Breadfruit

Breadfruit (Artocarpus altilis) is a species of flowering tree in the mulberry family, Moraceae, that is native to the Malay Peninsula and western Pacific islands. It has also been widely planted in tropical regions elsewhere.

Breadfruit at Tortuguero, Costa Rica

Breadfruit trees grow to a height of 20 meters (66 ft). The large and thick leaves are deeply cut into pinnate lobes. All parts of the tree yield latex, a milky juice, which is useful for boat caulking.

The trees are monoecious, with male and female flowers growing on the same tree. The male flowers emerge first, followed shortly afterward by the female flowers, which grow into a capitulum, which are capable of pollination just three days later. The pollinators are Old World fruit bats in the family Pteropodidae. The compound, false fruit develops from the swollen perianth and originates from 1,500-2,000 flowers. These are visible on the skin of the fruit as hexagon-like disks.

Breadfruit is one of the highest-yielding food plants, with a single tree producing up to 200 or more fruits per season. In the South Pacific, the trees yield 50 to 150 fruits per year. In southern India, normal production is 150 to 200 fruits annually. Productivity varies between wet and dry areas. In the Caribbean, a conservative estimate is 25 fruits per tree. Studies in Barbados indicate a reasonable potential of 6.7 to 13.4 tons per acre (16-32 tons/ha). The grapefruit-sized ovoid fruit has a rough surface, and each fruit is divided into many achenes, each achene surrounded by a fleshy perianth and growing on a fleshy receptacle. Some selectively-bred cultivars have seedless fruit.

The breadfruit is closely related to the breadnut and the jackfruit.

Habitat

Breadfruit is an equatorial lowland species that grows best below elevations of 650 metres (2,100 ft), but is found at elevations of 1,550 metres (5,100 ft). Its preferred rainfall is 1,500–3,000 millimetres (59–120 in) per year. Preferred soils are neutral to alkaline (pH of 6.1-7.4) and either sand, sandy loam, loam, or sandy clay loam. Breadfruit is able to grow in coral sands and saline soils.

Uses

Breadfruit is a staple food in many tropical regions. They were propagated far outside their native range by Polynesian voyagers who transported root cuttings and air-layered plants over long ocean distances. They are very rich in starch, and before being eaten they are roasted, baked, fried, or boiled. When cooked the taste is described as potato-like, or similar to fresh baked bread (hence the name).

The fruit of the breadfruit tree - whole, sliced lengthwise and in cross-section

Because breadfruit trees usually produce large crops at certain times of the year, preservation is an issue. One traditional preservation technique is to bury peeled and washed fruits in a leaf-lined pit where they ferment over several weeks and produce a sour, sticky paste. So stored, the product may last a year or more, and some pits are reported to have produced edible contents more than 20 years later. Fermented breadfruit mash goes by many names such as mahr, ma, masi, furo, and bwiru, among others.

Drawing of breadfruit by Sydney Parkinson

Most breadfruit varieties also produce a small number of fruits throughout the year, so fresh breadfruit is always available, but somewhat rare when not in season.

Breadfruit can be eaten once cooked, or can be further processed into a variety of other foods. A common product is a mixture of cooked or fermented breadfruit mash mixed with coconut milk and baked in banana leaves. Whole fruits can be cooked in an open fire, then cored and filled with other foods such as coconut milk, sugar and butter, cooked meats, or other fruits. The filled fruit can be further cooked so that the flavor of the filling permeates the flesh of the breadfruit.

The Hawaiian staple food called poi made of mashed taro root is easily substituted or augmented with mashed breadfruit. The resulting “breadfruit poi” is called poi ʻulu. In Puerto Rico it is called "panapen" or "pana", for short.

Breadfruit is roughly 25% carbohydrates and 70% water. It has an average amount of vitamin C (20 mg/100g) and small amounts of minerals (potassium and zinc) and thiamin (100 μg).

Breadfruit was widely and diversely used among Pacific Islanders. Its lightweight wood (specific gravity of 0.27) is resistant to termites and shipworms, and consequently was used as timber for structures and outrigger canoes. Its wood pulp can also be used to make paper, called breadfruit tapa. It is also used in traditional medicine to treat illnesses that range from sore eyes to sciatica.

In history

In a late-18th-century quest for cheap, high-energy food sources for British slaves in the Caribbean, William Bligh, Commanding Lieutenant of the HMS Bounty, collected and distributed botanical samples of breadfruit. Other sources say Captain James Cook was the first to introduce the South Pacific native plant to the Caribbean islands.

