Implementing food-based dietary guidelines for - United Nations ...

Human nutrition and genetic variation
Patrick J. Stover
Abstract
Human genetic variation is a determinant of nutrient
efficacy and of tolerances and intolerances and has the
potential to influence nutrient intake values (NIVs).
Knowledge derived from the comprehensive identification
of human genetic variation offers the potential to
predict the physiological and pathological consequences
of individual genetic differences and prevent and/or
manage adverse outcomes through diet. Nutrients and
genomes interact reciprocally; genomes confer differences
in nutrient utilization, whereas nutrients effectively
modify genome expression, stability, and viability.
Understanding the interactions that occur among human
genes, including all genetic variants thereof, and environmental
exposures is enabling the development of genotype-specific
nutritional regimens that prevent disease
and promote wellness for individuals and populations
throughout the life cycle. Genomic technologies may provide
new criteria for establishing NIVs. The impact of a
gene variant on NIVs will be dependent on its penetrance
and prevalence within a population. Recent experiences
indicate that few gene variants are anticipated to be sufficiently
penetrant to affect average requirement (AR)
values to a greater degree than environmental factors. If
highly penetrant gene variants are identified that affect
nutrient requirements, the prevalence of the variant in
that country or region will determine the feasibility and
necessity of deriving more than one AR or upper limit
(UL) for affected genetic subgroups.
Key words: Genome, nutrients, nutrition, polymorphism,
requirements, variation
The author is affiliated with Cornell University, Ithaca,
New York, USA.
Please direct queries to the author: Patrick J. Stover, Cornell
University, Division of Nutritional Sciences, 315 Savage
Hall, Ithaca, NY 14853, USA; e-mail: pjs13@cornell.edu.
Introduction
Knowledge derived from the comprehensive identification
of human genetic variation offers the potential
to predict, prevent, and/or manage physiological and
pathological consequences of individual genetic differences.
Genetic variation contributes to human disease
susceptibility, optimal nutritional requirements, food
tolerance, drug efficacy, inflammatory responses, longevity,
and virtually every human phenotype [1–8].
Nutrients and pharmaceuticals are two exposures that
are proven to be effective in modifying genome function
and stability for benefit, but whose utilization and
efficacy are modified by human genetic variation.
Dietary guidelines, both food- and nutrient-based,
are established to assist individuals and populations
achieve adequate dietary patterns to maintain health.
Their derivation and goals evolve continuously in
response to new knowledge [9, 10]. When possible,
guidelines for single nutrients and other food components
are scientifically and quantitatively derived,
and these numeric standards are essential to validate
the efficacy of food-based guidelines [10]. Nutrient
requirements vary within all human populations and
can be modified by age, sex, and life stage, among other
factors. Therefore, numeric standards are often derived
separately for population subgroups. It is established
that genetic variation can modify the efficacy, dosage,
and safety of pharmaceutical agents [5] and tolerance
for certain foods [11]. However, the contribution of
genetics to optimal nutrient requirements within and
among human populations remains to be evaluated
rigorously. This report focuses on advancements in our
understanding of the human genome and the emerging
application of the genome sciences to identify genetic
variation that affects optimal nutrient requirements
and food tolerance within and among populations,
understand the role of nutrients and dietary components
in modifying genome function for benefit and
the intake levels required to do so, understand both
the benefits and the risks of population-based nutrition
policies to subgroups, and develop genome-based
Food and Nutrition Bulletin, vol. 28, no. 1 (supplement) © 2007, The United Nations University. S101