'Pick the right veg' for health

Papaya is a fruit rich in beta-cryptoxanthin

Obvious choices of fruit and vegetables are not necessarily the healthiest, say researchers.

According to US experts, making simple swaps like eating sweet potatoes instead of carrots and papaya rather than oranges could make a difference.

Foods, like raspberries, watercress and kale, are richer in phytonutrients which may help prevent disease, they told a US meeting.

UK nutritionists said a balanced diet is essential to good health.

The British Nutrition Foundation warned that relying on eating a few select food types to boost health was ill-advised and said there was no such thing as a "superfood".

No one food can give you everything you need Dr Emma Williams of the British Nutrition Foundation

Experts recommend five portions a day of fruit and veg in a healthy diet.

Plant foods are known to contain "phytonutrient" chemicals that can protect the heart and arteries and prevent cancers.

But the most popular varieties may not be the best, according to US researchers.

They analysed data from US health surveys of people's dietary habits to look at the most common sources of phytonutrients.

They found that for 10 of the 14 phytonutrients studied, a single food type accounted for two-thirds or more of an individual's consumption, regardless of how much fruit and veg they ate overall.

Carrots were the most common source of beta-carotene, oranges and orange juice the most common source of beta-cryptoxanthin, spinach the most common source of lutein/zeaxanthin, strawberries the most common source of ellagic acid and mustard the biggest provider of isothiocyanates.

However, for each of these phytonutrients there was a richer food source available.

Richer foods

Switching from carrots to sweet potatoes would nearly double beta-carotene intake, say the researchers.

Similarly papaya contains 15 times more beta-cryptoxanthin than oranges, while kale has three times more lutein/zeaxanthin than spinach.

Raspberries have three times more ellagic acid than strawberries and one cup of watercress contains as much isothiocyanate as four teaspoonfuls of mustard.

Study leader Keith Randolph, who is a technology strategist for the supplement company Nutrilite, said: "These data highlight the importance of not only the quantity but also the significant impact the quality and variety of the fruits and vegetables you eat can have on your health."

Dr Emma Williams of the British Nutrition Foundation said: "They are right that some foods are richer sources of phytonutrients.

"But at the end of the day, to be healthy you need to make sure you have a varied and balanced diet.

"No one food can give you everything you need."

The findings were presented at the 2010 Experimental Biology conference in Anaheim, California.

She's been rearing a small group of apes as if they are people, to see what happens.

Chimps 'are people, too'

By Dick Taylor BBC Horizon

Danny Wallace investigates for Horizon

In a private facility just outside Des Moine, Iowa , primatologist Sue Savage-Rumbaugh is conducting an experiment that has lasted 26 years.

She's been rearing a small group of apes as if they are people, to see what happens.

Her results appear to be spectacular, at least to writer Danny Wallace: "Kanzi asked me for a present. I gave him the free toothbrush kit from my flight over. He brushed his teeth. We bonded."

Danny is a seasoned television campaigner: he showed us How To Start Your Own Country on BBC Two last year.

You could say that an adult chimp has more of the characteristics of a person than a new born baby Julian Baggini, philosopher

As a non-scientist, he's a useful man to investigate the extent to which our closest relatives, the chimpanzees, could indeed be people, too. Because, at the heart of primate research, there is a conundrum.

Many primatologists are devising experiments that show chimps are ever more people-like than was thought just a few years ago; and yet, as scientists, they will not countenance that chimps could ever be people.

Yes and no

At the Yerkes Primate Centre in Atlanta, Danny finds out from researcher Victoria Horner that chimps have culture...

Victoria: "This experiment is the first definite evidence that chimpanzees can pass on ideas to each other. That is the basis of culture."

Danny: "So, are they people then?"

Victoria: "No."

In Budongo National Park, Uganda. Katie Slocombe from St Andrews University is studying vocalisations with wild chimps...

Katie: "Chimps produce an incredibly wide range of sounds. It appears that they may have a rudimentary language."

Danny: "So, are they people then?

Katie: "No"

Alicia Melis of the Max Planck Institute in Leipzig conducts experiments to see if chimps have a quintessential human character, one that was thought to be absent till now: co-operation...

