Condition

Digestive Health

Digestive health reflects how well your gut breaks down food, absorbs nutrients and signals your brain, with troubles like bloating, constipation or reflux. The evidence is strongest for senna and psyllium fiber, and trials of senna found intestinal motility went up. Those studies were small, though, with 165 people for senna, and its trials centered on constipation after childbirth or surgery.

Sources: PMID 6996138; PMID 20207340

Supplements studied: 16
Medicines and peptides: 1
Graded outcomes: 17
Trials: 26
People studied: 1,462

Evidence by supplement

Strong
Moderate
Limited
Very limited

16 supplements

Senna

Senna: outcomes studied for Digestive Health
Grade	Outcome	Effect	Size	Studies	People
	Intestinal Motility Large Increase	Improves (the measure goes up)	Large effect	8 studies	165 people
Studies that measured intestinal motility Standardized senna in the management of constipation in the puerperium: A clinical trialS Afr Med J · PMID 6996138 The use of senna with docusate for postoperative constipation after pelvic reconstructive surgery: a randomized, double-blind, placebo-controlled trialAm J Obstet Gynecol · PMID 20207340 A volunteer model for the comparison of laxatives in opioid-related constipationJ Pain Symptom Manage · PMID 8935140 and 5 more on the Senna page
	Constipation Signs and Symptoms Large Improvement	Improves (the measure goes down)	Large effect	2 studies	31 people
Studies that measured constipation signs and symptoms Efficacy of senna versus lactulose in terminal cancer patients treated with opioidsJ Pain Symptom Manage · PMID 9436336 Safety and efficacy of a bulk laxative containing senna versus lactulose in the treatment of chronic constipation in geriatric patientsPharmacology · PMID 8234438

Psyllium

Psyllium: outcomes studied for Digestive Health
Grade	Outcome	Effect	Size	Studies	People
	Fecal Weight Large Increase	Improves (the measure goes down)	Large effect	3 studies	47 people
Studies that measured fecal weight Comparison of the effects of psyllium and wheat bran on gastrointestinal transit time and stool characteristicsJ Am Diet Assoc · PMID 2831263 The effects of a supplement of dietary fibre on faecal excretion by human subjectsBr J Nutr · PMID 465439 An unfermented gel component of psyllium seed husk promotes laxation as a lubricant in humansAm J Clin Nutr · PMID 10966900
	Intestinal Motility	Improves (the measure goes up)			12 people
	Lipid Absorption	Improves (the measure goes up)			4 people

Calcium

Fecal Bile Acids: improves
Lipid Absorption: improves
Fecal Cholesterol: changes; see studies

Calcium: outcomes studied for Digestive Health
Grade	Outcome	Effect	Size	Studies	People
	Fecal Bile Acids Small Increase	Improves (the measure goes up)	Small effect	1 study	48 people
Studies that measured fecal bile acids Faecal steroid excretion in humans is affected by calcium supplementation and shows gender-specific differencesEur J Nutr · PMID 19009227
	Lipid Absorption	Improves (the measure goes up)		1 study	13 people
Studies that measured lipid absorption Calcium in milk products precipitates intestinal fatty acids and secondary bile acids and thus inhibits colonic cytotoxicity in humansCancer Res · PMID 8764120
	Fecal Cholesterol	Changes; see studies			35 people
	Fecal Water Genotoxicity	Changes; see studies			35 people

Triphala (Emblica officinalis, Terminalia chebula, Terminalia bellirica)

