Both vinegar and cinnamon are well publicized to help with blood sugar regulation. While the research for cinnamon in this area is fairly hit and miss, vinegar absolutely does appear to have genuine effects at helping clear blood sugar and promote glycogen storage in muscle. The effect of vinegar seemingly stems from its acetic acid content. Acetic acid is an organic substance containing an acetyl group which is fundamental to the metabolism of fat and carbohydrates. Acetyl groups are naturally occurring in the body, but are generally kept at low levels because the pH effects cell processes. Incidentally, it is this pH effect that is believed to be how acetic acid helps promote glycogen storage (by inhibiting glycolysis).
Researchers in Switzerland wanted to see if there’d be an additive effect from combining acetic acid with cinnamon. They investigated both the change in blood sugar and the opinions of the participants on satiety. What they found was that while the combination did acutely lower blood sugar within 15 minutes of ingesting the meal over control, the two-hour mark showed no difference. What was more interesting is that the satiety score of the combination was greater than that of the control in the short term. This could be of benefit to those who struggle to keep calorie intake moderate during dieting due to the feeling of emptiness you get after a few weeks of cutting. I know from personal experience that vinegar can be of great benefit during difficult dieting days (try saying that fast) so I am interested in combining cinnamon to this.
Source: Mettler S, Schwarz I, Colombani PC. Additive postprandial blood glucose-attenuating and satiety-enhancing effect of cinnamon and acetic acid. Nutr Res. 2009 Oct;29(10):723-7.