Charlotte Martin: Change your diet to fit your jeans and genes

By Charlotte Martin

NZ Herald·

24 Apr, 2013 05:30 PM3 mins to read

Genetic variations can affect gene function, altering the way nutrients are metabolised. Photo / Getty Images

Nutrigenomic research ultimately aims to unravel the interactions between nutrients and genes. The father of Western medicine Hippocrates famously said: "Let food be thy medicine and medicine be thy food", arguing that disease was not a punishment from the gods, but the consequence of a poor diet.

Today, we know that lifestyle and environment interact with diet to affect our health. And we are increasingly recognising particular nutrients at key phases in our lives are not only essential to metabolism, but are also required in defined amounts if we are to reduce the risk of early and late-life diseases.

This approach, called personalised nutrition, results from genome sequencing and has provided a new perspective on nutritional advice by helping us understand the unique nutritional requirements of each individual. My area of research is called nutritional genetics, a component of the "omics" field known as nutrigenomics. Simply, this area analyses genetic variations found in human DNA called single nucleotide polymorphisms (SNPs). Almost all (99.9 per cent) of human DNA is the same and SNPs represent the remaining 0.01 per cent.

These SNPs are the most common type of genetic variation and account for approximately 10 million in the human genome.

Scientists working in the area of nutritional genetics look at how these genetic variations affect the body's interaction with nutrients.

The underlying basis of this is what we typically call a "gene-nutrient interaction".

The variations can affect gene function, altering the way nutrients are metabolised. This can have a detrimental effect on the body, influencing human phenotype - the observable, physical characteristic of a person. Changes to phenotype may be related to human behaviour, physiological characteristics or vulnerability to disease.

One example of gene-nutrient interaction can be found in cases of vitamin deficiencies. A vitamin deficiency can be caused by either insufficient intake, or by the body's ability to metabolise it because of a genetic variation - via the action of an SNP.

Nutritional requirements vary between individuals and at different stages of life. Certain micronutrients (vitamins and minerals) are important during early growth and development. Later in life, adequate nutrition is required to reduce the risk of chronic degenerative disorders.

Nutrigenomic research ultimately aims to unravel the interactions between nutrients and genes, to provide a more thorough understanding of their impact on human health. The idea behind personalised nutrition is that individuals vary in their nutrient metabolism and response to diet. So, the same diet followed by one person may result in good health and quality of life, but may cause ill health in another. This difference is likely due to genetic variations, which means we can design interventions to overcome genetic disease risk.