Constipation Relief: improves
Gut Microbiome Modulation: improves

Triphala (Emblica officinalis, Terminalia chebula, Terminalia bellirica): outcomes studied for Digestive Health
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Constipation Relief Clinical trial: 1 week treatment increased average weekly bowel frequency by 64.4%, and by 79.5% after 2 weeks. RCT: Triphala churna (3-6g at night with warm water) showed significant improvement in bowel parameters. Mild laxative effect without causing dependence, strengthens bowel musculature.	Improves (the measure goes up)	Moderate effect
	Gut Microbiome Modulation Double-blind RCT (PMID 32955913): Triphala supplementation showed trend toward decreased Firmicutes/Bacteroidetes ratio and increased Akkermansia muciniphila. Enhanced growth of beneficial Bifidobacteria and Lactobacillus while reducing harmful species. Increased short-chain fatty acid production, particularly butyrate.	Improves (the measure goes up)	Small effect

Ginger (Zingiber officinale)

Chemotherapy-Induced Vomiting: improves
Postoperative Nausea/Vomiting: improves
Gastric Emptying Rate: improves

Ginger (Zingiber officinale): outcomes studied for Digestive Health
Grade	Outcome	Effect	Size	Studies	People
	Chemotherapy-Induced Vomiting Meta-analysis (10 RCTs): OR 0.71 (95% CI 0.54-0.94, p=0.015) for CINV control. Systematic review update (18 articles): 60% reduced acute vomiting likelihood with ≤1g/day for >3 days vs control. Also reduced chemotherapy-related fatigue. Nausea results mixed due to clinical heterogeneity.	Improves (the measure goes down)	Moderate effect
	Postoperative Nausea/Vomiting Multiple systematic reviews: Ginger reduces PONV severity and decreases need for rescue antiemetics. Two of three RCTs found ginger superior to placebo and equally effective as metoclopramide. Typical dose: 1g before operation. Some meta-analyses show non-significant difference vs placebo.	Improves (the measure goes down)	Moderate effect
	Gastric Emptying Rate Small Increase	Improves (the measure goes up)	Small effect	4 studies	24 people
Studies that measured gastric emptying rate Effects of ginger on motion sickness susceptibility and gastric functionPharmacology · PMID 2062873 Effects of ginger on gastric emptying and motility in healthy humansEur J Gastroenterol Hepatol · PMID 18403946 Effect of ginger on gastric motility and symptoms of functional dyspepsiaWorld J Gastroenterol · PMID 21218090 and 1 more on the Ginger (Zingiber officinale) page
	Gastric Emptying Multiple small studies suggest ginger promotes gastric motility and accelerates gastric emptying. May benefit functional dyspepsia and gastroparesis. Mechanism involves cholinergic stimulation and prostaglandin modulation. More research needed for clinical recommendations.	Improves (the measure goes up)	Small effect
	Lower Esophageal Pressure	Improves (the measure goes up)		1 study	14 people
Studies that measured lower esophageal pressure Effect of ginger on lower esophageal sphincter pressureJ Med Assoc Thai · PMID 20420113

Ephedrine

Body Fat: improves
Weight: improves
Heart Rate: improves

Ephedrine: outcomes studied for Digestive Health
Grade	Outcome	Effect	Size	Studies	People
	Body Fat Moderate Decrease	Improves (the measure goes down)	Moderate effect	1 study	167 people
Studies that measured body fat An herbal supplement containing Ma Huang-Guarana for weight loss: a randomized, double-blind trialInt J Obes Relat Metab Disord · PMID 11319627
	Weight	Improves (the measure goes down)		9 studies	167 people
Studies that measured weight Multinutrient supplement containing ephedra and caffeine causes weight loss and improves metabolic risk factors in obese women: a randomized controlled trialInt J Obes · PMID 16552410 A randomized double-blind placebo-controlled clinical trial of a product containing ephedrine, caffeine, and other ingredients from herbal sources for treatment of overweight and obesity in the absence of lifestyle treatmentInt J Obes Relat Metab Disord · PMID 15356670 Does ephedrine promote weight loss in low-energy-adapted obese womenInt J Obes · PMID 3301709 and 6 more on the Ephedrine page
	Heart Rate	Improves (the measure goes down)		1 study	167 people
Studies that measured heart rate Efficacy and safety of single and multiple doses of pseudoephedrine in the treatment of nasal congestion associated with common coldAm J Rhinol · PMID 15794071
	High-density lipoprotein (HDL)	Improves (the measure goes up)			167 people
	Low-density lipoprotein (LDL)	Improves (the measure goes down)			167 people