Alicia: "Chimps can co-operate, they can even chose the best co-operator to help them when presented with a range of their mates."

Danny: "...they co-operate, they're people?

Alicia: "Sort of!"

Researchers continue to find more and more human-like behaviours

Now, Danny's bluff character and native wit carry him through these encounters, but there is a good reason why he persists in asking these seemingly crazy questions.

According to philosopher Julian Baggini, it is possible that non-human animals like chimps could be people.

"You could say that an adult chimp has more of the characteristics of a person than a new born baby," he says.

After all, though humans and chimps are different species, they share up to 99.4% of their most crucial DNA (the figure is difficult to calculate exactly and depends on the scientist you speak to). And to prove how similar we are to chimps, Danny takes part in a potentially humiliating experiment.

The scent of male sweat is controlled by their genes, in both chimps and men. In a blind test, three women were asked to sniff the sweat of Danny and Cody the chimp, to see which one they fancied most.

When they found out afterwards that one of the odours was from a chimp, there was laughter. When they realised that two out of three had preferred the chimp, there was nervous laughter.

'Learning key'

When Danny finally reaches Des Moines, the issue comes into focus.

The chimp and human genomes are very, very close

The apes Sue Savage Rumbaugh works with - and lives with - are bonobos. They are a kind of chimpanzee that is less aggressive than that found in most zoos.

Having brushed his teeth Kanzi, a 26-year-old bonobo, built like a heavyweight boxer and who is five times stronger than an average man, looks into Danny's eyes and asks him to play "Chase".

So they hang out together for a while, because that's what Kanzi has learned to do. And for Sue Savage Rumbaugh, learning is the key.

"Take a human child. If you lock him into a cage, never take him to the mall, never give him ice-cream, never teach him to communicate - how could he become a person?" asks Sue.

Chimps are human? Never. Chimps are people? You decide.

Horizon: Chimps Are People Too is on BBC Two at 2100 BST on Tuesday 10 October. Watch video highlights at Horizon's website.

Transport Secretary Lord Adonis has denied that the decision to lift UK flight restrictions was the result of pressure from the airline industry.

Ash cloud: Lord Adonis denies pressure to lift ban

Transport Secretary Lord Adonis: "We have done our best"

Transport Secretary Lord Adonis has denied that the decision to lift UK flight restrictions was the result of pressure from the airline industry.

The ban on flights due to the volcanic ash cloud from Iceland over the UK was removed at 2200 BST on Tuesday.

Lord Adonis said the move had been made after an assessment of how much ash in the atmosphere was safe for aircraft.

The Conservatives questioned why this had not been established earlier, and urged an inquiry into the "fiasco".

'Urgent issue'

Airlines and airports had been keen for the restrictions to be lifted, with several carriers - including British Airways - conducting test flights that they said demonstrated it was safe to fly.

On Monday, British Airways asked the European Union and the UK government for financial compensation for the disruption, saying the shutdown was costing it £15m-£20m a day.

UK airports operator BAA said the ban was costing it £5m-£6m a day.

Asked by presenter Jeremy Paxman on BBC Two's Newsnight programme about how much pressure the government had come under from the airlines, Lord Adonis said: "They have obviously wanted to be able to fly their planes - of course they have - but that has not been the issue at stake here.

"The issue at stake here has been the assessment of the safety authorities as to what is the safe way in which planes can fly when there is a presence of ash.

"The fact which has changed in the last week is we have had a volcanic eruption and having to assess safe levels of ash content in the atmosphere within which planes can fly has been an urgent issue which the safety authorities have had to deal with.

"That's been what's changed over the last five days - it's not been pressure from the industry."

'Let down'

Prime Minister Gordon Brown said: "This solution has been reached as a result of the close working between the government, the Civil Aviation Authority, airlines and the manufacturers, and will allow the thousands of UK citizens stranded abroad to return home to their families."

He added: "We will of course continue to monitor the situation closely. As we have said throughout safety is our primary concern."

But shadow transport secretary Theresa Villiers said Labour's "misjudgement and mismanagement" had "badly let down" the travelling public and urged the prime minister to immediately announce a full inquiry into the "fiasco".

