Grape Seed Extract by Vitabase

POSSIBLY EFFECTIVE

• Chronic venous insufficiency (CVI). Oral grape leaf extract might improve CVI symptoms. It is unknown if other grape products are beneficial for CVI. Details: Some clinical trials in patients with CVI show that taking a specific grape leaf extract, known as red vine leaf extract (AS 195, Antistax, Boehringer Ingelheim), seems to improve leg edema after 6 weeks of treatment when compared with placebo. Doses of 360 mg and 720 mg daily were both effective, but the higher dose produced a slightly greater effect. Patients also reported decreases in subjective complaints such as tired or heavy legs, tension, and tingling and pain after 2-12 weeks of treatment (2538,52985,53005,53206).

POSSIBLY INEFFECTIVE

• Allergic rhinitis (hay fever). Oral grape seed extract does not seem to improve hay fever symptoms. Details: A clinical study in patients with seasonal allergic rhinitis shows that taking grape seed extract 100 mg twice daily for 8 weeks before ragweed pollen season does not seem to decrease seasonal allergic rhinitis symptoms or antihistamine usage when compared with placebo (9182).
• Chemotherapy-induced nausea and vomiting (CINV). Drinking grape juice does not seem to improve CINV. Details: Clinical research shows that taking 4 ounces of chilled Concord grape juice 30 minutes prior to meals for a week following each of four cycles of chemotherapy does not seem to reduce CINV when compared with placebo (53175).
• Lower urinary tract symptoms (LUTS). Drinking grape juice does not seem to improve LUTS. Details: Clinical research in middle-aged and older men with LUTS shows that drinking 100% Concord grade juice 240 mL daily for 3 months does not improve symptoms when compared with placebo (96190).
• Mastalgia. Oral grape seed extract does not seem to improve mastalgia symptoms. Details: Clinical research in patients treated for early breast cancer using high-dose radiotherapy shows that taking the grape seed extract constituent proanthocyanidin 100 mg orally three times daily for 6 months does not reduce breast tissue hardness, pain, or tenderness when compared with placebo (53048).
• Obesity. Oral grape products do not seem to improve weight loss. Details: Clinical research in overweight or obese individuals shows that drinking Concord grape juice 480 mL daily for 12 weeks does not improve weight or body composition when compared to baseline (53181). Furthermore, taking grape pomace alone or in combination with schisandra fruit extract daily for 4-10 weeks does not improve body composition, abdominal fat, or body weight when compared with control (96200,99269,99270). Taking grape pomace 7-8 grams daily for 4-6 weeks seems to improve insulin resistance by about 33%, but does not affect blood lipids or blood pressure, when compared with placebo in overweight or obese adults with at least one metabolic syndrome factor (99269,99270).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Aging skin. Oral grape skin extract has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small study in adults with signs of aging skin shows that taking a specific combination product (Celergen, Laboratories-Dom) containing grape skin extract 10 mg, marine collagen peptides 570 mg, coenzyme Q10 10 mg, luteolin 10 mg, and selenium 0.05 mg, one capsule with breakfast and dinner for 2 months, might improve skin elasticity when compared with baseline. However, there was no effect on moisture or biological skin age (97930). It is not clear if these effects are due to grape skin extract, the other ingredients, or the combination.
• Age-related macular degeneration (AMD). Although there is interest in using oral grape seed for AMD, there is insufficient reliable information about the clinical effects of grape for this condition.
• Atherosclerosis. Oral grape seed extract has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in postmenopausal adults shows that taking a specific combination product (Karinat, INAT-Farma) containing grape seed extract constituent proanthocyanidin 40 mg, garlic 100 mg, hops 160 mg, green tea 115 mg, vitamin C 30 mg, silicon 8 mg, vitamin E 6.6 mg, and beta-carotene 0.5 mg three capsules daily for 12 months might slow the progression of atherosclerosis as measured by mean carotid intima thickness when compared with placebo. However, the combination product does not seem to affect the growth of existing plaques, and it does not seem to improve lipid parameters (97929). It is not clear if these effects are due to grape seed extract, the other ingredients, or the combination.
• Athletic performance. It is unclear if oral grape products are beneficial for athletic performance. Details: A small study in elite athletes shows that taking a specific grape extract (Powergrape, Naturex SA) 400 mg daily for one month can increase total power in a jumping task when compared with placebo, but has no effect on initial power and maintenance of power (53310). Another small study in recreationally active young adults shows that drinking juice prepared from 46 grams of a freeze-dried preparation of whole grapes daily for 6 weeks prior to a running exercise test does not improve maximal oxygen uptake or work capacity during exercise when compared with placebo (91540).
• Atopic dermatitis (eczema). Topical grape products have only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients with atopic dermatitis shows that twice daily application with a cream containing grape polyphenols, vitamin E, and epigallocatechin gallate for 28 days does not improve symptoms or reduce the affected area based on physician assessment when compared with placebo (96196).
