Nitrate from Beets Improves Glucose Response to 75g CHO - Antibacterial Mouthwash Blocks This + Other Benefits

Honestly, for me it's not the improved glucose management, but rather the proof that you must not use antibacterial mouthwash that's the takeaway, here.

What? Yes, the use of mouthwash can ruin all beneficial effects of nitrate containing foods - those on your blood pressure, those on your pump and - as a recent study from the Colorado State University indicates - even the beneficial effects the co-ingestion of beetroot juice with carbohydrates will have on obese individuals' glucose tolerance.

Oh, you're not obese? Well, in that case, the effect is not going to reach statistical significance, but since it's not going to be zero and you can learn something about the incompatibility of your nitrate-based pre-workout performance enhancing pump supplement and antibacterial mouthwash, it's still worth reading the rest of today's SuppVersity article.
At first, it may be odd that a "pump supplement" or "blood pressure regulator" is able to improve one's glucose handling. If we take into consideration that insulin resistance and obesity are characterized by low nitric oxide (NO) bioavailability, however, and know that nitrate the consumption of dietary nitrate (NO3−) increases NO formation, via NO3− reduction to nitrite (NO2−) by oral bacteria, the observations Joseph W. Beals and colleagues made in their latest study do no longer seem that odd.

Figure 1: Schematic of experimental visits. Two modifed oral glucose tolerance tests were administered, on two separate occasions, in a random order. At the start of one visit, participants completed 3 × 1 min mouthwash regimen. Without delay, they then ingested beet juice supplemented with glucose within 5 minutes. Venous blood was sampled repeatedly over 120 minutes and analyzed for concentrations of glucose and insulin. See text for more details (Beals. 2017).

And that's the case for both, (a) the observation that the co-ingestion of dietary nitrate (beet juice) with 25g of glucose (with the CHOs in the juice that's 75 g of total carbohydrates), significantly improved the glucose tolerance of the study's 10 obese adult subjects (34.0 ± 0.8 kg/m²).
And it also led to small but visible improvements in the 12 non-obese study participants (body mass index: 26.3 ± 0.8 kg/m²), and (b) the revelation that inhibiting the nitrate NO3- to nitrite NO2- reduction in the mouth by the prior use of antibacterial mouthwash blunted the effects.

Figure 2: Blood glucose concentration afer beet juice plus glucose consumption was greater in the obese compared with the nonobese adults at 60 and 90 minutes (p = 0.004 and denoted by ∗ | Beals. 2017)

While the co-administration of 500 mL of beet juice (BJ | Biotta, Carmel, Indiana, USA), estimated to contain approximately 17 mmol of nitrate, has only marginal effects in lean individuals (who usually don't suffer from reduced NO2-availability), it has practical relevant effects on the glycemia of obese adults, potentially NO2-deficient adults at risk of developing insulin resistance of whom Beals et al. highlight that they may see significant benefits from ingestion of healthy nitrate-rich foods during meals... as long as they stay away from anti-bacterial mouthwash (MW) in form of one 60s rinse with 10 mL of 1.5% H2O2 (Peroxyl; Colgate Oral Pharmaceuticals, Inc., New York, NY) followed by two 60s rinses with 10 mL of antibacterial mouthwash (chlorhexidine digluconate; Corsodyl, BCM Ltd., Nottingham, UK), that is.
References:

• Beals, Joseph W., et al. "Concurrent Beet Juice and Carbohydrate Ingestion: Influence on Glucose Tolerance in Obese and Nonobese Adults." Journal of Nutrition and Metabolism 2017 (2017).
• Vasconcellos, Julia, et al. "A Single Dose of Beetroot Gel Rich in Nitrate Does Not Improve Performance but Lowers Blood Glucose in Physically Active Individuals." Journal of Nutrition and Metabolism 2017 (2017).