Lemon juice and lime juice blunt blood glucose spikes through post-ingestive effects and by altering the neural response to sweet taste perception.

“If you also ingest something that's sour like lemon juice or lime juice, it adjusts the output of those neural circuits in your brain. So again, where you have a situation where you have two parallel pathways, one that's post-ingestive coming from phenomenon within our gut neurons, but also things like gastric emptying time, the clearance and transfer of food, and the conversion of food into particular nutrients and the circulation of glucose in your bloodstream and how it gets into the brain. But also simply by ingesting something sour, you are changing the way that sweet things impact your brain.”

“And sure enough, you could see a blunting of the blood glucose response. And of course this was real time, continuous, hence continuous, blood glucose monitoring.”

“When you ingest lemon juice or lime juice, the mechanism by which it blunts blood glucose is probably twofold. One is probably through the post-ongestive effects of glucose in the gut, meaning the way in which sugars are interacting with neurons and other components of your gut circuitry to impact things like gastric emptying time, to impact things like the firing of those neuropod cells and their signaling to the brain. But almost certainly it has something to do also with the perception of sour taste on the tongue.”

“The first of which um is simple lemon juice right or lime juice. Regardless, there are now data pointing to the fact that lemon juice and lime juice a couple tablespoons or so if ingested before or even during or even after consumption of sugary foods or I should say foods that sharply increase blood glucose or large carbohydrate meals can actually blunt the blood glucose response.”