In culture

According to an etiological Hawaiian myth, the breadfruit originated from the sacrifice of the war god Kū. After deciding to live secretly among mortals as a farmer, Kū married and had children. He and his family lived happily until a famine seized their island. When he could no longer bear to watch his children suffer, Kū told his wife that he could deliver them from starvation, but to do so he would have to leave them. Reluctantly, she agreed, and at her word, Kū descended into the ground right where he had stood until only the top of his head was visible. His family waited around the spot he had last been day and night, watering it with their tears until suddenly a small green shoot appeared where Kū had stood. Quickly, the shoot grew into a tall and leafy tree that was laden with heavy breadfruits that Kū's family and neighbors gratefully ate, joyfully saved from starvation.

Though they are widely distributed throughout the Pacific, many breadfruit hybrids and cultivars are seedless or otherwise biologically incapable of naturally dispersing long distances. Therefore, their distribution in the Pacific was clearly enabled by humans, specifically prehistoric groups who colonized the Pacific Islands. To investigate the patterns of human migration throughout the Pacific, scientists have used molecular dating of breadfruit hybrids and cultivars in concert with anthropological data. Results support the west-to-east migration hypothesis, in which the Lapita people are thought to have traveled from Melanesia to numerous Polynesian islands.

The world’s largest collection of breadfruit varieties has been established by botanist Diane Ragone, from over twenty years' travel to fifty Pacific islands, on a 10-acre plot outside of Hana, Hawaii on the isolated east coast of Maui.

Breadfruit trees grow to a height of about 20 meters (66 ft). The leaves are large, thick and are deeply cut into pinnate lobes. All parts of the tree, including the unripe fruit, are rich in milky juice, gummy latex, which is useful for boat caulking.

The breadfruit is closely related to the breadnut and the jackfruit. Breadfruit can be eaten at all stages of maturity when they are roasted, baked, fried, or boiled. They are rich in startch and when cooked the taste is very similar to potato-like, or fresh baked bread. One of the fermentation technique is to bury peeled and washed fruits in a leaf-lined pit over several weeks and produce a sour, sticky paste. Fermented stored breadfruit may last a year or more.

Fully ripe fruits that have harvested from the tree can be wrapped in polyethylene, or put into polyethylene bags, and can be kept for upto 10 days in storage at a temperature of 53.6'F (12'C). At lower temperature, the fruit may be damaged by chilling injury. Slightly unripe fruits that have been caught by hand when knocked down can be maintained for 15 days under the same conditions. The thickness of the polyethylene used to keep the fruit should be atleast equal or greater than 38 or even 50 micrometer.


Cuisines

A common product is a mixture of cooked or fermented breadfruit mash mixed with coconut milk and baked in banana leaves.

Whole fruits can be cooked in an open fire, then cored and filled with coconut milk, sugar and butter, cooked meats, or other fruits. The filled fruit can be then cooked so that the flavor of the filling permeates the flesh of the breadfruit.

The pulp scraped from soft, ripe breadfruits is combined with coconut milk, salt and sugar and baked to make a pudding. A more elaborate dessert is concocted of mashed ripe breadfruit, with butter, 2 beaten eggs, sugar, nutmeg, cinnamon and rosewater, a dash of sherry or brandy, blended and boiled. Breadfruit is also candied, or sometimes prepared as a sweet pickle.

The original method of making POI involved peeling, washing and halving the breadfruit, discarding the core, placing the fruits in stone pits lined with leaves of Cordylme terminalis Kunth, alternating the layers of fruit with old fermented pod, covering the upper layer with leaves, topping the pit with soil and rocks and leaving the contents to ferment, which acidifies and preserves the breadfruit for several years.

In Barbados and Brazil there is a way to substituting breadfruit in part for wheat flour in breadmaking, and it called Breadfruit flour. Breadfruit flour is much richer than wheat flour in lysine and other essential amino acids. This new combination has been found more nutritious than wheat flour alone.

The seeds from the breadfruit are boiled, steamed, roasted over a fire or in hot coals and eaten with salt.


Products

It's lightweight wood is highly resistant to termites and shipworms. Its wood pulp can also be used to make paper. The wood pulp is also used in traditional medicine to treat illnesses that range from sore eyes to sciatica.

Fiber from the bark is highly durable but difficult to extract. Malaysians fashioned it into clothing. Material for tape cloth is obtained from the inner bark of young trees and branches.


