Asia Pacific Journal of Clinical Nutrition

Volume 9, supplement, 2000

Contents	Abstract	Paper
The Garden of Eden: Implications for cardiovascular disease prevention DAVID JA. JENKINS, AL JENKINS, CWC KENDALL, V VUKSAN AND E VIDGEN	html	PDF
Evidence-based nutrition DIMITRIOS TRICHOPOULOS, PAGONA LAGIOU, ANTONIA TRICHOPOULOU	html	pdf
Your mother was right: Eat your vegetables JOHN D POTTER	html	pdf
Soy and other legumes: 'Bean' around a long time but are they the 'superfoods' of the millennium and what are the safety issues for their constituent phytoestrogens? KENNETH DR SETCHELL, SUE RADD	html	pdf
Whole grains, refined grains and fortified refined grains: What's the difference? JOANNE L SLAVIN	html	pdf
Nut consumption, lipids, and risk of a coronary event GARY E FRASER	html	pdf
Changing the diet of a nation: Population/regulatory strategies for a developed economy MARION NESTLE	html	pdf
Plant-based diets are traditional in developing countries: 21st century challenges for better nutrition and health NOEL W SOLOMONS	html	pdf
Clinicians changing individual food habits MARK L WAHLQVIST	html	pdf
Optimizing the plant-based diet JIM I MANN	html	pdf
Eat Well Australia: Developing a national strategic framework for public health nutrition JOHN CATFORD	html	pdf
Changing what we eat: Can a professional association play a role? SANDRA CAPRA	html	pdf
Colorectal disorders: A dietary management perspective GRAEME P YOUNG	html	pdf
Evolution of the diabetic diet: Fats and fallacies LESLEY V CAMPBELL	html	pdf
Food for prevention of coronary heart disease: Beyond the low fat, low cholesterol diet DAVID M COLQUHOUN	html	pdf
Nutritionally enhanced cereals: A sustainable foundation for a balanced diet ROBIN D GRAHAM, JULIA M HUMPHRIES, JULIE L KITCHEN	html	pdf
Food security and sustainability: Are we selling ourselves short? JOHN COVENEY	html	pdf
Food and health economics in the 21st century PHILLIP K RUTHVEN	html	pdf
Food and consumers: Where are we heading? ANTHONY WORSLEY	html	pdf
What makes a functional food functional? PETER RC HOWE	html	pdf
Gene technology and future foods SIMON ROBINSON, NIGEL SCOTT, ANGELA GACKLE	html	pdf
Recommended dietary intake levels for phytochemicals: Feasible or fanciful? IVOR E DREOSTI	html	pdf

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The Garden of Eden: Implications for cardiovascular disease prevention
DAVID JA. JENKINS, AL JENKINS, CWC KENDALL, V VUKSAN AND E VIDGEN
Creationists and evolutionists acknowledge that the human diet has passed through at least four phases. The original plant food-based diet; a second phase of increasing meat consumption; a third phase of agricultural dependence on starchy foods; and, finally, the supermarket high-saturated fat, low-fibre phase with minimal energy expenditure. Our aim is to define the value of the original or 'Garden of Eden' diet and to speculate on which components should be retained in the modern supermarket diet. The original plant-based diet would have been high in vegetable proteins, plant sterols, dietary fibre and antioxidants, and low in saturated fats with no trans fatty acids. This diet would increase fecal cholesterol losses from the body as bile acids and neutral sterols, while providing little stimulus to cholesterol synthesis. To replace the bile acid losses we would have adapted to a relatively high capacity for cholesterol synthesis. Now, in the high-saturated fat, low-fibre supermarket age, this may be a disadvantage and predisposes consumers to high serum cholesterol and increased risk of cardiovascular disease. We believe part of the solution is a return to the plant-based 'Garden of Eden' diet combined with physical activity. A lipid-lowering portfolio containing vegetable proteins, especially soy, plant sterols and high fibre intakes combined with low saturated and trans fatty acids and cholesterol, would go a long way to reducing serum lipids and coronary heart disease risk seen in the modern Western diet.
