Tuesday, August 16, 2016

Will Personalized Genetic Risk Knowledge Lead People to Change Their Diets?

Image Source: ThinnerGene
Certainly that's the notion behind the rise of the for-profit personalized medicine genetic testing industry. The thinking is that if people are made aware of their personalized genetic risks, and if those risks are modifiable by way of diet, that said knowledge will motivate people to affect dietary changes.

But does it?

That's the question a recently published randomized trial sought to answer. The study, The effect of the apolipoprotein E genotype on response to personalized dietary advice intervention: findings from the Food4Me randomized controlled trial, randomly assigned 1,466 participants to a 6 month trial of one of 4 interventions.

1. Standard non-personalized dietary and physical activity advice
2. Personalized advice based on dietary intake
3. Personalized advice based on dietary intake, physical activity, and standard blood biomarkers
4. Personalized advice based on dietary intake, physical activity, standard blood biomarkers, and genotyping

The genotyping was for apolipoprotein E (APOE) which in turn is thought to be a key regulator of cholesterol and lipids. It's also thought that differing APOE genotypes influence lipid responses to dietary fat and therefore given the known increased risk of certain APOE genotypes with coronary heart disease and on lipid responses to dietary fat, that risk carrying individuals if told about their genotypes, might be more likely to adopt gene-based personalized nutrition recommendations.

The study's findings aren't particularly heartening for personalized medicine as it pertains to individual behaviour change.

Personalized advice was found to be better than non-personalized advice, but there was no additional benefit to change found with those whose personalized advice warned them that their unique genetic makeups conferred greater risk.

There is a silver lining here though. Personalized advice based on an individual's dietary intake alone was just as likely to inspire change. So rather than spending your money on all sorts of tests, if you're worried about some diet related aspect of your health, go see an RD (but maybe not one who tries to sell you personalized genetic testing), and with the money you save on all that other testing, you can book a few follow ups and likely get an even bigger bang for your buck.