Knowing how genes and nutrients interact could likewise be the prescription for improved health.
During last Tuesday’s 2015 State of the Union address, President Barack Obama reminded us of the importance of personalized medicine. The White House Office of Sciences associate director, Jo Handelsman, describes precision medicine as “an emerging approach to promoting health and treating disease that takes into account individual differences in people’s genes, environments and lifestyles.”1
We’ve also heard from CURE,2 how precision medicine is a model in which a treatment plan is based on an individual’s genetic characteristics and tumor genetics. This, in place of a cookie-cutter approach to treatment that can be very effective for some but very limited for others. Cancer treatment has entered this new model as patients with breast, lung, colorectal cancers and melanoma routinely undergo DNA testing as part of their care enabling their physicians to select the best possible treatments for them individually. In fact, some genetic testing like the BRCA mutations, which increase the risk for breast and ovarian cancers, are required to be covered under the federal Affordable Care Act if recommended by a healthcare provider.
Knowing how genes and nutrients interact could likewise be the prescription for improved health. The United States Department of Agriculture reveals new dietary guidelines every five years.3 The National Cancer Institute,4,5 the American Cancer Society6 and the American Institute for Cancer Research7 also each provide recommendations for healthy nutrition. I too tend to fall back to these standards but they have very little to do with you specifically: your food preferences, your lifestyle, your metabolism, your genome. We already know we are what we eat but what if it were the other way around and we can eat for who we are?
Researchers at the University of Guelph have found a genetic variation for particular enzymes that can influence how readily people respond to healthy omega-3 fatty acids. Those who are poor converters may benefit from increased dose of fish oil.8 Researchers at Tufts University showed that those with a particular genetic variant have healthier blood lipid profiles and lower stroke risk than people without the variant, especially when following a Mediterranean diet.9
People are obsessed with food. We love to eat it and cook it. We love to tinker with it too, eliminating trans fats or red meat or gluten. Our diets shift along with our attention from one vilified or exalted component are another. The idea of using genomic information to provide tailored nutrition plans for “responders” is appealing but we cannot exclude other crucial factors including the influence of the gut microbiome on health and disease. As a licensed dietitian, I have been solicited by precision nutrition companies to provide a panel of genetic testing to my patients and I’ll admit that I’m tempted to try it and see what how the panel of elements dictates a recommended dietetic profile. The Academy of Nutrition and Dietetics have published a position paper on nutritional genomics and conclude that while the field offers insight into the interactions between genes and diets, the “emerging science and the use of nutrigenetic testing to provide dietary advice is not ready for routine dietetics practice”--for now.
Dr. Judith Gilbride, PhD, professor at New York University's Department of Nutrition, Food Studies and Public Health, who submitted the original proposal to the Academy to do a position paper on nutrigenomics says, "I think nutrition professionals must be vigilant in understanding the ongoing research and its potential and apply genetic thinking to patient care. The application is much more complex than original euphoria about the human genome. With Obama allocating funds to Precision Medicine involving DNA, for many conditions, nutrition and drugs not far behind. We must be ready!"10
What’s needed from a translational science point of view are large numbers of subjects to carry out solid gene-diet interaction studies. It will be interesting to include genetic makeup as part of nutrition and diet studies in order to understand the delicate dance they perform. No one really knows how many essential nutrients there are. While I remain moderately optimistic that our genetic signatures can provide a conduit to DNA-based diets, I think understanding how human bodies respond to nutrients, and respond to them differently, could be a key in making them that much better. For now, the improving diets remain the right thing to do in general whether because it’s an improvement in symptoms because of general better health or because of some underlying genetic threshold is impossible to tell.
There are simple rules to fall back on like those put out by the USDA, NCI, ACS and AICR but I’m reminded of the infinitely simple (if not always simple to practice) advice from best-selling author Michael Pollan, “eat food, not too much, mostly plants.
1. Handelsman, Jo. "Precision Medicine: Improving Health and Treating Disease." The White House Office of Science and Technology Policy. Accessed 25 January 2015. Available: http://www.whitehouse.gov/blog/2015/01/21/precision-medicine-improving-health-and-treating-disease.
2. Melton, Christen. "Precision Medicine: What's Next?" Cure Today. Accessed 25 January 2015. Available: https://www.curetoday.com/view/precision-medicine-whats-next.
3. "Dietary Guidelines for Americans." United States Department of Agriculture. Accessed: 25 January 2015. Available: http://www.cnpp.usda.gov/DietaryGuidelines.
4."Energy Balance: Weight and Obesity, Physical Activity, Diet." National Cancer Institute. Accessed 25 January 2015. Available: http://www.cancer.gov/cancertopics/prevention/energybalance.
5. "Fact Sheets: Diet and Nutrition." National Cancer Institute. Accessed 25 January 2015. Available: http://www.cancer.gov/cancertopics/factsheet/diet
6. "ACS Guidelines on Nutrition and Physical Activity for Cancer Prevention." American Cancer Society. Accessed 25 January 2015. Available: http://www.cancer.org/healthy/eathealthygetactive/acsguidelinesonnutritionphysicalactivityforcancerprevention/acs-guidelines-on-nutrition-and-physical-activity-for-cancer-prevention-guidelines
7. "Recommendations for Cancer Prevention." American Institute for Cancer Research. Accessed 25 January 2015. Available: http://www.aicr.org/reduce-your-cancer-risk/recommendations-for-cancer-prevention/.
8. Roke, K. "The role of FADS1/2 polymorphisms on cardiometabolic markers and fatty acid profiles in young adults consuming fish oil supplements." Nutrients. 2014 Jun 16;6(6):2290-304.
9. Garaulet, M. et.al., Pri12AIa interacts with fat intake for obesity and weight loss in a behavioral treatment based on the Mediterranean diet. Mol Nutr Food Res. 2011 Dec;55(12):1771-9.
10. Gilbride, J. (2015, January 26). Email Interview.