Food science and technology bulletin : functional foods. Vol. 3

98 Pages·2007·1.164 MB·98\98

by  Glenn R Gibson

Food Science and Technology Bulletin
Functional Foods
Volume 3
CHIEF EDITOR Professor Glenn R Gibson
University of Reading
Reading,UK
EDITORIAL ADVISORY BOARD
Dr Eric Decker
University of Massachusetts
Amherst,USA
Dr Edward Farnworth
Food Research and Development Centre
St.Hyacinthe,Canada
Dr Clare Hasler
Robert Mondavi Institute for Wine and Food Science
University of California,Davis,USA
Dr David P Richardson
dprnutrition
Croydon,UK
Dr Colette Shortt
McNeil Nutritionals
London,UK
Dr Tiina Mattila-Sandholm
Valio Ltd,Finland
Food Science and Technology Bulletin: Functional Foods comprises a minimum of eight minireviews per
year. It is published as an annual review journal by IFIS Publishing, Lane End House, Shinfield Road,
Shinfield, Reading RG2 9BB, UK. Tel. [phone]. Fax [phone]. Email [email protected].
Web: www.foodsciencecentral.com.
Charity registration no. 1068176.
ISSN 1476-2137
ISBN 978-0-86014-172-3
Copyright © 2007 IFIS Publishing. All rights reserved. No part of this publication may be reproduced,
stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical,
photocopying, recording or otherwise, without the prior permission of the copyright owner.
The information contained herein, including any expression of opinion and any projection or forecast, has
been obtained from or is based upon sources believed by IFIS Publishing to be reliable, but is not
guaranteed as to accuracy or completeness. The information is supplied without obligation and on the
understanding that any person who acts upon it or otherwise changes his/her position in reliance thereon
does so entirely at his/her own risk.
Purchase and subscription options
TheFood Science and Technology Bulletin: Functional Foods is available to purchase as:
Individual minireviews
Minireviews may be purchased and downloaded individually from IFIS Publishing’s website
(www.foodsciencecentral.com/home/bulletin-ff) or from Atypon Link (www.atypon-
link.com/IFIS/loi/fstb). An individual purchase gives unlimited access (by user name and password) to
minireviews for one month. Individual minireviews cost US$41/£23/€33 each, plus VAT.
Annual subscriptions
An annual subscription provides unlimited access to all the published minireviews for one year, in addition
to all previously published titles. Annual subscriptions for organizations cost US$289/£168/€246, plus
VAT. Terms and conditions apply.
Annual subscriptions for personal use are sold with a 66% discount - US$98/£56/€81, plus VAT.
Food Science Central® and FSTA – Food Science and Technology Abstracts® are registered trade marks
within Europe and the USA.
Volume 3
Contents
1 Nutrigenomics – new frontiers in antioxidant research 1
Jan Frank, Sonia de Pascual Teresa and Gerald Rimbach
2 Dietary fat composition and cardiovascular disease 13
Anne M. Minihane
3 Phytochemicals – a future in functional foods? 23
Toni E. Steer
4 Inulin: a prebiotic functional food ingredient 31
Duncan T. Brown and Kieran M. Tuohy
5 SPECIAL PAPER 47
Probiotics – the consumer perspective
Liisa Lähteenmäki and Aat M. Ledeboer
6 Assessment of the efficacy of probiotics, prebiotics and synbiotics in swine nutrition: 51
a review
Konstantinos C. Mountzouris
7 Lactitol, an emerging prebiotic: functional properties with a focus on digestive health 73
Alexandra Drakoularakou, Oliver Hasselwander, Melanie Edinburgh and Arthur C. Ouwehand
8 Guidelines for an evidence-based review system for the scientific justification of diet and 83
health relationships under Article 13 of the new European legislation on nutrition and health
claims
David P. Richardson, Nino M. Binns and Penelope Viner
Nutrigenomics – new frontiers in antioxidant research
Jan Frank1, Sonia de Pascual Teresa2 and Gerald Rimbach1*
1Christian-Albrechts-University, Institute of Human Nutrition and Food Science, Hermann-Rodewald-Str. 6, 24118 Kiel,
Germany. Tel. þ49 (0)431-880 2583. Fax þ49 (0)431-880 2628. E-mail [email protected]
2Department of Plant Food Science and Technology, Instituto del Frı´o (CSIC), Jose Antonio Novais, 10, 28040 Madrid,
Spain.