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Evidence-based nutrition
DIMITRIOS TRICHOPOULOS, PAGONA LAGIOU, ANTONIA TRICHOPOULOU
What are the objectives of an ideal diet? Are they to prolong life or maximize quality adjusted life expectancy? Does this focus on individuals or on the population at large, taking equity and resources into account? What about externalities that should take into account cultural heritage, protection of the environment and macroeconomic considerations? Few people have the experience, expertise and knowledge to adequately address these questions. It is only feasible to argue that there are two approaches in order to establish the proper diet, with the limited objective of longevity. Contrary to the assertions of several influential groups, there is no such thing as a 'positive health', and longevity can only be defined as the inverse of mortality from all causes. The crucial questions are: do we need to study the proper diet to reduce incidence of and mortality from particular common diseases and then find the common elements in these various diets in order to construct de novo the ideal diet (bottom up approach)? Alternatively, is it better to harvest the experience of various cultures whose diets appear to protect against premature morbidity and mortality (top down approach)? The first approach would rely on associations between food groups, foods and nutrients on the one hand and the incidence of specific diseases on the other, whereas the second would evaluate and quantify the effects of 'natural' diets on longevity. The first approach has been largely followed by mainstream nutritional epidemiologists, whereas the second has been advocated by a few international experts.
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Your mother was right: Eat your vegetables
JOHN D POTTER
A lower risk of cancer at many different sites is seen in association with higher intakes of vegetables and fruit. There are many biologically plausible reasons for this potentially protective association. It is argued that increasing intake of plant foods to 400-800 g/day is a public health strategy of considerable importance for individuals and communities worldwide.
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Soy and other legumes: 'Bean' around a long time but are they the 'superfoods' of the millennium and what are the safety issues for their constituent phytoestrogens?
KENNETH DR SETCHELL, SUE RADD
The recognition that legumes and, in particular, soybeans provide not only an excellent source of vegetable protein but also contain appreciable amounts of a number of phytoprotectants has increased general awareness of their potential nutritional and health properties. Since the discovery that soybeans are one of the richest dietary sources of bioavailable phytoestrogens, this legume has been elevated to the forefront of clinical nutritional research. These natural 'selective oestrogen receptor modulators' have been shown to be bioactive. The recent approval by the Food and Drug Administration in the United States for a health claim for soy protein reducing risk for heart disease by its effects on lowering cholesterol levels has led to the increased awareness of the health benefits of soy protein. However, the presence of high levels of phytoestrogens in soybeans has also led to concerns over the potential safety of soy foods. This review will focus on the cardioprotective benefits of legumes and discuss the hypothetical concerns regarding the constituent phytoestrogens.
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Whole grains, refined grains and fortified refined grains: What's the difference?
JOANNE L SLAVIN
Dietary guidance universally supports the importance of grains in the diet. The United States Department of Agriculture pyramid suggests that Americans consume from six to 11 servings of grains per day, with three of these servings being whole grain products. Whole grain contains the bran, germ and endosperm, while refined grain includes only endosperm. Both refined and whole grains can be fortified with nutrients to improve the nutrient profile of the product. Most grains consumed in developed countries are subjected to some type of processing to optimize flavor and provide shelf-stable products. Grains provide important sources of dietary fibre, plant protein, phytochemicals and needed vitamins and minerals. Additionally, in the United States grains have been chosen as the best vehicle to fortify our diets with vitamins and minerals that are typically in short supply. These nutrients include iron, thiamin, niacin, riboflavin and, more recently, folic acid and calcium. Grains contain antioxidants, including vitamins, trace minerals and non-nutrients such as phenolic acids, lignans and phytic acid, which are thought to protect against cardiovascular disease and cancer. Additionally, grains are our most dependable source of phytoestrogens, plant compounds known to protect against cancers such as breast and prostate. Grains are rich sources of oligosaccharides and resistant starch, carbohydrates that function like dietary fibre and enhance the intestinal environment and help improve immune function. Epidemiological studies find that whole grains are more protective than refined grains in the prevention of chronic disease, although instruments to define intake of refined, whole and fortified grains are limited. Nutritional guidance should support whole grain products over refined, with fortification of nutrients improving the nutrient profile of both refined and whole grain products.

