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Numerous companies now offer personalized testing services based on single nucleotide polymorphism (SNP) patterns, with a view to predicting healthy living based on optimization of diet and lifestyle, as well as supplement regimens consistent with health optimization.
However, questions remain: How does nutrigenetics work and how powerful is the science behind this technology? How can we use nutrigenetics in the clinic to improve outcomes for our patients? What tests are available, how do you interpret the results, and what are the costs?
In part one of this three part series, Dr Charles Desmarchelier, PharmD, PhD, joins host E Brian Johnson to share the science behind using nutrigenetics in clinical practice.
Key Take-Aways
Defining nutrigenetics
Our genetic information resides in our DNA sequence coded into a pattern of four types of nucleotides as 3.2 billion nucleotide base pairs. However, DNA is only 99.5% identical across individuals, with some variations in sequence termed genetic polymorphisms.
Specifically, single nucleotide polymorphisms (SNPs) reflect this variation in a manner that one nucleotide is replaced by another type, which alters the protein structure/function that the gene codes for.
Frequency of polymorphisms in SNPs
SNPs have a finite frequency within a given population and represent the most frequent genetic polymorphisms in humans, accounting for 90% of all genetic variations. Indeed, more than 500 million SNPs currently exist within the human genome.
Impact of polymorphisms
Even one base pair changing within your DNA sequence can modify a protein or transporter which will change a physiological parameter you can actually measure, often with an outcome you can observe. This could be giving you blue eyes, affecting the colour of your hair, or impacting your height. Often such outcomes are not only driven by one SNP, but by several SNPs acting in concert.
SNPs and disease pathology
Not all SNPs relate to disease. So, does a given SNP possess an effect? How big is any such effect? A good example is our capacity to digest lactose as adults. Normally, we are genetically programmed not to be able to digest lactose as adults. However, a SNP-related polymorphism in our DNA sequence for the lactase gene has enabled some individuals to digest lactose as adults.
Not all SNPs are created equal!
Considerable literature now exists defining the relation of SNPs to disease. However, for many SNPs we still do not have answers, so considerable research is presently deciphering mechanisms as well as establishing a rating system for the strength of association with disease. These rating systems factor in the number of studies, quality of each study, and strength of observed effect to arrive at a score for individual SNPs.
Benefits of SNP testing
Consider a patient with intestinal disorders. Having the knowledge as to which SNPs your patient carries associated with intestinal disorders, can help you in making a diagnosis. However, other lab test information needs to be available in order to make a fully informed diagnosis. Knowledge of SNPs can also guide toward a diagnosis related to risk of developing a specific disease in ten, 20 or 30 years.
Key Quotes
“SNPs are the most frequent genetic polymorphisms we have. This is 90% of all genetic variations. They are extremely frequent; we have 4 to 5 million in each individual and we know more than 500 million SNPs currently in the human genome.”
Dr Charles Desmarchelier
“What I want to make clear is just because you carry a SNP, even for lactose digestion, it doesn't mean you're going to be lactose intolerant. There are many factors involved..”
Dr Charles Desmarchelier
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The opinions expressed in this Nutramedica program are those of the guests and contributors. They do not necessarily reflect the opinions of Nutritional Fundamentals For Health Inc.
This video is intended for licensed or registered health professionals and students of health professions only. These statements have not been evaluated by the Food and Drug Administration. Information contained in these programs are not intended to diagnose, treat, cure or prevent any disease.
