Mulberry Leaf Extract

The co-ingestion of mulberry extract with 75 g sucrose significantly reduced the increase in blood glucose observed over the initial 120 min of testing in control and type 2 diabetic subjects (Fig. 1). Blood glucose declines at the tail end of the study were less with Mulberry Leaf Extract. Thus, peak-to-trough fluctuations in blood glucose were markedly reduced by mulberry ingestion.

The mulberry-induced reduction in blood glucose presumably reflects the ability of mulberry to inhibit intestinal sucrase (9). The increased H2 observed with mulberry indicates that this supplement induced sucrose malabsorption.

The reduction of blood glucose at early time points but higher values at later time points with mulberry would yield relatively minor alterations in A1C. However, factors other than A1C concentrations may play a role in the microvascular complications of diabetes (10,11). Brownlee (12) proposed that generation of reactive oxygen species is the common pathway responsible for diabetes complications, and glucose fluctuations are associated with increased markers of oxidative injury (13). Thus, reductions in blood glucose fluctuation with mulberry extract might reduce diabetes complications despite minor reduction of A1C.

Two drugs (acarbose and miglitol) that inhibit carbohydrate digestion produce modest reductions in fasting blood glucose and A1C (14) and slow progression of glucose intolerance to overt diabetes (15). Use of these drugs has been limited by associated bloating, gas, and diarrhea (16). These symptoms were not significantly increased by mulberry extract; however, convincing evidence of lesser side effects will require studies with extract ingested with each major meal.

Some individuals prefer an herbal over a pharmaceutical preparation, and such individuals might find mulberry extract more acceptable and better tolerated than acarbose or miglitol. In addition, mulberry extract contains compounds such as fagomine, which induces insulin secretion (17), and antioxidants that putatively reduce lipid peroxidation (5,18,19).

While Mulberry Leaf Extract is considered safe as a drug and a foodstuff in Asia (20), the extract contains multiple constituents, increasing the potential for idiosyncratic reactions. While unlikely, such reactions can be excluded only after extensive, monitored use of the extract.