*Corresponding author
Abstract
The field of nutrition research evolved over the last two and a half centuries from studying the basics of
nutritional physiology(e.g.nutrient digestion) toa highlyadvanceddisciplineemploying state-of-the-art tech-
niques to elucidate the role of dietary compounds in the maintenance of health and prevention of disease. In
this context, nutrigenomics is a rapidly growing field making use of molecular biology methodologies, such
as microarray technology, to study how specific nutrients or diets affect gene expression. The mode of opera-
tionofDNAmicroarraytechnologyand itsapplicationsinantioxidantresearchare discussed,andrecentpub-
lications reporting the use of DNA microarrays to investigate various aspects of the biological activities of
oxidants andantioxidants are reviewed.
Keywords: antioxidants, ascorbic acid, gene array, genomics, metabolomics, nutrigenetics, nutrigenomics,
oxidants,oxidative stress, proteomics, tocopherol,transcriptomics
1. Introduction in 2001 (McPherson et al. 2001; Venter et al. 2001) fol-
lowed shortly afterwards by the sequencing of the mouse
The dawn of the discipline of nutrition research falls
(Okazaki et al. 2002; Waterston et al. 2002) and rat geno-
around the time of the ‘chemical revolution’ at the end of
mes (Gibbs et al. 2004). Now, at the advent of the post-
the 18th century. Pioneering work was performed with the
genomic era, nutrition research has been given powerful
simple scientific tools available at that time to describe
tools to study the complex interplay of diet and/or specific
macronutrients, energy production and respiration. In the
nutrients with the genetic makeup and health of indivi-
course of the 19th century the connections between poor
duals, as well as entire populations.
nutrition and certain disorders, such as scurvy and goitre,
started to become apparent, but remained, nevertheless, a
matter of dispute among the members of the medical 2. Defining the ‘-omics’
society (Carpenter 2003a). Shortly after the turn of the
Rapid advancement in the development of high-through-
20th century the ‘golden age of nutrition’ commenced, and
put, molecular biology techniques and their frequent appli-
this lasted well into the 1940s. During this period most
cation in system-wide experimental approaches have led
essential nutrients (and almost all vitamins) were discover-
to a noticeable propagation of the so-called ‘-omics’ (e.g.
ed andnutritionists focused on studying diseases associated
genomics,transcriptomics,proteomics,metabolomics,etc.).
with the deficiency of a single nutrient (Carpenter 2003b).
Nutritionists are now making increasing use of these state-
During the following decades the focus of nutrition re-
of-the-art technologies in order to study the molecular
search shifted from nutritional deficiency to over-nutrition,
basis of the health effects of specific components of the
and scientists started to unravel the complex relationships
diet. The term ‘nutrigenomics’ – short for nutritional
between diet and the development of multi-factorial
genomics–referstothestudyoftheimpactofspecificnutri-
chronic diseases (Carpenter 2003c). Subsequently, the
entsordietsongeneexpression.Itisnottobeconfusedwith
revolutionary progress in recombinant DNA technology
‘nutrigenetics’, which investigates how genetic variability
culminated in the sequencing of the entire human genome
influences the body’s response to a nutrient or diet. Hence,
nutrigenomics and nutrigenetics are closely related dis-
FoodScienceandTechnologyBulletin:FunctionalFoods3(1)1–12
ciplines but approach the interplay of diet and genes
DOI:10.1616/1476-2137.14276.Published27February2006
ISSN1476-2137#IFISPublishing2006.AllRightsReserved from opposing starting points. Nutrigenomics is an up and