• Attention deficit-hyperactivity disorder (ADHD). Although there is interest in using oral grape seed for ADHD, there is insufficient reliable information about the clinical effects of grape for this condition.
• Canker sores. Although there is interest in using oral grape seed for canker sores, there is insufficient reliable information about the clinical effects of grape for this condition.
• Cardiovascular disease (CVD). It is unclear if oral grape products are beneficial for reducing CVD risk. Details: There is preliminary evidence that taking grape products, such as purple grape juice or red grape juice concentrate, might improve endothelium-dependent vasodilation, prevent low-density lipoprotein (LDL) oxidation, reduce markers of inflammation, and suppress platelet-mediated thrombosis. Theoretically, chronic ingestion of these products might reduce the risk of CVD in various patient populations, including adults with type 2 diabetes or hypercholesterolemia, those undergoing hemodialysis, and children with metabolic syndrome (8745,8746,52954,53030,53062,53106,53155,53174). However, a large meta-analysis shows that although taking grape products, including grape extract, grape juice, raisins, and grape seed extract, reduces levels of blood fats by a small amount in a mixed population of adults, these effects were not present in a subgroup of patients with CVD when compared with placebo. There was a small benefit on total cholesterol and high-density lipoprotein (HDL) cholesterol (102610).
• Cognitive function. It is unclear if oral grape products improve cognitive function. Details: Clinical research in healthy adults aged 55-75 years with no cognitive decline shows that taking a specific grape fruit extract (Cognigrape, Bionap srl) 250 mg daily for 12 weeks improves cognitive functioning by 4.5%, and overall neuropsychological status, including attention, language, and recall, by 6%, compared with no change in the placebo group (96198). Also, a preliminary clinical study in middle-aged women under moderate stress shows that drinking Concord grape juice 355 mL daily for 12 weeks improves immediate spacial memory and may improve executive function and verbal recall when compared with placebo (96195).
• Cognitive impairment. Small clinical studies suggest that oral grape products may not slow cognitive decline in older patients with cognitive impairment. Details: One very small study in in patients with mild cognitive decline shows that taking a freeze-dried grape powder 36 grams twice daily for 6 months does not improve most measures of cognitive function and memory, including immediate memory, delayed memory, speed of information processing, cognitive ability, or language, when compared with placebo (96199). Another very small study in older adults with signs of memory decline shows that drinking 100% Concord grape juice 6-9 mL/kg daily for 12 weeks does not improve delayed verbal recall or spatial memory when compared with placebo, although it does seem to moderately improve verbal learning (53166).
• Colorectal cancer. Oral grape seed extract is has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in patients with colorectal cancer shows that taking a product containing grape seed extract, turmeric extract, fermented soybean extract, green tea extract, spirulina, and Taiwanofungus camphoratus, 1920 mg three times daily for 16 weeks during a chemotherapy regimen might modestly increase the effectiveness of treatment when compared with placebo. No patients in the treatment group experienced disease progression, compared with 15.8% (6 patients) of the placebo group. However, there was no significant effect on overall survival or the best response to treatment (96183).
• Constipation. Although there is interest in using oral grape products for constipation, there is insufficient reliable information about the clinical effects of grape for this condition.
• Dental caries. Although there is interest in using topical grape seed for dental caries, there is insufficient reliable information about the clinical effects of grape for this purpose.
• Diabetes. Oral grape extract has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A large clinical study of males with type 2 diabetes mellitus and erectile dysfunction suggests that an oral combination product containing alpha lipoic acid, Gingko biloba, and grape extract (Blunorm Forte, Uriach S.p.A.) taken for 3 months may decrease fasting plasma glucose and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) score both alone and when combined with avanafil when compared with baseline and placebo (110707).
• Diabetic retinopathy. It is unclear if oral grape seed extract is beneficial in patients with diabetic retinopathy. Details: A preliminary clinical study in patients with non-proliferative diabetic retinopathy shows that taking a specific grape seed proanthocyanidin extract (Entelon, Hanlim Pharm) 50 mg three times daily for 12 months reduces the severity of hard exudates when compared with calcium dobesilate or placebo. Grape seed extract had a treatment success rate 3-fold and 5.5-fold higher than those of calcium dobesilate and placebo, respectively. Treatment success was defined as a 2-grade decrease in hard exudate severity. No significant improvements in retinopathy grade or visual acuity were reported (100954). However, the study may not have been adequately powered to detect a difference in these outcomes.
