GM Foods and Human Nutrition

The following series of questions address aspects of Genetic Modification, particularly as it relates to the food supply and to human nutrition.

For the summary click here 

This answer is brought to you by many of the Australian nutrition professionals who regularly contribute to a nutrition email discussion group.

What is genetic modification, and how does it differ from conventional breeding?

For thousands of years people have been altering the genes of animals and plants, particularly those that provide food. Until very recently, this has been possible only by 'conventional methods'. These are selective breeding (taking the animals or plants that have desirable characteristics and using only those individuals for breeding); crossing individuals from closely related species; and mutational breeding (whereby mutations are induced, e.g., with ultraviolet light, and some of the resulting plants are then retained for breeding if they happen to have desirable characteristics). 

These techniques are time-consuming and very haphazard. Also, conventional methods of altering genes allow only pre-existing desirable characteristics to be enhanced in a plant or animal. If the genes are not already there, it is not possible to introduce them by conventional methods.

As a result of this alteration of the genetic makeup of our food plants and animals, apart from seafood that was caught in the open ocean, nearly all the foods available in Western supermarkets today have had their genes altered significantly. That is, they are quite different to the natural forms that existed hundreds or thousands of years ago. Many have been altered to the extent that they bear little resemblance to the original species.

About 20 years ago, biotechnologists began to develop a new
technology--technically known as 'genetic engineering'--for changing the genetic makeup of plants and animals. This process allows DNA to be transferred between organisms that may be completely unrelated. This means that, unlike conventional gene alteration, genes can now be transferred between organisms from different kingdoms (i.e., from bacteria to animals or plants, from animals to plants, and from plants to animals).

The gene that is transferred will have a specific function--one that cannot be obtained by conventional methods. GM technology gives plant and animal breeders the chance to produce foods (and other products) with characteristics that have not been possible until now. (But note that some additional DNA will usually be carried over with the desired gene, and that the effects of this DNA will be unpredictable). 

Therefore, it is technically appropriate to talk of 'genetic engineering' (GE) as the new technique. However, it has become common for people to refer, for example, to 'genetically modified (GM) food' when the process has actually involved 'genetic engineering'. Because 'GM' has entered the public's consciousness as the name for this new technique of altering genes, and also because it has been accepted by the Australian government authority that sets food standards, 'GM' will be used throughout the remainder of this FAQ.

Is GM 'unnatural'? 

This depends on your meaning of 'unnatural'. Clearly, nothing like GM (as defined immediately above) occurs in nature, so by that definition it could be said to be entirely unnatural.

However, much human activity is now 'unnatural' (according to the same definition). As examples: treating diseases with antibiotics (or other drugs), engaging in space travel, and even wearing clothes are unnatural forms of behaviour (no other species does these). So if GM is unnatural, then it is in good company.

But if 'unnatural' means going against the laws of nature, then GM would not be considered unnatural. It is the laws of nature that allow people to treat disease with drugs, travel to the moon and back, and modify genes using GM.

Is GM food necessary?

It has been argued that GM is not necessary for overcoming the world's nutritional problems. Rather, this might be better achieved by developing sustainable systems of agriculture that use existing varieties of edible plants and animals, and/or those resulting from further conventional breeding.  

It is true that in the West we have available an abundance of wholesome food, and GM isn't essential for feeding people in developed nations. But in food science, as in virtually every other branch of science, researchers are encouraged to investigate potentially better applications of existing methods of production, and to develop new technologies that may lead to improvement of the human condition. Perhaps the same consideration should
apply to GM as to the development of better computers, aeroplanes, light globes, and so on. 

Also, with respect to the food supply in Western nations, the argument that we don't 'need' new foods, or more total food, doesn't take into account the poor diets of many people--diets that contribute significantly to conditions such as obesity, diabetes, heart disease and cancer. As discussed in greater detail in the answer to Question 7, one of the aims of biotechnologists is
to produce foods that look and taste the same as present foods, but promote better health though improved nutritional characteristics. 