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Nut consumption, lipids, and risk of a coronary event
GARY E FRASER
In the past many have avoided nuts because of their high fat content. The Dietary Approaches to Stop Hypertension diet, however, recommends regular consumption of this food along with seeds and dried beans (4-5 servings per week) as part of a diet to control hypertension. Nuts are nutrient-dense and most of their fat is unsaturated. They are also perhaps the best natural source of vitamin E and are relatively concentrated repositories of dietary fibre, magnesium, potassium and arginine, which is the dietary precursor of nitric oxide. Human feeding studies have demonstrated reductions of 8-12% in low-density lipoprotein (LDL) cholesterol when almonds and walnuts are substituted for more traditional fats. Other studies show that macadamias and hazelnuts appear at least as beneficial as fats in commonly recommended diets. Whether the daily consumption of modest quantities of nuts may promote obesity is not known with certainty, but preliminary data suggest that this is unlikely. Four of the best and largest cohort studies in nutritional epidemiology have now reported that eating nuts frequently is associated with a decreased risk of coronary heart disease in the order of 30-50%. The findings are very consistent in subgroup analyses and unlikely to be due to confounding. Possible mechanisms include reduction in LDL cholesterol, the antioxidant actions of vitamin E, and the effects on the endothelium and platelet function of higher levels of nitric oxide. Although nuts may account for a relatively small percentage of dietary kilojules, the potential interacting effects of these factors on disease risk may be considerable.
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Changing the diet of a nation: Population/regulatory strategies for a developed economy
MARION NESTLE
The principal nutritional problems of developed economies are related to the excessive and unbalanced intake of energy and nutrients. During the 20th century, as economies improved and food production became more efficient, conditions related to undernutrition were replaced by epidemics of coronary heart disease, certain cancers and other chronic conditions related to food overconsumption. In developed countries such as the United States, obesity became the predominant public health nutrition problem. To prevent obesity, people must consume less energy and be more active, but the food supplies of developed economies offer their populations amounts of energy that greatly exceed physiological need. Food overproduction causes competition in the food industry, limits its expansion, and leads food producers to invest heavily in marketing. To increase sales, food companies must encourage people to consume more of their products, substitute their products for others or develop new markets. Such efforts create an environment in which food is readily available at all times and readily overconsumed. Marketing expenditures for any single food product greatly exceed the total amounts available to governments for national campaigns to prevent chronic diseases. Existing government policies often support this environment through price supports and other means. To reverse obesity and its health consequences, governments need to consider ways to address the food environment through policies in education, agriculture, school meals, pricing, taxation and other means, as well as to develop mechanisms to fund new programme initiatives.
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Plant-based diets are traditional in developing countries: 21st century challenges for better nutrition and health
NOEL W SOLOMONS
The chronic degenerative diseases were virtually unknown in original hunter-gatherer societies. At the dawn of the 21st century, however, they represent the most important public health challenge to populations of both the industrialized, affluent nations of the temperate zones and the low-income developing countries of the tropics. The developing countries most closely reflect the legacy of our traditional foreparents while constituting three-quarters of the world's populace and public health interest. For economic, traditional, religious and cultural reasons, the majority of the dietary fares in the developing world are largely plant based. This is associated with high prevalences of deficiency states in vitamin A, iron, zinc, riboflavin and vitamin B12. Poor linear growth and chronic energy deficiency are concomitant conditions. Conversely, the major chronic diseases have low prevalences among the rural peasantry and tribal groups, with the exception of gastro-esophageal cancer, osteoarthritis and cataract. As a site for intensive research in food and nutritional sciences, Guatemala provides important lessons about the origin and evolvement of a congruent plant-based diet within a food system and which factors of demographic expansion, urbanization, environmental stress and food technology will carry it through the 21st century. We can conclude that, whatever was the 'original' dietary pattern of pre-agricultural humankind, a plant-based diet regimen provides the lowest content of promoters and the highest content of inhibitors of metabolic dysregulation that lead to the major causes of disease and debility in adults over 40 years of age. For developing countries, the challenge is to maintain and reinforce the traditional eating patterns while improving their delivery of micronutrients and obviating any adverse environmental consequences in their traditional preparation patterns. For developed countries, there is an opportunity to find a 'road map' of guidelines to allow correction of current, pathogenic dietary and lifestyle patterns by examining the food-ways of traditional developing societies' cuisines.