• Erectile Dysfunction (ED). Oral grape extract has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A large study of males with type 2 diabetes mellitus and erectile dysfunction suggests that a specific combination product containing alpha lipoic acid, grape extract, and gingko biloba (Blunorm Forte, Uriach S.p.A.) administered orally for three months with avanafil prior to sexual acts improves International Index of Erectile Function (IIEF) scores when compared with either product alone, placebo, and baseline, and may reduce markers of ED including high sensitivity-c-reactive protein, nitrates/nitrites, and metalloproteinases-2 and -9. These results suggest that an oral combination nutraceutical consisting of alpha lipoic acid, grape extract, and gingko biloba (Blunorm Forte, Uriach S.p.A.) may react synergistically with avanafil to enhance sexual performance in males with type 2 diabetes and erectile dysfunction. It is unclear if this effect is due to the alpha lipoic acid, grape extract, or gingko biloba, but researchers theorize that it may be due to the inhibition of phosphodiesterase-5 enzymes by grape extract (110707).
• Hemorrhoids. Although there is interest in using oral grape seed for hemorrhoids, there is insufficient reliable information about the clinical effects of grape for this purpose.
• Hypercholesterolemia. Small clinical studies suggest that oral grape products reduce cholesterol levels by a small amount. Details: A large meta-analysis of heterogeneous clinical trials shows that taking grape products, including grape extract, grape juice, raisins, or grape seed extract, for 2-54 weeks reduces levels of total and low-density lipoprotein (LDL) cholesterol, as well as triglycerides, by a small amount when compared with placebo in a mixed population of adults. In a sub-group of patients with any hyperlipidemia, the mean decreases in LDL cholesterol and triglycerides were 11 mg/dL and 14 mg/dL, respectively. There was no effect on levels of high-density lipoprotein (HDL) in the mixed population or in adults with hyperlipidemia (102610). Although some individual studies disagree, the most evidence for benefit is related to use of whole grape extract or grape seed extract. It is not clear if benefit is dependent on dose or duration of use. These results suggest a benefit of grape products in patients with hypercholesterolemia, but any benefit is likely to be small (42585,96816,102610).
• Hypertension. Some research suggests that oral grape products may modestly lower blood pressure; however, results are inconsistent. Details: Some clinical trials have shown modest benefit in patients with prehypertension, mild hypertension, or metabolic syndrome (18228,53149,96197), but conflicting results exists (91541,90079). A 2016 meta-analysis including 16 trials of 810 patients shows that when compared with placebo, grape seed extract or polyphenols reduces systolic blood pressure (SBP) and diastolic blood pressure (DBP) by about 6 mmHg and 3 mmHg, respectively, with greatest improvements observed in those with obesity or metabolic syndrome. This meta-analysis suggests that a minimum treatment duration of 8 weeks may be necessary before benefit is seen (96194). However, other research in adults with hypertension shows that taking grape seed polyphenols 1000 mg daily for 6 weeks does not alter blood pressure. Also, when grape seed polyphenols were combined with vitamin C 500 mg daily, some patients experienced an increase in blood pressure and worsening of nighttime and daytime variation in blood pressure (13162,90079). The reason for these conflicting findings is unclear but may due to patient characteristics and comorbidities. A meta-analysis of clinical research in various patient populations shows that taking grape seed extract 150-2100 mg for 2-25 weeks improves DBP and heart rate when compared with control, but does not improve SBP or flow-mediated dilation, regardless of dose, duration, sex, BMI, or health status. Additionally, subgroup analyses suggest that blood pressure effects may be greater in patients who are otherwise healthy, female, overweight, and/or under 50 years of age. Also, the use of lower doses and longer treatment durations may be associated with greater benefit (108090). The validity of these findings is limited by the high heterogeneity of included studies. A clinical study in adults with mildly elevated blood pressure shows that a specific grape seed extract (Enovita; Indena SpA) standardized to provide at least 95% oligomeric proanthocyanins, taken as 150 mg twice daily for 16 weeks, does not reduce SBP or DBP when compared with placebo. However, a subgroup analysis suggests that taking grape seed extract improves blood pressure in males, but not in females, when compared with placebo (108091). Some research has also evaluated the effects of grape juice on blood pressure. Two clinical studies in patients with hypertension show that drinking grape juice can reduce blood pressure when compared to baseline; however, another study shows that drinking grape juice does not reduce blood pressure when compared with placebo in these patients (53018,53156,53199).
• Melasma. It is unclear if oral grape seed extract is beneficial in patients with melasma. Details: A very small clinical study in Japanese females with melasma shows that taking grape seed extract (Gravinol, Kikkoman Co) containing 54 mg of proanthocyanidins three times daily for 6-11 months reduces skin hyperpigmentation when compared to pretreatment (53016). The validity of this finding is limited by the lack of a control group.
