Tuesday, 20 April 2010

The role of biofortification in combatting undernutrition

The role of biofortification in combating under-nutrition
By Jeremy Nagel

Introduction:
Charity advertisements often employ footage of emaciated children close to death. These confronting images are powerful examples of the devastation wrought by extreme poverty and are effective in raising support and income for charitable work [1],[2]. What is typically not shown, however, is a problem of similar magnitude and causation: under-nutrition.

Under-nutrition refers to a situation, whereby a diet provides enough calories to survive, but due to a reliance on a small number of staple crops, does not offer micronutrients in sufficient quantities to allow a human being to develop healthily. This can lead to permanent disadvantage as malnourished children are at higher risk of a litany of health issues such as suppressed growth [3-5] and neurological capacity[6-9], weak immunity[10],[11], poor bone health[12],[13] and damaged visual perception [14].

As an example, Vitamin A deficiency is endemic among children in south east Asia and Africa because the bulk of their diet consists of carbohydrate rich, yet nutritionally sparse foods such as rice, corn and cassava [15]. This deficiency can have long term effects on vision: it is estimated that 250 - 500,000 children become permanently blind every year[16].

Iron and Zinc are also often lacking in carbohydrate based diets [17], and this results in debilitating effects such as anaemia and a poorly developed immune system [18-21]. The economic impact of these dietary issues is immense. It has been estimated that malnutrition in India reduces GDP by 0.8 – 2.5% due to direct health costs and lost productivity [22].

The tremendous incidence of under-nutrition, and equally, the simplicity of its cause, has led to a consensus among aid and development agencies that addressing micronutrient deficiencies is likely to be one of the most effective methods of reaching the Millenium Development Goals [23-25].

Solving under-nutrition

One method of alleviating problems of malnourishment is to deliver conventional vitamin supplements to communities in developing nations. While supplements can be effective [26-28], they are relatively expensive to produce, logistically challenging to distribute and can lead to dependence on aid organisations [29].

An alternative mechanism, which has been receiving a large amount of attention recently, is bio-fortification.

Biofortification

Biofortification refers to the development of crop cultivars with enhanced micronutrient profiles. Using conventional breeding or genetic modification of existing staple crops, plants can be induced to take up or produce higher levels of critical vitamins and minerals, such as Iron, Zinc and Vitamin A.

The advantages of the technique are manifold. Biofortification is likely to be significantly cheaper than conventional supplementation as it requires only an initial investment in research and development and distribution of seeds, with very minimal maintenance costs [30]. Critically, biofortified plants can also deliver higher crop yields as minerals like Zinc and Iron are also essential nutrients for plants [31].

Biofortification has even been touted as one of the most important steps for developing nations to break out of extreme poverty. By reducing the number of Disability-Adjusted Life Years (DALYs - a framework, which quantifies the economic impact of disability and disease) lost due to undernutrition, biofortification could help developing nations to boost their economic output and prosperity [32]. For example, research on the benefits of Zinc biofortification in India estimates that 0.6 – 1.4 million DALYs per year could be saved at low cost [30].

Biofortification using conventional plant breeding techniques
The crop species that have been most widely taken up by farmers around the world are not necessarily the most productive or nutritious. Enormous genetic diversity exists among all of the commonly cultivated plants. There are over 4000 different varieties of potato, for instance, and many of these are far richer in important nutrients than the 'washed potatoes' that are common in Australian supermarkets [33]. Plant breeders take advantage of this diversity to generate new cultivars, which combine beneficial traits from multiple crop lines.

Significant advances have been seen through conventional breeding. Researchers working for HarvestPlus have established a variety of sweet potato with Vitamin A (stored as beta-carotene) levels 16 times higher than standard varieties [34]. At these concentrations, children can quite easily obtain sufficient Vitamin A through eating manageable quantities of the tuber.

Conventional breeding has the advantage of unopposed consumer acceptance in stark opposition to the situation faced by genetically modified (GM) crops. This also makes obtaining regulatory approval far easier.

