Nutrigenomics

The 1953 discovery of the DNA double helix marked a new beginning in understanding the genetic basis of inheritance and, more recently, the Human Genome Project exponentially advanced our knowledge about genetic factors that shape a broad group of diseases. These advances facilitated the advent of genetic testing, which is currently available for over 1,200 medical conditions. The plethora of information that became available has many health-related implications and regularly receives extensive media attention, but news stories often appear with little background to help the reader understand the significance of the various concepts.

In addition to identifying a large number of genes relevant for human disease, sequencing of the human genome revealed an interesting fact: It became apparent that any two unrelated individuals are 99.9% identical at the DNA level. The remaining 0.1% represents sites of variation, also known as single nucleotide polymorphisms (SNPs). Approximately 3.1 million SNPs were identified throughout the human genome, and some estimates predict that their actual number is approximately 10 million. These sites are particularly important, as they are thought to explain why individuals respond differently to the same nutrients and environmental chemicals or why, in different individuals, very different adverse effects to the same medication are observed.

As genetic factors are linked to increasing numbers of disease predispositions and inherited traits, [Page 528]it is essential to remember that most conditions are not simply determined by our chromosomes but shaped by complex interactions between genetic and environmental influences. The environment comprises a very diverse group of factors, including nutrients, smoking, alcohol, medications, microorganisms, radiation, chemicals, and social influences, all of which affect the way we develop and impact our susceptibility to disease. In other words, our genes are not our destiny. Of the many environmental influences to which humans are invariably exposed throughout their lives, food intake is thought to exert the most influential impact on diseases.

The importance of nutritional intake for human health has been recognized throughout history and in many different societies. With recent analyses estimating that 33% of the world's adult population was overweight or obese in 2005, and that by 2030 this number could exceed 57%, the nutritional sciences are expected to increasingly emerge as a public health focus. At the convergence between nutritional science and genomics, two new fields, nutrigenetics and nutrigenomics, are being shaped; while the two terms are often used interchangeably, nutrigenetics investigates how discrete genetic variations such as SNPs affect individual responses to specific dietary compounds, while nutrigenomics focuses on understanding how food components modulate changes in the gene expression profile of an individual.