• Menopausal symptoms. It is unclear if oral grape seed extract is beneficial in patients with menopausal symptoms. Details: Preliminary clinical research in adults with at least one menopausal symptom shows that taking grape seed extract (Gravinol, Kikkoman Biochemifa Co) containing proanthocyanidin 200 mg daily for 8 weeks reduces anxiety when compared with placebo. It also reduces hot flashes and other physical symptoms when compared to baseline, but not when compared with placebo. A lower dose of proanthocyanidin 100 mg daily does not appear to improve these outcomes. Neither doses improved insomnia or depression (91542).
• Metabolic syndrome. Small studies suggest that various oral grape products might improve lipid levels and blood pressure in patients with metabolic syndrome. Details: A meta-analysis of small clinical studies in adults with type 2 diabetes or metabolic syndrome shows that taking grape products, usually grape seed or grape extract, for 4-48 weeks reduces levels of total and low-density lipoprotein (LDL) cholesterol, as well as triglycerides, by a small amount when compared with placebo. The mean decreases in LDL cholesterol and triglycerides were 2.6 mg/dL and 11 mg/dL, respectively (102610). These findings are limited by significant heterogeneity of the included research. Also, a small clinical study in overweight or obese adults, most with metabolic syndrome, shows that taking grape pomace 8 grams daily for 6 weeks improves insulin resistance by about 33%, but does not affect blood lipids, blood pressure, or fasting glucose, when compared with placebo (99270). Some grape products have also shown benefit for improving blood pressure in patients with metabolic syndrome. One small clinical crossover study in males with metabolic syndrome shows that taking 46 grams daily of a freeze-dried, dehydrated preparation of grape polyphenols (equivalent to about 250 grams of fresh grapes daily) for 30 days seems to modestly lower systolic, but not diastolic, blood pressure, and increase brachial artery flow-mediated dilation (FMD) when compared with placebo (18228). Also, a small clinical study in adolescents with metabolic syndrome suggests that drinking natural grape juice 18 mL/kg daily for one month improves FMD when compared with baseline (53174).The validity of this finding is limited by the lack of a control group. A very small clinical study in patients with metabolic syndrome shows that taking a specific grape seed extract (Meganatural BP, Polyphenolics) 150-300 mg daily for 4 weeks modestly reduces blood pressure when compared with placebo (53149). The validity of this finding is limited due to small study size and because patients in the treatment groups had higher blood pressure at baseline.
• Minor bleeding. Topical grape vine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that topically applying 4 mL of a specific product (Ankaferd blood stopper) containing grape vine, alpinia, licorice, thyme, and stinging nettle reduces bleeding, but does not improve the surgical time for episiotomy repair, when compared with saline (31010). It is unclear if this effect is due to grape vine, other ingredients, or the combination.
• Muscle soreness. It is unclear if oral grape products improve muscle soreness. Details: One small study in active young adults shows that drinking juice, prepared from 46 grams of freeze-dried whole grapes, daily for 6 weeks prior to an eccentric arm exercise test does not reduce muscle inflammation or pain at 24 or 48 hours post-exercise when compared with placebo (91540).
• Night vision. Although there is interest in using oral grape seed extract for improving night vision, there is insufficient reliable information about the clinical effects of grape for purpose.
• Nonalcoholic fatty liver disease (NAFLD). It is unclear if oral grape seed extract reverses fatty liver in patients with NAFLD. Details: One small clinical study in adults with NAFLD shows that taking grape seed extract 1000 mg twice daily for 3 months improves some, but not all, markers of liver damage and improves the grade of fatty liver change when compared with vitamin C supplementation (53190).
• Ocular stress. Although there is interest in using oral grape seed extract for ocular stress, there is insufficient reliable information about the clinical effects of grape for this purpose.
• Premenstrual syndrome (PMS). Although there is interest in using oral grape seed extract for PMS, there is insufficient reliable information about the clinical effects of grape for this condition.
• Wound healing. Limited research suggests that topical grape seed extract might improve wound healing. Details: A small clinical study in adults undergoing surgical removal of minor skin lesions shows that applying red grape seed extract 2% cream twice daily to the affected areas reduces the time to complete wound healing by about 6 days when compared with a placebo cream (91539). Also, preliminary clinical research in patients recovering from cesarean section shows that applying grape seed extract 5% ointment twice daily to cesarean section wounds for 14 days improves wound healing, as measured by a scoring system assessing redness, edema, ecchymosis, discharge, and wound closure, when compared with a placebo ointment. A 2.5% ointment did not improve wound healing measures when compared with placebo (100955). More evidence is needed to rate grape for these uses.

