Nutritional Genomics: Can it deliver on

Its promises?

Kristin Gunderson, Amanda Carlson and Lindsay Sane

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

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.

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

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

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

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.

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.

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.

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.

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.

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.

Works Cited

Sizer, F., & Whitney, E. (2013). Nutrition: Concepts and Controversies, 13th Edition. Cengage Learning. Web.