Do chia seeds help with constipation?

Possibly, but chia seeds on their own have never been tested against a control for constipation. The closest thing is a 2025 randomized crossover trial in 60 people with irritable bowel syndrome with constipation, in which a powder of chia seed, pea protein and xyloglucan softened stools more than placebo at day 15 and day 28. Chia was one of three ingredients, so the result cannot be credited to chia. A 2024 meta-analysis of foods for chronic constipation gathered 23 studies in 1,714 adults, and none of them tested chia.

Unsettled. The case for chia rests on an argument from fiber rather than on a chia trial. Fiber supplements above 10 g a day added 1.60 bowel movements a week in a meta-analysis of randomized trials, with a confidence interval of 0.71 to 2.48. Those trials mostly used psyllium and pectin. Chia fiber is mostly insoluble and psyllium is a viscous soluble fiber, so whether chia behaves the same way is an open question.

What the trials found

The only randomized trial is the 2025 one in people with IBS-C. It was double-blind and placebo controlled, run at several centers, with 28 days on each arm and a 28-day washout between them. Stool consistency on the Bristol scale was better than placebo at day 15 (p = 0.04) and at day 28 (p below 0.001), and IBS symptoms were better at day 15 (p below 0.001). The abstract gives no effect size, does not list stool frequency among the outcomes and does not say how much chia was in each dose. The product is industry-linked.

The only study of chia by itself had no control group. Nine older women in Bahia, Brazil, with constipation by the Rome III criteria took 12 g of chia a day with water for 45 days, and every item on the Rome III questionnaire improved. They were advised to drink water at the same time, and with nine people and nothing to compare against, this cannot separate chia from the water, the attention or the passage of time.

The 2024 food meta-analysis is useful for a different reason. Its 23 studies covered kiwifruit, high-mineral water, prunes, rye bread, mango, fig, cereal, oat bran, yogurt and a few diets. In that review, fruits beat psyllium by 0.36 bowel movements a week. If you want a food with trial evidence behind it for constipation, the list starts there and chia is not on it yet.

Who should be careful

Not for everyone. Dry chia seeds absorb a lot of water and turn into a gel. A 2017 case report describes that gel blocking the esophagus of one adult with likely eosinophilic esophagitis, which needed an endoscopy to clear. It is a single case in someone with an existing esophageal problem. It is still the reason to soak chia or take it with plenty of fluid, and to be cautious if you have trouble swallowing.

Large amounts are a separate issue. A 59-year-old woman eating six tablespoons of chia and five handfuls of almonds a day to manage IBS developed calcium oxalate deposits in her kidneys, with creatinine rising from 1.3 to 1.8 mg/dL, and her results improved on a low-oxalate diet. The almonds contributed, and it is one case. Allergy to chia exists too. The EU food safety agency says allergic reactions to chia seeds may occur, on the strength of two case reports, and nobody knows how common it is. In the IBS-C trial no serious adverse events were reported over two 28-day treatment periods, and the abstract does not describe milder ones such as bloating or gas.

What expert bodies say

We found no expert body that recommends chia for constipation. The European Food Safety Authority assessed chia as a novel food in 2019. Reviewing human studies that used up to 50 g a day for up to six months, it found no changes in safety-related measures and no adverse events related to chia. The Panel notes those trials were not designed to test safety, and gut tolerance such as gas and bloating was not a studied outcome.

How we searched

What would change this answer

• A randomized trial of chia seeds alone, at a set dose, against placebo or psyllium, in adults with chronic constipation, reporting stool frequency and the share of people who respond. Comparing soaked with dry seeds in the same trial would also settle the practical question of how to take it.
• Publication of NCT05923723. It would add a result for a multi-fiber blend containing chia in older adults, though it still could not isolate chia.
• The full text of the 2025 IBS-C trial, which would show how much chia each dose contained and whether stool frequency changed.

More on chia, including what the trials on cholesterol, blood sugar and weight found: chia seeds →

Sources

1. ev-chco-01 · Randomized controlled trial(s) · multicenter double-blind randomized placebo-controlled crossover trial, 28 days per arm with 28-day washout · n = 60
   Results: Compared to the placebo, XP + CS significantly improved stool consistency (p = 0.04 and p < 0.001 at days 15 and 28, respectively), IBS symptoms (p < 0.001 at day 15), QoL (p < 0.001 from day 15 on), and nearly all SIP domains (p < 0.001 at all time-points).
   
   Who: patients with irritable bowel syndrome with constipation (IBS-C)
   Effect: stool consistency (Bristol scale) better than placebo at day 15 (p = 0.04) and day 28 (p < 0.001); IBS symptoms p < 0.001 at day 15; no effect size reported in the abstract
   Certainty: Chia is one of three ingredients, so the effect cannot be credited to chia; chia dose not given in the abstract and the full text (MDPI) returned 403. Stool frequency not among the listed outcomes. Industry-linked product.
   Gastrointestinal Disorders, 2025, Efficacy and Safety of Chia Seed Powder, Pea Protein, and Xyloglucan in Patients with Constipation-Predominant Irritable Bowel Syndrome: A Multicenter, Double-Blind, Randomized, Placebo-Controlled Trial · checked 2026-10-06 · we read the abstract
2. ev-chco-02 · Randomized controlled trial(s) · multicenter double-blind randomized placebo-controlled crossover trial · n = 60
   No serious adverse events were reported.
   
