{"id":"ff22fdae-f873-5805-b15d-a6191f818841","stable_key":"1b599eb7-b22a-5fda-bcf0-9d92b5ae1311:gb-the-control-worked-too","predicate":"reduces","statement":"In volunteers with mildly or moderately high blood pressure, both the fermented drinking water containing gamma-aminobutyric acid and the placebo drink of vinegar and dried bonito without GABA significantly decreased systolic blood pressure by 7.6 plus or minus 4.0 and 5.5 plus or minus 1.5 millimetres of mercury respectively and diastolic by 10.6 plus or minus 4.0 and 7.6 plus or minus 1.7 millimetres of mercury respectively compared to baseline at 12 weeks, there were no abnormal changes in haematological or blood chemistry variables, and these findings indicated that vinegar and dried bonito with or without GABA might have an effect on blood pressure.","claim_class":"observational","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"75f9c3fe-9c2c-522c-abce-4d8be3c73385","mechanism_event_label":"The drink without any GABA in it lowered blood pressure too, which is what the other trials had no way of detecting.","subject":{"id":"8de15909-9245-57e8-bcee-845895591b2b","slug":"fermented-drink-without-gaba","display_name":"The fermented vinegar and dried bonito drink without added GABA","entity_type_key":"chemical_species"},"object":{"id":"8fc0ee41-c9a7-52d4-aebe-418a5307d96d","slug":"systolic-blood-pressure","display_name":"Systolic blood pressure","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"75f9c3fe-9c2c-522c-abce-4d8be3c73385","stable_key":"1b599eb7-b22a-5fda-bcf0-9d92b5ae1311:gb-the-control-worked-too-event","event_type":"observed_intervention","label":"The drink without any GABA in it lowered blood pressure too, which is what the other trials had no way of detecting.","description":"In volunteers with mildly or moderately high blood pressure, both the fermented drinking water containing gamma-aminobutyric acid and the placebo drink of vinegar and dried bonito without GABA significantly decreased systolic blood pressure by 7.6 plus or minus 4.0 and 5.5 plus or minus 1.5 millimetres of mercury respectively and diastolic by 10.6 plus or minus 4.0 and 7.6 plus or minus 1.7 millimetres of mercury respectively compared to baseline at 12 weeks, there were no abnormal changes in haematological or blood chemistry variables, and these findings indicated that vinegar and dried bonito with or without GABA might have an effect on blood pressure.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"2ef146a7-26e4-5546-9acf-4eddcce5db95","slug":"gaba-enriched-food","display_name":"A GABA-enriched food or supplement preparation","entity_type_key":"chemical_species"},"role":"compared_preparation","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"8de15909-9245-57e8-bcee-845895591b2b","slug":"fermented-drink-without-gaba","display_name":"The fermented vinegar and dried bonito drink without added GABA","entity_type_key":"chemical_species"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"8fc0ee41-c9a7-52d4-aebe-418a5307d96d","slug":"systolic-blood-pressure","display_name":"Systolic blood pressure","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/gaba-research/19590713.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"cf28abaa2c4005e26679a43d2ee25123d4ca6fb7184943a6b8c7e0529e560e4a\", \"start_char\": 0, \"end_char\": 1206, \"text_sha256\": \"cf28abaa2c4005e26679a43d2ee25123d4ca6fb7184943a6b8c7e0529e560e4a\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Double-blind placebo-controlled randomised study with the same fermented drink prepared with and without GABA","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Fermented drinking water from sodium glutamate, vinegar and dried bonito, against the identical drink without GABA","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"The control is the same food matrix minus the GABA, which is the comparison the other blood-pressure studies lack.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"GABA research collection; topical membership is not evidence of a direct clinical effect, and the sign of a GABA response depends on the chloride gradient of the cell it was measured in.","comparator":null,"unit":null,"notes":"","entity":{"slug":"gaba","display_name":"Gamma-aminobutyric acid","entity_type_key":"small_molecule"}},{"dimension":"organism","value_text":"Human","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"The drink without any GABA in it lowered blood pressure too, which is what the other trials had no way of detecting.