Yacon

Fecal Weight: improves
Intestinal Motility: improves

Yacon: outcomes studied for Digestive Health
Grade	Outcome	Effect	Size	Studies	People
	Fecal Weight Small Increase	Improves (the measure goes down)	Small effect	1 study	16 people
Studies that measured fecal weight Effect of yacon (Smallanthus sonchifolius) on colonic transit time in healthy volunteersDigestion · PMID 18781073
	Intestinal Motility	Improves (the measure goes up)			16 people

Peppermint

Colonic Tension: improves
Pain: improves

Peppermint: outcomes studied for Digestive Health
Grade	Outcome	Effect	Size	Studies	People
	Colonic Tension Small Improvement	Improves (the measure goes up)	Small effect		65 people
	Pain	Improves (the measure goes down)		1 study	65 people
Studies that measured pain Premedication with peppermint oil capsules in colonoscopy: a double blind placebo-controlled randomized trial studyActa Gastroenterol Belg · PMID 23082707

Lactobacillus reuteri

Constipation Signs and Symptoms: improves
Infant crying: improves
Immunity: improves

Lactobacillus reuteri: outcomes studied for Digestive Health
Grade	Outcome	Effect	Size	Studies	People
	Constipation Signs and Symptoms Small Improvement	Improves (the measure goes down)	Small effect		468 people
	Infant crying	Improves (the measure goes up)		8 studies	468 people
Studies that measured infant crying Probiotics for infantile colic: Is there evidence beyond doubt? A meta-analysis and systematic review.Acta Paediatr · PMID 37962097 Probiotics to prevent or treat excessive infant crying: systematic review and meta-analysisJAMA Pediatr · PMID 24100440 Treating infant colic with the probiotic Lactobacillus reuteri: double blind, placebo controlled randomised trialBMJ · PMID 24690625 and 5 more on the Lactobacillus reuteri page
	Immunity	Improves (the measure goes up)		1 study	31 people
Studies that measured immunity Safety and tolerability of Lactobacillus reuteri DSM 17938 and effects on biomarkers in healthy adults: results from a randomized masked trialPLoS One · PMID 22970150
	Lung Function	Improves (the measure goes up)		1 study	30 people
Studies that measured lung function Improvement of digestive health and reduction in proteobacterial populations in the gut microbiota of cystic fibrosis patients using a Lactobacillus reuteri probiotic preparation: a double blind prospective studyJ Cyst Fibros · PMID 24636808
	TNF-Alpha	Improves (the measure goes down)		1 study	30 people
Studies that measured tnf-alpha Lactobacillus reuteri ATCC55730 in cystic fibrosisJ Pediatr Gastroenterol Nutr · PMID 24121143
	Interleukin 1-beta	Improves (the measure goes down)			30 people
	Interleukin 10	Improves (the measure goes up)			30 people
	Interleukin 6	Improves (the measure goes down)			30 people
	Interleukin 8	Changes; see studies			30 people
	Lipid Absorption	Improves (the measure goes up)			30 people
	Lymphocyte Count	Improves (the measure goes up)			31 people
	Monocyte Count	Improves (the measure goes up)			31 people
	Weight	Improves (the measure goes down)			30 people

Lactobacillus Casei

Blood glucose
Intestinal Permeability: improves
Immunity: improves

Lactobacillus Casei: outcomes studied for Digestive Health
Grade	Outcome	Effect	Size	Studies	People
	Blood glucose No effect		NoneNo effect		28 people
	Intestinal Permeability	Improves (the measure goes up)		1 study	28 people
Studies that measured intestinal permeability The influence of probiotic supplementation on gut permeability in patients with metabolic syndrome: an open label, randomized pilot studyEur J Clin Nutr · PMID 22872030
	Immunity	Improves (the measure goes up)			28 people
	Weight	Improves (the measure goes down)			28 people