2 Nutrigenomics–newfrontiersinantioxidantresearchJ.Franketal.
coming discipline that makes use of high-throughput, 3. The eukaryotic gene transcription machinery
molecular biology techniques such as transcriptomics, pro-
The genome of eukaryotic organisms is packaged in the
teomicsand metabolomics (Figure 1). The term ‘genomics’
cell nucleus where it is arranged in chromosomes, which,
refers to the study of all nucleotide sequences in the chro-
in turn, are built from a single DNA macromolecule. The
mosomes – the ‘genome’ – of an organism. It can be
genetic information stored in the chromosomes serves as a
divided further into ‘structural genomics’ (DNA sequence
‘construction plan’ for important biomolecules, more pre-
analysis and mapping of the genome of an organism) and
cisely, polypeptides and proteins. The amino acid sequence
‘functional genomics’ (system-wide experimental appro-
of a given protein is encoded in the sequence of nucleo-
aches to study gene function). The term ‘transcriptomics’
tides on the DNA of the gene coding for that protein.
is used to describe methods that measure the relative
Each of the 20 proteinogenic amino acids is coded for by
amounts of messenger RNA (mRNA) in order to deter-
a sequence of 3 nucleotides, a phenomenon that is highly
mine patterns and levels of gene expression, and their reg-
conserved among species (i.e. the same sequence of 3
ulation. ‘Proteomics’ is the study of the expression of the
nucleotides codes for the identical amino acid in almost
complete set of proteins expressed in a cell, tissue, or
all species) and is referred to as the (universal) ‘genetic
organism and, accordingly, ‘metabolomics’ investigates
code’. Since the genetic information is stored in the cell
the profile and functions of all metabolites generated in a
nucleus while proteins are synthesized on ribosomes in the
simple (e.g. cell) or complex (e.g. entire-organ or organ-
cytoplasm, this information needs to be transferred to
ism) system. Some scientists distinguish between these 2
smaller molecules (messenger RNA; mRNA) that serve as
approaches and refer to the study of metabolite formation
templates for the synthesis of proteins. The process of
in a simple system as ‘metabolomics’ and in a complex
synthesis of single-stranded RNA from the double-
system as ‘metabonomics’. The vast amount of data gener-
stranded DNA macromolecule is called ‘transcription’ and
ated with such system-wide approaches requires the appli-
is facilitated by specific enzymes, namely RNA polymer-
cation of advanced bioinformatics tools in order to manage
ases. Following export from the nucleus mRNA becomes
comprehensive data handling.
associated with ribosomes – supramolecular enzyme com-
The first book about nutrigenomics has recently been
plexes that catalyse the assembly of polypeptides – within
published, covering a wide variety of aspects relating to
the cytoplasm. The process of protein synthesis from an
the effects of oxidants and antioxidants on gene expression
mRNA template is called ‘translation’. Following synth-
and their role in health and disease. For further informa-
esis, proteins undergo a range of post-translational modifi-
tion on nutrigenomics the interested reader is referred to
cations in order to become fully functional proteins. Such
this comprehensive book (Rimbach et al. 2005) and the
modifications may include one or more of the following:
excellent reviews that have been published on this subject
cutting of the polypeptide by specific enzymes, addition of
(e.g. Elliott and Ong 2002; van Ommen and Stierum
functionalgroups(e.g.phosphate,methyl,oracetategroups),
2002; Ordovas and Mooser 2004; Muller and Kersten
formation of disulfide bridges, etc. Thus, the flow of
2003).
genetic information goes from DNA via RNA to protein
(see biochemistry textbooks for details, e.g. Stryer 1995).
4. Methods and applications of nutrigenomics
For a long time, the expression of individual genes has
been determined by quantification of RNA with Northern
blotting. This classical approach has been replaced by
more sensitive techniques such as real-time reverse tran-
scription PCR (real-time RT-PCR). Both techniques, how-
ever, can only analyse gene expression for a limited num-
ber of candidate genes at a time. The development of
DNA microarray technology has rendered it possible to
determine the expression of thousands of genes, or even
entire genomes, simultaneously. The operating principle of
DNA microarrays relies on the base pairing of oligonu-
cleotides within a sample with known immobilized oligo-
nucleotides, on a support material (e.g. glass slides). The
use of representative oligonucleotides rather than the entire
Figure 1. Transcriptomics, proteomics, and metabolomics nucleotide sequence of a given gene allows for a higher
as analytical tools in nutrition research. density (larger number) of probes and a smaller overall
Nutrigenomics–newfrontiersinantioxidantresearchJ.Franketal. 3
size of the microarray. A typical DNA microarray experi- tion of these 2 approaches guarantees microarrays that
ment follows a characteristic series of steps: produce data of very high quality.