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LIKELY SAFE ...when used orally in amounts commonly found in foods. Grapes and grape skin extracts have Generally Recognized As Safe (GRAS) status for use in foods in the US (4912).

POSSIBLY SAFE ...when the whole fruit of the grape, or extracts of the fruit, seed, or leaf, are used orally and appropriately in medicinal amounts. Grape seed extracts have been used with apparent safety in doses up to 200 mg daily for up to 11 months (9182,53016) and in doses up to 2000 mg daily for up to 3 months (53149,53190). Specific grape fruit extracts (Stilvid, Actafarma; Cognigrape, Bionap srl) have been used with apparent safety in doses up to 250-350 mg daily for 3-12 months or 700 mg daily for 6 months (53254,53256,96198). A specific grape leaf extract (AS 195, Antistax, Boehringer Ingelheim) has been used with apparent safety in doses up to 720 mg daily for up to 3 months (2538,52985,53005,53206). A preparation of dehydrated whole grapes, equivalent to 250 grams of fresh grapes daily, has also been used with apparent safety for up to 30 days (18228). A specific grape seed extract (Enovita; Indena SpA) 150 mg twice daily, standardized to provide at least 95% oligomeric proanthocyanins, has been used with apparent safety for up to 16 weeks (108091) ...when used topically and appropriately. Creams and ointments containing grape seed extract 2% or 5% have been used topically with apparent safety for up to 3 weeks (91539,100955). There is insufficient reliable information available about the safety of other grape plant parts when used topically.