However, even with modern high throughput screening technologies, conventional breeding is slow and difficult [35]. It is also debatable whether the possibility still exists to significantly improve staple crops given that they have been subject to artificial selection from humans since the inception of agriculture approximately 40,000 years ago. In addition, despite the broad branches of crop phylogenies, some species do not have a requirement for critical human micronutrients such as Vitamin A and hence lack genes for the accumulation of such compounds in their tissues [36]. In these situations, conventional breeding cannot be used to develop biofortified crop lines.

Biofortification through genetic modification

The key advantage of Genetic Modification is in its ability to allow genes to be transferred between biologically incompatible organisms. This can extend to the transfer of genetic material from organisms in different taxonomic kingdoms (e.g. the expression of biotoxins from the bacterium Bacillus thuringii in plants). In this manner, an almost limitless array of traits can be inserted into the genome of crop plants.

An example of the power of this technique is Golden Rice. Combined work from a number of research groups has led to the development of a variety of rice that expresses genes for the production of a high level of the vitamian A precursor, Beta Carotene [37]. Beta carotene is not naturally produced by any species of rice, and hence Golden rice provides an unprecedented opportunity to reduce the incidence of Vitamin A deficiency in communities in south east
Asia, which rely on the grain for sustenance [38].

The modular nature of genes also means that once a biosynthetic pathway has been implanted into one plant species, it is possible to effect the same change in another species relatively easily by using techniques such as codon optimisation [39], whole gene synthesis and high efficiency plant transformation [40]. In this sense, genetic modification could soon lead to a rapid development of biofortified crops.

On the other hand, GM crops face enormous obstacles in emerging from the laboratory into the field. There has traditionally been very strong consumer resistance to the introduction of GM foods, not only in developed nations, but also recently in a large number of African countries [41]. These consumer attitudes are mirrored in regulatory regimes, with GM crops being subject to a far higher degree of scrutiny than conventionally bred cultivars [42],[43].

Another potential roadblock to the development of biofortified GM crops is the commercial interests of large biotechnology firms, which have in the past laid claim to the intellectual property for genes that encode traits that are arguably a 'public good' (e.g. patenting of genetic risk markers for breast cancer [44]). For biofortification to be effective in combating nutritional deficiencies in developing nations, newly developed crops will need to be supplied at minimal cost to subsistence farmers [45].

Future outlook of biofortification

Despite the obstacles in place that may make the development and distribution of biofortified crops difficult to achieve, the future looks relatively bright for the technique.

Significant resources are being invested by collaborative research organisations, such as HarvestPlus, into conventional breeding programmes, which may gain fast tracked regulatory approval. There are also signs that large biotech firms are moving towards a business model incorporating corporate social responsibility. For example, Monsanto, a company which has previously been heavily criticised for its use of 'terminator genes' [46], recently agreed to provide drought tolerant maize crops to the Water Efficient Africa project on a royalty free basis [47]

Public opposition to GM crops may also be reduced in the case of biofortified crops due to the positive benefits they offer directly to the consumer [48]. This is in stark opposition to the first generation of GM crops, which were principally designed to enhance productivity for farmers, while subjecting consumers to a high level of perceived risk.

Similarly, due to the tremendous potential for biofortified crops to prevent illness and alleviate poverty, regulatory hurdles may be lowered for such GM crops. This is already being seen in the case of Golden Rice, which is expected to be delivered to farmers in developing nations in 2012 or 2013, eight years after its first successful field trial [49]. Although this is still a long time between development and approval, a significant portion of the delay can be attributed to the fact that many of the governments involved initially lacked GM regulations and had to develop policies on the issue. As a consequence, the approval process for subsequent GM cultivars may be more rapid.

Conclusion:
Biofortification offers a powerful solution to overcome micronutrient deficiency and thus help to achieve the Millenium Development Goals. While any potential safety risks must be investigated and attended to, the promise of biofortification, and in particular biofortified GM crops, is so large that purposeless regulations should be removed to allow the benefits to flow through as quickly as possible.

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