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Clinicians changing individual food habits
MARK L WAHLQVIST
There is ample evidence from repeat food surveys that people are actually and passively changing their food habits. Understanding the reasons for this are vital to any efforts by clinicians to enable individuals to move in an increasing healthful direction with their food intake, and to dispel the pessimism that often prevails about the ability to make a useful contribution to nutritional status by changing food intake. Current success and failure rates are predicated on inadequate methods and inappropriate outcome measures, rather than an inability to achieve outcomes. Factors that allow for or encourage change are food availability, exposure to new food experiences, food memory, pleasure, eating with peers or companions, health interest and changing constructs and beliefs about food. It is possible to change the health impact of food by non-food means like physical activity, stress management, recreational activities, improved relationships, changing the work environment and through adequate sleep (including siesta). Yet another consideration is that the full consequences of food choice are not appreciated with more and more food-health relationships being defined (e.g. with cataract, macular degeneration, in depression and cognitive function). These various approaches require a management strategy that underpins the field of behavioural therapy. In this approach it is possible to make progress through small but consequential changes, like climbing the stairs, or increasing intake of particular foods like fish or drinking more water; and exploring and contracting ways to do these things.

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Optimizing the plant-based diet
JIM I MANN
Any attempt to optimize a plant-based diet necessitates an identification of the features of the diet which confer benefit as well as any which may be associated with detrimental effects. The former task is more difficult than might be assumed as there is no doubt that some of the apparent health benefits observed amongst vegetarians are a consequence of environmental determinants of health which characterize groups of people who choose vegetarian diets, rather than dietary practices. This review will consider the major health benefits of plant-based diets, the specific foods or nutrients which confer the benefits as far as can be ascertained from present knowledge, potential nutrient deficiencies associated with a plant-based diet and nutritional strategies that can be employed to prevent any such deficiencies.

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Eat Well Australia: Developing a national strategic framework for public health nutrition
JOHN CATFORD
In Australia, diet-related disease ranks alongside tobacco-related disease as the most important preventable health area, accounting for at least 10% of the total burden of disease. A population approach to improve the nutrition of all Australians is a vital contribution to the nation's overall health and well-being, yet action has often been ineffective, uncoordinated and poorly resourced. Through the National Public Health Partnership's nutrition group, SIGNAL, an ambitious work program has been commenced to address this situation. This includes the development of a national framework for action in public health nutrition 2000-2010. Following extensive consultation with health groups and the food industry, the strategy, Eat Well Australia, is now in a late stage of development. Key priorities have been agreed and focus on: (i) Aboriginal and Torres Strait Islander people; (ii) vulnerable groups; (iii) maternal and child health; (iv) overweight and obesity; and (v) fruit, vegetables and legumes. Eat Well Australia should provide a new pathway for more concerted and integrated action from a wide range of organizations and interest groups. As a core component, SIGNAL has also developed an action plan to promote comsumption of fruits, vegetables and legumes, which should mobilize responses at local, regional and national levels. Close cooperation between the food industry and the governmental and non-governmental sectors will be vital for success. A partnership platform is needed with clearly defined directions, operating principles and roles and responsibilities. Encouragingly, new and energetic alliances are now developing, which will be supported by Eat Well Australia.

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Changing what we eat: Can a professional association play a role?
SANDRA CAPRA
Professional associations have traditionally focused their activities in the provision of services to members. However, this need not be their only role. The Dietitians Association of Australia has chosen to take a proactive approach to changing the way that the Australian people eat. Through a variety of strategies assisted by partnerships with industry, the Association has been able to increase skills of individual members, provide skills to other health providers, increase advocacy, implement health promotion programs and use the media to provide nutrition messages. Encouraging results have been achieved to date that support such a role for professional associations.
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Colorectal disorders: A dietary management perspective
GRAEME P YOUNG
Dietary lifestyle is relevant for prevention and treatment of various colorectal conditions. Colorectal disorders have significant morbidity and mortality in a western-style community, particularly irritable bowel syndrome (IBS), colorectal cancer, haemorrhoids, constipation and diverticular disease. This review addresses how bowel health can be maintained, what foods and dietary lifestyles are associated with risk for disease and what foods are of real value in management. Bowel health is that state where the individual is satisfied with defaecation, the diet does not create undue risk for disease and lumenal contents maintain an intact and functional mucosa. Bowel health depends on a healthy dietary lifestyle, but in particular on an adequate intake of non-digestable dietary polysaccharide. Diet influences biology in part by altering the lumenal environment. Effects such as high butyrate levels, lowered pH, a predominance of 'healthy'over 'unhealthy' bacteria, rapid intestinal transit, high faecal bulk, a non-leaky epithelial barrier, adsorption of dietary carcinogens by fibre, low bile salt concentrations, reduced generation of toxic bile salts or protein derivatives and provision of certain bioactive substances are seen as beneficial. Diet influences future risk for colorectal cancer (vegetables, animal fats, polysaccharides amongst others) and for diverticular disease (fibre). Adequate fibre and resistant starch can improve constipation and anorectal conditions such as fissure and haemorrhoids. The role of diet in managing patients with IBS is complex. Fibre may worsen symptoms in severe cases of IBS, diverticular disease and inflammatory bowel disease. Certain carbohydrates of limited digestibility/absorbability, such as lactose, fructose and sorbitol, can precipitate IBS symptoms. Low fat, high fibre diets may reduce recurrence of colorectal adenomas. Diet has a significant role to play in colorectal disorders.