Nutrition

Breadfruit is a relatively good source of iron, calcium, potassium, riboflavin, and niacin. The mature fruit is high in carbohydrates, low in fat and protein, and a good source of minerals and vitamins, especially B vitamins. The nutritional composition of breadfruit varies depending on the ripeness of the fruit as ripe breadfruit is more nutritious.


Medicinal uses

Decoction of the breadfruit leaf is believed to lower blood pressure, and is also said to relieve asthma. Crushed leaves are applied on the tongue as a treatment for thrush. Ashes from burned leaves are used on skin infections. A powder of roasted leaves is employed as a home remedy for enlarged spleen.

Toasted flowers are rubbed on the gums around an aching tooth.

The latex is used on skin diseases and is bandaged on the spine to relieve sciatica. Diluted latex is taken internally to overcome diarrhea.

Sapodilla

Sapodilla (Manilkara achras [Mill. (Fosberg)]) is a long-lived, evergreen tree native to southern Mexico, Central America and the West Indies. It is grown in huge quantities in India, Mexico and was introduced to the Philippines during Spanish colonisation.

Description

Sapodilla grows to 3-4 m tall. It is wind-resistant and the bark is rich in a white, gummy latex called chicle. The ornamental leaves are medium green and glossy. They are alternate, elliptic to ovate, 7-15 cm long, with an entire margin. The white flowers are inconspicuous and bell-like, with a six-lobed corolla.

The fruit is a large ellipsoid berry, 4-8 cm in diameter, very much resembling a smooth-skinned potato and containing 2-5 seeds. Inside, its flesh ranges from a pale yellow to an earthy brown color with a grainy texture akin to that of a well-ripened pear. The seeds are black and resemble beans, with a hook at one end that can catch in the throat if swallowed. The fruit has a high latex content and does not ripen until picked.

The flavor is exceptionally sweet and very tasty, with what can be described as a malty flavor. Many believe the flavor bears a striking resemblance to caramel. The unripe fruit is hard to the touch and contains high amounts of saponin, which has astringent properties similar to tannin, drying out the mouth.

The trees can only survive in warm, typically tropical environments, dying easily if the temperature drops below freezing. From germination, the sapodilla tree will usually take anywhere from 5-8 years to bear fruit. The sapodilla trees yield fruit twice a year, though flowering may continue year round. In Vietnam, the most famous varieties of sapodilla is grown in Xuân Đỉnh village, Hanoi.

Other names

Sapodilla is known as chikoo ("चिक्कू" or "chiku," "चीकू,") and sapota in India, sobeda/sofeda in eastern India and Bangladesh, Sabudheli ("ސަބުދެލި") in Maldives, sawo in Indonesia, hồng xiêm (lit. "Siamese persimmon"), lồng mứt or xa pô chê in Vietnam, lamoot (ละมุด) in Thailand, Laos and Cambodia, sapodilla in Guyana and Trinidad & Tobago, naseberry in Jamaica, sapathilla or rata-mi in Sri Lanka, níspero in Colombia, Nicaragua, El Salvador, Dominican Republic and Venezuela, nípero in Cuba, Puerto Rico and Dominican Republic, dilly in The Bahamas, naseberry in the rest of the Caribbean, sapoti in Brazil, chico in the Philippines and chico sapote in Mexico, Hawaii, southern California and southern Florida. In Kelantanese Malay, the fruit is called "sawo nilo" which is closer to the original name than the standard Malay "ciku". In Chinese, the name is mistakenly translated by many people roughly as "ginseng fruit" (人參果), though this is also the name used for the pepino, an unrelated fruit; it should instead be "heart fruit" (人心果) because it is shaped like the heart.

UK gets biofuels research centre

A centre that will act as the hub for biofuels research has been launched by Science Minister Lord Drayson.

The £27m institute has been tasked with developing economically competitive and environmentally sound alternatives to fossil fuels.

Last year, the government delayed its plans to increase the amount of biofuel blended into petrol and diesel.

Greenhouse gas emissions from road transport continue to grow

According to government figures, the transport sector accounts for about 25% of the UK's greenhouse gas emissions.

The Sustainable Bioenergy Centre, which will have hubs at six universities - including Cambridge, Dundee, York and Nottingham - has been established by the Biotechnology and Biological Sciences Research Council (BBSRC).

'Practical solutions'

"The UK has a world-leading research base in plant and microbial science," said BBSRC chief executive Professor Douglas Kell.

