|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 of their unique genetic makeups.
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.
For the most part, supplement sales and hype are built off of extrapolations. Extrapolations of animal studies to people, extrapolations of basic science to clinical utility, extrapolations of small studies to general conclusions.
And here’s an example of another extrapolation – the extrapolation of presumed causality.
The study, Habitual intake of anthocyanins and flavanones and risk of cardiovascular disease in men, is amazing.
Not in that it’s a great or conclusive study, but rather that despite the very clear first sentence,
“Although increased fruit intake reduces cardiovascular disease (CVD) risk, which fruits are most beneficial and what key constituents are responsible are unclear.”
a sentence that spells out the fact that while we know fruit consumption is healthful, we genuinely don’t know why, the article goes on to conclude, despite not in fact testing for it, that certain fruits’ anthocyanins and flavonone content reduce heart disease risk in men.
How’d they come to that conclusion?
Well they estimated how much anthocyanins and flavonones were consumed as a function of how much anthocyanin and flavonone containing fruit was reported in food frequency questionnaires and then looked at cardiovascular disease risk as a function of same.
Of course fruit contains more than simply anthocynanins and flavonones, so to suggest those were the causal agents of the study’s findings is purely a guess.
So putting aside why the American Journal of Clinical Nutrition published an article with a hugely misleading title and conclusion (and how it passed through peer review as is), why did the authors of this US Blueberry Highbush Council funded study (blueberries contain anthocyanins) focus on presumptive causal factors rather than the berries themselves?
Hard to say. Though it’s certainly not impossible that the study’s lead author’s 2013 patent, meant to provide phytonutrients (including anthocyanins and flavonones) to nursing mothers might have had some influence (and is probably something that should have been included in the study’s confict of interest statement).
Regardless, one things’s certain. For folks selling anthocyanin and flavonone supplements, studies like this one are a gold mine.
From the annals of corporate sponsored research comes this gem that was sponsored by the Corn Refiners Association,
Unfortunately for the Corn Refiners, no amount of p-hacking saw chocolate milk increasing brain function.
While undeniably there’s great research out there that is and was funded by industry, including the food industry, there’s really only one purpose for research like this – sales.
There’s no doubt that if even the tiniest change had been found, the finding would have served industry as a talking and marketing point, just as was the case with the Welch’s study that had them claiming grape juice gave working mothers better memories.
Those ends certainly aren’t a mystery to the researchers who run these studies. And probably not a my$tery either as to why researchers agree to run them.
Maybe by way of a blind universal fund, or by way of sugar-sweetened beverage tax revenues, or by more innovative approaches (see below), we need to find new ways to fund research because clearly, research funding is broken, and it needs fixing.
— Kevin C. Klatt (@Nutrevolve) August 4, 2016
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