Guide

Does Bio Complete 3 work? What is in the capsule and what the trials say

Bio Complete 3 is a two-capsule daily formula from Gundry MD that puts three kinds of ingredient in one serving: a prebiotic fiber blend, a postbiotic (tributyrin, a form of butyrate) and two probiotic species. The founder, Dr. Steven Gundry, is the brand’s face, and the capsule is sold through the brand site and Amazon. This page sets out what the panel prints, what each part has behind it in trials, how the daily dose is written, where the reviews split and what the brand’s terms say.

What Bio Complete 3 is, and what it is not

The Supplement Facts panel lists, per serving of two capsules, a Prebiotic Blend of 450 mg (acacia gum and partially hydrolyzed guar gum, no split between the two), a Postbiotic Blend of 300 mg (tributyrin) and a Probiotic Blend of 22 mg (Bacillus coagulans and Bifidobacterium bifidum). A bottle holds 30 servings. The panel gives no CFU count and no strain designations. The brand’s FAQ and Amazon name the guar fiber as Sunfiber, and retail pages name strains and about 2 billion CFU, but none of that is on the brand panel or in the certificate of analysis, so we treat it as unverified. Other ingredients are hypromellose, microcrystalline cellulose, silica, magnesium stearate and maltodextrin.

The formula has changed. Earlier retail and review pages describe a different panel (a tributyrin ingredient at 1,000 mg standardized to 30%, Sunfiber 200 mg and B. coagulans 16 mg), and many review sites still quote those figures. The current brand panel does not print them. The brand publishes a certificate of analysis for one lot that checks tributyrin potency (at least 300 mg a serving), microbes, heavy metals and milk, soy and wheat, all passing; it does not test the probiotic count or the fiber amount, and it does not name the laboratory.

The trial of the product itself

There is none. We searched PubMed and ClinicalTrials.gov for Bio Complete 3 and Gundry MD and found no study of this product. The brand page cites a 12-week consumer perception study of 26 participants (96% reporting smoother digestion, 92% regular bowel movements, 88% fewer cravings, 81% higher energy), which the page itself calls self-reported and subjective; we found no publication, protocol or control group.

The evidence for the ingredients

Guar fiber. In a 12-week trial, 121 people with IBS were randomized (108 analyzed) to 6 g a day of partially hydrolyzed guar gum or placebo. Bloating scores improved by 4.1 points against 1.2 (P = 0.03) and bloating plus gas by 4.3 against 1.12 (P = 0.035), with no effect on the other symptoms or the severity score; 49% dropped out on placebo against 22% on guar (Niv et al., Nutrition & Metabolism, 2016). The whole prebiotic blend on this label is 450 mg, about one-thirteenth of 6 g even if all of it were guar. A second trial in constipation, reported at a 2024 conference, used 10 g a day and found weekly bowel movements up by 1.57 against 1.14 on placebo. For acacia gum, we found a single-arm study of 12 people with constipation at 20 g a day for about ten weeks, roughly 44 times the blend here.

Tributyrin. The ingredient is CoreBiome. Its published work is a laboratory study: in a simulated upper gut, 40.9% (capsule) and 48.7% (softgel) of the tributyrin was split to butyrate in the small intestine and the rest reached the colon, and three weeks in a colon simulator raised butyrate and Bifidobacterium and Akkermansia (Duysburgh et al., Frontiers in Nutrition, 2025), funded by the ingredient’s maker. The one human trial we found, of 300 mg once a day for four weeks against placebo, was terminated with four participants and posted no results. The label’s 300 mg is that dose, but no efficacy trial in gut symptoms has been published.

Probiotics. The evidence for B. coagulans in IBS is strain-specific. In a network meta-analysis of 81 trials and 9,253 people, the strains Unique IS2 (MTCC 5260) and MTCC 5856 ranked among the most effective for abdominal pain (Xie et al., Nutrients, 2023). This label names no strain for either species, so those results cannot be matched to it.

How to take Bio Complete 3

The dose is written two ways. The brand site says take 2 capsules per day with water, preferably before a meal, though its FAQ also recommends a dose before breakfast and again before dinner. Amazon’s directions read “two small capsules twice per day, preferably before a meal.” That is two capsules or four, a bottle lasting 30 days or 15. An Amazon reviewer gave three stars for exactly this, calling the daily dose misrepresented. The directions we read name no trial length; reviewers who report a change usually describe it within the first week.