She added: "Six days into the crisis, we're suddenly told that there are actually levels of ash which are compatible with safe flying.

"The question angry passengers and airlines are already asking is why the government hadn't worked this out before the crisis occurred."

But Lord Adonis said: "The government has taken every measure we can, and at every stage. We have done everything we reasonably can to protect the travelling public."

Tolerance levels

Dame Deirdre Hutton, of the Civil Aviation Authority (CAA), said there had been detailed consultation with experts to reassess the tolerance of planes to the ash cloud.

The CAA said it was a "situation without precedent" and that decisions had been made based on "thorough gathering of data and analysis".

"The major barrier to resuming flights has been understanding tolerance levels of aircraft to ash," the CAA said.

"Manufacturers have now agreed increased tolerance levels in low ash density areas."

After the lifting of the restrictions, the first British Airways flight to touch down from Heathrow was a service already in the air from Vancouver, which landed shortly before 2200 BST.

The airline's chief executive Willie Walsh said he was pleased with the decision, but said it would take weeks to get back to normal levels of operation.

He said: "We're now at British Airways going to start the difficult task of getting our stranded customers back home. I think this is an airlift that is unprecedented but we will make every effort to get our people back home."

Mr Walsh said "lessons can be learned" and added: "There will be plenty of time for a post-mortem of what has happened over the last few days." He said parts of UK airspace could have been opened several days ago.

"My personal belief is that we could have safely continued operating for a period of time. I think there were occasions when the decision to close airspace could have been justified," he said.

Flights have been grounded across the UK and much of Europe since Thursday following the eruption of Icelandic volcano Eyjafjallajokull.

UK water use 'worsening global crisis'

By Richard Black Environment correspondent, BBC News

Climatic change will increase water stress in many places, the report says

The amount of water used to produce food and goods imported by developed countries is worsening water shortages in the developing world, a report says.

The report, focusing on the UK, says two-thirds of the water used to make UK imports is used outside its borders.

The Engineering the Future alliance of professional engineering bodies says this is unsustainable, given population growth and climate change.

It says countries such as the UK must help poorer nations curb water use.

"We must take account of how our water footprint is impacting on the rest of the world," said Professor Roger Falconer, director of the Hydro-Environmental Research Centre at Cardiff University and a member of the report's steering committee.

If the water crisis becomes critical, it will pose a serious threat to the UK's future development Professor Peter Guthrie

"If we are to prevent the 'perfect storm', urgent action is necessary."

The term perfect storm was used last year by the UK government's chief scientist, Professor John Beddington, to describe future shortages of energy, food and water.

Forecasts suggest that when the world's population soars beyond 8bn in 20 years time, the global demand for food and energy will jump by 50%, with the need for fresh water rising by 30%.

But developing countries are already using significant proportions of their water to grow food and produce goods for consumption in the West, the report says.

"The burgeoning demand from developed countries is putting severe pressure on areas that are already short of water," said Professor Peter Guthrie, head of the Centre for Sustainable Development at Cambridge University, who chaired the steering group.

WATER TRENDS How availability, use and needs are changing across the world In graphics

"If the water crisis becomes critical, it will pose a serious threat to the UK's future development because of the impact it would have on our access to vital resources."

Key to the report is the concept of "embedded water" - the water used to grow food and make things.

Embedded in a pint of beer, for example, is about 130 pints (74 litres) of water - the total amount needed to grow the ingredients and run all the processes that make the pint of beer.

A cup of coffee embeds about 140 litres (246 pints) of water, a cotton T-shirt about 2,000 litres, and a kilogram of steak 15,000 litres.

Using this methodology, UK consumers see only about 3% of the water usage they are responsible for.

The average UK consumer uses about 150 litres per day, the size of a large bath.

Ten times as much is embedded in the British-made goods bought by the average UK consumer; but that represents only about one-third of the total water embedded in all the average consumer's food and goods, with the remainder coming from imports.

The UK is not unique in this - the same pattern is seen in most developed countries.

