The randomised, double-blinded clinical trial funded by Ministry of Agriculture, Food and Rural Affairs in South Korea, also found that serum inflammation markers were reduced after consumption of the formula.
These findings suggest that the formula may improve insulin sensitivity, and reduce liver damage and inflammation.
Insulin resistance is a major factor of prediabetes, type 2 diabetes and a range of chronic diseases.
“When insulin resistance is elevated, pancreatic insulin secretion increases to normalise serum glucose levels, and if insulin secretion is insufficient, serum glucose concentrations increase and induce type 2 diabetes,” researchers wrote in the journal Foods.
Among Korean adults, the prevalence of type 2 diabetes has increased from 4.5% to 13.8% in the last 60 years.
In a previous animal study, oral intake of Aronia melanocarpa (black chokeberry) berries, red ginseng, and Lentinula edodes (Shiitake mushrooms) and nattokinase mixture (AGM) have been demonstrated to have anti-diabetic activity by reducing insulin resistance in type 2 diabetic rats.
In this study, researchers sought to understand the effect of AGM intake on glucose metabolism and insulin resistance in prediabetic adults.
This study recruited subjects aged 19 to 70 years, with a fasting serum glucose concentration 100 to 140 mg/dL, and a body mass index of 18.5–35 kg/m2. Those with a diagnosis of type 2 diabetes were excluded.
They were allocated to either the AGM group (n=37) or placebo (n=39).
YD Nutraceuticals in Korea formulated the test and placebo product. One pack contained 4g of fine granules of either freeze-dried Aronia, red ginseng, shiitake mushroom, and nattokinase, or corn starch.
Subjects were tasked to consume one pack twice a day for 12 weeks.
Primary outcome was the change in serum glucose concentrations at 0, 30, 60, 90, and 120 minutes after an oral intake of 75 g glucose at baseline and week 12.
Secondary outcomes were changes in serum insulin concentrations at 0, 30, and 60 minutes, and changes in other glucose-related biomarkers such as serum C-peptide, insulin, and haemoglobin (HbA1c) concentrations at baseline and week 12.
Insulin resistance was calculated using the HOMA (homeostasis model assessment) of insulin resistance (HOMA-IR) method, and insulin sensitivity using the Matsuda index.
Liver functions were assessed using levels of gamma-glutamyl transferase (γ-GT), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) and inflammatory statuses were assessed using serum high-sensitive C-reactive peptide (hs-CRP) concentrations.
Serum glucose and insulin
Findings showed that insulin resistance was significantly reduced in the AGM group at week 12, compared to placebo.
At week 12, serum insulin concentrations increased until 30 minutes in the AGM group, but they were elevated until 60 minutes in the placebo group.
However, results revealed there was no significant changes in serum glucose concentrations between both groups.
The HOMA-IR (insulin resistance index during a fasting state) decreased by 37.9% from baseline in the AGM at 12 weeks (p = 0.005), but not in the placebo group.
For insulin sensitivity, which was measured with the Matsuda index, AGM group observed higher values compared to the placebo.
A higher Matsuda index indicated better insulin sensitivity.
The findings suggest that AGM may have anti-diabetic activity in prediabetic and healthy adults by reducing insulin resistance, despite serum glucose levels which largely remained the same in the AGM and placebo groups after intervention.
Liver function markers
In analysing liver damage and inflammation markers, researchers found that serum γ-GT, AST and ALT, were significantly lower in the AGM group than in the placebo group after 12 weeks, which indicated AGM ameliorated liver damage.
Serum high sensitive-C-reactive protein concentrations in the AGM was also reduced in the AGM group after 12 weeks, compared to the placebo.
This suggest that AGM supplementation could reduce liver damage and improve hepatic insulin sensitivity.
These results suggest that AGM may possibly improve insulin sensitivity and reduce liver damage and inflammation in prediabetic adults.
Ingredients such as aronia and red ginseng extracts have been demonstrated to reduce fat deposits, improve insulin resistance, and promote glucose and lipid metabolism.
The vitamin D levels in mushrooms were also found to enhance glucose metabolism by promoting insulin sensitivity, insulin secretion, and immunity. Vitamin D deficiency has been associated with insulin resistance.
Researchers acknowledged that the study had some limitations, including the small sample size which “may have been inadequate for a study on healthy adults to identify treatment efficacy.”
In addition, age and gender generally influenced glucose metabolism, and this study had a slightly higher number of female participants.
“A further large clinical study with long-term duration (at least 1 year) is needed to confirm AGM’s impact on glucose homeostasis by improving insulin sensitivity in prediabetic and type 2 diabetic patients,” they recommended.
“Efficacy and Safety of Aronia, Red Ginseng, Shiitake Mushroom, and Nattokinase Mixture on Insulin Resistance in Prediabetic Adults: A Randomized, Double-Blinded, Placebo-Controlled Trial”
Authors: Sunmin Park, et al.