Driving home the benefits of plants

Plants can help aid both physical and mental health but the industry must do more to promote the facts, writes Professor Geoff Dixon.

Britain might be a "nation of gardeners" but there is woeful ignorance about the valuable contribution plants make to society and its health. And this ignorance is worst where plants could be at their most valuable.

On many of the poorest estates in London, Birmingham, Manchester and Glasgow barely a green plant is seen and fruit and vegetables are ignored. Life expectancy in these areas remains stubbornly low while alcoholism, nicotine and drug dependencies thrive. Encouraging a love of plants will not of itself cure these problems, but it does offer alternative and possibly more attractive lifestyles.

Crime and green space

Britain's population is preponderantly urban. The availability of green spaces is a fundamental human need and should be provided as a right. Beyond the simple aesthetic beauties of plants come more basic physical benefits such as purifying the atmosphere, modifying temperature extremes, providing shade and reducing noise pollution.

Some American studies find a direct link between the presence of green urban areas and greater social communication and cohesion, improved feelings of safety and reduced mental fatigue.

Perversely, the presence of plants is often minimised in socially deprived areas. Vegetation is cleared from crime-ridden areas on the false assumption that it offers hiding places for muggers and other criminals. The opposite view comes from recent studies linking plants with safer environments.

Work in Austin, Texas, for example, located crime scenes, described the areas, and measured their plant cover using infrared aerial photography. The absence of plants and number of crimes were found to be strongly linked. Similar results come from Chicago. Greener inner-city apartment blocks suffered less crime compared with those without plants. The presence of plants increases psychological coping mechanisms, reduces stress and depresses violence. The attitude that money is saved by cutting down trees and replacing them with concrete is wrong. The long-term price of "psychologically abusive" environments outweighs short-term budgetary saving.


Successful urban planting requires engagement and ownership, particularly by teenagers. The late David Welch clearly showed in Aberdeen that involving youth groups in greening their local environments is a route to ownership and civic pride.

School gardening programmes are similarly effective routes to engagement. In New York State, children as young as three and four years old voiced opinions, had knowledge and contributed to safer, greener, outdoor play areas. Pre-teens and teenagers can identify preferences that make areas enjoyable for them. Older youths can formulate planting plans, can map and test soil and build green recreational spaces. Appropriate education, such as the RHS Flourish Campaign, encourages the building of green areas in partnership with young people.

Urbanisation in Asia has rekindled the valuing of plants. South Korean schools are introducing horticulture into courses at all levels from kindergarten to high school. Gardening classes in schools reduced symptoms of withdrawal, somatic complaints, anxiousness and depression in children. Medical values of plants are recognised in hospitals providing psychiatric, general and rehabilitation care.

Health-care professionals appreciate "the healing effects of plants", asserts Dr Kwack of Seoul University. Horticulture in hospitals offers therapeutic tools aiding memory, socialisation, self-esteem and positive attitudes after strokes. It supports rehabilitation, enhancing cognition, socialisation, physical abilities and vocational training.

Gardening activities in prisons reduced violence, mental instability and irritability. Organisations such as Thrive, Trellis and Perennial in the UK have long advocated the medicinal benefits to communities and individuals of involvement with plants. Adding plants into San Diego's Children's Hospital improved patient recovery times, reduced dependence on serious post-operative drugs and increased the relaxation and focus of staff. The number of operations performed increased by 13 per cent and charitable donations rose by $16m (£8m) per year.

Plants at work

Introducing plants into office environments reduces fatigue, headaches, dizziness, eye irritation, blocked noses, sore and dry throats and coughs by between 11 and 38 per cent (see www.plants-for-people.org). Adding plants in the working environment of a Norwegian hospital radiology department reduced absenteeism from 15 to five per cent in six months. Plants provide value by:

- encouraging a feeling of wellbeing and of being valued by an employer;

- providing more natural and interesting surroundings in which to work;

- reducing ailments and allergies by improving the climate of work places.

Improved diet - longer life

Almost 20 years ago the UK Committee on Medical Aspects of Food Policy (COMA Report) recommended that "the consumption of vegetables and fruit in Great Britain should rise by 50%". In the ensuing decades diets have improved, but change has not reached those who need it most.

