“Genetic-risk score could be useful in identifying people who are predisposed to obesity and could ultimately lead to personalized dietary recommendations,” reads a Tufts press release about the study, which was published in 2014 in the Journal of the Academy of Nutrition and Dietetics.
All Eyes on FTO
Several genes associated with risk of obesity have been found in large studies, including FTO, MC4R, TMEM18, KCTD15, GNPDA2, SH2B1, MTCH2, and NEGR1, USC’s Allayee says. The FTO gene in particular is the subject of some studies cited by Ahmed El-Sohemy, PhD, professor and Canada research chair in nutrigenomics, Department of Nutritional Sciences, at the University of Toronto, in comments e-mailed to Nutritional Outlook.
In one of these, “FTO genotype and 2-year change in body composition and fat distribution in response to weight-loss diets: the POUNDS LOST Trial,” a randomized, controlled study published in the journal Diabetes in 2012, the authors wrote, “We found that dietary protein intake might modify the FTO variant’s effect on changes in body composition and fat distribution.”2 Specifically, “a high-protein diet may be beneficial for weight loss in individuals with the risk allele of an FTO variant.”
El-Sohemy, who founded a company called Nutrigenomix, which provides customers with genetic testing and subsequent lifestyle advice based on test results, says that FTO in particular has also been shown to determine whether a person is more or less likely to lose weight by altering the amount of saturated and unsaturated fat in his or her diet.3 “And another factor that has been linked to the FTO gene is metabolic response to physical activity,” he adds.
El-Sohemy acknowledges that “the FTO gene alone is not a very strong predictor of whether or not a person will become obese,” an opinion with which USC’s Allayee agrees. “There are just too many factors—social, environmental, genetic, et cetera—that affect a person’s risk. But knowing which version of the FTO gene a person has can help determine whether they are likely to benefit from certain dietary changes, or whether they need to focus on another aspect of their diet,” El-Sohemy contends.
Knowing one’s FTO status could also be useful simply as a behavioral motivator for those seeking to lose weight, according to a finding published in the American Journal of Clinical Nutrition this year.4 Results from the randomized, controlled Food4Me European trial showed that when an individual is provided information about his or her FTO-gene status (specifically, whether he or she carries the obesity-risk allele) in addition to dietary advice, that individual loses more weight than someone provided dietary advice alone.
“That study,” explains Allayee, “showed that if you inform people that they are genetically susceptible, and if you give them the genetic info, it makes people more aware, and they are more likely to stick to dietary recommendations,” whatever those recommendations may be.
Beyond FTO: New Research Begins on a Liver-Fat Gene
Turning their attention to a potential nutrigenetic association within a segment of the pediatric population, Allayee and colleagues are currently recruiting participants for a study that examines whether reducing sugar consumption in children at genetic risk for developing fatty liver decreases their amount of fat in the liver at the end of six months.5
“Fatty liver is a big problem in Hispanic children who tend to be overweight or obese,” Allayee explains. “We found that if you carry the genetic variant that increases liver fat [GG genotype of gene PNPLA3], it was especially bad for kids who had a lot of sugar in their diets. That’s another nutrigenetic association.”
If the researchers’ hypothesis (that reducing sugar will reduce liver fat in children who carry the risk allele) is correct, there could be valuable clinical applications in terms of personalizing dietary recommendations for these children and their families. “That’s where the field has to go,” Allayee says.
While leveraging existing nutrigenetic findings for the creation of commercial personalized-nutrition and -lifestyle products and recommendations is not condoned by some in academia, others disagree and are doing just that.
El-Sohemy’s University of Toronto−based biotech startup, Nutrigenomix, offers a genetic test (made available through participating healthcare providers) that analyzes an individual’s DNA through a saliva sample and tailors personalized dietary and lifestyle recommendations based on the results. The Nutrigenomix test includes 45 genetic biomarkers, including those related to FTO variants and weight management.
El-Sohemy stands behind his company’s product and maintains that there is currently “plenty of evidence to show that we can give specific recommendations for those with the FTO risk variant.” He cites the previously referenced POUNDS LOST Trial as well as another study published in the Journal of Nutrigenetics and Nutrigenomics in 2015 that connects a low-carbohydrate, high-protein diet with better weight-management results in individuals with the FTO risk allele.6 A Diabetes piece published the same year analyzed 16,000 children and adolescents from 14 studies and reached the same conclusion, El-Sohemy adds.7
Another industry player who is already applying nutrigenetic findings to a commercial personalized-nutrition program is Amway, the direct-selling business based in Ada, MI, that was worth $8.8 billion in 2016. Amway offers a genetic test and subsequent lifestyle recommendations and related food and supplement products as part of its BodyKey by Nutrilite line. BodyKey was launched in the United States in 2013.
Nick Wasmiller, PR lead, Global Media Relations at Amway, explains that the genetic test that is part of the BodyKey Jump Start kit in the United States and Europe is provided by Inherent Health (an Interleukin Genetics brand) and includes gene testing related to weight management. Based on an individual’s test results, BodyKey recommends a particular dietary plan (such as reduced carbohydrates or reduced fat) plus BodyKey food products (such as snack bars) and Nutrilite supplements (such as Nutrilite CLA 500). Forty-nine percent of Amway’s 2016 sales were in the nutrition category, up 3% from 2015, and its Nutrilite line of supplements is one of its top-selling brands.
- 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