"The centre draws together some of these world-beating scientists in order to help develop technology and understanding to support the sustainable bioenergy sector," he added.

"By working closely with industrial partners, the centre's scientists will be able to quickly translate their progress into practical solutions to all our benefit and ultimately, by supporting the sustainable bioenergy sector, help to create thousands of new 'green collar' jobs in the UK."

While other sectors have curtailed or reduced overall emissions, CO2 from transport has continued to rise.

In an attempt to address the problem, the UK government introduced the "Renewable Transport Fuel Obligation" in April 2008, which required 2.5% of all the fuel sold at petrol stations to be biofuels.

Ministers originally had intended to increase this to 5% by 2010, but accepted a recommendation by the Gallagher Review to delay this until at least 2013.

Non-food crops, such as jatropha, do not distort food prices Slowing the biofuel bonanza

Mounting pressure from environmentalists has also led to the European Union revising its targets.

It had stipulated that 10% of transport fuel had to be biofuels by 2020, but this was modified in December 2008.

Now, the 10% target can be met by any renewable source, including fuel cells, hydrogen or solar power.

Once widely viewed as an acceptable alternative to fossil fuels, biofuels have fallen foul of environmental concerns in recent years.

The global surge in biofuel production led to questions being asked about how the impacts of the supposedly green fuel.

Some production methods, especially in South-East Asia, led to huge areas of old-growth rainforests being felled and burned, only to be replaced by vast oil palm plantations.

Not only did it undermine efforts to curb carbon dioxide emissions, conservationists said it threatened the long-term survival of many endangered species, such as orangutans.

Robbing Peter

Another impact was the effect biofuels were having on global food prices. As the demand for the biodiesel and bio-ethanol grew, many farmers were selling their crops to fuel producers rather than food producers.

This, combined with a series of poor harvests around the world, led to prices reaching unprecedented levels.

However, scientists at the BBSRC centre plan to focus their efforts on "second generation" biofuels.

These fuels can be generated from a wider range of feedstocks, meaning any plant-derived materials, or biomass, not just food crops.

This means that second generation biofuels are generally more efficient, are not in conflict with food supplies, and have a smaller environmental impact.

However, as this process is much more complex, it is also more expensive and struggles to be commercially competitive.

The new centre hopes to make "sustainable bioenergy a practical solution" by improving the yield and quality of non-food biomass, and also improving the processes used to convert this into biofuels.

Swedes divided over bunny biofuel

Residents in Stockholm are divided over reports that rabbits are being used to make biofuel.

The bodies of thousands of rabbits are fuelling a heating plant in central Sweden, local newspapers say.

Bodies of thousands of rabbits are reportedly fuelling a heating plant

The city of Stockholm has an annual cull of thousands of rabbits to protect the capital's parks and green spaces.

The rabbits, not native to Sweden, are mainly the offspring of pets released by owners, and are said to be destroying parks in the capital.

Since they have no natural predators, the city administration of Stockholm employs hunters to kill the rabbits.

Tommy Tuvunger, one of the hunters, told Germany's Spiegel website that 6,000 rabbits were culled last year, and another 3,000 this year.

"They are a very big problem," he said. "Once culled, the rabbits are frozen and when we have enough, a contractor comes and takes them away."

The frozen rabbits are then taken to a heating plant in Karlskoga which incinerates them to heat homes.

Bunny boilers

Leo Virta, the Managing Director of Konvex - the plant's suppliers - told the BBC that Konvex has developed a new way of processing animal waste with funding from the EU as part of the Biomal project.

He says that with this new method, raw animal material is crushed, ground and then pumped to a boiler where it is burned together with wood chips, peat or waste to produce renewable heat.

"It is a good system as it solves the problem of dealing with animal waste and it provides heat," said Mr Virta.

Reaction in Sweden has been divided, said James Savage, managing editor of The Local - an online news service covering Sweden.

"In the town where they are burning them the reaction of the residents is quite relaxed," Mr Savage told the BBC World Service. "But in Stockholm there's the big city attitude of the rabbits being cute.

"That's amongst some people, particularly among some animal rights activists who think this is not a good way to treat rabbits."

Butterfly

Male Heliconius charithoni butterflies sit on and guard the pupae of female butterflies, mating with the females as soon as they emerge. A study led by Catalina Estrada from the University of Texas at Austin, US, has revealed how males assess the maturity and sex of the pupae.

Maldives cabinet makes a splash

The government of the Maldives has held a cabinet meeting underwater to highlight the threat of global warming to the low-lying Indian Ocean nation.