Side effects and who should not take it

The label lists no side effects, and the brand page prints no warnings. Amazon’s safety text says to talk to a doctor before beginning any supplement, especially with a medical condition, on medication, pregnant or breastfeeding, and to stop if allergic to any ingredient. The brand states it is lectin-free, sugar-free, gluten-free, soy-free, dairy-free and free of artificial sweeteners; it does not state it is vegan. Reviewers report nausea to the point of vomiting, constipation, bloating or headache in some cases, and Amazon’s own summary calls the digestive effects mixed, with some less bloated and others constipated.

What the reviews say

Amazon shows 4.2 from 3,910 ratings (65% five-star, 12% four, 10% three, 3% two, 10% one). Trustpilot rates Gundry MD as a whole 3.5 from 7,366 reviews (58% five-star, 12% one-star). The Better Business Bureau lists the company as accredited with an A+ rating and customer reviews averaging 4.05 from 1,284, with 185 complaints in three years. The brand page cites “41,000+ verified 5-star reviews” across all its products. The recurring praise is a change in regularity within the first week, less heartburn and bloating, and helpful staff when delaying a subscription. The recurring complaints are price (“it worked but then it didn’t”), side effects or no effect, and the unclear daily dose.

The subscription and refund terms

Prices on the brand site, per bottle count:

The brand states “Cancel Anytime” for subscriptions and a 90-day money-back guarantee. Reviewers on Trustpilot and the Better Business Bureau, writing about the brand as a whole, report unexpected renewals, a cancelled subscription resumed, shipments charged but not sent, refunds refused after 90 days and having to pay return shipping; one complaint says a requested delay was not applied and the customer was told to return the product before being refunded. The brand replies to these publicly, and resolved complaints show refunds issued. The brand page says it sells only through its own site and Amazon and calls other listings unauthorized and outside the guarantee. Amazon lists the single bottle at $69.95.

Who Bio Complete 3 is for

• Bloating, gas, irregularity or general abdominal discomfort, the pattern the reviews most often describe.
• Someone who wants fiber, tributyrin and two probiotic species in one daily capsule and accepts that none has a trial at the label amount.
• Someone who will take it every day, and who has confirmed the capsule count per day before ordering.

If the fiber is the part you are after, the guar trial dose is the one supplied by the California Gold Nutrition PHGG powder. If a strain name matters, the Seed DS-01 guide covers a probiotic with strains printed, and which probiotic should I take starts from the symptom. Gundry MD’s other gut product has its own page at Total Restore.

Cost

At two capsules a day, a $69.95 bottle is $2.33 a day; with the free account price of $49.95 it is $1.67, and on the monthly subscription at $44.95 it is $1.50. The six-bottle one-time price of $353.70 is $1.97 a day. If Amazon’s twice-daily directions are followed, $69.95 for 15 days is $4.66 a day.

The products in this catalog

Common questions

Sources

• Niv E, Halak A, Tiommny E, et al. "Randomized clinical study: Partially hydrolyzed guar gum (PHGG) versus placebo in the treatment of patients with irritable bowel syndrome." Nutrition & Metabolism, 2016;13:10. doi.org/10.1186/s12986-016-0070-5
• Duysburgh C, Verstrepen L, Van Meulebroek L, et al. "Tributyrin (CoreBiome) enhances butyrate levels and modulates the gut microbiota, barrier function, and immune response in vitro." Frontiers in Nutrition, 2025;12:1712993. doi.org/10.3389/fnut.2025.1712993
• Xie P, Luo M, Deng X, et al. "Outcome-Specific Efficacy of Different Probiotic Strains and Mixtures in Irritable Bowel Syndrome: A Systematic Review and Network Meta-Analysis." Nutrients, 2023;15(17):3856. doi.org/10.3390/nu15173856
• ClinicalTrials.gov NCT06501898: CoreBiome tributyrin 300 mg against placebo (terminated, 4 participants) and NCT04382456: acacia gum in chronic constipation (single-arm, 12 participants). NCT06501898, NCT04382456
• UEG Week 2024 conference report: guar gum in IBS-related constipation, 10 g a day. esanum.com
• Brand page: label, certificate of analysis, directions and price. gundrymd.com/p/bio-complete-3
• Amazon listing: directions, safety information, price and ratings. amazon.com/dp/B0CHC9MMR1
• Trustpilot: gundrymd.com reviews. trustpilot.com/review/gundrymd.com
• Better Business Bureau profile: Gundry MD. bbb.org