FUTURE WATER STRESS Interactive map: Rising water stress in a changing world

The engineering institutions say it means nations such as the UK have a duty to help curb water use in the developing world, where about one billion people already do not have sufficient access to clean drinking water.

UK-funded aid projects should have water conservation as a central tenet, the report recommends, while companies should examine their supply chains and reduce the water used in them.

This could lead to difficult questions being asked, such as whether it is right for the UK to import beans and flowers from water-stressed countries such as Kenya.

While growing crops such as these uses water, selling them brings foreign exchange into poor nations.

In the West, the report suggests, concerns over water could eventually lead to goods carrying a label denoting their embedded water content, in the same way as electrical goods now sport information about their energy consumption.

The Engineering the Future alliance includes the Institution of Civil Engineers (ICE), the Royal Academy of Engineering (RAE) and the Chartered Institute of Water and Environmental Management (CIWEM).

The Icelandic eruption

Icelandic volcanic ash alert grounds UK flights

The Icelandic eruption - airport officials say the ash represents a very serious risk to aircraft

Airline passengers are facing massive disruption across the UK after an ash cloud from a volcanic eruption in Iceland grounded planes.

In Scotland, all airports are shut and there is disruption at many others including Manchester, Liverpool, Stansted, Newcastle and Birmingham.

The Air Traffic Control Service (Nats) imposed restrictions after the Met Office warned ash could damage engines.

Passengers are being advised to contact their airlines prior to travel.

Experts have warned that the tiny particles of rock, glass and sand contained in the ash cloud would be sufficient to jam aircraft engines.

'Significant disruption'

Aberdeen, Edinburgh and Glasgow airports were shut as Nats said it was restricting flights "in accordance with international civil aviation policy".

The ash cloud disrupted all flights to and from Manchester with a similar picture at Newcastle airport where all arrivals were cancelled and all outbound flights either cancelled or subject to indefinite delay.

Liverpool's John Lennon airport suspended all flights until at least 1300BST.

Airports in Scotland were the first to suspend flights overnight

British Airways said it had cancelled all domestic flights for the whole of Thursday, which affected flights at London's Gatwick, Heathrow and City airports.

Birmingham airport warned of severe disruption with about 90% of flights cancelled, and there were problems reported at East Midlands, Leeds Bradford, Cardiff and Bristol.

Most flights were suspended at Belfast International Airport and George Best Belfast City Airport, with some in and out of Dublin airport also hit.

A Nats spokesman said: "The Volcanic Ash Advisory Centre has issued a forecast that the ash cloud from the volcanic eruption in Iceland will track over Europe tonight.

"Nats is working with Eurocontrol and our colleagues in Europe's other air navigation service providers to take the appropriate action to ensure safety in accordance with international aviation policy."

Engines shut

The European air safety body, Eurocontrol, said the cloud of ash had reached 55,000ft and was expected to move through northern UK and Scotland by 1300BST.

Brian Flynn, assistant head of operations of its central flow management unit, told the BBC: "As it moves toward the Netherlands and Belgium it will dissipate and lose intensity, like any weather phenomenon. But we don't know what the extent of it will be."

VOLCANIC ASH CLOUD The eruption in the Eyjafjallajoekull area is the second to occur in a month This eruption has released ash to significantly greater heights Volcanic ash contains tiny particles of rock and even glass, which can wreak havoc with machinery A 1982 BA flight unknowingly flew into an ash cloud, shutting down all four engines Animated guide: Volcanoes

Further south, five easyJet flights due to depart from Stansted airport in Essex were cancelled, along with all northbound flights from Southampton and Newquay airports.

Bournemouth airport grounded a flight to Dublin but said all other departures were on schedule.

Met Office forecaster Philip Avery said the ash could take several days to clear.

He said: "It is showing up on imagery at the moment, extending down as far as the Faroes but it looks as though the wind will drag it a good deal further south.

"Nats has good cause to be very cautious about this because in about 1982 a British Airways jumbo had the unnerving experience of having all four engines shut down as it flew through a plume of volcanic ash."

There was a nearly identical incident on 15 December 1989 when KLM Flight 867, a B747-400 from Amsterdam to Anchorage, Alaska, flew into the plume of the erupting Mount Redoubt, causing all four engines to fail.