CHILDREN: LIKELY SAFE
when used orally in amounts commonly found in foods. Grapes and grape skin extracts have Generally Recognized As Safe (GRAS) status for use in foods in the US (4912). However, whole grapes should be eaten with caution in children aged 5 years and under. Whole grapes can be a choking hazard for young children (96193). To reduce the risk of choking, whole grapes should be cut in half or quartered before being given to children. There is insufficient reliable information available about the safety of grape when used in medicinal amounts in children.

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in amounts commonly found in foods. There is insufficient reliable information available about the safety of medicinal amounts during pregnancy and breast-feeding; avoid using in amounts greater than what is commonly found in foods.

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ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, grape extracts may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.  Details In vitro evidence suggests that grape extracts might decrease platelet aggregation (53017,53087).

CYCLOSPORINE (Neoral, Sandimmune) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Ingesting grape juice with cyclosporine can reduce cyclosporine absorption.  Details A small pharmacokinetic study in healthy young adults shows that intake of purple grape juice 200 mL along with cyclosporine can decrease the absorption of cyclosporine by up to 30% when compared with water (53177). Separate doses of grape juice and cyclosporine by at least 2 hours to avoid this interaction.

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, grape juice might reduce the levels of CYP1A2 substrates.  Details A small pharmacokinetic study in healthy adults shows that ingestion of 200 mL of grape juice decreases phenacetin plasma levels. This is thought to be due to induction of CYP1A2 (2539).

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = D It is unclear if grape juice or grape seed extract inhibits CYP2C9; research is conflicting.  Details In vitro evidence shows that grape seed extract or grape juice might inhibit CYP2C9 enzymes (11094,53011,53089). However, a small pharmacokinetic study in healthy adults shows that drinking 8 ounces of grape juice once does not affect the clearance of flurbiprofen, a probe-drug for CYP2C9 metabolism (11094). The effects of continued grape juice consumption are unclear.

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, grape seed extract may increase the levels of CYP2D6 substrates.  Details In vitro evidence suggests that grape seed extract might inhibit CYP2D6 enzymes (53011). However, this interaction has not been reported in humans.

CYTOCHROME P450 2E1 (CYP2E1) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, grape seed extract might increase the levels of CYP2E1 substrates.  Details In vitro and animal research suggests that grape seed proanthocyanidin extract inhibits CYP2E1 enzymes (52949). However, this interaction has not been reported in humans.

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D It is unclear if grape seed extract inhibits or induces CYP3A4; research is conflicting.  Details In vitro evidence suggests that grape seed extract might inhibit CYP3A4 enzymes (53089). However, evidence from animal research shows that grape seed extract may induce CYP3A4 in the liver (53011). So far, these interactions have not been reported in humans.

MIDAZOLAM (Versed) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, long-term intake of grape seed extract might decrease the effects of midazolam.  Details Animal research shows that subchronic ingestions of grape seed extract can increase the elimination of intravenous midazolam by increasing hepatic CYP3A4 activity. Single doses of grape seed extract do not appear to affect midazolam elimination (53011).

PHENACETIN Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Grape juice might decrease phenacetin absorption.  Details A small pharmacokinetic study in healthy adults shows that ingestion of 200 mL of grape juice decreases phenacetin plasma levels. This is thought to be due to induction of cytochrome P450 1A2 (CYP1A2) (2539).

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General ...Orally, the whole fruit, as well as the seed, fruit, and leaf extracts, seem to be well tolerated. Topically, grape seed extracts seem to be well tolerated.
Most Common Adverse Effects:
Orally: Abdominal pain, diarrhea, dry mouth, dyspepsia, headache, joint pain, and nausea.
Serious Adverse Effects (Rare):
Orally: Anaphylaxis to grape skin has been reported.

Dermatologic ...Orally, mild hair thinning has been reported in a patient taking a specific grape leaf extract AS195 KG) (2538). Urticaria (hives) has also been reported with this same extract (53206). Cases of contact dermatitis have been reported in grape workers, including those working in California vineyards (53270,53272,53275).

