Today’s guest post comes from Dylan MacKay. Dylan is a nutritional biochemist who has type 1 diabetes and when I saw RD Marie Spano’s Instagram post, I knew he would have both personal and professional thoughts to share and so I invited him to do so.
I don’t know what it is with grapes but they always seem to be raisin my ire…
I mean as a person with type 1 diabetes, a PhD in Human Nutritional Science, and who does diabetes research and occasionally clinical trials looking at glucose response, maybe I’m not the one to talk about this, but I just can’t not.
Recently a Welch’s (*cough* big grape juice) “nutrition advisor” posted the above nutrition translation travesty on Instagram.
This is really kind of surprised me because when I have low blood sugar I often drink grape juice, How am I still alive? I mean I can honestly say there are times grape juice may have saved my life (by raising my blood sugar). Yet you could potentially look at this Instagram post and fairly think
“drinking 100% juice made from polyphenol-rich fruit juice does not raise your blood sugar”
unlike apparently that bad candy or pop that raises your blood sugar.
That would be of course 100% wrong.
Polyphenols are not magic sugar blockers, otherwise we would be using them to treat diabetes and you would get serious gastrointestinal upset from eating berries and grapes. I feel like you don’t even really need to be an RD to see this messaging is bad (Seriously, Welch’s advisors, how much do you get paid for your credibility?). Especially on a social media platform, where someone might not scroll to the end of the associated comment and look at the “reference” provided.
Speaking of the reference used for this knowledge translation crime, it is for a review article called Impact of Dietary Polyphenols on Carbohydrate Metabolism and having reviewed it I can say it does not in support the claim in that post. Most of the article talks about animal or cell culture results that show polyphenols may impact glucose digestion or absorption, but there’s nothing in the article showing it stops it. It even concludes that
“To confirm the implications of polyphenol consumption for prevention of insulin resistance, metabolic syndrome and eventually type 2 diabetes, human trials with well-defined diets, controlled study designs and clinically relevant endpoints… are needed.”
The closest thing in the article supporting the Instagram post is
“The shape of the plasma glucose curve with reduced concentrations in the early phase and a slightly elevated concentration in the later phase indicates delayed response due to berry consumption”
about a study done with 12 healthy participants looking at berry puree (rich in polyphenols). The polyphenols (or something else in the berries) changed the timing of the blood sugar elevation.
I suppose the Welch’s RD nutrition advisor might say
“well actually Dylan, changing the shape of the blood sugar elevation means it doesn’t actually raise blood sugar like candy”
and we could get into a long argument of how you define “like”. When people are arguing over minutia or semantics big food companies have won.
This type of nutrition misinformation advertising works because ultimately it is designed to ruin peoples’ trust in nutritional science and nutrition experts (especially RDs). If consumers are confused and can’t trust anything in nutrition, they are ripe for the next trend or fad or advertising claim. That is a good thing for companies, but a bad thing for people.
If you like grape juice, drink it, I sometimes do when I have low blood sugar (I have chugged maple syrup for that too so…), but know that grape juice will raise your blood sugar, and liquid calories, like those found from the 9 teaspoons of sugar per glass of grape juice, are an easy way to go over on your energy intake. Most of us are trying to avoid excess energy intake, so for that, in my opinion, you can’t beat water.
Dylan MacKay PhD is a nutritional biochemist and an Assistant Professor at the University of Manitoba in Winnipeg. He is also a Clinical Trialist at the George and Fay Yee Center for Healthcare Innovation. Dylan has a special interest in human clinical trials related to lifestyle and diabetes. He is originally from St. John’s, Newfoundland where he started his graduate studies at Memorial University.