Jose M. Ordovas, a pioneer researcher in the field,
uses the following definition: ‘Nutritional genomics
covers nutrigenomics, which explores the effects of
nutrients on the genome, proteome and metabolome,
and nutrigenetics, the major goal of which is to eluci-
date the effect of genetic variation on the interaction
between diet and disease.’ The genome is the DNA
that makes up an individual’s genes. The proteome
consists of all of the proteins—the products of gene
expression—that are produced under specific condi-
tions. The metabolome is comprised of all of the
metabolites in the body under specific dietary and
physiological conditions. However many authors do
not distinguish between the terms nutritional genomics,
nutrigenomics, and nutrigenetics.Origins
The concept that diet influences health is an
ancient one. In 400 B.C. Hippocrates advised physi-
cians: ‘Leave your drugs in the chemist’s pot if you can
heal your patient with food.’ Likewise it has long been
known that individuals can differ in their requirements
for a given nutrient.
Nutrigenomics includes known interactions
between food and inherited genes, called ‘inborn errors
of metabolism,’ that have long been treated by manip-
ulating the diet:
Phenylketonuria (PKU) is caused by a change (muta-
tion) in a single gene. Affected individuals must
avoid food containing the amino acid phenylalanine.
Many Asians have a defective aldehyde dehydrogen-
ase enzyme, which is involved in ethanol metabolism.
Alcohol consumption has unpleasant effects on these
individuals.
Galactosemia—caused by an inherited defect in one
of three enzymes involved in the metabolism of thesugar galactose—is controlled with a milk-free diet,
since galactose is a metabolite or breakdown product
of lactose or milk sugar.
The majority of adults in the world are lactose intol-
erant, meaning that they cannot digest milk prod-
ucts, because the gene encoding lactase, the enzyme
that breaks down lactose, is normally ‘turned off’
after weaning. However some 10,000–12,000 years
ago a polymorphism in a single DNA nucleotide
appeared among northern Europeans. This single
nucleotide polymorphism—a SNP—resulted in the
continued expression of the lactase gene into adult-
hood. This was advantageous because people with
this SNP could utilize nutritionally-rich dairy prod-
ucts in regions with short growing seasons.
With the revolution in molecular genetics in the
late twentieth century, scientists set out to identify
other genes that interact with dietary components.
By the 1980s companies were commercializing nutri-
genomics. The Human Genome Project of the 1990s,
which sequenced all of the DNA in the human
genome, jump-started the science of nutrigenomics.
By 2007 scientists were discovering numerous interre-
lationships between genes, nutrition, and disease.DescriptionPrinciples of nutrigenomics
Nutrigenomics draws from various scientific dis-
ciplines including:
genetics
molecular biology
bioinformatics
biocomputation
physiology
pathology
nutrition
sociology
ethics.
There are five principles of nutrigenomics:
Diet can be a serious risk factor for a number of diseases
for some individuals under certain circumstances.
Substances in the diet can act on the human genome,
either directly or indirectly, to alter gene structure or
expression.
Individual genetic makeup or genotype can influence
the balance between health and disease.
Genes that are regulated by dietary factors can play a
role in the onset, incidence, progression, and/or
severity of chronic diseases.Known interactions between food and inherited genesGenetic condition Foods to avoid
Phenylketonuria (PKU)Defective aldehyde
dehydrogenase enzyme
Galactosemia (lack of a liver
enzyme to digest galactose)
Lactose intolerance (shortage
of the enzyme lactase)Food containing the amino acid
phenylalanine, including high protein
foods such as fish, chicken, eggs,
milk, cheese, dried beans, nuts, and
tofu
Alcohol
Diets which contain no lactose or
galactose, including all milk and milk
products
Milk and milk products(Illustration by GGS Information Services/Thomson Gale.)Nutrigenomics