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Evolution of the diabetic diet: Fats and fallacies
LESLEY V CAMPBELL
The Diabetes Control and Complications Trial and United Kingdom Prospective Diabetes Study (UKPDS) trials have provided evidence for the pivotal importance of optimizing glycaemic control to prevent complications in type 1 and 2 diabetes mellitus. Both patients and diabetes professionals consider lifestyle change and appropriate medication as cornerstones for achieving good glycaemic control. The frequent reversals in the recommended diabetic diet in the past century warn that in the nutritional area the hypotheses are many, but the proofs are few. In type 1 diabetes, the patient is still advised to spread out carbohyrate foods during the day with three short-acting insulin injections at meal times to minimize postprandial hyperglycaemia. In type 2 diabetes, weight loss is the major target, because 80% of patients are overweight or obese. However, it is salutory to note that in the UKPDS trial, no modality of treatment delayed the relentless deterioration of glycaemic control in type 2 diabetes, the extent of which was predicted by the insulin secretion. Controversy still exists regarding whether lowering the dietary fat enhances weight loss of itself and whether dietary carbohydrate, fat and fibre influence insulin sensitivity and glycaemia. The American Diabetes Association's evidence-based recommendations currently offer a choice between a high carbohyrate and modified fat diet, with monounsaturated fat replacing the saturated fat instead of carbohydrate. The role of omega-3 fatty acids in man is not resolved. The reason for the surprising lack of definitive evidence lies in the limitations of nutritional research. Under-reporting of diet is common and dietary assessment tools are often inaccurate. Sustained weight loss is unattainable by the majority of patients, perhaps because of the strongly genetic nature of obesity and the sedentary lifestyle. Compliance may be improved by suggesting small, sustained dietary changes, setting small weight loss targets and encouraging a permanent increase in total activity.

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Food for prevention of coronary heart disease: Beyond the low fat, low cholesterol diet
DAVID M COLQUHOUN
The single major cause of death throughout the world is coronary heart disease. Prevalence is stable or decreasing in North America, Australasia and most of Europe, while rapidly increasing in eastern Europe, Asia and Africa. Atherosclerosis is the underlying pathology. This is one of the classic lifestyle diseases on the background of genetic susceptibility. Diet plays a key role in the initiation and progression of coronary heart disease. A low total fat diet is almost universally recommended throughout the world. However, the most successful secondary prevention diet trials have used modification of fat, rather than decrease in total fat per se. Successful diet trials suggest that diet modification is as effective as accepted drug therapy to prevent recurrent coronary events, and importantly is very cost effective. Marine lipid supplementation has been demonstrated beyond reasonable doubt to decrease total mortality and in particular sudden death in patients who have survived their first myocardial infarction. Large-scale diet intervention trials are indicated to improve the scientific basis for dietary recommendations to prevent initial and recurrrent coronary heart disease.
