2. What is nutritional genomics?
The study of all genes in an organism and
their interactions with environmental
factors
Scientist are identifying specific traits
within the human genome which may
predispose and individual to developing a
disease and combatting these genetic
profiles with bioactive food components to
alter the outcome of patients.
Bioactive food components are nutrients and
phytochemicals of foods that alter physiological
traits by interacting directly or indirectly with
genes
3. Research
Nutritional Genomic Research strives to:
Identify the gene which could cause disease
Explain the mechanisms of how bioactive foods could alter the outcome of
the gene
Develop practical applications for which nutrient intake levels would help
maintain health along with a whole diet that could prevent or relieve
chronic disease
Use DNA microarray technology
Process by which a robotic arm fastens a single DNA strand to a known DNA
sequence on a slide
A computer then compares the pattern of the known DNA strand and that of the
unknown addition to the DNA
The comparision reveals which genes are active and which are inactive in response
to certain conditions
This process allows for the identification of inherited disease tendencies, unusual
nutrient needs and other medical concerns.
4. DNA Variations
Small variations of genes are called mutations
Most common mutations are called SNPs (snips)
This involves a variation of a single molecule (nucleotide) in a strand of DNA
Most SNPs do not cause disease directly but can predispose an individual to have an increased risk when
exposed to certain environmental factors
Example: Higher risk of heart disease if have gene disposition along with environmental factor of a poor diet
Rarely, a SNP can cause severe disease immediately at birth when SNP is on a high-powered gene
Example: Born with PKU, the inability to properly handle the amino acid phenylalanine
5. Complexity of SNP- Disease Relationships
Disease is often cause by a combination of multiple SNPs on many genes
which interact with environmental factors such as dietary habits
DNA are the primary carriers of information for cells but they combine to
make a larger complex bank of information in the epigenome.
The epigenome consists of proteins and other molecules that interact with DNA to
regulate the expression of genes by turning genes “on” or “off”
The epigenome is responsive to environmental factors, especially during the early
developmental years
Difference between the genome and epigenome:
Genome is like pen on paper, it is more resistant to change even when influenced
by the environment
Epigenome is like pencil on paper, it can be easily erased based on the
environment
Epigenome has the special talent to differentiate cells in the body by turning
“on” or “off” specific genes
Does not change the DNA of a cell, just helps to regulate the DNAs action
6. How Epigenetic regulation works
DNA makes up chromosomes which are filled with supporting
structures called histones. Histones have tails that stick out of the
chromosome and interact with chemical signals from the
environment. These signals cause the DNA to unwrap which triggers
the genes to become activated.
Many of the chemical signals that cause histones to respond are triggered
by dietary interactions.
Example: the phytochemical, sulforafane, in broccoli may affect
cancer processes by reversing the histone changes caused by cancer
and reinstate normal cell division.
Other phytochemical which have positive effects on histone reactions
include tea flavonoids, curcumin from tumeric, sulfur compounds from
onions
Nutrients which have positive effects include folate, vitamin B12, vitamin
D, selenium and zinc
7. Methyl groups also impact the expression of genes. Methyl groups are tiny,
organic compounds that arise from the diet and attach onto directly onto DNA.
If the methyl group attaches to the beginning of a gene, the gene is turned off.
Removing the methyl group from the gene turns it on again which allows protein
replication to occur.
Example: A B vitamin, folate, is essential for transferring methyl groups to other
molecules including DNA. With too little folate, genes will not be properly
methylated which causes unneeded proteins to be produced and not enough
suppression of the gene. If too much folate is ingested, then too many genes may
become suppressed causing a decrease in protein reproduction.
8. Can adults change their epigenome?
To a degree, adults can impact their
epigenome factors through bioactive food
components consumption.
These changes may be temporary.
Shown by the results of broccoli consumptions
affect on cancers.
Negative nutrient consumption such as a food
toxin, may cause removal of methyl groups and
damage to histones which can cause cancer.
9. Researchers conclude that most epigenome changes occur during the
embryonic development phase.
Researchers are questioning how identical twins, with identical DNA,
could develop different diseases and are finding that the environment
and the timing of exposure to stimuli can trigger certain genes to turn
on or off and lead to disease.
10. Genetic Testing
In order for nutritional genomics to be effective, people must be
willing to be genetically tested.
Supporters of genetic testing claim:
It provides information to improve a patients health.
People could be warned about changes to make to ward off disease in the
future.
Could help combat today’s major killers- heart disease and cancer.
Arguments against genetic testing include:
More information is not always better.
Those who test positive for higher risk of disease, such as diabetes or high
cholesterol, are not always willing to make the lifestyle changes needed
to reduce their risk.
Ethical concerns regarding family disclosure, insurance and employer
discrimination.
11. Nutritional Genomics Fraud
Unethical companies have been found to incorrectly test DNA or not
even test the DNA, yet provide advice to patients based on simple
assessments.
Recommend expensive supplements said to meet “personal nutrition
requirements” or to “strengthen the body against disease risk”
These supplements may cost up to 30 times more then supplements
bought at a grocery store yet provide the same effect.
12. Conclusion
Nutritional genomics provides a great opportunity for dietitians as
they will be able to provide reliable, science based evidence on how
to improve ones gene expression through whole food consumption
rather then reliance on supplementation.
Registered dietitians will be able to provide personalized nutrition
information to help improve patients overall health and minimize
their risk for disease which will be more accurate by knowing their
unique genetic make up.
13. Works Cited
Sizer, F., & Whitney, E. (2013). Nutrition: Concepts and Controversies, 13th
Edition. Cengage Learning. Web.
