Acknowledgements: Thanks /u/genetastic for advice on the statistical analysis!
This post is an update on my experiments to quantify the effect of vinegar on blood glucose & to better understand the underlying mechanism by determining how this effect varies with person/metabolic status, dose, source of calories, and type of acid.
In Phase 1, /u/genetastic, /u/kabong, and I replicated the literature showing that vinegar can reduce the blood sugar impact of complex carbohydrates (white bread). From those experiments, we found that:
Vinegar significantly lowered blood glucose
Peak change in blood glucose & iAuC were reduced by 20% and time to peak blood glucose & initial rise were slowed by 15-20 min. (30-50%).
P-values were all <0.05, with the exception of the drop in iAuC, which was 0.12
The concentration of vinegar we used was extremely unpleasant to consume. So much so that I, at least, wouldn’t be willing to use it for additional experiments, much less daily life.
In this Phase, I tested a more palatable protocol, vinegar diluted in water (~30g vinegar in ~325g water) drank immediately before the meal. Here’s a summary of the results & next steps (full details below):
Diluted vinegar had a statistically significant and meaningful impact on blood glucose compared with no vinagar:
Peak change in blood glucose and iAuC were reduced by ~20% and time to peak was slowed by ~20 min.
P-value was <0.05 for the change in peak blood glucose, but not for iAuC and time to peak.
Diluted vinegar gave very similar results to undiluted, with virtually no change in peak blood glucose and only a modest increase in iAuC and decrease in time to peak. None of these differences were statistically significant.
These results give further evidence that the effect of vinegar on blood glucose is real and provide a practical protocol that can be used for further experiments. For the next phase, I will be testing the following:
Alternate macronutrients (simple sugars, proteins) to determine scope of the effect
Alternate acid sources to test the amylase-inhibition hypothesis
Whether this effect is significant with full meals, including insulin doses
For this last experiment, I will randomly drink 30g ACV in 325g water before my standard breakfast (50g ketochow, 2 tbsp butter, water to 12 oz total volume) and monitor BG impact.
It would significantly improve the study to have a larger number of participants. If you’re interested in collaborating on this or other scientifically rigorous self-experiments with low-carb foods, supplements, or other health interventions, please let me know in the comments or via the contact form on the right.
About a week ago a reader, /u/genetastic, reached out about collaborating on experiments to determine the effect of vinegar on blood glucose after meal consumption.
Like most of you, I had heard all the nigh-magical, pseudoscience claims about using apple cider vinegar to treat diabetes. However, when you dig into the literature, there’s a sizable number of peer-reviewed studies, including several decent meta-analyses, showing that consumption of vinegar with a meal can reduce the blood glucose impact in both diabetic and non-diabetic subjects (see background below for details). There’s also a lot of open questions, including:
Is the effect large enough to matter for practical meals?
What types of meals does vinegar affect?
What is the best protocol to get a large effect without unpleasant side effects?
What’s the underlying mechanism?
Is the effect specific to vinegar or do other acids work?
/u/genetastic, a third collaborator /u/kabong, and I decided to answer these questions with community self-experiment.
Below, I give more details on the background literature and pre-register our protocol and analyses.
It would significantly improve the study to have a larger number of participants. If you’re interested in collaborating on this or other scientifically rigorous self-experiments with low-carb foods, supplements, or other health interventions, please let me know in the comments or via the contact form on the right.
Details
Purpose
To replicate (or fail to replicate) the existing literature and quantify the effect of vinegar on blood glucose level after consumption of complex carbohydrates.
To better understand the underlying mechanism by determining how this effect varies with person/metabolic status, dose, source of calories, and type of acid.
Figure 1. Forest plot showing individual and pooled random effect standard mean difference (95% CI) of trials testing the effect of vinegar on glucose area under the curve. Test of overall effect: z = 2.42, p = 0.01.Figure 2. Forest plot showing individual and pooled random effect standard mean difference (95% CI) of trials testing the effect of vinegar on insulin area under the curve. Test of overall effect: z = 3.73, p < 0.001.
All together this is decent evidence for the acid as inhibitor of alpha-amylase as mechanism hypothesis
One of the biggest challenges in the vinegar/acid literature is that all of the experiments were done with different meals, protocols, and doses, making it difficult to integrate data from multiple studies. To address this issue and answer some of the open questions about this effect, /u/genetastic, /u/kabong, and I decided to do a series of community self-experiments.
While we each have different motivations and interests, overall, the questions we’re looking to answer are:
Is the effect large enough to matter for practical meals?
What types of meals does vinegar affect?
What is the best protocol to get a large effect without unpleasant side effects?
What’s the underlying mechanism?
Is the effect specific to vinegar or do other acids work?
To answer these questions, we will be conducting experiments using the protocol below.
Methods
Materials
Meals:
white bread (starch)
dried dates (simple sugars)
tortilla with beans, salsa, & avocado (starch, fat, and protein)
Vinegar:
Apple cider or white vinegar
As large a quantity as comfortable, not to exceed 30g
Diluted in as little water as tolerable
Blinding
Vinegar supplementation will not be blinded
However, the protocol was established in advance and adhered to without modification once experiments started.
Procedure
Each participant is using a slightly different procedure