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[gb-p19590713] The Effects of gamma-Aminobutyric Acid, Vinegar, and Dried Bonito on Blood Pressure in Normotensive and Mildly or Moderately Hypertensive Volunteers. (2009). https://pubmed.ncbi.nlm.nih.gov/19590713/ DOI: 10.3164/jcbn.09-04","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Systemic circulation","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"42d066a3-0b7b-5638-a061-ac4b88abc0a2","evidence_kind":"source_excerpt","locator":"Lines 391-402","start_line":391,"end_line":402,"excerpt":"### gb-the-control-worked-too\nIn volunteers with mildly or moderately high blood pressure, both the fermented drinking water containing gamma-aminobutyric acid and the placebo drink of vinegar and dried bonito without GABA significantly decreased systolic blood pressure by 7.6 plus or minus 4.0 and 5.5 plus or minus 1.5 millimetres of mercury respectively and diastolic by 10.6 plus or minus 4.0 and 7.6 plus or minus 1.7 millimetres of mercury respectively compared to baseline at 12 weeks, there were no abnormal changes in haematological or blood chemistry variables, and these findings indicated that vinegar and dried bonito with or without GABA might have an effect on blood pressure.\nCondition category: normal\nnutrient_topic: GABA research collection; topical membership is not evidence of a direct clinical effect, and the sign of a GABA response depends on the chloride gradient of the cell it was measured in.\nplain_language: The drink without any GABA in it lowered blood pressure too, which is what the other trials had no way of detecting.\norganism: Human\ntissue_or_cell_type: Systemic circulation\nexperimental_model: Double-blind placebo-controlled randomised study with the same fermented drink prepared with and without GABA\nlimitations: The control is the same food matrix minus the GABA, which is the comparison the other blood-pressure studies lack.\nexposure: Fermented drinking water from sodium glutamate, vinegar and dried bonito, against the identical drink without GABA\nevidence_span: {\"source_cache\": \"artifacts/gaba-research/19590713.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"cf28abaa2c4005e26679a43d2ee25123d4ca6fb7184943a6b8c7e0529e560e4a\", \"start_char\": 0, \"end_char\": 1206, \"text_sha256\": \"cf28abaa2c4005e26679a43d2ee25123d4ca6fb7184943a6b8c7e0529e560e4a\"}\n[gb-p19590713] The Effects of gamma-Aminobutyric Acid, Vinegar, and Dried Bonito on Blood Pressure in Normotensive and Mildly or Moderately Hypertensive Volunteers. (2009). https://pubmed.ncbi.nlm.nih.gov/19590713/ DOI: 10.3164/jcbn.09-04","model_system":"Double-blind placebo-controlled randomised study with the same fermented drink prepared with and without GABA","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [gb-p19590713] The Effects of gamma-Aminobutyric Acid, Vinegar, and Dried Bonito on Blood Pressure in Normotensive and Mildly or Moderately Hypertensive Volunteers. (2009). https://pubmed.ncbi.nlm.nih.gov/19590713/ DOI: 10.3164/jcbn.09-04","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"197c25bb-45fa-5e97-b3ab-2d2eff4e0d0a","stable_key":"import-1b599eb7-b22a-5fda-bcf0-9d92b5ae1311","title":"GABA: a ligand with no sign of its own, the cofactor that limits its synthesis, the barrier that keeps it out of the brain, and the immune settings where the same molecule protects and harms (2026-09-22)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text.","file_path":"","sha256":"07e36027ff70dbbe5563cddfa4758fd9b9b6eec148faecccafd476900b770456","revision_id":"a12d61de-f189-5bda-af3d-f31a1e61bccf","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[{"id":"49666a25-de11-5da3-b945-ff34954e46e3","title":"Does swallowing GABA produce an effect, and if so where?","kind":"qualification","status":"open","why":"Three lines have to be held together. The barrier records say the molecule is largely kept out of the brain: the carrier at the barrier has a Michaelis constant of 679 micromolar, the brain exports GABA back to blood with a half-time of five to fifteen minutes, and systemic infusion across a thousand-fold dose range raised cerebrospinal fluid GABA only from about 0.5 to 11 micromolar. Against that, a single oral dose shifted the electroencephalogram within an hour in thirteen people, and two placebo-controlled trials found blood pressure reductions. The third line