nutrition Day. For, according to a statement by the Secretary-General of the United Nations this weekend, in a world that can produce enough food to feed everyone, nearly a billion people will go hungry today. And that is one in seven of us.

A welter of little-noticed reports have been published on the subject in the past week, notably a study of worldwide food insecurity by the UN Food and Agriculture Organisation (FAO). This estimated that a total of 925 million people were undernourished in 2010, two-thirds of whom lived in just seven countries – Bangladesh, China, the Democratic Republic of Congo, Ethiopia, India, Indonesia and Pakistan. The report makes a distinction between those living below subsistence level, and those in countries such as Somalia in "protracted crisis". About 166 million in such places are starving or undernourished.

The reports make quite clear that rising food prices, stock market speculation in crop futures, conflict, climate change and corrupt, repressive regimes are the reasons why so many people go hungry – not humanity's inability to grow enough crops. The findings come three months after the declaration of a major famine in the Horn of Africa – a glaring instance of several of these dread factors working at once.

There are few countries in East Africa left unaffected by the terrible drought in the region, but it is only in Somalia that persistent conflict and a lack of an effective central government have tipped the situation into a full-scale famine. Money has poured in from governments, agencies and individuals, all wanting to help. The total raised so far is about £1.8bn – equating to £140 in aid for each of the 13 million people at risk of starvation.

Despite this, there are still hundreds of thousands who are not getting help because they are trapped in parts of the country controlled by the al-Qa'ida-linked terror group al-Shabaab. Most Western agencies are blocked from accessing south and central Somalia by al-Shabaab, and those that can get in are well aware of the security risk. With the most significant shortfalls in the delivery of aid occurring in the areas of greatest need, an estimated 25,000 children have died in Somalia since the start of the crisis.

In the Dadaab refugee camp in Kenya, previously seen as one of the safer locations for aid workers, the kidnapping of two Spanish women working for Médecins Sans Frontières has caused agencies to begin withdrawing international staff. The UN refugee agency, UNHCR, has suspended non-critical operations at the sprawling camp after Thursday's broad-daylight attack in the heart of Dadaab. Aid agencies are becoming increasingly concerned by the worsening insecurity at the camp, where refugee numbers have swollen to more than 460,000 this year as famine and conflict drive Somalis across the border.

However, in some drought-affected areas in Kenya and Ethiopia, the situation is gradually beginning to improve. More aid is getting through, some harvests are being reaped and the long-awaited arrival of rain is making pasture available for surviving livestock. Most regions are starting to see rain, although forecasts suggest the north of Somalia will not get enough to ensure a decent harvest. But the rains will not be the panacea that people hoped for, as disease and flooding take the place of famine. Torrential rain hit drought-displaced families living in camps in Mogadishu last week, sweeping at least two children away, killing a pregnant woman and leaving thousands of people without shelter.

Today marks 100 days since the Disasters Emergency Committee (DEC) launched its East Africa Crisis Appeal, which has now reached £72m, the largest total ever raised by the organisation for famine relief. Brendan Gormley, the DEC's chief executive, said: "The incredibly generous support of the UK public has made the difference between life and death for many people in the region. The situation remains grave, however, particularly in those areas of Somalia where access for most aid agencies remains severely restricted."

He added: "We must also confront the hard truth that the worst of this crisis could have been averted. After the 1984-85 famine in Ethiopia, systems were put in place to warn the world should famine ever threaten the region again."

A lack of proper planning and prevention has once again created a crisis in East Africa, despite many thwarted attempts to break the cycle of famine. In 2000 the UN Secretary-General announced the establishment of an inter-agency task force in the Horn of Africa. A strategy was published but, after much political wrangling, never implemented.

Kostas Stamoulis, director of agricultural development economics for the UN, said: "Unless we stick to a long-term plan for getting regions out of crisis and out of vulnerability, then every five years we'll be talking about the Horn of Africa." Mr Stamoulis is aware that while crises such as the one in Somalia will be reported on, the long-term problem, with nearly a billion people going hungry across the globe, continues to be ignored. "Emergencies affect hundreds of thousands of people every year but chronic hunger is a huge problem," he said. "We can't mobilise food aid to feed nearly one billion – it just isn't feasible."

The UN believes part of the reason for food shortages is a lack of investment in agriculture. In countries in protracted crisis, the FAO report says that only 3-4 per cent of funds for development and humanitarian assistance go towards agriculture.

Mr Stamoulis said: "Some 75 per cent of those going hungry are rural people who derive most of their living from agriculture. We have neglected agriculture for too long. For years, people felt the way out of economic difficulties was to industrialise, but that meant agriculture was neglected in terms of research and in terms of rural infrastructure ... If we don't do something now we're going to face even more of these food security crises in the future. If you add in climate change and the fact that natural resources to produce food are declining, we'll be in pretty bad shape."

In Yemen, a deteriorating situation has quickly become a disaster. Last week the World Food Programme warned that the country faces a humanitarian crisis after rising food prices combined with political instability to put 3.5 million people at risk of starvation. In Afghanistan, three decades of war and instability have had a similar effect. Almost one-third of the population do not have access to enough food to stay healthy.

In many countries, humanitarian relief is complicated by politics. The Obama administration was last week accused of dithering over sending food aid to North Korea. A third of all children under five in the Communist country are chronically malnourished but the US says it will not give aid until the state guarantees it will reach the most needy and until there is an improvement in relations with South Korea. North Korea's dysfunctional food-distribution system, rising global food prices and sanctions imposed because of its nuclear and missile programmes have all contributed to the crisis. On top of this came recent typhoons and flooding.

But for many of the millions going hungry each year, it is not war or natural disaster that prevents them from having enough to eat but simply not having sufficient money in their pockets. Worldwide food prices have been high since 2006, when speculation by traders caused staples such as rice to rise by up to 320 per cent in a year. From 2005 to 2008, the worldwide average price of food went up by 80 per cent – and it is still rising.

For those whose income was only ever enough to fund their subsistence, it has meant being priced out of life.

Additional reporting by Eliza Craston

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