Citrulline

Blood Flow: improves

Citrulline: outcomes studied for Digestive Health
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Blood Flow	Improves (the measure goes up)		2 studies	10 people
Studies that measured blood flow Acute effects of Nitrosigine® and citrulline malate on vasodilation in young adultsJ Int Soc Sports Nutr · PMID 32093766 L-citrulline improves splanchnic perfusion and reduces gut injury during exerciseMed Sci Sports Exerc · PMID 24621960

Fish Oil

Intestinal Permeability: improves

Fish Oil: outcomes studied for Digestive Health
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Intestinal Permeability	Improves (the measure goes up)		1 study	200 people
Studies that measured intestinal permeability The impact of probiotics and n-3 long-chain polyunsaturated fatty acids on intestinal permeability in pregnancy: a randomised clinical trialBenef Microbes · PMID 29345158

Green Tea Extract

Carbohydrate Absorption: improves

Green Tea Extract: outcomes studied for Digestive Health
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Carbohydrate Absorption	Improves (the measure goes up)		1 study	28 people

Colostrum

Intestinal Permeability: improves

Colostrum: outcomes studied for Digestive Health
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Intestinal Permeability	Improves (the measure goes up)		1 study	22 people

Curcumin

Intestinal Motility: improves

Curcumin: outcomes studied for Digestive Health
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Intestinal Motility	Improves (the measure goes up)		1 study	8 people

Astaxanthin

Inflammation: changes; see studies

Astaxanthin: outcomes studied for Digestive Health
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Inflammation	Changes; see studies		1 study	44 people

Prescription medicines and peptides studied, for context

These are not supplements. Most need a prescription, and some are research compounds with no approved use. They are listed so the supplement evidence above can be read against them.

1 medicine or peptide

Ipamorelin

Gastric Motility: improves
Postoperative Recovery

Ipamorelin: outcomes studied for Digestive Health
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Gastric Motility Ipamorelin demonstrated dose-dependent improvement in gastric emptying in rodent models of postoperative ileus, though human clinical trials showed no significant difference versus placebo.	Improves (the measure goes up)	Moderate effect	5 studies
	Postoperative Recovery In a randomized controlled trial of bowel resection patients, ipamorelin was well-tolerated but showed no significant differences versus placebo in time to first bowel movement or hospital discharge.		NoneNo effect	4 studies

What the published studies found

5 automated readings

Automated reading of the published studies (Decosa evidence engine), for outcomes Dr. Grey has not graded yet. It is not a Dr. Grey grade and does not change one. How it is read

