The effect of genetic variations on the dietary response is called Nutrigenetics. That means depending on Single Nucleotide Polymorphism or genetic variations we metabolize or absorb dietary nutrients differently.

On the other hand, nutrients and bioactive food compounds have an effect on gene expression which is called Nutrigenomics.

Nutrition research has traditionally focused on the assumption that all individuals have the same nutritional requirements, although nutrionists do recognise differing needs of children as compared with adults, and of males as compared with females. Dietary guidelines in most countries have assumed a need to prevent deficiency diseases. These are typically presented as RDAs and state the amount of a nutrient that is needed per day for most people to stay healthy. The RDA is updated periodically to reflect new knowledge, but chronic diseases related to nutrition have shown a burgeoning increase in recent years.

More recent years have seen advances in the era of nutrigenomics and nutrigenetics, whereby researchers investigated the effects of genes and gene variants on dietary requirements. It is increasingly becoming possible to bring an understanding of the genetic basis of health and disease to the achievable approach of personalised nutrition, using nutrigenetic approaches. Nutritional experts are learning to analyse information on genes and genetic variants, diet, lifestyle and environment, in order to develop nutritional strategies based on genetic makeup, typically but not exclusively in the form of SNPs and lifestyle.

Nutrigenetic knowledge helps in weigh loss and curing obesity. Arkadianos et al. developed a personalised calorie-controlled diet, using 24 variants in 19 genes that were involved in metabolism to a weight reduction programme. These authors compared weight loss and weight loss maintenance in 50 individuals who received exercise and dietary advice tailored to their genotype to optimise nutrient intake during weight loss and 43 control individuals who were given only generic diet and exercise advice. They were able to show that the group receiving personalised dietary advice not only performed better during the weight loss period, but also in weight loss retention over the following year.

Given the advances in diagnostics technologies assessing DNA damage, it has now become feasible to (a) determine dietary reference values for DNA damage prevention and to start translating into practice the Genome Health Clinic concept of DNA damage prevention. The latter is based on the recognition that damage to the genome is the most fundamental cause of developmental and degenerative diseases which can be accurately diagnosed and prevented by appropriate diet and lifestyle intervention at a genetic subgroup and personalised level.