Could knowledge of our individual genetic variants guide us in making better, more personalized lifestyle choices, including the foods we eat and the dietary supplements we take? And could we leverage this information to mitigate our individual risk of obesity and other conditions? Experts in the fields of genetics, microbiology, the “-omics” (including metabolomics, proteomics, and more) and nutritional science generally say yes—but their opinions differ on what conclusions we can draw now with the information we currently have in this field, and how and when the science will be translatable into meaningful, scientifically sound commercial applications.
Much more than a trendy buzzword, nutrigenetics “has as its main goal to understand the gene-based differences in response to dietary components and to develop recommendations that are the most compatible with the health status of individuals based on their genetic makeup,” explains José M. Ordovás, PhD, director, Nutrition and Genomics, and professor, Nutrition and Genetics, at the Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University (Boston). Another way of putting it? “Nutrigenetics is about how individual responses to food are driven by genetic differences.”
Hooman Allayee, PhD, professor, Departments of Preventive Medicine & Biochemistry and Molecular Medicine, at the Keck School of Medicine, University of Southern California (Los Angeles), and president-elect, International Society of Nutrigenetics/Nutrigenomics, adds, “Nutrigenetics asks, ‘Do the DNA differences between any two people make them respond differently to nutrients?’ The concept is based on relating genetic differences at the DNA level to the response to nutritional components.”
This science is poised to disrupt the nutrition field and its blanket public-health guidelines as we now know them, and the potential applications hold tantalizing appeal for industry and consumers alike. “The ultimate personalized nutrition comes, of course, from nutrigenetics,” Ordovás says.
Characterizing the field as “extremely complex,” Ordovás explains that while he and his colleagues have been studying nutrigenetics for decades, it is, in his opinion, “still in its infancy” from a practical perspective. Early on, progress was limited by more-primitive technology and poor knowledge of the human genome, Ordovás says. Since then, technology has “vastly improved,” and our knowledge of the human genome is better—“though rather incomplete.”
“Still,” Ordovás says, “we have to integrate nutrition and genetics using very solid scientific approaches if we want the field of nutrigenetics to mature and yield meaningful solutions and applications.”
Nutrigenetics & Weight Management: What We Know, What We Have Still to Learn
The question, “What do we currently know about nutrigenetics, particularly related to obesity and weight management, and what can we do with that knowledge?” yields varying answers depending on whom you ask. A portion of an American Heart Association statement published in the journal Circulation: Cardiovascular Genetics in 2016 and to which both Ordovás and Allayee contributed reads, “Nutrigenomics has the potential to identify genetic predictors of disease-relevant responses to diet, and this potential and its applicability in the context of personalized nutrition have popular appeal. However, nutrigenomics has also been the subject of much hyperbole and has been ascribed much promise, particularly in the arenas of personalized nutrition, functional foods, and nutraceuticals. Unfortunately, the science has not yet fully delivered on this unrealized potential.” The statement does acknowledge “enthusiasm about possible clinical applications” but maintains that “the evidence base remains limited.”
While the tone of that particular statement is one of cautious optimism, Tufts’ Ordovás does, in comments shared with Nutritional Outlook, point to “promising findings related to nutrigenetics and weight management,” including research performed at Tufts University that concluded that limiting saturated-fat intake may help promote healthy body-mass index (BMI) especially in people whose genetic makeup increases their risk of obesity.1 (For this study, researchers identified 63 gene variants related to obesity and used them to calculate a genetic-risk score for obesity for more than 2800 white adults. Participants with a higher genetic-risk score who also consumed more of their calories as saturated fat were more likely to have a higher BMI, the researchers found.)
- Casas-Agustench P et al., “Saturated fat intake modulates the association between an obesity genetic risk score and body mass index in two US populations,” Journal of the Academy of Nutrition and Dietetics, vol. 114, no. 12 (December 2014): 1954-1966
- Zhang X et al., “FTO genotype and 2-year change in body composition and fat distribution in response to weight-loss diets: the POUNDS LOST Trial,” Diabetes, vol. 61, no. 11 (November 2012): 3005-3011
- Phillips CM et al., “High dietary saturated fat intake accentuates obesity risk associated with the fat mass and obesity-associated gene in adults,” Journal of Nutrition, vol. 142, no. 5 (May 2012): 824-831
- Celis-Morales C et al., “Can genetic-based advice help you lose weight? Findings from the Food4Me European randomized controlled trial,” American Journal of Clinical Nutrition. Published online April 5, 2017.
- Goran MI and Allayee H, “Nutrigenetic Intervention to Reduce Liver Fat in Hispanics.” Research project currently underway at University of Southern California, Los Angeles. Funded by NIH, National Institute on Minority Health and Health Disparities.
- De Luis DA et al., “Effects of a high-protein/low-carbohydrate diet versus a standard hypocaloric diet on weight and cardiovascular risk factors: role of a genetic variation in the rs9939609 FTO gene variant,” Journal of Nutrigenetics and Nutrigenomics, vol. 8, no. 3 (November 2015): 128-136
- Qi Q et al., “Dietary intake, FTO genetic variants, and adiposity: a combined analysis of over 16,000 children and adolescents,” Diabetes, vol. 64, no. 7 (July 2015): 2467-2476