GABA 100 mg [Discontinued] by Superior Source

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Anxiety. Although there has been interest in using oral GABA for anxiety, there is insufficient reliable information about the clinical effects of GABA for this condition.
• Athletic performance. Although there has been interest in using sublingual GABA for athletic performance, there is insufficient reliable information about the clinical effects of GABA for this purpose.
• Attention deficit-hyperactivity disorder (ADHD). Although there has been interest in using oral GABA for ADHD, there is insufficient reliable information about the clinical effects of GABA for this condition.
• Cerebral palsy. It is unclear if oral GABA is beneficial for cerebral palsy in children. Details: Preliminary clinical research in children with cerebral palsy shows that taking a specific product containing GABA (Gammalon) one to four tablets daily (depending on age) for 2 months, in addition to standard therapy for cerebral palsy, improves mental development, learning, vocabulary, physical function, motor strength and activity, and motor hyperactivity in a greater percentage of children when compared with standard therapy alone (19362). These findings are limited by poor study design.
• Chronic bronchitis. It is unclear if oral GABA is beneficial for chronic bronchitis. Details: Preliminary clinical research in adults with chronic bronchitis shows that taking a specific GABA product (Aminalon) 1.5-3 grams daily for 18-20 days, along with conventional treatment for acute exacerbations of bronchitis, increases the duration of subsequent remission by about 3 months when compared with conventional treatment alone (19361).
• Cushing syndrome. It is unclear if oral GABA is beneficial for Cushing syndrome. Details: Preliminary clinical research shows that taking a specific GABA product (Aminalon) 1-3 grams daily for one month decreases plasma levels of adrenocorticotropic hormone (ACTH) 60 minutes after administration, as well as cortisol and ACTH levels up to 2 days after GABA discontinuation, when compared with baseline (19363). The validity of these findings is limited by the lack of a comparator group.
• Depression. Although there has been interest in using oral GABA for depression, there is insufficient reliable information about the clinical effects of GABA for this condition.
• Epilepsy. It is unclear if oral GABA is beneficial for epilepsy. Details: Preliminary clinical research shows that taking a combination of GABA 2.5-3 grams and phosphatidylserine 500 mg daily for 3-8 months reduces seizure frequency when compared with placebo in patients with absence seizures, but not in those with focal aware or focal impaired awareness seizures (19364). Other preliminary clinical research suggests that taking GABA 3 grams with phosphatidylserine 600-1200 mg daily for 2 days does not affect the seizure photosensitivity range in people with photoconvulsive responses (5113).
• Hypertension. Preliminary clinical research suggests that oral GABA may modestly reduce blood pressure in patients with mild or borderline hypertension. Details: Preliminary clinical research in adults with hypertension shows that drinking 100 mL of fermented milk containing GABA 10-12 mg daily at breakfast for 12 weeks reduces systolic and diastolic blood pressure by about 17 mmHg and 7 mmHg, respectively, when compared with baseline. Compared with patients treated with a placebo milk, these reductions were significant. However, it is unclear if the placebo milk also differed from the fermented milk in other ways (19367). Other preliminary clinical research in patients with borderline hypertension shows that taking a chlorella supplement containing GABA 20 mg twice daily for 12 weeks reduces systolic blood pressure when compared with placebo (19368). However, these findings are limited by poor study design.
• Insomnia. It is unclear if oral GABA is beneficial for insomnia. Details: Two small clinical studies in adults with insomnia show that taking fermented rice germ extract, standardized to provide GABA 75 mg or 300 mg, one hour before bedtime for 4 weeks modestly decreases sleep latency when compared with placebo, but does not improve sleep efficacy or reduce episodes of waking after sleep onset (110134,110135). As these doses were evaluated in separate studies, no direct comparison between GABA 75 mg and 300 mg has been conducted.
• Meningitis. It is unclear if oral GABA is beneficial for meningitis. Details: Preliminary clinical research in children aged 7 months to 16 years with meningitis shows that taking a specific GABA product (Aminalon) 0.5-1.5 grams daily, starting within 2-4 weeks of illness and continuing for one month thereafter, decreases the incidence of residual disease manifestations and prevents the development of cerebrospinal syndrome when compared with control (19369). However, this study was conducted prior to the development of current treatment guidelines for meningitis; it is unclear if GABA is beneficial when used in conjunction with current standard care.
• Menopausal symptoms. Although there has been interest in using oral GABA for menopausal symptoms, there is insufficient reliable information about the clinical effects of GABA for this purpose.
• Motion sickness. It is unclear if oral GABA is beneficial for motion sickness. Details: Preliminary clinical research shows that taking a specific GABA product (Aminalon) 0.5 grams as a single dose 40-50 minutes before induced motion sickness or three times daily for 4 days significantly delays onset of motion sickness when compared with placebo. GABA also decreases the occurrence of motion sickness symptoms including chills, cold sweats, and pallor when compared with placebo (19370).
• Obesity. Although there has been interest in using oral and sublingual GABA for weight loss, there is insufficient reliable information about the clinical effects of GABA for this purpose.
• Pain (acute). Although there has been interest in using oral and sublingual GABA for acute pain, there is insufficient reliable information about the clinical effects of GABA for this purpose.
• Post-traumatic stress disorder (PTSD). Although there has been interest in using oral GABA for PTSD, there is insufficient reliable information about the clinical effects of GABA for this condition.
• Premenstrual syndrome (PMS). Although there has been interest in using oral GABA for PMS, there is insufficient reliable information about the clinical effects of GABA for this condition.
• Psychological well-being. Although there has been interest in using oral and sublingual GABA to improve well-being, there is insufficient reliable information about the clinical effects of GABA for this purpose.
• Stress. It is unclear if oral GABA is beneficial for stress. Details: Preliminary clinical research shows that taking a single dose of GABA 100-200 mg by mouth 10-70 minutes prior to completing a mentally stressful task does not appear to reduce subjective measure of stress when compared with placebo (90568). However, it does attenuate alpha wave reduction and reduces beta wave upsurge on the EEG during testing when compared with placebo (19373,90568). More evidence is needed to rate GABA for these uses.