Ginger (Zingiber officinale): bloating
The 3 studies read (121 people in all) mostly found an improvement in bloating. The evidence is limited.
3 studies counted of 8 read: 3 trials (121 people in the trials).
1. Randomised trial, 2023; 52 people; patients with relapsing-remitting multiple sclerosis: improves. severity (-11.57 ± 5.09 vs. 3.97 ± 3.99, P = 0.047) of bloating The effects of ginger supplementation on common gastrointestinal symptoms in patients with relapsing-remitting multiple sclerosis: a double-blind randomized placebo-controlled trialPubMed 37891539
2. Randomised trial, 2022; 50 people: improves. upper abdominal bloating and early satiation was 64% in subjects receiving ONLP-06 A Randomized, Double-Blind, Placebo Controlled, Parallel-Group, Comparative Clinical Study to Evaluate the Efficacy and Safety of OLNP-06 versus Placebo in Subjects with Functional DyspepsiaPubMed 33305631
3. Crossover trial, 2011; 19 people; healthy male volunteers: no clear difference. bloating, fullness, nausea, discomfort and hunger was not different The effects of ginger on gallbladder motility in healthy male humansPubMed 22148111
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Peppermint: bloating
The studies read are too weak to tell whether Peppermint changes bloating. They lean toward an improvement, which is not enough to claim one. The evidence is very weak.
3 studies counted of 8 read: 2 trials (89 people in the trials).
1. Study, 2025; patients with functional dyspepsia: improves. Updated document on the management of functional dyspepsia by the Asociación Española de Neurogastroenterologia y Motilidad (ASENEM) and Sociedad Española de Medicina Familiar y Comunitaria (semFYC)PubMed 39812003
2. Randomised trial, 2024; 32 people: improves. POCO induced less epigastric burning, bloating, and fullness The combination of L-menthol and caraway oil does not affect gastric function but increases hunger in healthy subjectsPubMed 39056471
3. Randomised trial, 2007; 57 people: improves. statistically significant reduction of the total irritable bowel syndrome symptoms score Peppermint oil (Mintoil) in the treatment of irritable bowel syndrome: a prospective double blind placebo-controlled randomized trialPubMed 17420159
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Probiotics: gastrointestinal symptoms
The studies disagree. A Cochrane review (2022, 5 studies, 250 people) did not settle it for gastrointestinal symptoms, while 8 of the 10 studies read found an improvement. The evidence is very weak.
10 studies counted of 11 read: 6 reviews and 4 trials (161 people in the trials).
1. Systematic review, 2022; 5 studies, 250 people; solid organ transplant recipients: unclear: evidence too weak to tell (the review the verdict rests on). Probiotics had uncertain effects on GI side effects Synbiotics, prebiotics and probiotics for solid organ transplant recipientsPubMed 36126902
2. Systematic review, 2026; 15 studies, 1,015 people; individuals with autism spectrum disorder: improves. improvements in GI symptoms, such as reduced abdominal pain Pre- and probiotics for gastrointestinal and behavioral symptoms in autism spectrum disorder: a systematic reviewPubMed 42682264
3. Meta-analysis, 2026; 28 studies; patients with Helicobacter pylori infection: improves. Evaluating probiotic monotherapy in Helicobacter pylori infection: A meta-analysis of randomized controlled trials with trial sequential analysisPubMed 41581709
4. Meta-analysis, 2026; 12 studies; adults with colorectal cancer receiving chemotherapy: improves. significantly reduced chemotherapy-related diarrhea (odds ratio 0.48 Comparative Effects of Microbiota-Modifying Interventions for Gastrointestinal Disorders in Adults with Colorectal Cancer: A Systematic Review and Network Meta-AnalysisPubMed 42804968
5. Meta-analysis, 2025; 18 studies, 1,246 people: improves. alleviated gastrointestinal disturbances, such as diarrhea Research progress of probiotics intervention on reconstruction of intestinal flora and improvement of quality of life in patients after endometrial cancer surgeryPubMed 41050754
6. Meta-analysis, 2015; 23 studies, 3,938 people; children receiving antibiotics: improves. incidence of AAD in the probiotic group was 8% Probiotics for the prevention of pediatric antibiotic-associated diarrheaPubMed 26695080
7. Randomised trial, 2025; 59 people; overweight and obese adults aged 20-40: improves. alleviated symptoms such as gastroesophageal reflux Impact of probiotic Lactobacillus plantarum GKM3 on gastrointestinal health in overweight and obese individuals: A randomized clinical trialPubMed 40383259
8. Randomised trial, 2025; 22 people; patients with irritable bowel syndrome with predominant diarrhea: improves. Colonoscopic administration of probiotics to treat irritable bowel syndrome with predominant diarrhea: a randomized placebo-controlled clinical trialPubMed 39849073
9. Randomised trial, 2025; 16 people; female dancers: no clear difference. No improvement in gastrointestinal symptoms was observed A Randomized Controlled Trial Evaluating the Effects of a Probiotic Containing Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 on Gastrointestinal Symptoms and Metabolomic Profiles in Female DancersPubMed 40565286
10. Randomised trial, 2017; 64 people; patients receiving aspirin for more than one month: improves. FSSG and GSRS scores were also significantly improved Yogurt Containing Lactobacillus gasseri Mitigates Aspirin-Induced Small Bowel Injuries: A Prospective, Randomized, Double-Blind, Placebo-Controlled TrialPubMed 28052291
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Probiotics: irritable bowel syndrome symptoms
A Cochrane review (2023, 18 studies, 1,309 people) found a large improvement in irritable bowel syndrome symptoms. That review studied children with functional abdominal pain disorders. 9 of the 11 studies read agree; 1 found no clear answer, 1 found no clear difference. The evidence is limited.