Since it is beyond the scope of this paper to describe in
(cid:2) RNA extraction from a sample detail all the available variants of microarray technology,
(cid:2) Reverse transcription of the RNA in order to obtain the interested reader is referred to the comprehensive book
complementary DNA (cDNA) followed by: edited by Schena (1999), who has been a pioneer in the
* Labelling of the cDNA with specific dye(s) development of DNA microarray technology, and to the
(usuallyfluorophores,suchasCyanine3and5),or excellent reviews of Elliott et al. (2004), Liu-Stratton
* Reverse transcription of the cDNA in order to et al. (2004), and Spielbauer and Stahl (2005) for a more
obtain cRNA and labelling of the cRNA detailed description of microarray technology and its
(cid:2) Hybridization of the labelled cDNA or cRNA onto
numerous applications in nutrition and food research.
the microarray under defined conditions (e.g. time,
A single microarray experiment results in an enormous
temperature, etc.)
amount of gene expression data, which should be scruti-
(cid:2) Washing of the slides to remove non-hybridized
nized for evidently flawed results. The remaining data
labelled oligonucleotides
points need to be normalized (e.g. for background signal,
(cid:2) Signal detection (e.g. using an appropriate scanning
dye intensity, array-to-array variations, etc.) before com-
device)
parative analyses of the obtained data can be accom-
(cid:2) Data analysis (Figure 2).
plished. The huge number of data points generated during
microarray experiments also requires careful selection and
Modifications of this general approach were adopted by
1 application of mathematical and statistical procedures in
Affymetrix during the development of their GeneChip
1 order to detect changes in gene expression. Indeed, data
arrays. On Affymetrix GeneChip arrays, several different
processing with sophisticated bioinformatics tools and the
oligonucleotideprobesarephotolitographicallyspottedonto
identification of (truly and not arbitrarily) differentially
quartz wafers for each gene. Furthermore, for each nucleo-
expressed genes in response to a specific nutrient or diet
tide sequence (probe) designed to match a specific target
certainly pose the greatest challenges in the application of
sequence, a second, almost identical probe is synthesized,
microarray technology in the field of nutrigenomics.
which differs in only one base in the centre of the nucleo-
Because of the complexity of the data generated and the
tide sequence. This allows the quantification and subtrac-
plethora of factors that may affect the outcome of micro-
tion of non-specific cross-hybridization, and the combina-
array experiments (such as differences in experimental
design (e.g. treatment), RNA extraction protocols, hybridi-
zation conditions, or normalization procedures, to name a
few) a grass-rootsmovement, the Microarray Gene Expres-
sion Database Society (MGED), has established itself in
an attempt to develop standards for data handling (Brazma
et al. 2001). An additional problem with microarray
experiments that makes the comparison of gene expression
data generated in different laboratories difficult, is the out-
put of the data in a number of different formats and units.
DNA microarrays are a comparatively new tool for the
quantification of gene expression. Hence, there has been a
lackofstandardstofollowforobtainingmeaningfulpresen-
tationofdata.Suchstandardizationwouldallowmicroarray
data to be easily interpreted, experiments to be reproduced,
and would assist in the establishment of gene expression
databases.Inanefforttocreatesuchguidelines,theMGED
group has formulated the ‘minimum information about a
microarray experiment (MIAME)’ that should be recorded
and reported when referring to microarray data (Brazma
etal.2001).TheMGEDconsortiumidentified6crucialparts
ofamicroarrayexperimentthatshouldbecarefullydescribed
usingcontrolledvocabularies:
Figure 2. Schematic representation of the analytical steps (cid:2) Experimental design
involved in a gene chip experiment. (cid:2) Array design
4 Nutrigenomics–newfrontiersinantioxidantresearchJ.Franketal.
Minimum information about a microarray experiment
Part 1: Experimental design. Description of the experiment, contact details of the
author/submitter, title. Information given in this section should enable the user to
reconstruct the experimental design.
