Disclosure of Genetic Information for Personalized Nutrition and Change in Dietary Intake

Background: Personal genetic information has become increasingly accessible as a result of consumer genetic tests. Proponents claim that the information may motivate positive behavioural changes aimed at chronic disease prevention, however, the effects of disclosing genetic information on dietary behaviour have not been well explored.Objectives: To determine the effects of DNA-based dietary advice on intakes of caffeine, vitamin C, added sugar and sodium, as well as to explore individual perceptions of genetic testing and personalized nutrition. Methods: A randomized trial was conducted with men and women aged 20-35 years (n=138). Subjects in the intervention group (I) were given DNA-based dietary advice and those in the control group (C) were given general dietary recommendations. Food frequency questionnaires were collected at baseline, 3- and 12-months and general linear models were used to compare changes in intake between groups. A survey was completed at baseline, the intervention point, and 3- and 12-months to assess perceptions between groups. The chi-square test and Wilcoxon signed-rank test were used to compare responses.Results: Subjects in the intervention group were more likely to agree that the advice would be useful when considering diet (88% [I] vs. 72% [C]; p=0.02). A significant reduction in sodium intake was observed at 12-months among subjects who received DNA-based advice when compared to the control group (mean ± SE: -287.3 ± 114.1 mg/day [I] vs. 129.8 ± 118.2 mg/day [C]; p=0.008). Compared to baseline, subjects rated higher agreement with the statement "I am interested in the relationship between diet and genetics" at 3-months (mean change ± SD: 0.28 ± 0.99, p=0.0002) and 12-months (0.20 ± 1.04, p=0.02). The majority of subjects indicated that a university research lab (47%) or healthcare professional (41%) were the best sources for obtaining accurate personal genetic information, while direct-to-consumer genetic testing company received the fewest selections (12%). Most subjects (56%) considered registered dietitians to be the best source of personalized nutrition.Conclusions: These findings demonstrate that DNA-based dietary advice is more effective than general dietary recommendations at motivating individuals to adopt dietary changes for certain nutrients, and therefore, may be more useful for chronic disease prevention.Ph.D