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an understanding of the genetic basis of health and chronic disease, there is lack of
consideration of the interaction with environmental exposure such as to diet. There
is need for further studies on gene-diet interactions that may enable rational selec-
tion of functional foods leading to optimal health or reduced risk of chronic disease
(Ferguson 2009 ). This information would be useful for personalized nutritional
counselling.
Nutrigenetics and Personalized Medicine
Interindividual genetic variation is an important determinant of differences in nutri-
tion requirements. A common genetic polymorphism results from a CāT substitu-
tion in the gene encoding methylenetetrahydrofolate reductase (MTHFR), leads to
metabolic changes that modify risk for chronic disease and neural tube defects
when accompanied by folate defi ciency. The modulation of these metabolic abnor-
malities by increasing folate intake suggests that folate requirements may be differ-
ent in affected individuals (T/T) relative to normal (C/C) or heterozygous (C/T)
individuals.
Study of nutrigenetics may provide a way of determining responses to bioactive
food components and to evaluate these components as biomarkers for predicting
risk and tumor behavior. In 2011, the National Cancer Institute (NCI) of USA was
asking interested researchers and other parties to provide suggestions about how to
design dietary intervention trials to study nutrigenetic approaches to preventing,
treating, or making predictions about cancer. There is an increasing amount of evi-
dence that points to diet as a modifi er of cancer risk and tumor behavior, but there
are many inconsistencies in the literature. Genetic variants involved in food absorp-
tion, metabolism, and excretion could serve as biomarkers for predicting which
individuals will respond best to dietary modifi cations for preventing or treating can-
cer. Such genetic interactions could also potentially be used to predict which indi-
viduals may be at risk when consuming suboptimal diets at low, exaggerated, or
excessive intakes. NCI is interested in advanced studies in these areas, including
research into diet-sensitive genetic modifi cations that could be used as cancer inter-
vention studies, bioactive food components that warrant further study, specifi c pro-
cesses related to genes with molecular targets that are diet sensitive, and other
critical issues that are limiting this area of investigation.
Nutrigenomics and Personalized Medicine
SNPs are powerful tools for investigating the role of nutrition in human disease and
may help to defi ne optimized diets in individuals. In future it may lead to adjustment
of dietary recommendations on the basis of genotype ā personalized diet.
Nutrigenomics holds the promise to revolutionize both clinical and public health
nutrition practice by better targeted nutritional interventions (including micronutri-
ent fortifi cation) and facilitate individualized medical nutrition therapy for disease
19 Personalized Non-pharmacological Therapies