Part 2: Array design. Systematic description of all arrays used in the experiment,
includingthephysicaldesignandthegenesrepresented.Detailedspecificationof(1)array
as a whole (e.g. support material); (2) each type of element or spot (e.g. synthesized
oligonucleotides); and (3) properties of each element (e.g. DNA sequence).
Part3:Samples.Descriptionofthelabellednucleicacidsusedforhybridization.Detailed
information on source of sample (such as organism or cell type), treatment(s) applied, as
well as extraction and labelling of the nucleic acids.
Part 4: Hybridization. Description of hybridization procedure (hybridization solution,
blocking agent, washing procedure, quantity of labelled target used, hybridization time,
volume, temperature, apparatus).
Part 5: Measurements. Descriptionoftheexperimentalresultsbyprovidingimagesof
theoriginalarrayscans,thequantificationmatricesbasedonimageanalysis,andthefinal
geneexpressionmatrixafternormalization.Thereportedinformationshouldfacilitatethe
comprehension of the image analysis performed and the underlying methodology (e.g.
calculations).
Part 6: Normalization controls. Specification of normalization strategy (e.g.
housekeepinggenes),normalizationandqualitycontrolalgorithms,identitiesandlocation
of the array elements used as controls, and hybridization extract preparation.
Source: Brazma et al. 2001
(cid:2) Samples 2 different forms (natural and synthetic) of vitamin E that
(cid:2) Hybridization are frequently employed as ingredients in vitamin E and
(cid:2) Measurements multi-vitamin supplements. As a model system, HepG2
(cid:2) Normalization controls (see Textbox; Brazma et al.
cells were used and supplemented with increasing concen-
2001).
trations (0–300 mM) of natural-source RRR-a-tocopherol
and synthetic all rac-a-tocopherol for 7 days. Genes that
The innovative tools of nutrigenomics, especially gene were dose-dependently up- or down-regulated were identi-
arraytechnology,maybeusedtodevelopnovelapproaches fied by global gene expression profiling. Analysis of the
for the study of the biological functions of oxidants and microarray data revealed that both forms of the vitamin
antioxidants. DNA microarrays, for example, allow the induced or repressed an identical set of 215 genes. The
genome-wide scanning for effects of nutrients without the authors recorded the concentrations of RRR- and all
necessity to limit one’s attention to one or more specific rac-a-tocopherol in the cell media that were necessary to
target gene(s), thus reducingthe risk of failure to recognize produce a 50% induction (EC ) or 50% inhibition (IC )
50 50
a biological effect. Therefore, nutrigenomics may help in of gene expression. They then calculated a biopotency
clarifying the molecular functions of oxidants and antioxi- ratio for each of the 215 genes by dividing the EC and
50
dants. Nutrigenomics may also serve to characterize the IC values for RRR-a-tocopherol by those for all rac-a-
50
toxicity of dietary compounds or to identify and establish tocopherol.Themeanvalueobtainedforall215biopotency
new biomarkers. One example could be the development ratios was 1.05, which led the authors to conclude that
of reliable biomarkers for oxidative stress, which is an as there appears to be no difference in the gene-regulatory
yet unresolved task. Another novel application of microar- activity of natural-source RRR-a-tocopherol and that of its
ray technology could be the study of the bioavailability syntheticanalogueallrac-a-tocopherol(Mulleretal.2005).
and/or bioactivity/biopotency of nutrients. In this context, This study shows that gene microarray technology can be
Muller and co-workers (2005) have recently reported successfully employed to determine and compare the bio-
1
the use of Affymetrix GeneChip technology to assess logical activities and potencies of antioxidants and other
the biopotency, based on their gene-regulatory activity, of nutrients. As can be derived from the above, the potential
Nutrigenomics–newfrontiersinantioxidantresearchJ.Franketal. 5
applications of nutrigenomics and particularly transcrip-
tomics in the field of antioxidant and free radical research
are manifold.
5. How do oxidants and antioxidants affect
gene expression?