11 studies counted of 11 read: 11 reviews.
1. Meta-analysis, 2023; 18 studies, 1,309 people; children with functional abdominal pain disorders: improves (the review the verdict rests on). Probiotics may achieve more treatment success when compared with placebo Probiotics for management of functional abdominal pain disorders in childrenPubMed 36799531
2. Meta-analysis, 2026; 12 studies, 1,303 people; patients with irritable bowel syndrome: improves. Multistrain probiotics significantly reduced total IBS-SSS scores [mean difference = -43.66, 95% confidence interval (CI): … Effect of multistrain probiotics on symptom severity in irritable bowel syndrome: a systematic review and meta-analysis of irritable bowel syndrome-symptom severity score outcomesPubMed 41433106
3. Meta-analysis, 2025; 16 studies, 2,823 people: improves. Probiotics showed a clinically significant overall improvement Efficacy of Specific Probiotic Strains in Subtypes of Irritable Bowel Syndrome: Systematic Review and Meta-Analysis of Randomized Controlled TrialsPubMed 41597375
4. Systematic review, 2025; 44 studies; patients with irritable bowel syndrome: improves. significantly lower effectiveness than the probiotics group Effects of Probiotics and Diet Management in Patients With Irritable Bowel Syndrome: A Systematic Review and Network Meta-analysisPubMed 39862384
5. Meta-analysis, 2024; 23 studies, 3,288 people: improves. Efficacy of Probiotics in the Management of Irritable Bowel Syndrome: A Systematic Review and Meta-AnalysisPubMed 39830577
6. Meta-analysis, 2024; 20 studies, 3,011 people: improves. probiotics are more effective than placebo in reducing global IBS symptoms improvement rate Efficacy and safety of probiotics in irritable bowel syndrome: A systematic review and meta-analysisPubMed 38479936
7. Meta-analysis, 2023; 72 studies; people with irritable bowel syndrome: improves. significantly better overall effect of probiotics than placebo Probiotics for the management of irritable bowel syndrome: a systematic review and three-level meta-analysisPubMed 37565634
8. Meta-analysis, 2022; 16 studies, 1,585 people; patients with diarrhea: improves. Meta-analysis of the efficacy of probiotics to treat diarrheaPubMed 36197181
9. Meta-analysis, 2018; 53 studies, 5,545 people; adults with irritable bowel syndrome: unclear: evidence too weak to tell. beneficial effects on global IBS symptoms and abdominal pain Systematic review with meta-analysis: the efficacy of prebiotics, probiotics, synbiotics and antibiotics in irritable bowel syndromePubMed 30294792
10. Meta-analysis, 2017; 19 studies, 1,453 people; children with recurrent abdominal pain or irritable bowel syndrome: improves. probiotics were more likely to experience improvement in pain Dietary interventions for recurrent abdominal pain in childhoodPubMed 28334433
11. Systematic review, 2009; 2 studies, 168 people; school-age children with recurrent abdominal pain: no clear difference. Dietary interventions for recurrent abdominal pain (RAP) and irritable bowel syndrome (IBS) in childhoodPubMed 19160214
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Probiotics: bloating
The best available review (2013, 37 studies) found an improvement in bloating. That review studied adults with lower gastrointestinal symptoms. 5 of the 7 studies read agree; 2 found no clear difference. The evidence is moderate.
Side effects: 1 of the 8 studies that reported on them found more with Probiotics (gastrointestinal adverse events).
7 studies counted of 11 read: 4 reviews and 3 trials (500 people in the trials).
1. Systematic review, 2013; 37 studies; adults with lower gastrointestinal symptoms: improves (the review the verdict rests on). reduce bloating/distension and improve bowel movement frequency/consistency in some IBS patients Systematic review: probiotics in the management of lower gastrointestinal symptoms in clinical practice -- an evidence-based international guidePubMed 23981066
2. Systematic review, 2026; patients with irritable bowel syndrome: improves. probiotics can modestly improve global symptoms, abdominal pain, and bloating in IBS Clinical guidance and practical recommendations for probiotic use in patients with irritable bowel syndrome, functional constipation, and Clostridioides difficile infection considering sex-based differences: a Korean translationPubMed 41980747
3. Meta-analysis, 2024; 23 studies, 3,288 people: improves. Efficacy of Probiotics in the Management of Irritable Bowel Syndrome: A Systematic Review and Meta-AnalysisPubMed 39830577
4. Meta-analysis, 2022; 13 studies; healthy adults: no clear difference. No improvement in abdominal pain and bloating was found. Effects of Bifidobacterium animalis subspecies lactis supplementation on gastrointestinal symptoms: systematic review with meta-analysisPubMed 34918142
5. Randomised trial, 2026; 350 people; healthy individuals with self-reported bloating or indigestion: improves. Bloating and gas were reduced in the synbiotic arm A Randomized, Placebo-Controlled Trial Evaluating Multi-Species Synbiotic Supplementation for Bloating, Gas, and Abdominal DiscomfortPubMed 41599868
6. Crossover trial, 2026; 25 people; healthy adults: no clear difference. A high-fibre snack containing Lacticaseibacillus rhamnosus GG for healthy adults: a randomised, double-blind, placebo-controlled crossover trialPubMed 42642033
7. Randomised trial, 2023; 125 people; patients with functional abdominal bloating: improves. patients in the probiotic group had a significantly lower frequency of abdominal bloating Evaluation and comparison of therapeutic effects of probiotics and colloidal bismuth subcitrate on abdominal bloatingPubMed 37520877
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.