Once the flight cleared the ash cloud, the crew was able to restart each engine and then make a safe landing at Anchorage, but the aircraft was substantially damaged.

The volcanic ash cloud reached about 55,000ft, Eurocontrol says

A BAA spokesman said: "Passengers intending to fly today are asked to contact their airline for further information and should expect disruption in the coming hours.

The Royal Air Force has confirmed it will maintain its search and rescue operations.

A spokesman said: "We will continue to provide full search and rescue cover, however we will consider all requests we get on a case by case basis.

"The ash is mainly affecting the air traffic control radar but we can fly in cloud and reduced visibility.

The eruption under a glacier in the Eyjafjallajoekull area of Iceland is the second in the country in less than a month.

A Nats spokesperson said the volcano was still erupting.

Japan annual whale hunt 'halved by activists'

By Roland Buerk BBC News, Tokyo

Anti-whaling activists aim to prevent the hunt from going ahead

Japan's whaling fleet has revealed how much anti-whaling activists disrupted the annual hunt off Antarctica.

The ships have returned to port with just over half as many whales - 507 - as they had set out to catch.

Whalers said they were angry, and blamed what they described as "violent interference" from the anti-whaling Sea Shepherd Conservation Society.

Clashes at sea between Sea Shepherd and the whaling ships paralysed the hunt for 31 days.

The last ship of the whaling fleet to return home sailed into Tokyo bay, with much of the hunt's catch in her hold.

The whalers had set out late last year to kill nearly 1,000 whales in the waters off Antarctica, but they caught 506 minke whales and one fin whale.

It is the smallest catch for years.

One of the Sea Shepherd activists, Peter Bethune, is awaiting trial in Japan after boarding a harpoon ship and trying to perform a citizen's arrest on her captain.

Prosecutors have charged him with five crimes. If convicted he could go to prison.

Commercial whaling has been banned worldwide since 1986 but Japan justifies its annual hunt as scientific research.

Meat not used for study ends up in restaurants and shops

NHS left with 34m stockpile of swine flu jabs

By Nick Triggle Health reporter, BBC News

Priority groups and health workers have been offered the vaccine

The NHS has more than 34 million unused doses of swine flu vaccine despite agreeing deals to break its contracts.

The UK government had signed deals with two firms - Baxter and GlaxoSmithKline - for more than 120m doses of the jabs.

But just 44m will now be bought as cases have petered out since December. Of these, 6m have already been used and 3.8m is being sent to help Africa.

Ministers said the renegotiated deal was good value, but the Tories said millions of pounds had been wasted.

This is a careless waste of precious NHS money Andrew Lansley, shadow health secretary

Of the nearly 44m vaccines that the UK has agreed to pay for, 6m have already been used on priority groups and health workers, while 3.8m are being handed to the World Health Organization for Africa.

Of the rest, 10.6m is already with GPs who will be ready to act if more people entitled to the jab come forward. But the remaining 23.6m will be held in reserve.

Estimates have put the value of the stockpile at between £100m to £150m, although the government has refused to confirm cost saying it was commercially confidential.

Health Secretary Andy Burnham said: "I am pleased we have reached an agreement that is good value for the taxpayer and means that the department has retained a strategic stockpile to protect the UK population without incurring a cancellation fee."

It is also possible the vaccine could be used to combat seasonal flu this winter as it is thought the swine flu virus will become the dominant strain.

Under the terms of the deal with GSK, the government is also purchasing anti-flu drugs as well as bird flu vaccine. These will be held in reserve in case a completely different pandemic emerges.

Shadow health secretary Andrew Lansley said: "This is a careless waste of precious NHS money. Labour failed to ensure there were proper break clauses in the contracts which means that British taxpayers have got an extremely bad deal."

Liberal Democrat health spokesman Norman Lamb added: "Today's announcement underscores the need for a thorough independent examination of how the NHS responded to the swine flu pandemic."

Does red meat give you bowel cancer?