And although people in the West may not need GM foods, many scientists in developing nations argue that if they do not have access to biotechnology, then the developing world's nutritional problems will only continue to worsen. Examples of foods that may eventually contribute to overcoming the world's major nutritional deficiency diseases are described in the answer to Question 7. 

However, it remains to be seen if GM will be able to contribute to safely achieving these laudable aims with minimal harmful impact on the environment. As mentioned in the answer to the next question, and elsewhere in this FAQ, so far GM has shown more promise of nutritional  benefits than actual results.

What benefit has GM been to our food supply?

Until now, the application of GM has been of greater direct benefit to producers than to consumers. The 'Roundup Ready' crops are probably the best known application of GM to food production. These crops have had a gene incorporated into the plant that confers resistance to the herbicide Roundup. This reduces the work needed to control weeds, because the farmer can now simply sow and then spray with Roundup while the crop is actively
growing.

Another gene that has been used to simplify production is the 'Bt' gene. This is a gene taken from a bacterium that produces a natural insecticide. By having the plant produce the Bt insecticide, the need for spraying against insect pests is much reduced.

Neither Roundup Ready nor Bt crops provide any direct benefits for consumers.

Another production benefit worth mentioning is the development of grape vines that have been modified to protect themselves against a bacterial disease that is decimating wine production in some areas of the United States, and for which there is no effective treatment.

Are there potential problems for human health and safety associated with GM foods?

Each time a new gene is introduced into a food, there is a risk that the gene (or other DNA that was carried over with that gene) will lead to toxic or allergic effects in people. In Australia all new GM foods must have been subjected to safety testing before they can be offered for sale. The same requirement for safety testing does not apply to new varieties produced by conventional methods, so it could be argued that new GM foods should be safer to human health than new conventional foods.

For example, in the United States a variety of celery was developed in the 1980s--using conventional breeding methods--to have enhanced natural protection against insect pests. No safety testing was conducted. When the celery was handled it led to severe skin rashes. An inadvertent effect of the breeding program had been to increase the quantity of a chemical that became an irritant to human skin when exposed to sunlight.

By way of contrast, in the mid 1990s a form of GM soy was developed that incorporated a protein from the Brazil nut (to enhance the nutritional quality of the soy protein). This was subjected to safety testing and was found, somewhat unexpectedly, to cause reactions in people who were allergic
to the Brazil nut. Unlike the conventionally-developed celery, this GM food did not proceed to commercial production.

However, unlike conventional breeding, the GM process does not have a long history of producing new and (generally) safe varieties of plant and animal foods. The potential for unexpected toxic effects may be greater for GM than for conventional breeding, so safety testing is essential, as discussed in greater detail in the answer to the next question. 

It should also be pointed out that safety testing may be more problematic for GM foods than for new conventionally-developed foods. This is because the process of gene transfer is not yet precise enough to be able to predict what potential safety problems might occur. That is, if researchers do not even have some knowledge of the likely nature of a potential problem, it is
difficult to know what sort of safety tests need to be conducted.

What are the regulations regarding GM products, and GM food in particular?

In Australia, the overall responsibility for genetically modified organisms (GMOs) lies with the Office of the Gene Technology Regulator (OGTR). The OGTR is neither 'for' nor 'against' the use of GM technology. Rather, it exists to ensure that GMOs grown in Australia are safe.

The OGTR requires that GMOs must not be grown in Australia unless they have been approved and so are on the register. The approval procedure involves analysis of the risks/benefits, including reference to likely environmental effects. Public comment must always be sought. The process must be 'transparent': that is, the reasons for the acceptance/rejection of the GMO must be available to the public.

The OGTR has been given strong legislative backing--fines of up to $1.1 million per day for continued breaches, and/or prison sentences can be applied.

The responsibility for the regulation of GM food rests largely with Food Standards Australia New Zealand (FSANZ, formerly known as ANZFA). The two major aspects of regulation of GM food are safety testing and labelling.

Safety Testing

As mentioned in the answer to Question 4, all GM foods offered for sale in Australia must have been tested for toxicity and allergenicity. They must also have been tested for any effects on nutritional quality. This testing will usually have been conducted overseas. Because the genes that are incorporated in the GM plant are often accompanied by small sections of DNA of unknown function, this testing is essential, even if the gene that was transplanted is extremely unlikely to lead to toxic or allergic effects.