is what decides how much weight the second carries: in the one study that used the same fermented food prepared without GABA as its control, the control lowered blood pressure as well, by 5.5 over 7.6 millimetres of mercury. So an effect of these preparations on blood pressure is reasonably supported and an effect of GABA specifically is not, and any central effect has to be reconciled with a barrier that demonstrably pushes the molecule back out.","resolution":"Unresolved for the central effects. For blood pressure the food matrix is a live alternative explanation that only one of these trials was designed to detect.","created_at":"2026-09-23 01:18:27","record_type":"conflict","display_label":"Recorded conflict","record_url":"/conflicts/49666a25-de11-5da3-b945-ff34954e46e3","sides":[{"conflict_id":"49666a25-de11-5da3-b945-ff34954e46e3","ordinal":0,"label":"The brain actively pumps this molecule back out, and flooding the bloodstream with it barely shifts the concentration inside.","revision_id":"a12d61de-f189-5bda-af3d-f31a1e61bccf","start_line":339,"end_line":350,"quote":"### gb-the-brain-pushes-gaba-back-out\nStudy of brain to blood efflux transport of carbon-14 GABA after loading the brain by vascular perfusion revealed that the half-time of elimination was significantly shorter in spontaneously hypertensive rats at 5.35 plus or minus 0.66 minutes than in Wistar Kyoto rats at 14.83 plus or minus 1.94 minutes, the faster efflux might at least partially compensate for increased uptake and preserve the protective function of the barrier towards GABA, and systemic infusion of GABA within a wide range of administered doses from 0.004 to 5.00 milligrams per kilogram produced an increase in cerebrospinal fluid GABA concentration from around 0.5 micromolar to only 11 micromolar.\nCondition category: normal\nnutrient_topic: GABA research collection; topical membership is not evidence of a direct clinical effect, and the sign of a GABA response depends on the chloride gradient of the cell it was measured in.\nplain_language: The brain actively pumps this molecule back out, and flooding the bloodstream with it barely shifts the concentration inside.\norganism: Rat\ntissue_or_cell_type: Brain, cerebrospinal fluid and cerebral capillaries\nexperimental_model: In situ brain perfusion with efflux measurement and cerebrospinal fluid sampling across a range of systemic doses\nlimitations: Anaesthetised rats, and the comparison is between hypertensive and normotensive strains. The dose-ranging cerebrospinal fluid measurement is the part that bears on oral supplementation.\nexposure: Carbon-14 GABA by bilateral in situ brain perfusion, and systemic GABA infusion from 0.004 to 5.00 milligrams per kilogram\nevidence_span: {\"source_cache\": \"artifacts/gaba-research/16616765.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"550c910f870ffc48b56fbcfe95555a4fec6441bdbef7b1369ef79d1bcba6df5d\", \"start_char\": 0, \"end_char\": 1941, \"text_sha256\": \"550c910f870ffc48b56fbcfe95555a4fec6441bdbef7b1369ef79d1bcba6df5d\"}\n[gb-p16616765] Increased brain uptake and brain to blood efflux transport of 14C-GABA in spontaneously hypertensive rats. (2006). https://pubmed.ncbi.nlm.nih.gov/16616765/ DOI: 10.1016/j.lfs.2006.02.039","source_key":"import-1b599eb7-b22a-5fda-bcf0-9d92b5ae1311","source_title":"GABA: a ligand with no sign of its own, the cofactor that limits its synthesis, the barrier that keeps it out of the brain, and the immune settings where the same molecule protects and harms (2026-09-22)","claim_ids":["d17f2e54-1430-5910-b33c-8212dbab9ea2"]},{"conflict_id":"49666a25-de11-5da3-b945-ff34954e46e3","ordinal":1,"label":"A gram taken by mouth changed the pattern of brain waves within an hour in thirteen people.","revision_id":"a12d61de-f189-5bda-af3d-f31a1e61bccf","start_line":352,"end_line":363,"quote":"### gb-oral-gaba-shifts-the-eeg\nThe first study evaluated the effect of GABA intake by 13 subjects on their brain waves, with electroencephalograms obtained after three tests on each volunteer taking only water, GABA, or L-theanine, and after 60 minutes of administration GABA significantly increased alpha waves and decreased beta waves compared to water or L-theanine, while in a second study eight acrophobic subjects crossing a suspended bridge as a stressful stimulus showed a marked decrease of salivary immunoglobulin A in the placebo group while the GABA group showed significantly higher levels.