Gymnema Sylvestre 400 mg by GNC Herbal Plus

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Diabetes. It is unclear if oral gymnema is beneficial for diabetes. Details: A meta-analysis of 10 small clinical studies in adults with type 2 diabetes shows that taking gymnema modestly reduces fasting and postprandial blood glucose levels, and also seems to reduce glycated hemoglobin (HbA1c), when compared to baseline. Gymnema may also modestly reduce total cholesterol and triglyceride levels. (110022). Another meta-analysis of 6 small clinical studies, that includes some of the same studies, also shows that taking gymnema modestly reduces fasting blood glucose, total cholesterol, and triglyceride levels when compared with diet or placebo. However, this analysis shows that gymnema does not improve HbA1c, oral glucose tolerance, or low-density lipoprotein cholesterol (112184). The validity of these analyses is limited by the inclusion of mostly low-quality studies that enrolled heterogeneous patient populations and employed varying gymnema dosing regimens of 0.4-10 grams daily, sometimes in conjunction with antidiabetes medications. In addition, many of the included studies were non-randomized and lacked a comparator group.
• Impaired glucose tolerance (prediabetes). It is unclear if oral gymnema is beneficial for impaired glucose tolerance. Details: One small clinical study in overweight or obese patients with impaired glucose tolerance shows that taking gymnema (Swanson Superior Herbs) 300 mg twice daily for 12 weeks does not improve glucose control, lipid profile, anthropometric indices, or blood pressure when compared with placebo (105346). However, this study may have been inadequately powered to detect a difference between groups.
• Metabolic syndrome. It is unclear if oral gymnema is beneficial for metabolic syndrome. Details: One small clinical study shows that taking gymnema leaf (Swanson Premium G. sylvestre leaf, Swanson Health Products) 300 mg twice daily for 12 weeks reduces body weight by 4% and body mass index (BMI) by 2% when compared to baseline in overweight adults with metabolic syndrome. However, it is unclear if these changes are significant when compared with placebo. In addition, gymnema does not appear to improve blood glucose levels, insulin sensitivity, or blood lipid levels when compared with placebo (96235).
• Obesity. It is unclear if oral gymnema improves weight loss in overweight or obese adults. Details: One small clinical study shows that taking gymnema leaf (Swanson Premium G. sylvestre leaf, Swanson Health Products) 300 mg twice daily for 12 weeks modestly reduces body weight and body mass index (BMI) when compared to baseline in overweight adults with metabolic syndrome. However, it is unclear if these changes are significant when compared with placebo (96235). Another small clinical study by the same authors evaluating overweight adults with impaired glucose tolerance shows that taking gymnema (Swanson Superior Herbs) 300 mg twice daily for 12 weeks does not reduce body weight or BMI when compared with placebo (105346). Gymnema has also been studied in combination with other ingredients. One small clinical study shows that taking a combination of gymnema extract 400 mg, hydroxycitric acid 2800 mg, and niacin-bound chromium 4 mg orally daily for 8 weeks decreases BMI and body weight when compared to baseline in overweight and obese adults. This product provided 400 mcg of elemental chromium and 100 mg of gymnemic acids (42604). It is unclear if these effects are due to gymnema, other ingredients, or the combination. More evidence is needed to rate gymnema for these uses.

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POSSIBLY SAFE ...when used orally and appropriately. Gymnema leaf extract has been used safely in doses of 200 mg twice daily for up to 20 months or 300 mg twice daily for 12 weeks (45,46,42604,105346).

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.

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ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, taking gymnema with antidiabetes drugs might increase the risk of hypoglycemia.  Details Gymnema reduces blood glucose levels in some human and animal research. In human studies, it has been shown to enhance the blood glucose lowering effects of hypoglycemic drugs (45,46,92119,92121,92123). However, other research in adults with prediabetes or metabolic syndrome suggests that gymnema does not reduce fasting levels of blood glucose (96235,105346). Until more is known, monitor blood glucose levels closely.

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, gymnema might increase levels of drugs metabolized by CYP1A2.  Details Animal and in vitro research shows that gymnema can inhibit the CYP1A2 enzyme (96236,96237,96238). In one animal study, oral administration of gymnema for 7 days increased the plasma concentrations of phenacetin, a CYP1A2 substrate, by about 1.4-fold and reduced the clearance of phenacetin by about 29% (96237).

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, gymnema might increase or decrease levels of drugs metabolized by CYP2C9.  Details Animal research shows that gymnema can induce the CYP2C9 enzyme. In one animal study, gymnema caused a 2.4-fold increase in the clearance of tolbutamide, a CYP2C9 substrate, in rats (96237). In vitro research also shows that gymnema can inhibit CYP2C9 (96236,96238).

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = D Theoretically, gymnema might increase levels of drugs metabolized by CYP3A4.  Details One in vitro study using rat liver microsomes shows that gymnema can modestly inhibit the CYP3A4 enzyme (96238). However, other in vitro research using human liver microsomes shows that gymnema does not affect CYP3A4 activity (96236). Animal research also shows that gymnema does not alter the function of CYP3A4. In one study in rats, oral administration of gymnema for 7 days did not alter the clearance of amlodipine, a CYP3A4 substrate (96237).

PHENACETIN Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking gymnema with phenacetin might increase the levels of phenacetin.  Details Animal research shows that gymnema, administered orally for 7 days, decreases the clearance of phenacetin in a dose-dependent manner by about 21% to 29% and increases plasma levels about 1.3- to 1.4-fold when compared to control (96237,96238).

TOLBUTAMIDE (Orinase) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking gymnema with tolbutamide might the decrease levels of tolbutamide.  Details Animal research shows that gymnema, administered orally for 7 days, increases the clearance of tolbutamide by 2.4-fold when compared to control (96237).

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General ...Orally, gymnema seems to be well tolerated.

Hepatic ...A case of drug-induced hepatitis characterized by weakness, fatigue, jaundice, and elevated liver enzymes, has been reported for a patient who consumed gymnema tea three times daily for 10 days. The patient was administered prednisone 60 mg once daily and was eventually tapered off prednisone and discharged. Laboratory values normalized after 6 months (95005). A case of hepatitis-associated aplastic anemia characterized by jaundice, elevated liver function tests, and pancytopenia has been reported for a patient who consumed gymnema 2 grams twice daily for at least a month. Treatment with ursodeoxycholic acid for 8 weeks led to resolution of cholestatic hepatitis; however, the pancytopenia was not responsive to treatment with immunosuppressive drugs and the patient died 5 months after presentation (110021). The exact reason for these adverse effects is not clear; they may have been idiosyncratic.

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