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INSUFFICIENT RELIABLE EVIDENCE to RATE

• Diabetes. It is unclear if oral stevia is beneficial in patients with diabetes; the available research is conflicting. Details: A small single-dose study shows that taking stevia leaf extract 1000 mg, standardized to contain 91% stevioside, along with a meal reduces postprandial glucose levels by 18% in adults with type 2 diabetes when compared with a starch control (11812). However, clinical research in patients with type 1 or type 2 diabetes shows that taking stevioside 250 mg three times daily for 3 months does not affect blood glucose levels or glycated hemoglobin (HbA1C) when compared with baseline (16705). Also, a small clinical study in patients with diabetes shows that drinking 200 mL of black tea, sweetened with stevia extract 2%, three times daily for 8 weeks does not affect glycemic indices when compared with drinking tea sweetened with sucralose (103695).
• Hypertension. It is unclear if oral stevia is beneficial in patients with hypertension; the available research is conflicting. Details: Some clinical research in patients with mild to moderate hypertension shows that taking stevioside, a constituent of stevia, 750-1500 mg in three divided doses daily reduces systolic blood pressure by 10-14 mmHg and diastolic blood pressure by 6-14 mmHg within one week to three months of treatment initiation and continuing for up to 2 years (11809,11810). However, other clinical research in patients with mild hypertension shows that taking stevioside in doses up to 15 mg/kg daily does not significantly reduce blood pressure (16706).
• Obesity. It is unclear if oral stevia is beneficial in patients with obesity; the available research is conflicting. Details: Although a small clinical study in healthy adults shows that drinking water with stevia (Truvia) 245 ppm as a single dose reduces appetite and energy intake when compared with drinking water alone (103697), other small, single-dose studies have shown no effect of stevia 15.3 mg or 1 gram as a single dose on satiety, energy intake, or fullness when compared with either water alone or a non-nutritive sweetener (103696,110124). A small clinical study in healthy adults shows that taking an aqueous stevia leaf extract (SweetLeaf) twice daily for 12 weeks does not affect body weight, compared with an increase in weight in the control group. This suggests that stevia extract may have attenuated weight gain in this study (106458). More evidence is needed to rate stevia for these uses.

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LIKELY SAFE ...when used orally in amounts commonly found in foods.

POSSIBLY SAFE ...when used orally in medicinal amounts, short-term. GABA has been used with apparent safety in doses of 75 mg to 1.5 grams daily for up to one month in small clinical studies (19361,19363,19369,110134,110135). There is insufficient reliable information available about the safety of GABA when used orally for longer than one month or when used sublingually or intravenously.

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

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LIKELY SAFE ...when certain stevia constituents, including stevioside and rebaudiosides A, D, and M, are used orally as sweeteners in foods. These constituents have generally recognized as safe (GRAS) status in the US for this purpose (16699,16700,16702,16705,16706,108049). The stevia constituent stevioside has been safely used in doses of up to 1500 mg daily for 2 years (11809,11810,11811). There is insufficient reliable information available about the safety of whole stevia or stevia extracts when used orally. The European Food Safety Authority (EFSA) has determined that the acceptable intake of steviol glycosides is 4 mg/kg daily (106456); however, it is unclear how this relates to the use of whole stevia or stevia extract.