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Nutritionally enhanced cereals: A sustainable foundation for a balanced diet
ROBIN D GRAHAM, JULIA M HUMPHRIES, JULIE L KITCHEN
Three nutrients, iron, zinc and pro-vitamin A, are widely deficient in humans, especially among low socio-economic groups in developing countries, but they remain significant concerns in industrialized countries as well. Cereals provide the majority of the intake of these nutrients in low-income families. Moreover, these three nutrients may interact synergistically in absorption and function to such an extent that there are potentially huge advantages in providing all three together in the one staple food. Because of this, they may be more bioavailable to deficient individuals than current thinking allows. To do so would provide a sound basis on which to build a better balanced diet for nutritionally compromised individuals. Genetic variation in nutrient composition exists in cereals and can be exploited in conventional breeding programmes and through gene technology. Cultural techniques, including fertiliser technology and organic farming, have also impacted upon the nutrient composition of cereals. Human iron and zinc intake can be doubled at least, and essential carotenoid intakes can be increased dramatically. Preliminary feeding trials with nutrient-dense grains have been encouraging. Moreover, nutrient-dense seeds also produce more vigorous seedlings and higher grain yield in soils where these nutrients are poorly available, so that to a significant extent agronomic and health objectives coincide. New varieties are rapidly adopted, especially where there are yield advantages, ensuring maximum impact without new inputs. This approach is potentially more sustainable than fortification and supplementation programmes because intake is continuous, which is especially important for zinc because it is needed almost daily.
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Food security and sustainability: Are we selling ourselves short?
JOHN COVENEY
This paper deals with the question: do some food systems engender a more positive social environment than others, and does this matter? The pressure to generate financial capital from food production is enormous, especially for a country like Australia, and financial imperatives clearly drive choice of food production methods. Many have argued that environmental costs of food production are hardly ever factored into the profitability equation and the notion of sustainable development represents a position where consideration is given to environmental concerns while at the same time maximizing economic returns. While the importance of choice of food system in order to benefit the natural environment has been argued for, another environment that of the social environment remains relatively underexplored.
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Food and health economics in the 21st century
PHILLIP K RUTHVEN
People are living longer and with more pain-free and comfortable lives as we begin the 21st century in 2001. Life expectancy was just 53 years (for males) in the beginning of the 20th century and is now 78 years. One in four children born in 2000 are expected to live beyond 100 years. There are many reasons for such advancement: fewer accidents, particularly work and travel related; better diets; and more and better health care. Australia's health spending is around 8.4% of gross domestic product, ranking eighth in the Organization for Economic Cooperation and Development, and has arguably one of the best value-for-money programs in the world. However, the make-up of the $50 billion expenditure in 2000 is reflecting changes from the past. We are moving away from institutional health care, embracing preventative care and 'alternative' approaches via fitness, diets, well-being programs and more natural remedies. Few, however, would suggest that pharmacology and surgery (including less invasive) are not important; they are. Food continues to play a vital role in our healthy lives. In 2000 we will expend approximately $90 billion on food and liquor prepared and consumed at home, or prepared and/or eaten out of the home. The latter is increasing as we outsource more and more of our meals (currently one in five). Our diet is changing. We are consuming more poultry, seafood, fruit and fruit products (including juices), vegetables, grain products and wine. We are consuming less red meat and meat products, eggs, oils and fats, sugars and beer. Our lifestyles are changing dramatically as we leave the Industrial Age further and further behind. The New Age began around 1965 (and should itself be displaced around 2040). Included in these changes are working wives, outsourcing of more and more household chores, embracing the Internet and electronic 'guardian angels' and much more. It promises to be an exciting, healthier and longer living new century.
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Food and consumers: Where are we heading?
ANTHONY WORSLEY
The translation of recent advances in nutrition sciences into enhanced population health and well-being depends on the development of a deeper understanding of human food consumption patterns and the factors which influence them. Food consumption patterns are dynamic and are influenced by complex, interrelated biological, social, cultural and psychological processes. These are evident in recent attempts to discriminate nutrition and health-related dietary patterns in terms of consumer lifestyles and belief systems. Consumers' pursuit of health and well-being through food consumption will be illustrated through reference to recent Australian studies. Some of the effects of societal changes associated with globalization: gender, work and family roles; materialism; information technology; and increasing longevity, on food consumption trends will be explored. Finally, the implications of these developments for the activities of health professionals, food companies and other agencies will be raised.
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What makes a functional food functional?