As discussed in the answer to Question 5, because the effects of
incorporating new DNA into an organism are not always predictable, there are potential problems with safety testing. However, so far as is known, no-one has yet been poisoned by eating GM food.

Labelling

FSANZ requires labelling of GM food where that food contains novel DNA (the transferred gene or genes) or protein (the product of the novel DNA). If the food is indistinguishable from the conventional alternative (e.g., if it is a refined oil that has no novel DNA or protein, but was produced from GM plants) then labelling is not required. This is one area of concern for some people, e.g, those who would like to avoid all GM products because they have
philosophical or ethical objections to the process. 

Accidental mixing of a very small amount of GM food with predominantly conventional food will also be permitted, without affecting the labelling of that food. An example would be where a truck that has been used to transport GM food grain is then used to transport conventional grain, with a small amount of the GM grain remaining. Up to 1% GM food will be tolerated without
affecting labelling when this sort of accidental mixing occurs.

Of course, having strict legislation is only one factor in regulating a new technology that has the potential to profoundly alter our food supply. The other major factor is ensuring that the regulatory bodies have adequate staffing and funding to carry out their responsibilities. A survey conducted in the UK in 1995 found that many people were concerned that the regulator may not be able to ensure compliance to the regulations by powerful multinational companies. This appears to be a concern in Australia too. The
OGTR was formed only in June 2001. Its effectiveness in regulating GMO production in Australia has yet to be tested. 

Are there any potential effects on the environment of growing GM foods?

Many scientists have expressed concern about possible detrimental effects of GM on the environment. These effects can be direct or indirect.

Direct effects that would very likely occur include the inadvertent
poisoning of 'non-target' species of insects. For example, Bt crops would be just as poisonous to ecologically beneficial insects that feed on the Bt corn or cotton plant as they would to harmful insects.

An example of a possible indirect effect was described recently. In a 'modelling' study, the likely effect on the wildlife of rural England of growing Roundup Ready sugar beet was investigated. According to the results of this (theoretical) study, this might lead to starvation of skylarks, because their major food, the weed 'fat hen', would no longer be available.

Other potential detrimental environmental effects include the possibility that herbicide resistance might cross to weeds or other plants that are closely related to food crops, and 'escapes' of genes to neighbouring conventional or organic crops (meaning that those farmers could no longer sell their product as 'non-GM'). Environmentalists have also expressed concern at the possibility that GM crops might lead to adverse effects on organisms that are essential to maintaining soil fertility.  

Although there may be technological solutions to many of these problems, perhaps the most worrying environmental effects are those that are not readily predictable. An example of an unpredictable effect is illustrated by the results of a laboratory study conducted in the United States. Monarch butterfly larvae, which do not feed on corn, died when they ate milkweed
that had been sprinkled with Bt corn pollen (simulating the situation that might occur on farms where this crop is grown). 

Another issue that needs to be addressed is the possible effect of the introduction of GM technology on the diversity of the world's food crops. If only a few GM varieties of the major food crops are grown, the risk that a disease could wipe out a substantial proportion of our food production is much greater than if a wide range of varieties are grown. There are also nutrient differences between varieties of food plants (and animals). With our incomplete knowledge of human nutritional needs, if only a few varieties are grown, the nutritional quality of the food supply may be adversely affected. Although this problem exists (and has existed for many years) with conventional farming, the application of GM has the potential to even further reduce the diversity of the world's food production.   

On a more positive note, one of the potential advantages of Bt crops is that their use would reduce the number of non-target insect species directly harmed, because there will be less need to spray. Only those insects that actually feed on the crop should be directly affected by the Bt insecticide. (But note that an unpredicted effect occurred with Monarch butterfly larvae
in a laboratory study, as described earlier in the answer to this question).

It should also be pointed out that GM is not unique in posing problems to the environment. Conventional methods of agriculture--involving spraying with insecticides and herbicides, pollution of waterways with fertilisers and so on--have been causing damage to the environment for many decades. 

