Condition

Constipation

Constipation happens when stool moves too slowly through the colon, so extra water is absorbed and stools turn hard and difficult to pass. The evidence is strongest for linaclotide and plecanatide, and trials found people had more complete spontaneous bowel movements each week than those on placebo, with linaclotide also improving stool consistency and reducing straining. Gentler options like psyllium, senna and jujube have limited evidence, mostly from a few small studies.

Sources: PMID 29380823; PMID 23644388; PMID 28169285

Supplements studied: 6
Medicines and peptides: 2
Graded outcomes: 8
Trials: 8
People studied: 735

Evidence by supplement

Strong
Moderate
Limited
Very limited

6 supplements

Senna

Senna: outcomes studied for Constipation
Grade	Outcome	Effect	Size	Studies	People
	Constipation Signs and Symptoms Large Improvement	Improves (the measure goes down)	Large effect	2 studies	30 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
	Intestinal Motility	Improves (the measure goes up)		8 studies	30 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

Jujube

Jujube: outcomes studied for Constipation
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Constipation Signs and Symptoms Small Improvement	Improves (the measure goes down)	Small effect	1 study	37 people
Studies that measured constipation signs and symptoms Ziziphus jujuba extract for the treatment of chronic idiopathic constipation: a controlled clinical trialDigestion · PMID 19142004

Psyllium

Constipation Signs and Symptoms: improves
Fecal Weight: improves
Stool Consistency: improves

Psyllium: outcomes studied for Constipation
Grade	Outcome	Effect	Size	Studies	People
	Constipation Signs and Symptoms Moderate Improvement	Improves (the measure goes down)	Moderate effect	1 study	297 people
Studies that measured constipation signs and symptoms The effect of fiber supplementation on chronic constipation in adults: an updated systematic review and meta-analysis of randomized controlled trials.Am J Clin Nutr · PMID 35816465
	Fecal Weight	Improves (the measure goes down)		3 studies	15 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
	Stool Consistency	Improves (the measure goes up)			297 people

Lactobacillus reuteri

Constipation Signs and Symptoms: improves
Fecal Weight: improves

Lactobacillus reuteri: outcomes studied for Constipation
Grade	Outcome	Effect	Size	Studies	People
	Constipation Signs and Symptoms Small Improvement	Improves (the measure goes down)	Small effect		44 people
	Fecal Weight	Improves (the measure goes down)		1 study	44 people
Studies that measured fecal weight Lactobacillus reuteri (DSM 17938) in infants with functional chronic constipation: a double-blind, randomized, placebo-controlled studyJ Pediatr · PMID 20542295

Magnesium

Constipation Signs and Symptoms: improves

Magnesium: outcomes studied for Constipation
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Constipation Signs and Symptoms	Improves (the measure goes down)		3 studies	184 people
Studies that measured constipation signs and symptoms Senna Versus Magnesium Oxide for the Treatment of Chronic Constipation: A Randomized, Placebo-Controlled Trial.Am J Gastroenterol · PMID 32969946 Lactobacillus reuteri DSM 17938 and Magnesium Oxide in Children with Functional Chronic Constipation: A Double-Blind and Randomized Clinical Trial.Nutrients · PMID 31952280 A Randomized Double-blind Placebo-controlled Trial on the Effect of Magnesium Oxide in Patients With Chronic Constipation.J Neurogastroenterol Motil · PMID 31587548

Inulin

Constipation Signs and Symptoms: improves

Inulin: outcomes studied for Constipation
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Constipation Signs and Symptoms	Improves (the measure goes down)		1 study	252 people
Studies that measured constipation signs and symptoms Effectiveness of inulin intake on indicators of chronic constipation; a meta-analysis of controlled randomized clinical trials.Nutr Hosp · PMID 25208775

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.

2 medicines and peptides

Linaclotide (Linzess)

Abdominal Bloating: improves
Complete Spontaneous BM: improves

Linaclotide (Linzess): outcomes studied for Constipation
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Abdominal Bloating Phase 3b: Significant reduction in moderate-to-severe bloating. Improved quality of life and global assessment. Both 145 and 290 mcg doses effective for bloating symptom relief.	Improves (the measure goes down)	Large effect	23 studies
	Complete Spontaneous BM Significant increase in CSBMs/week vs placebo. Phase 3 CIC: ≥3 CSBMs/week with ≥1 increase from baseline achieved in significantly more patients. Improved stool consistency and reduced straining.	Improves (the measure goes up)	Large effect	22 studies

Plecanatide (Trulance)

Abdominal Bloating: improves
Durable CSBM Response CIC: improves

Plecanatide (Trulance): outcomes studied for Constipation
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Abdominal Bloating Significant improvement in bloating, cramping, discomfort, and fullness vs placebo. Benefits observed by week 1 and sustained through 12 weeks. Similar efficacy to linaclotide with lower diarrhea rate.	Improves (the measure goes down)	Large effect	12 studies
	Durable CSBM Response CIC Phase 3: 21.0% durable overall CSBM responders (3mg) vs 10.2% placebo (P<0.001). Responders had ≥3 CSBMs/week with ≥1 increase for ≥9 of 12 weeks. CSBM frequency increased 2.5/week vs 1.2/week placebo.	Improves (the measure goes up)	Large effect	11 studies

What the published studies found

1 automated reading

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

Magnesium: constipation
The best available review (2023, 8 studies, 787 people) found a large improvement in constipation. That review studied adults with chronic constipation. All 5 studies read agree. The evidence is moderate.
Side effects: 1 of the 3 studies that reported on them found more with Magnesium (diarrhea).
5 studies counted of 11 read: 1 review and 4 trials (455 people in the trials).
1. Meta-analysis, 2023; 8 studies, 787 people; adults with chronic constipation: improves (the review the verdict rests on). 68% responded to magnesium oxide and 19% to control The effect of food, vitamin, or mineral supplements on chronic constipation in adults: A systematic review and meta-analysis of randomized controlled trialsPubMed 37243443
2. Randomised trial, 2021; 90 people; patients with chronic idiopathic constipation: improves. 68.3% in the MgO group (P < 0.0001) Senna Versus Magnesium Oxide for the Treatment of Chronic Constipation: A Randomized, Placebo-Controlled TrialPubMed 32969946
3. Randomised trial, 2019; 226 people; outpatients with functional constipation: improves. Treatment response was more frequent in the Hépar arm Time to treatment response of a magnesium- and sulphate-rich natural mineral water in functional constipationPubMed 31170680
4. Randomised trial, 2019; 33 people; japanese female patients with chronic constipation: improves. met by 25.0% of placebo vs 70.6% of MgO group A Randomized Double-blind Placebo-controlled Trial on the Effect of Magnesium Oxide in Patients With Chronic ConstipationPubMed 31587548
5. Randomised trial, 2017; 106 people: improves. complete spontaneous bowel movements per week tended to be higher Efficacy and safety of a natural mineral water rich in magnesium and sulphate for bowel function: a double-blind, randomized, placebo-controlled studyPubMed 26582579
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

Constipation Signs and SymptomsSennaImproves (the measure goes down)

The Constipation protocol

2 primary supplements · 2 supporting supplements

Magnesium400–800 mg daily (citrate or oxide form)
Psyllium Husk5–10 g daily with plenty of water

See the full protocol

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Studies cited

1 study from PubMed

Effects of a kefir supplement on symptoms, colonic transit, and bowel satisfaction score in patients with chronic constipation: a pilot studyTurk J Gastroenterol · PMID 25599776