Nutrigenomics

- [Instructor] Would you believe it if I told you that 99.9% of all human's DNA is identical?

You may be wondering, if that's the case, why do all humans look different, have different personalities, and like different foods?

Believe it or not, the 0.1% of DNA that varies between individuals, is responsible for all the differences there are.

Many of the differences are in the form of single nucleotide polymorphisms, or SNPs, which are essentially mutations in the DNA.

These SNPs can no effect on health, or they can cause major risk for disease, depending on their location within the genome.

Nutrigenomics is the branch of science that aims to understand how food, nutrients, and compounds found in food impact gene behavior.

By better understanding these nutrient gene interactions, it is hoped that experts will be able to prevent certain diseases and provide personalized nutrition advice, based on an individual's genetic profile.

Nutrigenomics is a highly complex area of research and there are many disciplines involved in its study.

In order to become better understood, nutrigenomics requires insight from the fields of nutrition, food science, biology, medicine, genomics, and public health.

The study of nutrigenomics is based on three core concepts.

The first, is that each individual's inherited genome are different, and these differences influence nutrient metabolism.

The second, is that people vary greatly in nutrient availability and choices, as a result of differences in culture, taste preference, socioeconomic status, and geographical location.

The third core concept is that both nutritional deficiency and nutrient excess affect gene expression and genome stability.

Genome instability is what often results in mutations in the gene sequence or chromosomes, which can cause many adverse affects.

With these three pillars in mind, let's explore how what we eat is linked to our genes and their activity.

Research in the past decade has identified that genes determine our ability to metabolize nutrients.

This is because genes are responsible for the production of nutritional important proteins, in particular, digestive enzymes, transport molecules that carry nutrients and co-factors that help enzymes do their jobs.

In turn, the nutrients that we eat impact the behavior and expression of our genes.

As mentioned previously, mutations in these genes or genome instability, can lead to many diseases and conditions, such as, infertility, developmental defects, and cancer.

DNA damage is accelerated by oxidative stressors, such as, tobacco smoke, strenuous exercise, and a high fat diet.

On the other hand, folate, antioxidant nutrients, and certain plant compounds are known to enhance DNA repair and reduce damage.

Other diet related factors that influence genomes stability include diet composition, fiber content, food structure, antioxidant capacity and gut microbiome composition.

There are certain snips, or genetic variations, that are known to influence nutrient requirements in susceptible individuals.

One example, is a disease called phenylketonuria, or PKU.

In this condition a genetic variation decreases the production of a particular enzyme needed to break down the amino acid phenylalanine.

Individuals with this genetic mutation can manage their condition by eliminating the amount of protein they eat.

Another example is celiac disease.

In this condition, exposure to gluten modifies the expression of certain genes, resulting in intestinal damage.

Lactose intolerance is a well known condition that affects the gene that produces the lactase enzyme, resulting in inadequate production and an inability to properly digest lactose.

There are two overarching goals in the study of nutrigenomics, these are, prevention of disease and customization of therapy.

Over the course of time, diet has changed our internal human processes, leading to the onset of new diseases.

Nutrient gene interactions have been associated with metabolic stress, cardiovascular disease, diabetes, cancer, obesity, and irritable bowel disease.

It is thought that the use of genome protective nutrients in individuals with certain gene variance, could result in prevention of these major diseases.

Nutrigenomic testing allows an individual to see what conditions they may be predisposed to and make dietary adjustments to help prevent onset.

Customization of therapy in the realm of nutrigenomics means tailoring nutritional advise to an individual based on their genetic profile and specific gene variations.

We know that people are genetically and metabolically different, and that people respond differently to food and nutrients.

We also know that there are important health implications of diet gene interactions, and being able to identify a person's risk factors, and recommend a dietary pattern accordingly, could have significant beneficial affects.

Additionally, numerous studies have shown that people respond better to personalized advice that applies specifically to themselves, as opposed to one size fits all recommendations.

How does nutrigenomic testing work?

At present, testing is most commonly offered direct to consumer, from commercial businesses.

Most healthcare providers are not offering testing yet.

The actual process for consumers is quite simple and requires only a saliva sample, obtained via a cheek swab.

Thesample is then analyzed using advanced technology to identify genetic variants that modify the affects of dietary factors, increased disease risk, or influence food preferences.

Typically, only 30 to 50 genes are analyzed in a test based on their known functions.

The cost of nutrigenomic testing has varied drastically since genome sequencing became possible.

The first genome sequencing took 10 years of work and cost more than a hundred million dollars.

In 2013, a complete sequence could be done for about $5,000, and in 2016 it could be done by a robot in 24 hours, for less than $1,000.

Today, several companies offer testing and interpretation of results for $300 to $500.

The study of nutrigenomics has yielded promising research in recent years, however, there's a great need for more supporting evidence before genetic testing becomes the basis for nutrition and dietary advice.

This is also the position of the Academy of Nutrition and Dietetics, many studies that have been conducted and published have only made weak associations due to limited resources, or small study groups.

Larger, controlled trials will create more sound evidence, linking nutrient intake to gene behavior.

Nutrigenomics is a young science with much room for growth and advancement.