In a new report issued yesterday, WHO also stresses the need for continued safety assessments on GM before they are marketed, to prevent risks to both human health and the environment.
Investigating potential benefits and risks associated with GM foods, the report confirms that GM foods can increase crop yield, food quality and the diversity of foods which can be grown in a given area.
"This in turn can lead to better health and nutrition, which can then help to raise health and living standards," says WHO.
On the flip side, the UN body warns that "some of the genes used to manufacture GM foods have not been in the food chain before ", highlighting their introduction could cause changes in the existing genetic make-up of the crop.
"Therefore, the potential human health effects of new GM foods should always be assessed before they are grown and marketed, and long-term monitoring must be carried out to catch any possible adverse effects early," claims the report.
"We can hope to gain the health and nutritional improvements of GM foods when we can help countries to research how they can control and exploit the introduction of GM products for the benefit of their own people," comments Dr Jorgen Schlundt, director of WHO's food safety department.
The first major GM food hit the global market in the mid-1990s. Since then, GM strains of maize, soybeans, rapeseed and cotton have been marketed and traded nationally and internationally in several areas.
In addition, GM varieties of papaya, potato, rice, squash, sugar beet and tomato have been released in certain countries. And the production of GM crops has increased significantly over the last decade: it is estimated that at the end of 2004 GM crops covered almost 4 per cent of the total global arable land.
Most of this production is centred in relatively few countries, the US being the biggest.
In Europe, consumers are archly suspicious of GM food ingredients, unconvinced by that they pose no risk to health, and therefore effectively rejecting any foods found to contain genetically engineered produce.
Praised by consumer groups but criticised by the food industry, last year Europe introduced the toughest rules on GM labelling in the world. They dictate that all foods which contain or consist of GMOs, or which are produced from GMOs, have to be labelled, regardless of the presence of GM material in the final product.
The WHO report points out that pre-market risk assessments have been performed on all GM products where these products are marketed.
"In this regard, GM foods are examined more thoroughly than normal foods for their potential health and environmental impacts. To date, the consumption of GM foods has not caused any known negative health effects," asserts the report.
WHO recommends that in future, evaluations of GM foods should be widened to include social, cultural and ethical considerations, to help ensure there is no "genetic divide" between groups of countries which do and do not allow the growth, cultivation and marketing of GM products.
Currently, evaluations primarily focus on the agronomic ramifications and on possible health effects. The GM food aid crisis in southern Africa in 2002, where a number of countries did not permit GM food aid as a result of mostly socio-economic concerns, illustrates the need for broader evaluations, says WHO.
There are now 15 international legally-binding instruments and non-binding codes of practice which address some aspect of GM organisms. While many developed countries have established specific pre-market regulatory systems requiring the rigorous case-by-case risk assessment of GM foods prior to their release, many developing countries lack the capacity to implement a similar system.
WHO is currently working with partners such as the Food and Agriculture Organisation and the UN's Environment Programme to help countries examine the introduction of a given GM food from all angles.