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

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ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, taking GABA with antihypertensive drugs might increase the risk of hypotension.  Details Some clinical research shows that GABA can decrease blood pressure in patients with hypertension (19367).

CNS DEPRESSANTS Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = D Theoretically, GABA might have additive sedative effects when used in conjunction with CNS depressants. However, it is unclear if this concern is clinically relevant.  Details Endogenous GABA has well-established relaxant effects (51152) and GABA(A) receptors have an established physiological role in sleep (51143). However, the effects of GABA supplements are unclear, as it is unknown whether exogenous GABA crosses the blood-brain barrier (51120,51153,90570). Although there have been limited reports of drowsiness or tiredness with GABA supplements (5115,19364), these effects have not been widely reported in clinical studies. Additionally, intravenous GABA 0.1-1 mg/kg has been shown to induce anxiety in a dose-dependent manner (5116).

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ANTIDIABETES DRUGS Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, stevia might increase the risk for hypoglycemia when combined with antidiabetes drugs.  Details Preliminary clinical research in patients with type 2 diabetes suggests that taking a single dose of stevia extract 1000 mg reduces postprandial blood glucose levels when taken with a meal (11812). However, other clinical research in patients with type 1 or type 2 diabetes suggests that taking stevioside 250 mg three times daily does not significantly affect blood glucose levels or glycated hemoglobin (HbA1C) after three months of treatment (16705).

ANTIHYPERTENSIVE DRUGS Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, combining stevia or stevia constituents with antihypertensive agents might increase the risk of hypotension.  Details Stevia extract and stevioside might lower blood pressure in patients with hypertension (3745,3747,5031,11809,11810). However, other clinical research suggests that stevioside does not significantly lower blood pressure in patients with hypertension (16706).

LITHIUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, stevia might decrease clearance and increase levels of lithium.  Details Animal research suggests that stevia extracts might have diuretic activity (3746,3747). Theoretically, increased reabsorption of lithium along with sodium might reduce excretion and increase levels of lithium.

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General ...Orally, GABA seems to be generally well tolerated. Sublingually, no adverse effects have been reported. However, a thorough evaluation of safety outcomes has not been conducted.
Most Common Adverse Effects:
Orally: Drowsiness, gastric upset, minor throat burning, muscle weakness, and nausea.

Cardiovascular ...Intravenously, GABA can cause dose-related increases in blood pressure and pulse (5116).

Gastrointestinal ...Orally, minor throat burning has been associated with GABA in one study (5115). In another study in which GABA was administered with phosphatidylserine, one patient experienced severe gastric distress, two patients reported moderate nausea, and one reported constipation (19364). Children with cerebral palsy taking GABA experienced nausea and decreased appetite (19362).

Genitourinary ...In one study, one patient treated with oral GABA and phosphatidylserine reported transient amenorrhea (19364).

Musculoskeletal ...Orally, minor adverse effects associated with GABA included muscle weakness (5115).

Neurologic/CNS ...Orally, GABA may cause drowsiness or tiredness (5115,19364). Four children with cerebral palsy taking GABA had convulsions, and an unspecified number experienced motor restlessness. However, causality of these adverse effects was not clear, and the dose of GABA was not specified (19362). Intravenously, GABA 50 mg has been associated with a "lack of alertness" in healthy female volunteers (51159).

Psychiatric ...Intravenously, GABA 0. 1-1.0 mg/kg has been shown to induce anxiety, dysphoria, and mood disturbances in a dose-dependent manner (5116).

Other ...In one study, patients taking GABA experienced a slight warming of the body (19370).

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General ...Orally, stevia and steviol glycosides appear to be well tolerated. Most minor adverse effects seem to resolve after the first week of use.
Most Common Adverse Effects:
Abdominal bloating, dizziness, headache, myalgia, nausea, and numbness.
Serious Adverse Effects (Rare):
Allergic reactions.

Gastrointestinal ...Orally, stevia and steviol glycosides such as stevioside, can cause gastrointestinal adverse effects such as abdominal fullness and nausea. However, these generally resolve after the first week of use (11809,11810).

Immunologic ...Theoretically, stevia might cause allergic reactions in individuals sensitive to plants in the Asteraceae/Compositae family (11811). Members of this family include ragweed, chrysanthemums, marigolds, daisies, and many other herbs.

Musculoskeletal ...Orally, stevia and steviol glycosides may cause myalgia, but this generally resolves after the first week of use (11809,11810).

Neurologic/CNS ...Orally, stevia and steviol glycosides may cause headache, dizziness, and numbness (11809,11810).

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