President Mohamed Nasheed and his cabinet signed a document calling for global cuts in carbon emissions.

Ministers spent half an hour on the sea bed, communicating with white boards and hand signals.

The president said the UN climate change conference in Copenhagen this December cannot be allowed to fail.

At a later press conference while still in the water, President Nasheed was asked what would happen if the summit fails. "We are going to die," he replied.

The Maldives stand an average of 2.1 metres (7ft) above sea level, and the government says they face being wiped out if oceans rise.

"We're now actually trying to send our message, let the world know what is happening, and what will happen to the Maldives if climate change is not checked," President Nasheed said.

"If the Maldives cannot be saved today we do not feel that there is much of a chance for the rest of the world," he added.

Military minders

Three of the 14 cabinet ministers missed the underwater meeting, about 20 minutes by boat from the capital, Male, because two were not given medical permission and another was abroad, officials said.

President Nasheed and other cabinet members taking part had been practising their slow breathing to get into the right mental frame for the meeting, a government source said.

The cabinet were joined by instructors and military escorts

About 5m underwater, in a blue-green lagoon on a small island used for military training, they were observed by a clutch of snorkelling journalists.

Each minister was accompanied by a diving instructor and a military minder.

While underwater, they signed a document ahead of the UN Climate Change Conference in Copenhagen in December, calling on all nations to cut their carbon emissions.

World leaders at the summit aim to create a new agreement to replace the 1997 Kyoto Protocol, which expires in 2012.

Maldives government dives for climate change

GIRIFUSHI, Maldives – Members of the Maldives' Cabinet donned scuba gear and used hand signals Saturday at an underwater meeting staged to highlight the threat of global warming to the lowest-lying nation on earth.

President Mohammed Nasheed and 13 other government officials submerged and took their seats at a table on the sea floor — 20 feet (6 meters) below the surface of a lagoon off Girifushi, an island usually used for military training.

With a backdrop of coral, the meeting was a bid to draw attention to fears that rising sea levels caused by the melting of polar ice caps could swamp this Indian Ocean archipelago within a century. Its islands average 7 feet (2.1 meters) above sea level.

"What we are trying to make people realize is that the Maldives is a frontline state. This is not merely an issue for the Maldives but for the world," Nasheed said.

As bubbles floated up from their face masks, the president, vice president, Cabinet secretary and 11 ministers signed a document calling on all countries to cut their carbon dioxide emissions.

The issue has taken on urgency ahead of a major U.N. climate change conference scheduled for December in Copenhagen. At that meeting countries will negotiate a successor to the Kyoto Protocol with aims to cut the emission of greenhouse gases such as carbon dioxide that scientists blame for causing global warming by trapping heat in the atmosphere.

Wealthy nations want broad emissions cuts from all countries, while poorer ones say industrialized countries should carry most of the burden.

Dozens of Maldives soldiers guarded the event Saturday, but the only intruders were groupers and other fish.

Nasheed had already announced plans for a fund to buy a new homeland for his people if the 1,192 low-lying coral islands are submerged. He has promised to make the Maldives, with a population of 350,000, the world's first carbon-neutral nation within a decade.

"We have to get the message across by being more imaginative, more creative and so this is what we are doing," he said in an interview on a boat en route to the dive site.

Nasheed, who has emerged as a key, and colorful, voice on climate change, is a certified diver, but the others had to take diving lessons in recent weeks.

Three ministers missed the underwater meeting because two were not given medical permission and another was abroad.

Arctic ice cap 'to disappear in future summers'

LONDON – The Arctic ice cap will disappear completely in summer months within 20 to 30 years, a polar research team said as they presented findings from an expedition led by adventurer Pen Hadow.

It is likely to be largely ice-free during the warmer months within a decade, the experts added.

Veteran polar explorer Hadow and two other Britons went out on the Arctic ice cap for 73 days during the northern spring, taking more than 6,000 measurements and observations of the sea ice.

The raw data they collected from March to May has been analysed, producing some stark predictions about the state of the ice cap.

"The summer ice cover will completely vanish in 20 to 30 years but in less than that it will have considerably retreated," said Professor Peter Wadhams, head of the polar ocean physics group at Britain's prestigious Cambridge University.

"In about 10 years, the Arctic ice will be considered as open sea."

Starting off from northern Canada, Hadow, Martin Hartley and Ann Daniels skied over the ice cap to measure the thickness of the remaining ice, assessing its density and the depth of overlying snow, as well as taking weather and sea temperature readings.