The application of molecular and cell biology in nutrition
research has enhanced our understanding of how antioxi-
dants exert their biological functions. By altering the
activity of transcription factors, oxidants and antioxidants
may markedly alter mRNA and protein concentrations.
Another mechanism by which they may affect gene ex-
pression is by binding to cell receptors (e.g. isoflavones
(phyto-oestrogens) bind to oestrogen receptors alpha and
beta) and altering the activity of key enzymes such as
Figure 3. Cell receptors, cellular key enzymes, and tran-
phosphatases and kinases (Figure 3).
scription factors as molecular targets of oxidants and anti-
Vitamin E, the major lipophilic antioxidant in the body
oxidants.
(Burton et al. 1982), is a good example of an antioxidant
whose role in gene expression is currently being unra-
velled. Vitamin E is a generic term for 8 structurally was also shown to modulate the gene expression of seve-
related compounds, namely a-, b-, g-, and d-tocopherols ral proteins at the transcriptional level. For example, the
and -tocotrienols, consisting of a chroman head substituted mRNA levels of the following proteins were shown to be
with a saturated (tocopherols) or unsaturated (tocotrienols) up-regulated by vitamin E: a-tocopherol transfer protein
16-carbon side-chain (Kamal-Eldin and Appelqvist 1996). (Fechner et al. 1998), protein kinase C (Azzi et al. 1998),
Vitamin E was initially recognized as an essential nutrient a-tropomyosin (Aratri et al. 1999), cytochrome P 3A4
450
for successful reproduction of rats (Evans and Bishop and3A5(Landesetal.2003),andconnectivetissuegrowth
1922). Some decades later its antioxidant properties were factor (Villacorta et al. 2003). Conversely, the mRNA
discovered (Dam 1952) and, for a long time, thought to be levels for interleukin-1 (Akeson et al. 1991), collagenase
the prime function of the vitamin. In 1991, however, Bos- (Chojkier et al. 1998), and scavenger receptor-A (Teupser
coboinik and co-workers were the first to report biological et al. 1999) were down-regulated. Recently, a vitamin E-
activitiesofa-tocopherolthatwerenotrelatedtoitsantiox- dependent transcription factor, tocopherol associated pro-
idant capacity. In particular, they described the inhibition tein (TAP), has been described which specifically binds
of protein kinase C in smooth muscle cells by a-tocopherol a-tocopherol but not the other vitamin E isoforms. Upon
as the first evidence of a role for vitamin E in cellular sig- binding of a-tocopherol, TAP, which is also known under
nalling (Boscoboinik et al. 1991). Subsequently, vitamin E the name of ‘supernatant protein factor’, translocates from
Table 1. Studies on the effects of oxidative stressors on differential gene expression in cultured cells, laboratory
animals and humans
Oxidant Cell/Tissue Species Number ofgenes Reference
monitored
Cigarette smoke Swiss3T3 Mouse 513 (Bosioetal.2002)
Hydrogenperoxide Breast cancer cells Human 17000 (Chuang etal.2002)
Menadione
t-Butylhydroperoxide
Hydrogenperoxide Retinal pigmentepithelium cells Human 1176 (Weigel etal.2003)
4-Hydroxynonenal
t-Butylhydroperoxide
Oxidized LDL Aortic smoothmuscle cells Human 35932 (Sukhanov etal.2003)
Oxidized LDL Endothelial cells Human 588 (Virgilietal.2003)
Ozone Lung Mouse 4000 (Gohil etal. 2003)
UVB radiation Keratinocytes Human 6000 (Sesto etal.2002)