By Clare Murphy Health reporter, BBC News

Everyone agrees you can still enjoy a steak

A bitter row has broken out between members of the British meat industry and the World Cancer Research Fund over whether red meat increases the risk of bowel cancer. What do we know about this link?

The WCRF says the evidence that red and processed meats increase the risk of colorectal cancer is "convincing", and since 2007 - when it published a major report on lifestyle and cancer - has urged the public to limit their consumption of steak and sausages.

These conclusions, claim an array of organisations representing meat producers, are flawed. They point to a number of independent scientists who have questioned the conviction with which the link between red meat and cancer was presented in the report.

The WCRF has published a list of "minor errors" with the report - some relating to the findings on red meat and bowel cancer - but says it has no intention of altering the conclusions based on an expert panel's review of the scientific literature.

According to the recommendations, red meat should be consumed in modest amounts, and salami and ham should almost always be avoided.

Veggies' risk

This latest spat is driven by the fact that the government's Scientific Advisory Committee on Nutrition cited the WCRF report in draft conclusions on the impact of cutting red meat on the nation's iron levels.

The WCRF findings, argues the lobby group for the English beef and lamb industry - EBLEX, should not be used as a "point of reference".

It's an enigma - nobody knows the truth Professor Tim Key Oxford University

But there have already been clashes within the pages of the leading scientific journal on diet and disease.

In a letter last year to the American Journal of Clinical Nutrition, Professor Stewart Truswell of the University of Sydney questioned why several large studies which found no link had been discarded by the panel, and also pinpointed errors in the reporting of data.

In response, the WCRF explained that a series of studies on meat had been omitted because they did not report on red meat specifically, but it did accept some mistakes in the reporting of the data. This did not however "change the overall picture", it stressed.

Many in the scientific community were however taken aback by the findings of a large study into the relationship between diet and cancer, published in the same nutrition journal last year.

Looking at all the research, the evidence linking red and processed meat and bowel cancer is overwhelming Professor Martin Wiseman WCRF

The European Prospective Investigation into Cancer and Nutrition-Oxford (EPIC-Oxford), which followed 65,000 people during the 1990s, found that far from being protected from bowel cancer as anticipated, vegetarians in fact displayed a slightly higher incidence of this form of the disease.

It ran counter to the the findings of a previous arm of the EPIC study which suggested that very high levels of red and processed meat consumption - more than two pork chops every day - was associated with a 35% higher risk of bowel cancer when compared with those who rarely ate red meat.

"Our findings did come as something of a surprise. At the simplest level if meat causes colorectal cancer you would expect to see lower rates in the vegetarians, and we didn't," says Professor Tim Key, the epidemiologist who led the Oxford study.

"It's definitely a really tricky area. It's an enigma - nobody knows the truth. We can be much clearer on the relationship between obesity and cancer, or alcohol and cancer, because it's relatively easy to measure these things. Understanding the exact role specific foods play is much harder to quantify.

"There is a lot of evidence for meat, but it's not completely compelling."

It's not no

The WCRF says the Oxford findings on vegetarians could be explained by chance, noting there were only 28,000 non-meat eaters in the study. Vegetarians, it said, may consume fewer dairy products - "and our report found that milk probably reduces risk of bowel cancer".

RED MEAT CONTENT Medium steak: 145g Pork chop: 75g Spaghetti bolognese with beef: 140g Serving of roast beef: 90g

"We are in the process of reviewing the evidence on meat and bowel cancer and that is expected to be published later this year," says Professor Martin Wiseman, the project director. "But no research has been published since our report to make us question the finding that there is convincing evidence red and processed meat increase risk of bowel cancer."

"It is easy for anyone to find an individual study to support almost any view they wish to hold. But looking at all the research, the evidence linking red and processed meat and bowel cancer is overwhelming."

The WRCF does not in any event advocate a vegetarian diet, or a complete abstention from red meat. In fact its recommendations that people keep within 500g a week - the equivalent of a fair serving of roast beef on five of those days - is not far off average consumption.

Nell Barrie, Cancer Research UK's science information officer, said: "Two of the world's largest studies on diet and cancer have found that people are more likely to develop some cancers, such as bowel cancer, if they eat too much red or processed meat.

