Objective: We conducted a double-blind, placebo-controlled, parallel group study to assess the anti-glycation effect of mixed herbal extract (MHE) in individuals with pre-diabetes mellitus. MHE was produced using hot water extraction from Anthemis nobilis (Roman chamomile), Crataegus oxyacantha (hawthorn berry), Houttuynia cordata (dokudami), and Vitis vinifera (grape leaf). We also assessed whether MHE showed favorable effects on one's quality of life (QOL).
Design: The subjects consisted of 26 volunteers (male: 21; female: 5; age: 50.5 ± 8.5 years) with pre- diabetes mellitus (HbA1c: 5.5 - 6.7%). They were divided into two groups, the Test Group (13 subjects, age: 52.8 ± 8.2 years) and the Control Group (12 subjects, age: 49.3 ± 7.8 years). The Test Group was administered 1,200 mg of MHE (solid substance) per day for 8 weeks. The Control Group was administered a placebo.
Results: The inter-group analysis using the Anti-Aging QOL Common Questionnaire (AAQol) showed that the score for the parameters, “muscular pain/stiffness”, “headache”, “easily angered”, “reluctance to talk with others”, “memory lapse”, and “inability to readily make judgments” was significantly improved in the Test Group (p ‹ 0.05). In terms of sugar metabolism, no significant variation was observed in fasting blood glucose, HbA1c, glycoalbumin, and insulin. A significant variation was not observed in the Test Group with regard to 3-deoxyglucosone (3DG), an intermediate of glycation, and N^ε-(carboxymethyl)lysine (CML) and pentosidine, advanced glycation endproducts (AGEs), in blood after 8 weeks. However, in the subjects with HbA1c of equal to or higher than 5.9%, the subclass inter-group analysis showed that the supplementation of MHE significantly inhibited (p ‹ 0.05) an increase of CML in the Test Group, while CML increased in the Control Group. There was no significant variation in the Test Group regarding the oxidative stress markers, 8-hydroxy-2'-deoxyguanosine (8-OHdG) and isoprostane in urine. The skin elasticity index (R2) obtained by using the cutometer started to decrease significantly in the Control Group after 4 weeks (p ‹ 0.05), while the index showed a tendency that the skin elasticity was successfully maintained in the Test Group. There was no adverse event which was associated with the test product.
Conclusion: These results suggest that MHE may improve the symptoms related to QOL as well as inhibit the generation of CML, one of AGEs, in individuals with abnormal sugar metabolism. Furthermore, the 8 weeks supplementation of MHE was considered to be safe.