6 Nutrigenomics–newfrontiersinantioxidantresearchJ.Franketal.
Table 2. Studies on the effects of antioxidants on differential gene expression in cultured cells, laboratory animals
and humans
Antioxidant Cell/Tissue Species Numberof genes Reference
monitored
Ascorbicacid Keratinocytes Human 588 (Catani etal. 2002)
Ascorbicacid Monocytes Human 256 (Majewicz etal. 2005)
CoenzymeQ10 Skeletal muscle Human 12000 (Linnane etal. 2002)
Copper Macrophages Human 6800 (Svensson etal. 2003)
Epigallocatechin-3-gallate Cervical cancer cells Human 384 (Ahn etal.2003)
Epigallocatechin-3-gallate Lungcancer cells Human 588 (Fujiki etal. 2001)
Epigallocatechin-3-gallate Lungcancer cells Human 588 (Okabe etal. 2001)
Epigallocatechin-3-gallate Prostatecarcinoma cells Human 250 (Wang andMukhtar 2002)
Epigallocatechin-3-gallate Neuroblastoma cells Human 25 (Weinreb etal. 2003)
Melatonin
Ginkgobiloba Brain Rat 8000 (Li etal.2003a)
Ginkgobiloba Brain Mouse 7000 (Watanabe etal.2001)
Genistein Prostatecancer cells Human 557 (Suzuki etal.2002)
Indole-3-carbinol Prostatecancer cells Human 22215 (Li etal.2003c)
Lycopene Prostate Rat 7000 (Siler etal.2004)
VitaminE
Melatonin Retina Rat 24000 (Wiechmann 2002)
Methylseleninic acid Premalignantbreast cells Human 316 (Dong etal. 2002)
Proanthocyanidin extract Endothelial cells Human 2400 (Bagchi etal.2002)
from grapeseed
Procyanidins frompine bark Keratinocytes Human 588 (Rihn etal. 2001)
Resveratrol Prostatecancer cells Human 2400 (Narayanan etal. 2003)
Selenium Mammaryepithelial organoids Rat 588 (Dong etal. 2001)
Selenium Intestine Mouse 6347 (Rao etal. 2001)
Sulphoraphane Smallintestine Mouse 6000 (Thimmulappa etal. 2002)
VitaminA Airway tissues Human 30000 (Soref etal. 2001)
VitaminA andEand selenium Skeletal muscle Rat 800 (Sreekumar etal. 2002)
VitaminD3 Osteosarcoma cells Rat 5000 (Farach-Carson and Xu2002)
VitaminD3 Prostatecancer cells Human 20000 (Krishnan etal.2003)
VitaminD3 Kidney Mouse 12422 (Li etal.2003b)
VitaminE Liver Rat 7000 (Barella etal. 2004)
VitaminE Aortic smoothmuclecells Human 10000 (Villacorta etal.2003)
VitaminE(tocotrienol) Foetal brains Rat 8000 (Roy etal. 2002)
VitaminE(RRR- and HepG2 hepatocarcinoma cells Human 14500 (Muller etal. 2005)
all rac-a-tocopherol)
VitaminEand selenium Liver Rat 465 (Fischer etal. 2001)
Zinc Mucosacells ofsmall intestine Rat 1185 (Blanchard etal. 2001)
Zinc Liver Rat 2500 (tom Dieck etal.2003)
the cytosol to the nucleus where it activates gene expres- to concentrations of other well-known signalling molecules
sion (Yamauchi et al. 2001). A non-antioxidant derivative suchasinositolphosphate,itseemsimplausiblethata-toco-
of a-tocopherol, a-tocopheryl-phosphate, has been reported pheryl-phosphate serves as a storage form of vitamin E
to be a more potent inhibitor of both mRNA and total (Gianelloetal.2005;Negisetal.2005).Instead,ithasbeen
protein expression for the scavenger receptor CD36 in proposed that a-tocopheryl-phosphate may act as a signal-
humanand rat cell lines, compared tothe parent compound lingmolecule(Negisetal.2005).Inorderfora-tocopheryl-
a-tocopherol (Munteanu et al. 2004). Since a-tocopheryl- phosphate to be an effective part of a signalling cascade,
phosphate is present in tissues at minute concentrations however, its synthesis and decomposition need to be under
(100–250 ng/g tissue) which are much lower than those of the control of suitable kinases and phosphatases. Although
a-tocopherol (approximately 10 g/g tissue) but comparable preliminary evidence for the existence of such kinase and
Nutrigenomics–newfrontiersinantioxidantresearchJ.Franketal. 7
targets in gene expression (Sen and Packer 1996). NF-kB
regulates the expression of genes that are involved in
inflammation and cell proliferation. Again, supplemental
vitamin E has been shown to inhibit NF-kB in vitro,
for example in Kupffer cells (Fox et al. 1997), as well
as in vivo in Sprague-Dawley rats (Calfee-Mason et al.
