Over-consumed, overweight and over here

A recent Access Economics report commissioned by Diabetes Australia estimated that obesity and overweight are now costing Australia a massive $21 billion a year.

The costs reflect the direct effects of obesity and overweight on the increasing rate of type 2 diabetes, cardiovascular disease, stroke, osteoarthritis and cancer. Access Economics estimated that by 2025, as many as 7.2 million Australians - 28 per cent of the population - could be clinically obese.

The complex links between diet, obesity, and ill health are the subject of intense research in affluent Western nations. Researchers are exploring the molecular pathways through which obesity wreaks havoc on the human body, but the immediate causes of the obesity epidemic are no mystery: too little exercise and an excess of kilojoules, especially from foods with high levels of unhealthy trans fatty acids, a prime cause of cardiovascular disease, a surfeit of high glycaemic-index carbohydrates and too little dietary fibre.

If people can't - or won't - change their dietary habits, a potential alternative is to modify everyday foods to make them healthier, and not just for the masses, but for the individual.

Personalised nutrition is emerging as an important complement to personalised medicine. That's the view of Shaun Coffey, former chief of CSIRO Livestock Industries and now CEO of Industrial Research, one of New Zealand's Crown Research Institutes.

Coffey says the world faces three different food-related crises: 1 billion humans are overweight, 300 million are obese, and 800 million are undernourished.

In industrialised nations, food is abundant and cheap - over the past century, agriculture has become increasingly efficient, reducing the cost of food as a component of household budgets.

"It's strange psychology that as people vote with their feet in supermarkets for cheap food, they're also demanding improved environment, social and community values, yet these aren't reflected in the prices we pay for food," Coffey says.

'Cheap food' production has many unintended and insidious effects on the economy, contributing to over-consumption, diabetes and heart disease, rural displacement, over-urbanisation, social dislocation, loss of community, soil loss, nutrient displacement, species and habitat loss, groundwater depletion and contamination, and animal stress.

Nutrigenomics seeks to understand how nutrients influence cellular and organism metabolism by modulating the activity of genes and proteins.

It's also concerned with how bioactive components of food, DNA, RNA, proteins and metabolites influence individual phenotypes. Expectations for nutrigenomics research are high and activity is frenetic, but the field lacks focus and progress is slow, Coffey says.

Nutrigenomics incorporates nutritional epigenetics and transcriptomics (how nutrition influences gene regulation and transcription patterns in tissues and organs), as well as proteomics and metabolonomics.

Coffey says epigenetic changes in the developing foetus, in response to maternal nutritional constraints, can contribute to health problems such as obesity in adulthood.

Similarly, research has shown that the failure of female rats to groom and nurture their newborn pups can cause epigenetic changes in the brain that permanently change their behaviours - the pups suffer from elevated levels of stress hormones and a reduced ability to explore their environment.

"There is a growing literature on how critical components of the environment can significantly alter the genetic potential of the animal," he says.

"But this can be turned into a positive. If we can intervene at critical points during a [livestock] animal's growth and lifecycle, we may be better able to influence the ultimate product."

Coffey says the application of nutrigenomics would change human diets, in turn changing the demand conditions for animal agriculture. Improving the performance of agriculture was a desirable goal in its own right, but would also improve the industry's prosperity.

Promising trends

Over the past 20 years, consumer demands for improved quality assurance standards for animal food products had been focused beyond the farm gate. But attention is now turning to the role of on-farm processes in quality assurance.

"The trend towards fresh and chilled food, and organic foods, also emphasises pre-farm gate processes," Coffey says. "Total supermarket purchases of food in the UK, for example, have been relatively constant for the last 10 years at $6 billion. But in the past 10 years, almost $1 billion worth of organic produce have replaced non-organic products in that purchase.

"People are starting to move away from highly processed foods. We're beginning to see calls to regulate or even tax processed food high in fats and sugar, as happened with the tobacco industry. There was a move against animal products a decade ago, but demand for animal products has continued to grow, relative to plant products. Meat and milk consumption in Asia is growing strongly."

Coffey says there is a clear trend away from consumption of saturated fatty acids around the world.

"Just as increased consumption of plant seeds and fish could reduce saturated fats in humans, the fatty acid composition of animal products is highly responsive to plant and oilseed feed supplements and raised monounsaturated and polyunsaturated fatty acid levels in meat and milk."

Researchers have tended to look simplistically at biomarkers, but their role should now be extended to encompass markers for exposure, effect and susceptibility, he says.

Multiple markers could be developed for specific applications, while transgenes or gene deletions could be used to develop healthier animal foods for human consumption.

For example, deleting the intestinal lactase gene in dairy cattle could produce low-lactose milk for lactose-intolerant individuals - lactose intolerance is common in Asian populations.

Introducing the stearoyl coA desaturase gene into pigs could modify the animal's lipid composition, improving levels of unsaturated fats, while reducing myostatin expression in sheep could increase muscle mass and leanness.

Marketing challenge

Coffey says the challenge would be to market these new products in a climate in which consumers were still wary of gene technology.

They would need to be convinced that modified animal foods would improve their health and nutrition," he says. "Understanding where public perceptions of foods come from is very important."

Concerns in the European Union and the UK about food safety and the environmental impact of new technologies could be traced to adverse publicity over Salmonella contamination of eggs in 1988; the subsequent link between 'mad cow' disease and variant Creutzfeldt Jakob disease in humans in the 1990s; and the 2001 UK epidemic of foot and mouth disease, had all profoundly affected consumer perceptions of food safety and farming practices.

A poor understanding of how new technology is transforming agriculture, and the rapid growth and diversification of the food industry, continue to cause concerns among consumers.

"We need to bring together nutrition, animal management, and genomics," Coffey says. "We'll begin to have an impact when we understand how to manage individual genotypes within a population."