"Cutting down on these foods can help to reduce the risk of developing cancer."

But cancer specialist Professor Karol Sikora said those who enjoyed eating red meat should continue to do so.

"We have created a nightmare situation of confusing messages based on very little evidence. Eating red meat in the context of a balanced diet should really not be viewed as a problem.

"Yes, avoid a high calorie, high fat diet - but by all means enjoy that steak."

a study into the link between diet and disease has found.

Five-a-day has little impact on cancer, study finds

By Clare Murphy Health reporter, BBC News

Researchers are trying to harness key chemicals like lycopene in tomatoes

Eating more fruit and vegetables has only a modest effect on protecting against cancer, a study into the link between diet and disease has found.

The study of 500,000 Europeans joins a growing body of evidence undermining the high hopes that pushing "five-a-day" might slash Western cancer rates.

The international team of researchers estimates only around 2.5% of cancers could be averted by increasing intake.

But experts stress eating fruit and vegetables is still key to good health.

In 1990, the World Health Organization recommended that everyone consume at least five portions of fruit and vegetables a day to prevent cancer and other chronic diseases.

The advice has formed a central plank of public health campaigns in many developed countries. It has been promoted in the UK since 2003 and in the US for nearly two decades.

But research has failed to substantiate the suggestion that as many as 50% of cancers could be prevented by boosting the public's consumption of fruit and vegetables.

It's still a good idea to eat your five-a-day but remember that fruits and vegetables are pieces in a much larger lifestyle jigsaw Yinka Ebo Cancer Research UK

This latest study, which analysed recruits from 10 countries to the highly-regarded European Prospective Investigation into Cancer and Nutrition, confirms that the association between fruit and vegetable intake and reduced cancer risk is indeed weak.

The team, led by researchers from the Mount Sinai School of Medicine, in New York, took into account lifestyle factors such as smoking and exercise when drawing their conclusions.

But writing in the Journal of the National Cancer Institute, they said they could not rule out that even the small reduction in cancer risk seen was down to the fact that the kind of people who ate more fruit and vegetables lived healthier lives in many other respects too.

Broccoli not biscuits

In the best case scenario, an extra two portions of fruit and vegetables each day could prevent 2.6% of cancers in men and 2.3% of cases in women, the study concluded.

Research should focus more sharply on specific fruits and vegetables and their constitutents Walter Willett Harvard School of Public Health

Vegetables, which tend to be richer in nutrients, appeared to be more beneficial than fruits, while heavy drinkers seemed to gain the most from a higher intake of both when it came to protection from cancers caused by alcohol and smoking.

In an accompanying editorial, Professor Walter Willet of Harvard University said the research strongly confirmed the findings of other studies, showing "that any association of intake and fruits and vegetables with risk of cancer is weak at best".

But he stressed specific substances contained in certain fruit and vegetables, if harnessed, could still have an important, protective effect.

Substantial evidence suggests lycopene from tomatoes, for instance, may reduce the risk of prostate cancer, while chemicals in broccoli are thought to stimulate a gene which protects against bowel cancer.

And data still suggests fruit and vegetables may provide protection against cardiovascular disease, one of the major killers in the developed world - although this too has yet to be proven categorically.

Prof Sikora: 'Eating five-a-day still has health benefits'

Keeping lean

But while the links between diet and cancer remain unclear, obesity is now seen as an established risk factor.

Fruit and vegetables could therefore be beneficial just by virtue of taking the place of more calorific fare, health experts say.

In any event, a reduced risk of 2.5% should not be dismissed out of hand, the World Cancer Research Fund argues.

"For the UK, this works out as about 7,000 cases a year, which is a significant number," says Dr Rachel Thompson from the charity, which in a major 1997 report said there was "convincing evidence" of the protective effect of fruit and vegetables.

Yinka Ebo of Cancer Research UK said: "It's still a good idea to eat your five-a-day but remember that fruits and vegetables are pieces in a much larger lifestyle jigsaw.

"There are many things we can do to lower our chances of developing cancer such as not smoking, keeping a healthy weight, cutting down on alcohol, eating a healthy balanced diet, being physically active and staying safe in the sun."