\nCondition category: normal\nnutrient_topic: GABA research collection; topical membership is not evidence of a direct clinical effect, and the sign of a GABA response depends on the chloride gradient of the cell it was measured in.\nplain_language: A gram taken by mouth changed the pattern of brain waves within an hour in thirteen people.\norganism: Human\ntissue_or_cell_type: Brain electrical activity and saliva\nexperimental_model: Two small studies: electroencephalography after a single intake, and salivary immunoglobulin during a stressor\nlimitations: Thirteen subjects in the first study and eight in the second, with no correction for multiple comparisons reported. The immunity claim rests on salivary immunoglobulin A in eight people.\nexposure: Orally administered GABA against water and against L-theanine, and GABA against placebo in acrophobic subjects crossing a suspended bridge\nevidence_span: {\"source_cache\": \"artifacts/gaba-research/16971751.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"f0958495814a3c685efcafef73349d34248a2648872afa7e4a92c93132d9b631\", \"start_char\": 0, \"end_char\": 1322, \"text_sha256\": \"f0958495814a3c685efcafef73349d34248a2648872afa7e4a92c93132d9b631\"}\n[gb-p16971751] Relaxation and immunity enhancement effects of gamma-aminobutyric acid (GABA) administration in humans. (2006). https://pubmed.ncbi.nlm.nih.gov/16971751/ DOI: 10.1002/biof.5520260305","source_key":"import-1b599eb7-b22a-5fda-bcf0-9d92b5ae1311","source_title":"GABA: a ligand with no sign of its own, the cofactor that limits its synthesis, the barrier that keeps it out of the brain, and the immune settings where the same molecule protects and harms (2026-09-22)","claim_ids":["67459451-8322-5472-b532-045e198595a4"]},{"conflict_id":"49666a25-de11-5da3-b945-ff34954e46e3","ordinal":2,"label":"The drink without any GABA in it lowered blood pressure too, which is what the other trials had no way of detecting.","revision_id":"a12d61de-f189-5bda-af3d-f31a1e61bccf","start_line":391,"end_line":402,"quote":"### gb-the-control-worked-too\nIn volunteers with mildly or moderately high blood pressure, both the fermented drinking water containing gamma-aminobutyric acid and the placebo drink of vinegar and dried bonito without GABA significantly decreased systolic blood pressure by 7.6 plus or minus 4.0 and 5.5 plus or minus 1.5 millimetres of mercury respectively and diastolic by 10.6 plus or minus 4.0 and 7.6 plus or minus 1.7 millimetres of mercury respectively compared to baseline at 12 weeks, there were no abnormal changes in haematological or blood chemistry variables, and these findings indicated that vinegar and dried bonito with or without GABA might have an effect on blood pressure.\nCondition category: normal\nnutrient_topic: GABA research collection; topical membership is not evidence of a direct clinical effect, and the sign of a GABA response depends on the chloride gradient of the cell it was measured in.\nplain_language: The drink without any GABA in it lowered blood pressure too, which is what the other trials had no way of detecting.\norganism: Human\ntissue_or_cell_type: Systemic circulation\nexperimental_model: Double-blind placebo-controlled randomised study with the same fermented drink prepared with and without GABA\nlimitations: The control is the same food matrix minus the GABA, which is the comparison the other blood-pressure studies lack.\nexposure: Fermented drinking water from sodium glutamate, vinegar and dried bonito, against the identical drink without GABA\nevidence_span: {\"source_cache\": \"artifacts/gaba-research/19590713.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"cf28abaa2c4005e26679a43d2ee25123d4ca6fb7184943a6b8c7e0529e560e4a\", \"start_char\": 0, \"end_char\": 1206, \"text_sha256\": \"cf28abaa2c4005e26679a43d2ee25123d4ca6fb7184943a6b8c7e0529e560e4a\"}\n[gb-p19590713] The Effects of gamma-Aminobutyric Acid, Vinegar, and Dried Bonito on Blood Pressure in Normotensive and Mildly or Moderately Hypertensive Volunteers. (2009). https://pubmed.ncbi.nlm.nih.gov/19590713/ DOI: 10.3164/jcbn.09-04","source_key":"import-1b599eb7-b22a-5fda-bcf0-9d92b5ae1311","source_title":"GABA: a ligand with no sign of its own, the cofactor that limits its synthesis, the barrier that keeps it out of the brain, and the immune settings where the same molecule protects and harms (2026-09-22)","claim_ids":["ff22fdae-f873-5805-b15d-a6191f818841"]}]}],"corrections":[],"research":null}