There is general agreement that the longer-term risks of contracting cancers of the lung, colon, breast, cervix, oesophagus, oral cavity, stomach, bladder, pancreas and ovary are diminished by eating fruit and vegetables. Those people with low intakes of fruit and vegetables appear about twice as liable to suffer from cancer diseases.

Fruit and vegetables contain a broad mixture of compounds acting as a package. Studies endorsing this conclusion have now come from around the world. Poor diet, where fruit and vegetables are absent, doubles the likelihood of contracting cancer and this degree of susceptibility equates with liabilities associated with smoking and alcohol abuse. The social message is delightfully simple - eat more fruit and vegetables. And the vast majority of people enjoy eating fruit even if somewhat less keen on vegetables. The Japanese emphasise the importance of "green and yellow vegetables" using the slogan "Carotene not Nicotine".

Benefits of fruit and vegetables

Three of the most important vitamins associated with health are found in fruit and vegetables. These are: vitamin A (vitamin precursor, carotene), vitamin B9 (folic acid) and vitamin C (ascorbic acid). Other carotenoids, sulphur compounds, polyphenols and phytosterols found in fruit and vegetables interact with and support the effects of these vitamins.

In combination they produce: antioxidant, anti-degenerative, anti-inflammatory, anti-microbial, hormonal, lipid-controlling, enzyme-stimulatory and health benefits.

Antioxidants are particularly associated with lowering the risk from cancers because they reduce free-radical-induced oxidative stress in cells. Oxidative stress results from either a decrease of natural cell antioxidant capacity or an increase in the amount of reactive oxygen species in cells.

Reactive oxygen concentrations increase for example as a result of smoking or alcohol abuse. Carotene is a powerful antioxidant found especially in brassicas, carrots, parsley, spinach, apricots, melons and nectarines. It aids the immune system and reduces risks of heart disease, stroke, cardiovascular disease, chronic fatigue syndrome, psoriasis, skin cancer, lupus, night blindness and cataracts.

Ascorbic acid is found in broccoli, citrus fruit, muskmelon, peppers, potatoes, strawberries and tomatoes. It is crucial for healthy immune systems, reducing colds by preventing secondary viral and bacterial infections, protection from damage by reducing free radicals and prevention of cardiovascular disease.

Folic acid comes from asparagus, beans, broccoli and butterhead lettuce. It aids the transport of amino acids for protein formation, stimulates nuclear methylation, cell division, differentiation and regulation.

Horticulture's opportunity and failure

Concentrations of phytochemicals can be increased significantly by plant breeding, but high-quality husbandry is paramount in maximising the advantages of these improved cultivars.

Growing on mineral compared with organic peat soils, maintenance of optimal pH, use of mineral fertilisers rather than organic manures and application of furrow and trickle irrigation will help increase phytochemical content. Land location and aspect are also important. For example, blackcurrants grown in dry, sunny fields contained 247mg/100gm ascorbic acid compared with just 110mg/100gm ascorbic acid in crops grown on wet, cool fields.

The British horticulture industry fails abysmally in capturing the marketing opportunities that are offered by the dietary and social values of its products. Both the Promar Report (National Horticulture Forum) and more recently English Farming & Food Partnerships' analysis Collaboration in the English Horticultural Sector identified significant "inabilities to meet market (customer) need".

Both assessments reflect Professor David Hughes' conclusions that horticulture is woefully ignorant of its markets and the needs and desires of consumers. No other industry has products that have such unassailable benefits for its customers, yet fails to publicise them to any visible extent.

Even the credit for the benefits that flowed from the Bangor Project - funded in part by the HDC - seem to have gone to celebrity chefs. However, an independent economic assessment showed that immense value should come from the investment of levy money. When measured by HM Treasury's own benchmark value of a single human life being worth £3m, adding more fruit and vegetables into the diet will be immensely cost beneficial.

Our Continental competitors are far from being so slow. The French are forging ahead with strong interdisciplinary developments supported jointly by their agricultural and medical research councils.

- Professor Geoff Dixon is managing director of GreenGene International/

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