Kombucha & Blood Sugar Control
This week, I'd like to talk about potential beneficial effects of kombucha.
I don’t think that I have ever addressed kombucha here before, and there is a very good reason for that — despite the pervasive hype that surrounds it, there is astonishingly little actual research testing the beverage.
But kombucha, at least in theory, has quite a lot going for it:
- Flavonoids found in green/black tea, including catechins, theaflavins, thearubins
- Probiotic bacteria like Lactobacillus
- Acidic compounds generated during the fermentation process, such as acetic and lactic acid
Two recent trials now suggest that consuming kombucha could help with blood sugar regulation, both in healthy individuals and in people with type 2 diabetes. It might be doing this through a couple of different mechanisms.
First of all, we do know that the catechins found in tea (as well as certain probiotic strains) are linked to improved glycemic control. For instance, tannins in tea can bind to digestive enzymes, leading to slower starch breakdown.
Additionally, the acetic acid component of kombucha may be a key mediator here. Previous trials have shown that consuming vinegar leads to reductions in blood sugar, especially in the context of a higher-carb meal. Vinegar appears to interfere with enzymes that break down starch, thus slowing down the digestion of complex carbohydrates.
Furthermore, acetic acid has been shown to activate an enzyme called adenosine monophosphate activated protein kinase, or AMPK for short. AMPK is often characterized as a sort of cellular fuel gauge, because it can detect energy levels in the cell, and it intervenes in various ways when cellular energy status is compromised, most notably during exercise. To make sure that muscle cells are able to refuel, AMPK increases the activity of glucose transporters to help skeletal muscle take up sugar, which in turn lowers blood glucose. This is a major reason why regular exercise increases insulin sensitivity. Acetic acid in vinegar, by activating AMPK, in essence acts as an exercise mimetic, which is pretty cool. Indeed, one trial found that supplementing vinegar led to a significant decrease in insulin resistance, and in turn to reductions in blood sugar and insulin levels.
However, some caveats are warranted here. First of all, believe it or not, there have been multiple case reports of deaths due to kombucha, usually attributed to faulty preparation. This typically happens when people are trying to brew it at home, and make a mistake either in sanitation or fermentation. So, if you're going to drink kombucha, it might be smart to leave the brewing to the experts and purchase it already made at the grocery.
Secondly, kombucha seems to be exceptionally bad for your teeth, even compared to other dentally-unfriendly drinks, which is not too surprising given its low pH. This article has some good tips on how to manage that particular issue.
This Week’s Research Highlights
Drinking kombucha with a meal significantly lowers the postprandial glycemic response.
Researchers in Australia recruited 11 healthy adults, and had them visit the lab in six separate sessions. On the morning of each session, participants arrived fasted, and then consumed a standardized meal of rice and peas that was rated high in the Glycemic Index (GI), combined with either soda water, diet lemonade soft drink, or kombucha. Blood samples were collected at various intervals to determine how the beverages affected their glycemic response. When the test meal was consumed with either soda water or diet soft drink, a similar high peak glucose response was elicited at the 30 min mark, followed by a steady decline. However, the test meal combined with kombucha produced a more moderate peak response, followed by a more gradual drop-off. The postprandial insulin responses, as you would expect, closely mirrored the trends of the plasma glucose. When the researchers calculated and compared the glycemic index values of the meals based on these responses, they determined that the mean GI value for the kombucha meal was significantly lower (68) compared to both the soda water meal (86) and the diet soda meal (84). This is a difference of 20%, lowering the GI rating of the meal from "high" to "medium."
Drinking kombucha daily resulted in lower fasting blood sugar in people with diabetes.
Researchers affiliated with Georgetown University Medical Center in DC recruited 12 participants with type 2 diabetes. Subjects were randomly assigned to consume either 240 mL of kombucha or an unfermented sparkling beverage daily for four weeks. Then, after an 8-week washout period, every participant was switched to the opposite drink, which they drank for another 4-week interval. Fasting blood sugar levels were measured at baseline, and then at the end of each treatment period. Analysis of the blood samples revealed that drinking kombucha resulted in a substantial reduction in average fasting blood glucose compared to baseline levels (164 mg/dL vs. 116 mg/dL), while the placebo beverage did not have a statistically significant impact (162 mg/dL vs. 141 mg/dL). Worth noting that this was a small pilot study with high attrition, and there was tremendous variability in blood sugar levels among the participants who completed the study. However, if similar findings emerge in larger, sufficiently powered trials, this could prove to be a useful dietary tool for diabetes management.
Random Trivia & Weird News
Fruit flies (Drosophila melanogaster) are exquisitely sensitive to the scent of acetic acid, which accumulated on overripe fruit as it ferments.
If you find yourself battling an infestation of these critters in your kitchen, you can create a DIY trap that exploits this propensity by mixing together apple cider vinegar with a few drops of dish soap.
Podcasts We Loved This Week
- Benjamin Miller: Muscle plasticity, aging, and exercise. Via Inside Exercise.
- Stuart McGill: Back pain hot topics — surgery, psychology, sauna, blood flow restriction, and yoga. Via The Reason & Well-Being Podcast.
Products We Are Enjoying
When you exercise hard, lactic acid is generated, which is subsequently broken down into lactate and hydrogen ions. This causes cellular pH to drop, producing the well-known burning sensation and making it hard to maintain force production.
This is where LactiGo can help. LactiGo is a fast acting gel containing carnosine. Carnosine has long been known to act as a pH buffer, and higher levels of carnosine in muscle can help prevent accumulation of hydrogen ions during high-intensity exercise. This increases the power you can produce during a workout, and potentially aiding recovery, while still enabling you to reap the benefits of lactate-generating activity. Pretty cool!
To learn more about how it works, and how it could enhance your own training, check out our past interview with Brad Dieter, LactiGo’s lead scientist. 👀
humanOS Catalog Feature of the Week
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This week, we’d like to highlight one of the lessons from the Ideal Weight Program, developed by Stephan Guyenet.
In this lesson, Stephan explains how exercise seems to prevent or slow weight gain, entirely apart from its impact on energy balance.
Needless to say, findings like this should encourage most of us to try to maintain an active lifestyle!
