Designer Diets?

Throughout our lives, we are exposed to a complex mixture of food compounds. Intricate biochemical processes extract from food the energy and other useful components that enable us to grow and function. Many compounds, seemingly unimportant in the past, are now recognized as influencing our health. For example, lycopene from cooked tomato sauces may help prevent prostate cancer.

Everyone, indeed, knows that food can have a positive or negative impact on health. Food may never cure any particular disease, but diets rich in fruits and vegetables, cereals and plant-sourced oils offer protection from many cancers, cardiovascular disease, and other illnesses associated with old age. The problem, for scientists and consumers alike, is that the benefits are not the same for everyone.

So we need to understand how what we eat interacts with our bodies – or, more specifically, our genes – to affect our health. This is the science of nutrigenomics. The long-term aim of nutrigenomics is to define how the whole body responds to food using so called “systems biology.”

Every cell in your body (except mature red blood cells) – there are about 50 trillion in an adult – contains copies of your DNA, which are coiled up tightly to form 46 separate bundles called chromosomes. These chromosomes are stored in the core of the cell (nucleus), and there are 22 matching pairs, one of each pair from each of your biological parents, plus an X-chromosome from your mother and either an X- or Y-chromosome from your father; XX makes you a girl and XY a boy.

DNA stores information that is vital to the growth, repair, replacement, and correct functioning of our cells. It consists of two strings – formed from phosphate and sugar – along which four unique chemical compounds (DNA bases) are attached. There are about three billion bases, and the sequences in which they occur is our genetic code, or human genome.

Within the genetic code, there are 30,000-40,000 highly organized regions called genes. Genes are the basic unit of heredity, and, unless you are an identical twin, the combination of genes inherited from your parents is unique to you. The genes that you have make up your genotype. The resulting product, for example eye color, is your phenotype.

Genotyping can be used to determine which genes you have, but it cannot always predict your phenotype. The inheritance of some characteristics, including eye color, is simple. The majority of phenotypes are, however, the product of complex multi-gene interaction, environment, and lifestyle choices. This includes our risk of developing a host of age-related diseases.

Genes code for proteins, the body’s workers, which are not made directly from DNA, because they do not speak the same language. Ribonucleic acid (RNA) acts as an interpreter in a process called transcription (the reading of genes). Translation from RNA creates three-dimensional proteins from combinations of 22 essential amino acids – essential only because our bodies are not able to make them, so they must be obtained from our diet instead. The proteins that are produced, their quantities, and their characteristics collectively form the proteome, and their activities, in combination or in response to signals from within the body or external to it, form our metabolism.

Such is the complexity of nutrigenomics that it is no longer possible for nutritional researchers to work alone. Expertise in a wide variety of different areas – molecular and cell biology, mathematics and statistics, nutrition and diet, food chemistry, and social science – is fundamental to progress.

To this end, 22 leading groups have united to create The European Nutrigenomics Organization, or NuGO. Funded by the European Commission, NuGO gives scientists from organizations that usually compete for funding and the best researchers their first real opportunity to work together. Difficulties stemming from professional jargon, organizational structure, and distance are more than offset by the benefits of integrating nutrigenomics facilities and expertise to ensure cooperative use of knowledge and its application in nutritional research.

Nutrigenomics is not the Holy Grail of nutrition, but neither is it irrelevant to all but the worried-but-wealthy few that will be able to afford the new food products when they arrive. Determining the structure of DNA and the sequence of the human genome has revolutionized biology and medicine. It has created new specialties and advanced our understanding of disease. But rarely does this knowledge allow us to control outcomes – prevention rather than cure. Indeed, in the twenty-first century, we still cannot describe health except in terms of the absence of disease.

Today’s new technologies enable health to be identified in terms of patterns of gene expression, protein production, and metabolic response. Applied to nutrition, nutrigenomics will allow us to understand, and perhaps more importantly, to manipulate our individual response to existing foods so as to benefit our health.

For some people, this will mean expensive genetic testing and designer diets, but for most, it will mean realistic advice based on visibly demonstrable phenotypes – a tendency to gain weight, for example, or an intolerance or allergic response to certain food types. Above all, nutrigenomics holds out the promise of providing the healthy independence that everyone hopes for in later years.