   Who: patients with irritable bowel syndrome with constipation (IBS-C)
   Effect: no serious adverse events over two 28-day treatment periods
   Certainty: Short trial; mild events (bloating, gas) not described in the abstract.
   Gastrointestinal Disorders, 2025, Efficacy and Safety of Chia Seed Powder, Pea Protein, and Xyloglucan in Patients with Constipation-Predominant Irritable Bowel Syndrome: A Multicenter, Double-Blind, Randomized, Placebo-Controlled Trial · checked 2026-10-06 · we read the abstract
3. ev-chco-03 · Observational data · uncontrolled before-and-after intervention study · n = 9
   Results: We have observed that the seed was able to suppress the intestinal constipation, and we verified an improvement in all the factors investigated by the Roma III Questionnaire.
   
   Who: elderly women with intestinal constipation (Rome III), Planalto, Bahia
   Effect: improvement in all Rome III items after 45 days; no statistics on stool frequency in the abstract; weight and waist unchanged
   Certainty: No control group, 9 participants (pre n=9, post n=9 in Table 1 of the PDF), water advice given at the same time. Journal not in MEDLINE.
   O Mundo da Saude, 2017, 41(3):315-322, The effect of chia on intestinal function, anthropometric and Hemodynamic parameters in elderly women · checked 2026-10-06 · we read the fulltext
4. ev-chco-04 · Meta-analysis or systematic review · systematic review and meta-analysis · n = 23 studies, 1714 participants
   RESULTS: We included 23 studies (17 RCTs, 6 uncontrolled; 1714 participants): kiwifruit (n = 7), high-mineral water (n = 4), prunes (n = 2), rye bread (n = 2), mango, fig, cereal, oat bran, yoghurt, water supplementation, prune juice, high-fibre diet, no-fibre diet (n = 1).
   
   Who: adults with chronic constipation in intervention trials of foods, drinks and diets, searched to July 2023
   Effect: foods studied: kiwifruit, mineral water, prunes, rye bread, mango, fig, cereal, oat bran, yogurt and others; no chia or other seed trials
   Certainty: Absence of chia is the finding; fruits beat psyllium by 0.36 bowel movements a week, rye bread beat white bread.
   Aliment Pharmacol Ther, 2024 · checked 2026-10-06 · we read the abstract
5. ev-chco-05 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs, subgroup analysis · n = —
   High fiber doses (>10 g/d) increased stool frequency [MD: +1.60 bowel movements/week (95% CI: 0.71, 2.48 bowel movements/week; P = 0.0004); I2 = 85% (P < 0.00001)], but low fiber doses (≤10 g/d) did not, with a significant subgroup effect (P = 0.07).
   
   Who: adults with chronic constipation, subgroup of RCTs of fiber supplements reporting bowel movements per week
   Effect: doses above 10 g/d MD +1.60 bowel movements/week (95% CI 0.71 to 2.48); doses of 10 g/d or less no significant effect
   Certainty: Indirect: trials used supplements (psyllium, pectin), not chia. Chia fiber is mostly insoluble, psyllium is viscous soluble, so transfer is uncertain. Chia fiber content (about 34 g/100 g) is from USDA SR Legacy and not carded here.
   Am J Clin Nutr, 2022 · checked 2026-10-06 · we read the fulltext
6. ev-chco-06 · Laboratory or animal data · case report · n = 1
   Chia seeds, a staple known for health benefits, have an uncanny ability to absorb large quantities of water leading to a hydrated gel-like substance which can cause an obstruction.
   
   Who: one adult patient with likely eosinophilic esophagitis
   Effect: esophageal food impaction by hydrated chia gel requiring endoscopic clearance
   Certainty: Single case; underlying esophageal disease. Supports soaking chia or taking it with fluid, and caution in people with swallowing problems.
   Case Reports in Internal Medicine, 2017, 4(2):49, Watch it grow: Esophageal impaction with chia seeds · checked 2026-10-06 · we read the abstract
7. ev-chco-07 · Laboratory or animal data · case report · n = 1
   Diet included six tablespoons of chia seeds and five handfuls of almonds daily to manage IBS symptoms.
   
   Who: 59-year-old woman with controlled hypertension managing IBS symptoms by diet
   Effect: creatinine rose from 1.3 to 1.8 mg/dL; biopsy showed calcium oxalate deposition; labs improved after a low-oxalate diet
   Certainty: Single case; almonds contributed; dose far above usual 1 to 2 tablespoons.
   BMJ Case Rep, 2020 · checked 2026-10-06 · we read the abstract
8. ev-chco-08 · Position of an expert body · scientific opinion of the EFSA NDA Panel (novel food safety assessment) · n = 2 case reports
   The information available indicates that allergic reactions upon consumption of chia seeds may occur.
   
   Who: consumers of chia seeds; case reports from Spain
   Effect: allergic reactions reported in case reports; prevalence of chia allergy unknown
   Certainty: Case reports only; no prevalence data.
   EFSA Journal, 2019, Safety of chia seeds (Salvia hispanica L.) as a novel food for extended uses pursuant to Regulation (EU) 2015/2283 · checked 2026-10-06 · we read the fulltext
9. ev-chco-09 · Position of an expert body · scientific opinion of the EFSA NDA Panel (novel food safety assessment) · n = studies of 10 to 77 participants
   The Panel notes that no changes were found in the studied safety-related parameters and no adverse events related to the consumption of chia seeds were reported.
   
   Who: adults in human studies of chia seeds reviewed by EFSA, up to 50 g/day for up to 6 months
   Effect: no changes in safety-related parameters and no chia-related adverse events reported
   Certainty: The Panel notes the trials were not designed for safety; gut tolerance (gas, bloating) was not a studied endpoint.
   EFSA Journal, 2019, Safety of chia seeds (Salvia hispanica L.) as a novel food for extended uses pursuant to Regulation (EU) 2015/2283 · checked 2026-10-06 · we read the fulltext