Study: Mulberry extract shrinks blood sugar spike by 40%

By Nikki Hancocks

- Last updated on GMT

Getty | Gam1983
Getty | Gam1983

Related tags Blood glucose levels Weight management Obesity Insulin

Phynova's mulberry leaf extract 'Reducose' was able to suppress postprandial blood glucose and insulin spikes by more than 40% in a newly published clinical trial.

Mulberry leaves are nutritious and contain numerous health benefiting plant metabolites including iminosugars, which resemble carbohydrate monosaccharides. The most widely studied iminosugar is 1-deoxynojirimycin (DNJ).

This similarity with carbohydrates allows them to interact with enzymes and receptors involved in carbohydrate digestion, and therefore inhibit the digestion of carbohydrates.

Reducose is a proprietary extract of mulberry leaves standardised to contain 5% (w/w) DNJ specifically developed for use in food, drink and supplements.

Phynova researchers, in collaboration with researchers from Oxford Brookes Centre for Nutrition and Health, at Oxford Brookes University, conducted a randomised, double-blind, placebo-controlled study in 37 healthy adults to investigate the effectiveness of a small dose - 250mg - of Reducose on lowering blood glucose and blood insulin responses after the ingestion of sugar (sucrose).

After an overnight fast, participants were given 75 g sucrose with white mulberry leaf extract, or 75 g sucrose alone in a drink. Capillary blood samples were collected at 15-min intervals in the first hour and at 30-min intervals over the second hour to determine glucose and plasma insulin levels. Data analysis was conducted using a paired samples T test or a Wilcoxon signed rank test.

The results suggest consumption of the extract reduced peak postprandial glucose by 42% and postprandial plasma insulin by 41%, compared to placebo. 

The researchers conclude that in order to get the best effect from mulberry leaf extract, a suitable intake form such as liquids, fast-dissolving tablets or capsules, or chewable dosage forms should be considered. The ingredient is already utilised in some food, beverage and supplement formulas sold around the world, such as Sugar Break's 'Stabilize Kids' gummy supplement​, sold in the US.

The authors note some limitations of this study, including its short-term nature which meant it did not capture any benefits or potential side effects that could occur with long-term administration. They also used a simple carbohydrate in fasted individuals and did not evaluate the effects of when carbs are mixed with fats and proteins.

Mechanism of action

The water extract white mulberry extract works immediately after ingestion, with the effects lasting for 60 around minutes. It works by mimicking glucose, thereby keeping the body's sucrose and carb-digesting enzymes busy and allowing some of the carbs in the consumed food or drink to pass through undigested.

"After inhibiting the digestive enzymes, Reducose dissociates from the enzyme and unlike other ‘carb blockers’ is absorbed out of the gut into the blood stream where it is rapidly excreted unmetabolised through the kidneys"​  says Andrew Gallagher, Phynova’s lead scientist in the study. "This is important from a side-effect perspective as the microbiome utilizes the same enzymes to break down undigested foods and inhibitors remaining in the gut with the food bolus will impact this activity.

"Not only does this reduce the speed and size of postprandial blood glucose spikes but it allows the undigested carbs to travel down the small intestine. Once they reach the ileum, the last part of the small intestine, they trigger what’s termed the ileal brake which induces satiety."

What's more, Gallagher explains that having a low GI intake in one meal lowers the postprandial glycemic response (PPGR) in a subsequent meal. This 'second meal effect' increases the rate of fat oxidation and favours the use of fat to meet the body’s energy requirements, whilst people who eat high GI meals favor fat storage and the use of carbohydrates for energy (Henry et al., 2017).

Gallagher says an additional benefit of Reducose is the effect it has on the microbiome.

"After passing through the ileum, the carbohydrates that weren’t digested due to Reducose enter the large intestine where they become food for the the gut microbiome.

"There are numerous health benefits associated with providing carbohydrates, especially longer-chain carbohydrates to the microbiome. These carbohydrates feed and nourish the bacteria in the microbiome that have a saccharolytic (carbohydrate) metabolism - Lactobacilli and Bifidobacteria are important beneficial bacteria and are almost exclusively saccharolytic."

Glucose tracking 'revolution'

Wouter Claerhout, Phynova's chief marketing officer, says this ingredient will market itself as consumers become more aware of the impact that blood glucose spikes can have on their health.

GettyImages dzika mrowka
Blood glucose tracker (Getty Dzika mrowka)

"The effect is immediate and lasts for about an hour. This is a huge benefit as there's a revolution coming which is in continuous glucose monitoring with convenient glucose tracking devices that do not require pin pricking.

"These devices are no longer only used by diabetics, but also by elite athletes such as Chris Froome who has advocated the benefits of monitoring his blood glucose levels in order to improve his performance.

"We also see biohackers buying into these devices as they look to personalise their diets.

"The proliferation of wearable trackers will build interest in blood glucose responses and will allow the market to see for themselves the benefits that Reducose can offer."

Source: Nutrition & Metabolism

Thondre. P. S., Lightowler. H., Ahlstrom. L., and Gallagher. A.,

"Mulberry leaf ​extract improves glycaemic response and insulaemic response to sucrose in healthy subjects: results of a randomized, double blind, placebo‑controlled study"

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