It is challenging to achieve long-term dietary change and adherence to dietary guidelines; typically, nutrition interventions result in short-term dietary change, but these changes are not sustained long-term.
Nutrigenomics, which explores interactions between individual genetic variation, dietary intake and changes in gene expression, structure and function, has garnered significant attention in recent years with a number of companies now offering nutrigenetic testing for weight management. Yet there is little research in human intervention studies deciphering the effectiveness of this method. And any genetic testing behaviour change research previously done had not incorporated the Theory of Planned Behaviour (TPB), and incorporation of behaviour change theory in general is fundamentally lacking.
A team of Canadian researchers therefore decided to carry out a Nutrigenomics, Overweight/Obesity, and Weight Management (NOW) parallel-group, clinical trial involving 140 participants at East Elgin Family Health Team (EEFHT) in Ontario, to address the limitations of previous work. They considered the TPB in the dietary interventions and statistical analyses, and providing a high-quality, personalised, genetic-based lifestyle intervention.
Their results indicated that the addition of an actionable nutrigenomics intervention enhanced dietary change and adherence to dietary guidelines over 12 months.
Their report states: "The results of this study provide convincing evidence that the addition of nutrigenomics to one of the most effective public health weight management and diabetes prevention programmes can help motivate and optimise long term, clinically meaningful differences in nutritional intake and adherence to dietary guidelines."
Participants were pre-randomised 1:1 to receive either the standard Group Lifestyle Balance (BLB) programme or a modified GLB+nutrigenomics (GLB+NGx) programme.
Three 24-hour recalls were collected at baseline, 3, 6 and 12 months using the validated multiple pass method. Research assistants collecting the three 24-hour recalls were blinded to the participants’ group assignments.
Statistical analyses included split plot analyses of variance (ANOVAs), two-way ANOVAs, binary logistic regression, χ2 and Fisher’s exact tests. Using the Theory of Planned Behaviour as guidance, key confounding factors of behaviour change were considered in the analyses. This study was registered with clinicaltrials.gov.
Results revealed that only the GLB+NGx group significantly reduced their total fat intake from baseline to 12-month follow-up (from 36.0%±4.8%kcal to 30.2%±8.7%kcal, p=0.02). Long-term dietary adherence to total fat and saturated fat guidelines was also significantly (p<0.05) greater in the GLB+NGx group compared to the standard GLB group.
The researchers conclude that weight management interventions guided by nutrigenomics can motivate long-term improvements in dietary fat intake above and beyond gold-standard population-based interventions.
This research is one of only four completed RCTs assessing change in dietary intake resulting from a nutrigenetic intervention over a 12-month period. Previously, Hietaranta-Luoma et al similarly found that a nutrigenetic cardiovascular disease intervention motivated greater long-term changes in dietary intake, and further motivated greater short-term and moderate-term changes compared to a control group.
There have been no RCTs demonstrating that nutrigenomics is ineffective at motivating changes in dietary intake after 12-month follow-up.
Source: BMJ Nutrition, Prevention, and Health
Horne J, Gilliland J, O'Connor C, et al.
"Enhanced long-term dietary change and adherence in a nutrigenomics-guided lifestyle intervention compared to a population-based (GLB/DPP) lifestyle intervention for weight management: results from the NOW randomised controlled trial"