2002).
Thus, evidence is accumulating that antioxidants (e.g.
vitamin E, carotenoids, ascorbic acid (vitamin C), lipoic
acid, flavonoids, and extracts of ginkgo biloba, as well as
trace elements like zinc and selenium) and oxidative stress
(induced by e.g. ozone, cigarette smoke, UV radiation, or
oxidized low-density lipoprotein (LDL)) markedly affect
gene expression in cultured cells, animals, and humans
(Table 1, Table 2). Most experiments to study the effects
Figure 4. Antioxidants as free radical scavengers, metal
of antioxidants on gene expression have been performed
chelators, and redox signalling molecules. Prevention of
in cell culture or model animals. However, the impact of
oxidativedamagetowardslipids,proteinsandDNA,aswell
antioxidantsupplementtreatmentondifferentialgeneexpres-
as redox signalling contribute to their potential beneficial
sion has recently been investigated in human volunteers
effectswithregardtodegenerativedisorders.
with a heterozygous apolipoprotein E4 (apoE4) genotype
by use of cDNA array technology (Majewicz et al. 2005).
phosphatase activities has been published (Gianello et al. Supplementation with 60 mg/d ascorbic acid for 4 weeks
2005; Negis et al. 2005), the actual existence of enzymes increased circulating plasma vitamin C concentrations by
thatspecificallyphosphorylatetocopherolsanddephosphor- 43% in smokers, but had no effect in non-smokers. How-
ylate tocopheryl-phosphates needs to be verified, and their ever, baseline concentrations of vitamin C were signifi-
regulationandactivitiesneedtobecharacterized. cantly lower in smokers compared to non-smokers and did
In cell culture experiments, it has been demonstrated not entirely reach the levels observed in non-smokers,
that vitamin E inhibits inflammation, cell adhesion, plate- even after supplementation. Corresponding to the observed
let aggregation, and smooth muscle cell proliferation, and alterations in plasma levels of the vitamin, ascorbic acid
that many of these cellular functions are independent of treatment down-regulated the expression of genes related
the antioxidant properties of the vitamin (Rimbach et al. toinflammatoryresponse(tumournecrosisfactorb,tumour
2002). However, the intracellular balance of oxidants and necrosis factor receptor, neurotropin-3 growth factor
antioxidants, and hence the reduction-oxidation (redox) receptor, and monocyte chemoattractant) in monocytes of
state within the cell, has also been proven to be a key fac- apoE4 smokers but not in non-smokers. Thus, the authors
tor in the regulation of the expression of certain genes. identified vitamin C responsive genes which appear to be
The transcription factors nuclear factor-kB (NF-kB) and centrally involved in processes leading to inflammation
activator protein-1 are 2 examples of such redox-sensitive and atherogenesis, and which may explain, on a molecular
Table 3. Proteomics studies on the effects of oxidative stressors in cultured cells, laboratory animals and humans
Oxidant Cell/Tissue Species Reference
Benzo[a]pyrene Amnionepithelial cells Human (Gao etal.2004)
Cigarette smoke Aortic endothelialcells Human (Raveendran etal.2005)
Hydrogenperoxide Cardiac myocytes Human (Brennan etal.2004)
HepG2 hepato-carcinoma cells Human (Cesaratto etal.2005)
Peripheral bloodmononuclear cells Human (Fratelli etal.2002)
Fibroblastcells Hamster (Keightley etal.2004)
Epithelial lenscells Human (Paronet al.2004)
Leukaemia cells Human (Seong etal. 2002)
Heart membrane Rabbit (Sethuraman etal.2004)
Ionizing radiation Liver Mice (An etal.2004)
Oxidized LDL Monoblastic leukaemiacells Human (Yu etal.2003)
Promyelomonocytic cells Human (Fach etal.2004)
Endothelial cells Human (Fuchs etal. 2005a,2005b)
Ozone Airway epithelium Rat (Wheelock etal.2005)