You have mentioned possible risks to the environment and few nutritional benefits so far. Is there any likelihood of direct benefits to people from GM food in the future?

As discussed in the answer to Question 3, until now the main benefits of GM have been to food production. In the last few years development has begun of GM foods that may provide nutritional benefits. Biotechnologists believe that these are just the tip of the iceberg, and that many more useful foods will be produced over the next decade or two.

The most promising one so far is 'golden rice', so called because it has a yellow tinge. The colour comes from the presence of a substance called beta-carotene, derived from a gene that was 'borrowed' from the daffodil.  In the human body, beta-carotene is converted to vitamin A. With an estimated 700 million people suffering from vitamin A deficiency, and an estimated 2 million dying each year as a result, golden rice is believed by its inventors to have the potential to dramatically reduce this major nutritional problem.

However, there is some controversy about the potential of golden rice to actually have a significant beneficial effect on people who are suffering from vitamin A deficiency, with experts disagreeing on just how effective it is likely to be.  

But golden rice does not just attempt to reduce vitamin A deficiency. It has also been modified to tackle another major nutritional problem. In addition to the gene for beta-carotene, it also contains a gene that will increase the uptake of iron from the soil by the rice plant, and another that will increase the rate of absorption of that iron into the human body.  Approximately 2 billion people suffer from iron-deficiency anaemia, so golden rice has the potential to make a major contribution to human health
by reducing the incidence of iron deficiency.

It is also true that the most effective way of satisfying the body's need for vitamin A and iron (and all other essential nutrients) is to eat a wide variety of nutritious foods. Suitable foods include lean red meat and cereal foods (for iron), orange/yellow fruits and vegetables and leafy green vegetables (for beta-carotene). As discussed in greater detail in Question 11, one of the problems leading to world hunger is food availability: many people in developing nations do not have access to the nutritious foods that
we take for granted. Because rice is a staple in those areas of the
developing world where the nutritional problems are the greatest, making rice available that has additional beta-carotene and iron may be successful in improving vitamin A and iron status where other strategies have failed.

At this stage, golden rice is undergoing further development at the
International Rice Research Institute. The developers are aiming to increase the quantity of beta-carotene it produces (which is currently rather low).  It will be several years before it is ready for testing in the field.

Another GM food with possible nutritional benefits to people in developing nations is a form of rice that has about 30% greater yield than normal rice.  Like golden rice, this high-yielding GM rice is in the early stages of research and development. 

There are also developments of significance to people in developed nations, including the possibility of growing coffee beans with low caffeine content, plant oils with improved nutritional characteristics, and wheat that can be tailored to allow the production of bread with higher levels of 'resistant starch' (a form of starch that exerts health benefits similar to those conferred by dietary fibre). 

GM has been in existence for only about 20 years. The potential for direct benefits to consumers, as opposed to producers, is only now being demonstrated.

What is the trend in attitudes to GM foods?

In the developed world there has been a hardening of attitudes against GM foods in the last few years. Surveys conducted in 2000 found that about 50% of Australians and Americans, 60% of people in the UK, and 70% of French people were opposed to the use of GM technology to produce food.

Attitudes in Australia

A series of surveys conducted in Australia by CSIRO found that people were less accepting of GM food in 1999 than in 1998. During this time there was significant adverse publicity about GM food as a result of a study that was later criticised as involving poor science. 

The following year, GM food appeared to become less controversial in Australia--by late 2000, acceptance rates were about midway between those of 1998 and 1999. For example, in 2000, about 40% of respondents believed that it was a 'highly acceptable' application of GM to produce foods with health
benefits (up from 36% the previous year). 

But acceptance to Australians of GM food is dependent very strongly on the level of risks involved to either people or the environment. For example, in 2000, 76% of respondents were in favour of using GM to improve vitamin and mineral content of fruits and vegetables if it had been shown that there was 'no risk' to the environment. But only 7% found this appropriate if the risk involved was 'unknown'.

Acceptance is also dependent on perceived value. About 40% of respondents in the 2000 Australian survey would eat GM foods if they had nutritional advantages over conventional foods and cost about the same (while 25% would not, and 35% were undecided). But fewer than 30% would try the nutritionally superior GM alternative if it cost more.

