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  • Does your DNA Hold the Secret to Your Optimal Diet?

    by Guest Blogger | Aug 12, 2016

    By:Nanci S. Guest, MSc, RD, CSCS

    From August 5 through August 22, the ACSM Sports Performance Blog is featuring a special content series in celebration of the achievements of elite athletes participating in international competition. Be sure to follow the blog as well as Facebook, Twitter and Instagram (acsm1954) and share using #ScienceofSport.

    While it has long been suspected that genetics play a critical role in determining how we respond to foods and nutrients, only recently has research in the emerging field of


    been able to demonstrate this scientifically. As a result, there has been an interest in using genetic testing to gain a better understanding of how we can feed our body exactly what it needs.

    Nutrigenomics uses the results of DNA analysis from a simple saliva test to uncover the relationship between genes, nutrition and human health and performance. Research in this field has shown how our unique genetic makeup affects the way we absorb, metabolize, and use  nutrients, and how that influences our health and performance.

    We are all unique:

    We all know someone who can hit the gym for two weeks and lose five pounds or follow a specific diet for a month and drop a dress size. But others may spend months sweating through daily workouts and adhering to a strict diet with less than impressive results. Maybe we aren’t doing what’s right for our body?

    Recent research has shown that DNA-based dietary advice results in improved motivation and better outcomes. Individuals can now receive, at a reasonable cost, a personalized dietary report based on their genetics to improve their health and optimize their performance. This type of information is being used by athletes to help them gain a competitive edge. Individuals can order a genetic test either direct-to-consumer or through a health care provider. Using a health care provider that has received training in genetic testing and nutrition offers the benefit of ensuring that the results are interpreted correctly. A trained health care provider can also answer any questions regarding the genetic test results. 

    What will a genetic test tell you:

    Caffeine has been shown to increase the risk of heart attack or high blood pressure in people with a specific version of a gene called CYP1A2. Below is an example of a test result for an individual’s response to caffeine. We know some people should limit caffeine intake because they have an elevated risk based on their CYP1A2 gene, which determines the rate at which caffeine is broken down and eliminated from the body. Recent research involving this same gene has also shown that athletes may have improved or worsened sport performance when they consume caffeine.







    GA or AA


    Limit caffeine consumption to 200 mg/day.



    Limit caffeine intake to 400 mg per day


    What to look for when choosing a genetic test

    • Many consumer genetic tests assess a wide variety of health factors beyond nutrition, so hone in on those that focus on diet and exercise.
    • Look for a genetic test from a reputable company. Some companies offer tests that misinterpret the science, so a little research can go a long way here.In addition, look for companies that have a scientific advisory board consisting of experts and credentialed professionals in nutrition and genetics.
    • Be careful not to choose quantity over quality. Companies may offer testing for a large number of genes, but further investigation can reveal poor evidence supporting their science. Choose tests that include only genes that have the highest level of evidence to ensure reliable results. This might not be obvious to someone with little scientific training, which is why it’s best to go with a company that uses trained or certified providers.

    For more information:

    1. Diet by DNA:

    Nanci S. Guest, MSc, RD, CSCS served as the head dietitian for the 2010 Winter Olympics and 2015 Pan Am Games. 

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