PETER RC HOWE
Functional foods are foods that, by nature or design, can deliver benefits beyond that of sustenance. They bridge the traditional gap between food and drugs, offering consumers greater opportunity to take their health care into their own hands. Rapidly increasing knowledge of the physiological effects of nutrients and their potential health benefits offers exciting prospects for the food industry and consumers alike. However, we must ensure that newly developed functional foods are indeed functional. The mere presence in a food of nutrients with well-publicised health attributes can infer that the food will deliver health benefits. We need to be certain that it will be efficacious for the indication specified and the nature and extent of benefit will be clearly understood by consumers. With the introduction of health claims, the onus will be on food manufacturers to provide scientific substantiation based not only on the literature related to an active nutrient, but also on intervention trials that demonstrate bioavailability and efficacy of the nutrient when delivered in a specific type of food. Such an approach, while demanding in terms of research and development investment, offers significant opportunities for product innovation. We can extend the variety of foods through which consumers may source a particular health-giving nutrient. Moreover, recognizing that a particular condition such as heart or bowel health may be influenced by more than one type of nutrient, manufacturers can design and evaluate unique foods with appropriate combinations of nutrients to optimise health status. Even though a new type of food may be shown to be efficacious in short-term, controlled clinical trials, can we be certain that consumers will derive long-term benefits free from adverse affects? Will food manufacturers undertake postmarketing surveillance or will this task be left to consumer watchdogs? The transition from traditional foods and herbal remedies of uncertain value to designer foods with guaranteed health benefits could be facilitated by adopting aspects of the pharmaceutical approach to substantiation and regulation.
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Gene technology and future foods
SIMON ROBINSON, NIGEL SCOTT, ANGELA GACKLE
Molecular biology is revolutionizing biology, agriculture and medicine. It is now possible to isolate and sequence the basic genetic material (DNA) from any organism and techniques have been developed to copy and 'cut and paste' DNA molecules to produce new combinations. This has led to the development of genetically modified (GM) plants by the targeted introduction of a small number of well-defined genes directly into the cells of an existing plant variety to improve its quality or performance. Early efforts concentrated on major field crops, such as corn, soybeans and canola. Products from these plants, such as oil and flour, are components of many processed foods, so the rapid adoption of GM commodity crops in the United States has led to widespread appearance of GM plant material in foods. The initial traits targeted, such as herbicide tolerance and pest resistance, provide improved production efficiency with benefits for agrochemical and seed producers, farmers and the environment, but little obvious benefit to consumers. The second generation of GM plants will provide consumer benefits and will extend beyond bulk commodity crops. Genetically modified plants with improved flavour, nutritional composition and shelf life are currently being developed in a range of grains, fruits and vegetables. Genetically modified plants pose no risks for human health beyond those that we readily accept in other foods. In most developed countries, GM plants undergo thorough testing and evaluation, well beyond that required for a conventionally bred new variety, and this should ensure that the current high safety and quality of foods is maintained.
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Recommended dietary intake levels for phytochemicals: Feasible or fanciful?
IVOR E DREOSTI
Phytochemicals are biologically active compounds, found in plants in small amounts, which are not established nutrients but which nevertheless seem to contribute significantly to protection against degenerative disease. At present, most interest in phytochemicals is focused on the polyphenolic flavonoids and on the carotenoids, although allium compounds, glucosinolates, indoles and coumarins have also received attention, especially with respect to cancer. Mechanistically, phytochemicals are thought to act in many ways, which include their activity as anti-oxidants, antibacterial/viral agents, phytoestrogens and as inducers or inhibitors of a variety of key enzymes. Recommended dietary intakes (RDI) are the levels of intakes of essential nutrients considered adequate to meet the known nutritional needs of practically all healthy persons. To be regarded as an essential nutrient, a dietary component must be a single identified compound or a close derivative. It should have a demonstrated key biological role and characteristic deficiency syndrome, both of which should respond to nutritional manipulation and are used as a basis for setting an RDI. In these terms, allocating RDI to phytochemicals is problematic, due in part to the large number of chemically different phytochemicals and the lack of a distinctive deficiency syndrome or inherent physiological role in almost all cases. Accordingly, allocation of a single RDI to a general class of phytochemicals would be impracticable, although for an individual phytochemical it may be feasible if acceptable justification for an RDI is extended to include optimum health and evidence is forthcoming of a key inherent role for that compound in maintaining optimum physiological function. However, a distinction will need to be drawn between phytochemicals that participate as integral components of an essential biological system and become recognized as nutrients and those that act as valuable non-nutrient health-promoting agents. Both classes of phytochemicals occur in foods and both could be incorporated into functional foods. Both could be addressed in recommendations such as dietary guidelines, but at present only established nutrient phytochemicals would be eligible for an RDI.
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Last Updated: September 2004