Across their 450-kilometre (290 mile) route, the average thickness of the ice floes was 1.8 metres (six feet), while it was 4.8 metres when incorporating the compressed ridges of ice.

"An average thickness of 1.8 metres is typical of first year ice, which is more vulnerable in the summer. And the multi-year ice is shrinking back more rapidly," said Wadhams.

"It's a concrete example of global change in action.

"With a larger part of the region now in first year ice, it is clearly more vulnerable. The area is now more likely to become open water each summer, bringing forward the potential date when the summer sea ice will be completely gone."

Doctor Martin Sommerkorn, senior climate change adviser for the World Wide Fund for Nature's international Arctic programme, said the survey painted a sombre picture of the ice meltdown, which was happening "faster than we thought".

"Remove the Arctic ice cap and we are left with a very different and much warmer world," he said.

Loss of sea ice cover will "set in motion powerful climate feedbacks which will have an impact far beyond the Arctic itself," he added.

"This could lead to flooding affecting one quarter of the world's population, substantial increases in greenhouse gas emission from massive carbon pools and extreme global weather changes."

"Today's findings provide yet another urgent call for action to world leaders ahead of the United Nations climate summit in Copenhagen in December to rapidly and effectively curb global greenhouse gas emissions."

Green spaces 'improve health'

There is more evidence that living near a 'green space' has health benefits.

Research in the Journal of Epidemiology and Community Health says the impact is particularly noticeable in reducing rates of mental ill health.

The best health benefits come from living less than a kilometre (0.62miles) from a green space

The annual rates of 15 out of 24 major physical diseases were also significantly lower among those living closer to green spaces.

One environmental expert said the study confirmed that green spaces create 'oases' of improved health around them.

The researchers from the VU University Medical Centre in Amsterdam looked at the health records of 350,000 people registered with 195 family doctors across the Netherlands.

Only people who had been registered with their GP for longer than 12 months were included because the study assumed this was the minimum amount of time people would have to live in an environment before any effect of it would be noticeable.

Health impact

The percentages of green space within a one and three kilometre (0.62 and 1.86 miles) radius of their home were calculated using their postcode.

On average, green space accounted for 42% of the residential area within one kilometre (0.62 miles) radius and almost 61% within a three kilometre (1.86 miles) radius of people's homes.

And the annual rates for 24 diseases in 7 different categories were calculated.

The health benefits for most of the diseases were only seen when the greenery was within a one kilometre ( 0.62 miles ) radius of the home.

DISEASES THAT BENEFIT MOST FROM GREEN SPACES

Coronary heart disease

Neck, shoulder, back, wrist and hand complaints

Depression and anxiety

Diabetes

Respiratory infections and asthma

Migraine and vertigo

Stomach bugs and urinary tract infections

Unexplained physical symptoms

The exceptions to this were anxiety disorders, infectious diseases of the digestive system and medically unexplained physical symptoms which were seen to benefit even when the green spaces were within three kilometres of the home.

The biggest impact was on anxiety disorders and depression.

Anxiety disorders

The annual prevalence of anxiety disorders for those living in a residential area containing 10% of green space within a one kilometre (0.62 miles) radius of their home was 26 per 1000 whereas for those living in an area containing 90% of green space it was 18 per 1000.

For depression the rates were 32 per 1000 for the people in the more built up areas and 24 per 1000 for those in the greener areas.

The researchers also showed that this relation was strongest for children younger than 12.

They were 21% less likely to suffer from depression in the greener areas.

Two unexpected findings were that the greener spaces did not show benefits for high blood pressure and that the relation appeared stronger for people aged 46 to 65 than for the elderly.

The researchers think the green spaces help recovery from stress and offer greater opportunities for social contacts.

They say the free physical exercise and better air quality could also contribute.

Dr Jolanda Maas of the VU University Medical Centre in Amsterdam, said: "It clearly shows that green spaces are not just a luxury but they relate directly to diseases and the way people feel in their living environments."

"Most of the diseases which are related to green spaces are diseases which are highly prevalent and costly to treat so policy makers need to realise that this is something they may be able to diminish with green spaces."

Professor Barbara Maher of the Lancaster Environment Centre said the study confirmed that green spaces create oases of improved health around them especially for children.

She said: "At least part of this 'oasis' effect probably reflects changes in air quality.

"Anything that reduces our exposure to the modern-day 'cocktail' of atmospheric pollutants has got to be a good thing."