Labelling is also important to Australians. In another survey conducted in 2001 in Tasmania, about two-thirds of people over the age of 18 agreed that it would be appropriate to offer GM food for sale, provided that it was adequately labelled. However, two-thirds of this same group of Tasmanians did not want GM food to be actually grown in Tasmania. (It is perhaps relevant to mention here that Tasmania has declared a moratorium against the
commercial growing of GM plants. This moratorium will apply until at least mid-2003).

To summarise attitudes in Australia to GM foods, the major concerns of people appear to be the risks versus benefits, transparency of decision-making, freedom of choice, and price compared to the conventional alternatives.

Attitudes in Europe

It is in Europe that the anti-GM sentiment is strongest. Perhaps this is because of problems that have occurred with Europe's food supply, such as 'mad cow disease'--a disease that is believed to have resulted from inappropriate feeding practices that occurred several decades ago. Having been assured by governments that mad cow disease would not affect humans, and then finding out that it does affect people, Europeans are (not surprisingly) suspicious of any new technology that has the potential to
substantially alter their food. This suspicion might also have been
exacerbated (and not only in Europe, but throughout the world) by the realisation that pesticides are not as harmless as the chemical companies originally claimed. Attitudes in Europe have hardened against GM to the extent that some US farmers have been unable to sell their produce to Europe.

What are the trends in world production of GM foods?

Paralleling the hardening of attitudes against GM food, there was a significant plateauing in the growth of GM crops in the year 2000. Only GM soy production increased, while less GM corn was produced in 2000 than in 1999. The 1999 levels of production of the other two major GM crops (canola and cotton) were maintained in 2000. 

What is the future for GM foods likely to be?

This is the one question that no-one can answer at present. World production of GM food crops has plateaued and attitudes in the West are hardening against GM foods. Perhaps it was unfortunate that the first GM foods had little in the way of nutritional benefits, and that the companies who produced them did not realise how strongly the public would resist having novel foods made available without adequate labelling.

But the world's human population is already over 6 billion, and is
increasing at an estimated rate of about 80 million per annum. The world's agricultural land is, of course, not expanding. In fact, much of the arable land is being lost to food production because of salination, desertification, erosion and nutrient depletion of soils. To be able to feed the estimated 8-9 billion people who will be alive in 2050, new and sustainable ways of producing food must be found. Some recent developments in GM suggest the possibility that this new form of biotechnology may contribute to the feeding of these additional 2-3 billion people.

However, the problems of undernutrition relate not only to production, but also to availability of food. Simply producing more food (by GM or otherwise) will not overcome the current inequitable distribution that allows a majority of adults in Western countries to be overweight while many developing countries are suffering from food shortages.  

Whether or not GM proves to be capable of being a major player in overcoming the problems of world hunger remains to be seen. The 'second wave' of GM foods is only now beginning. Some of these foods (e.g., golden rice and the high yielding GM rice) appear to have at least a theoretical potential to make a significant contribution to human health. 

Provided that adequate safety testing and appropriate testing for
environmental effects are conducted, the vast majority of scientists support continued research into GM food. It is probably also reasonable to state that all scientists would recommend caution when deciding whether or not to release GMOs into the environment. Setting and enforcing strong regulations (such as those legislated in Australia) will be essential to minimise the
risks and maximise any benefits that GM technology may be able to bring to human nutrition.

Sir Robert May, the UK's Chief Scientific Adviser, has said that it is inappropriate to be 'for' or 'against' GM foods. Rather, the risks should be weighed against the potential benefits for each new GM food. Only if the potential benefits clearly and substantially outweigh the risks should consideration be given to producing that GM food.

Suggested Further Reading

http://www.fao.org/Ethics/ser_en.htm 
(Scroll down to section 2, entitled 'Genetically modified organisms,
consumers, food safety and the environment')

Back to Frequently Asked Questions Index

[Date Issued: August 2001]

Disclaimer: This material is provided on the basis that it constitutes advice of a general nature only. It is not intended to replace the advice of a physician or a dietitian.