Gastrointestinal ...Orally, abdominal pain and nausea have been reported with use of grape seed extract, but these effects typically occur at rates similar to placebo (9182,13162). In a case report of a 57-year-old man, intermittent nausea, vomiting, and diarrhea occurred over a 10-day period and improved once grape seed extract was stopped (96764). Gastrointestinal adverse effects have also been reported with use of a different grape seed extract (Entelon, Hanlim Pharm). However, the specific types of gastrointestinal effects were not described (100954). A specific grape leaf extract AS195 (Antistax, Boehringer Ingelheim Pharma GmbH & Co. KG) has reportedly caused flatulence, mild constipation, gastrointestinal discomfort, diarrhea, dyspepsia, dry mouth, and retching (2538,52985,53206). Diarrhea, gastrointestinal distress, indigestion, and aversion to taste have been reported with use of Concord grape juice (52972,53166,53175,53181,53199). Loose stools have been reported in a clinical trial of grape pomace (99270). Bowel obstruction caused by intact grapes and grape seeds has been described in case reports (53241,53284,53278). Excessive consumption of grapes, dried grapes, raisins, or sultanas might cause diarrhea due to laxative effects (4201).

Hematologic ...Orally, one case of leg hematoma following a minor trauma was reported in a person using grape leaf extract (2538). Also, one case of bruising was reported in a person drinking Concord grape juice daily for 2 weeks (52972).

Immunologic ...Orally, there is one report of an anaphylactic reaction to oral grape skin extract, which included urticaria and angioedema (4073).

Musculoskeletal ...Orally, musculoskeletal disorders, including back pain, have been reported with use of a specific grape leaf extract AS195 KG) (2538,53206). Joint pain and lumbago have been reported with use of grape seed extract, but these effects occur at rates similar to placebo (91541).

Neurologic/CNS ...Orally, headache has been reported with use of grape seed extract, but this effect occurs at rates similar to placebo (9182,91541). A specific grape leaf extract AS195 (Antistax, Boehringer Ingelheim Pharma GmbH & Co. KG) has reportedly caused dizziness, tiredness, headache, and sleep problems (2538,53206). As a class, nervous system adverse effects have been reported with use of a specific grape seed extract (Entelon, Hanlim Pharm). However, the specific types of adverse neurologic effects were not described (100954).

Ocular/Otic ...Orally, ocular adverse effects have been reported with use of a specific grape seed extract (Entelon, Hanlim Pharm). However, the specific types of ocular adverse effects were not described (100954).

Pulmonary/Respiratory ...Orally, nasopharyngitis and oropharyngeal pain have been reported with use of a specific grape leaf extract AS195 KG) (53206). Sore throat, cough, allergic rhinitis, and nasopharyngitis have been reported with use of grape seed extract, but these effects occur at rates similar to placebo (9182,91541). One case report describes a 16-year-old female who developed increased levels of immunoglobulin E (IgE) following skin-prick exposure to grape vine pollen, as well as positive test responses following bronchial and conjunctival provocation (53301). Reduced forced vital capacity has been described in California grape workers (53080,53081). Occupational eosinophilic lung was diagnosed in a grape grower with a history of asthma. Respiratory exposure to sulfites in grape was implicated as the cause of the adverse reaction (53285).

Other ...Orally, grape products can cause adverse effects due to contamination with pesticides or mycotoxins. Some evidence has shown that pesticides used in vineyards may remain on grape surfaces post-harvesting. For example, the fungicide folpet sprayed on grapevines has been shown to remain on the grape surface. Although there was minimal penetration of the epicuticular wax, it showed high resistance to washing (52935). Carbaryl has been identified in over 58% of juice samples collected in Canada. This pesticide reportedly occurred more frequently in grape than in other juices. However, estimates of short-term intake were below proposed acute reference doses (53003).
Ochratoxin A is a mycotoxin that is suspected to be nephrotoxic, teratogenic, hepatotoxic and carcinogenic and has been identified in grape juice, frozen grape pulps, and red and white wine sold in Rio de Janeiro, Brazil. However, the highest levels identified in grape products were lower than the established virtually safe dose of 5 ng/kg of body weight daily (53010,53004). Ochratoxin A has also been identified in red, but not white, grape juice marketed in Switzerland, Canada, and the U.S. (53292,53020).

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