Australasian Science: Australia's authority on science since 1938

Facts and Furphies about Functional Foods

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Products can have just a smidgen of a supplement and companies may still market the food as if the bioactive is the major ingredient.

By Manohar Garg

Bioactive ingredients are not magic bullets to fight against chronic diseases but have the potential to alleviate human ailments if their efficacy, bioavailability, appropriate dosage levels and safety in humans can be validated.

The rise of non-infectious diseases has been linked to poor or unbalanced dietary intakes. Health authorities and regulatory bodies all over the world are formulating, evaluating and implementing policies to promote healthy eating with the ultimate goal of attenuating or preventing the rapidly increasing incidence of diet-related diseases.

Functional foods fortified with physiologically active food components have potential benefits beyond basic nutrition in the prevention and treatment of chronic conditions. When consumed in sufficient quantities on a regular basis, functional foods aid in decreasing the disease risk via several mechanisms: lowering blood lipid levels, improving arterial compliance, reducing low-density lipoprotein oxidation, reducing inflammation, decreasing plaque formation, scavenging free radicals, inhibiting platelet aggregation and influencing gene expression.

Many plant-based foods contain bioactive compounds that can have specific functions within our bodies that maintain health or prevent disease. Dietary supplements, functional foods and fortified beverages with bioactive ingredients or components have the potential for use in the prevention and treatment of chronic disease.

Research to examine how bioactive compounds could help to keep us healthy has escalated in recent years. To date, emphasis has been placed on developing a greater understanding of how these bioactive compounds work, how they are taken up by the body and how they modify metabolic processes.

However, the crucial evidence regarding long-term safety and efficacy, optimal dose and delivery methods essential to substantiate health claims on bioactive compounds is lacking. With the human genome now sequenced and the emergence of micro-array techniques to unravel how bioactive compounds influence gene expression, it will be possible to offer functional foods or bioactive-rich dietary supplements for the prevention and treatment of chronic diseases.

While some parts of the world continue to suffer from malnutrition due to a deficiency of essential nutrients, modern lifestyle changes including increased consumption of energy-rich processed foods and lack of physical activity have resulted in an astounding rise in the incidence of non-communicable diseases such as Type 2 diabetes, cardiovascular disease, specific types of cancer and inflammation-mediated diseases.

Once considered a problem limited to Western countries, diet- and lifestyle-related non-communicable diseases have become more prevalent in economically developing countries including India and China. For example, India has the highest number of people with Type 2 diabetes of any country, with a considerably earlier onset than Western countries. Enhancing the nutritional quality of foods by fortifying commonly consumed foods items, such as breads, cereals and beverages, with bioactive compounds or even dietary supplementation with bioactives are potentially useful options to tackle the global health burden of nutrient insufficiencies and diet-related non-communicable diseases.

For example, developments in biotechnology have led to significant health benefits for children in parts of Africa through the production of orange-fleshed sweet potatoes and the introduction of yellow rice that provide rich sources of β-carotene, the precursor for vitamin A. Genetic manipulation of oil seeds has resulted in the development of plant oils that are rich in eicosapentaenoic and docosahexaenoic acids that were otherwise of marine origin only. Omega-3 polyunsaturated fatty acids exclusively of algal origin have also appeared in pharmacies and health food stores. Resveratrol, which gives red wine many of its health benefits, has been chemically synthesised and marketed by DSM as resVida®.

By contrast, it is more challenging to identify bioactives whose presence in fresh foods and fortification in processed foods could significantly reduce the burden of chronic disease. For a functional food to be effective it has to be consumed regularly as part of a healthy diet and the bioactive ingredients must be added to the food in a matrix that facilitates its absorption without affecting the shelf life of the product.

The appearance of functional foods in the supermarket shelves has been facilitated by advances in food technology that allow the incorporation of the active constituents in more than one food. Micro-emulsification and nanotechnology have allowed food manufacturers to incorporate otherwise unpalatable ingredients, such as marine omega-3 fatty acids, into foods with added protection against oxidative damage.

Like many other countries in the world, Australia has an ageing population with people aged 65 years and over representing a growing percentage of society. The health consequences of ageing include an increased prevalence of chronic diseases and a widening gap between the cost of health care and GDP. Therefore evidence-based, affordable strategies for health optimisation, disease prevention and early intervention are highly desirable.

Although health claims for functional foods and dietary supplements range from the eccentric to the magnificent, most of these claims are based on cell culture studies and have not been validated in human clinical trials. Therefore it is premature to make public health recommendations. Some foods have been successful in trials and approved by the US Food and Drug Administration, but many others still lack clinical proof.

Advertising agencies are jumping all over the concept because no matter what their product they can fortify it with something to make it more marketable and appear healthy. On the negative side there aren’t a lot of regulations for companies when it comes to advertising this new concept. Products can have just a smidgen of a supplement and companies may still market the food as if the bioactive is the major ingredient.

Following international trends, Australia’s food industry has expressed increasing interest in value-added functional foods and beverages. After 20 years of planning, the Food Standards Code for Australia and New Zealand has introduced a new health claims policy that will further stimulate interest in functional foods. Concurrently, Australia’s vitamin and supplement industry is also rapidly expanding due to increasing consumer demand. Historically the Therapeutic Goods Administration has been reluctant to deal with advertising, but is beginning to alter its policy for listed medicines, requiring stringent levels of evidence of efficacy for health indications for these products.

Bioactive food ingredients and components hold significant promise in alleviating the from disease. For this potential to be fulfilled, much more research is needed to document efficacy, bioavailability, appropriate dose levels and safety in humans.

The demand for functional foods will continue to grow as scientists, driven by consumer demand, continue to search for a disease-free life through diet. Scientifically sound clinical trials with functional foods, not just looking at indicators of heart health but with other health end points, are urgently warranted in order to receive endorsement from medical professionals. Substantial budget commitments from government bodies and food manufacturers, as is the case for pharmaceutical companies in drug research, are essential to evaluate the safety and efficacy of functional foods and ingredients.

It would not be prudent to think of functional foods and ingredients as “magic bullets” against disease, but it would also be highly risky to ignore the evidence that poor dietary habits are increasing the risk of some chronic diseases. Functional foods and ingredients hold promise for disease prevention but they are less likely to be beneficial in the treatment of chronic conditions. More research is needed.

Professor Manohar Garg is the Director of the Nutraceuticals Research Unit and Co-Director of the newly formed Clinical Nutrition Research Centre at the University of Newcastle.