Key findings

Intestinal MotilitySennaImproves (the measure goes up)
Fecal WeightPsylliumImproves (the measure goes down)
Constipation Signs and SymptomsSennaImproves (the measure goes down)

The Digestive Health (General GI Support) protocol

2 primary supplements · 5 supporting supplements

Probiotics (Multi-strain)10–50 billion CFU daily (Lactobacillus, Bifidobacterium strains)
Psyllium Fiber5–10 g daily with plenty of water

See the full protocol

Shop the evidence-backed picks

Fullscript collectionGut and digestion: evidence-graded picksOpen on Fullscript

The collection holds the supplements we grade A or B for its theme, in third-party tested products where the catalog has them. It opens in our Fullscript store. You can look through it without signing in; Fullscript asks for a free account to order.

Or shop one supplement

The supplements graded A or B for Digestive Health. Each opens third-party tested products for that supplement.

Grade A
Grade A
Grade B
Grade B
Grade B

We earn from purchases made in our Fullscript store, and links to Fullscript, iHerb or Thorne carry our referral, so we may earn a commission at no extra cost to you. Grades come from the research and never change based on what we earn. Full disclosure

Studies cited

2 studies from PubMed

Impact of 24-h high and low fermentable oligo-, di-, monosaccharide, and polyol diets on markers of exercise-induced gastrointestinal syndrome in response to exertional heat stressAppl Physiol Nutr Metab · PMID 31652404
Effects of kefir or milk supplementation on zonulin in overweight subjectsJ Dairy Sci · PMID 32171508