Floyd “Ski” Chilton, author of “The Gene Smart Diet” and professor of physiology and pharmacology in the Wake Forest University School of Medicine, offers his perspectives below on key aspects of precision nutrition. He kicks off the opening-night reception of the “Feeding Your Genome: Precision Nutrition and Health” conference on February 22, at a “Food, Wine and Healthy Living Event.” Open to the public, the reception takes place from 5:30 to 8:30 p.m. in the courtyard of the Environmental and Natural Resources 2 (ENR2) Building on the University of Arizona campus.
He is also speaking at the two-day scientific Feeding Your Genome conference, hosted by the Department of Nutritional Sciences in the College of Agriculture and Life Sciences on February 23-24.
Q: What does “Feeding Your Genome” mean?
A: The Human Genome Project was launched in 1990 and completed in 2003. This Project defined the structural genome by providing the sequence of 3 billion base pairs and the identification of ~22,300 genes that coded for proteins made by humans. At the time, the scientific community was very confident that this would provide a great deal of information about who an individual was and what they would become. This was called the structural genome and is the “unchangeable genetics” because this set of blueprints is put in place at the beginning of life and barring a rare mutation, the basic information it provides does not change. Importantly, this information plays a key role in building every cell in the body and thus is the basic foundation behind physical, cognitive, and behavioral characteristics.
However, there were a number of questions that arose from our understanding of the human genome. First, we had far fewer genes than expected. We were expecting over 100,000, and we had a little over 22,000. Then, it was discovered that there were only ~3 million base pair differences between different people. That’s a small percentage of the 3 billion base pairs that make up the human genome, so essentially, one human is 99.9 percent (from just a sequence perspective) like everyone else. Additionally, sequence differences explained a low percentage of differences with regard to disease risk and physical and behavioral characteristics.
Yet over the past 20 years or so, another type of genetics called epigenetics has rapidly emerged, and epigenetics has fundamentally changed science’s view of genetics and development. The revolutionary concept brought about by epigenetics is that as humans (or animals and plants) interact with their environment in certain ways, the chemical structure of their DNA and thus how genes (and thus characteristics) are expressed are all altered. All of the changes made to the structural genome are collectively called the epigenome and this is what I call our “changeable genetics.”
For me, this was such a paradigm shift because we went from a view where we believed so much of our fate was intrinsically determined to one where our thoughts, actions, habits and ultimately our destinies were changeable at the most basic DNA level. Thus the fate of a human is not determined at conception, but evolves through modifications to the structural genome, which then has the capacity to change us in a highly dynamic and lifelong process.
In that light, “Feeding Your Genome” means being aware and honoring the process that your decisions and the environments (such as diet and exercise) that you expose yourself to are constantly improving or destroying your physical and mental health through epigenetics. To live is to change and you have the freedom to “Feed Your Genome” as you wish. One of the coolest parts about being a scientist is that we get to study the underpinnings of epigenetics that allows all this change to take place.
Q: How do gene-food interactions affect health and disease?
A: There are numerous ways gene-food interactions affect health and disease. The interactions that we study in our lab are often driven by ancestry and human evolution and address why the modern Western diet (MWD) punishes certain populations with more inflammation and related diseases than others. Much of this work points back to evolutionary drivers during human development. Diets were dramatically different on the African Savannah 150,000 years ago than in “Out of Africa” European populations 15,000 years ago when organized fishing, hunting, animal and plant husbandry were firmly in place. Consequently, it should come as no surprise that genetic and epigenetic variations that impact metabolism of nutrients are dramatically different in distinct ancestry populations. Consequently, it also would be predicted that the modern Western diet would impact populations differently.
Q: How can precision nutrition be used to prevent chronic disease?
A: I will give you a real world example from our work. There has been a dramatic increase (~3 fold) in the ingestion of the omega-6 polyunsaturated fatty acids (PUFAs) in the modern Western diet over the past 50 years. In contrast, the ingestion of omega-3 PUFAs has remained relatively constant. Americans currently eat 6-8 percent of their total calories as omega-6 PUFAs. Our work indicates that African Ancestry populations have much higher frequencies (than European Ancestry populations) of gene variants that efficiently convert these omega-6 PUFAs to circulating pro-inflammatory, pro-tumorigenic mediators, and this is likely an important biological basis for health disparities observed in African Americans.
These disparities are seen in many inflammatory diseases including cardiovascular disease, diabetes and several cancers. So dietary PUFA recommendations for certain individuals and populations can’t be uniform. These studies demonstrate a critical need to conduct studies across racial/ethnic groups and point out how risk stratification may be affected by dietary PUFA-gene interactions. Understudied populations create a vital challenge (and opportunity) to understanding the impact of gene-diet interactions on mediators that affect chronic inflammation and carcinogenesis.
Q: In your opinion, why isn’t personalized or precision nutrition something we haven’t already been doing?
A: I don’t think that we are quite ready for it yet, especially with a wide range of nutrients. However, it is coming quickly. That’s why research examining gene-diet interactions is so crucial at this juncture in time. I think the current research is saying that “One Size Fits ALL” approaches to nutrition is not going to be appropriate for all individuals and populations. I also believe there is a great capacity to move human health forward as we learn more and then utilize what we have learned.