Metagenics® UltraFlora® Night Rest & Digest: A Pharmacist’s Guide

Dai Tran, PharmD, MBA, B.S.

CEO & Lead Pharmacist, Khang Pharmacy • CA/MN/TX Licensed Pharmacist

Clinical Insights Series • APhA Immunization Certified • 10+ Years Clinical Experience

The Clinical Question

What does published human clinical research establish about the individual ingredients in Metagenics® UltraFlora® Night Rest & Digest — specifically the heat-treated Bifidobacterium longum ES1 postbiotic, the Asafin® asafetida extract, the Poolzyme® enzyme blend, and milk thistle extract — for digestive symptom relief, gut–brain axis modulation, and sleep support? And how directly does that ingredient-level evidence apply to this finished product?

Bottom Line Up Front

The strongest human evidence relevant to this formula comes from the heat-treated B. longum ES1 postbiotic and Asafin®/asafoetida preparations. HT-ES1 significantly improved symptoms in one randomized trial in adults with IBS-D, while a separate pilot trial in otherwise healthy adults found minimal GI symptom improvement despite microbiome changes. Asafin® has been evaluated in a small randomized controlled trial in functional dyspepsia using 500 mg/day, with significant improvement in validated dyspepsia symptom measures — at a total daily dose twice the amount in one capsule of this product. A newer 2025 randomized trial of a 250-mg/day asafoetida formulation in 62 participants with functional dyspepsia symptoms reported improvements in digestive symptoms, microbiome measures, and Bergen Insomnia Scale scores over 14 days — a dose directly relevant to this product’s one-capsule regimen. Both Asafin® trials involved industry funding and investigator affiliations with the ingredient developer, which warrants appropriate weight alongside the small sample sizes and need for independent replication. These ingredient-level findings are promising but do not establish that UltraFlora® Night Rest & Digest as a finished combination product improves digestive symptoms or sleep.

The Gut–Brain Axis and Digestive Health

The gastrointestinal tract and central nervous system communicate bidirectionally through neural, endocrine, immune, and microbial pathways collectively described as the gut–brain axis. Digestive symptoms — including bloating and discomfort — can interfere with sleep, while sleep and circadian rhythms also influence gastrointestinal physiology. Randomized trials of Asafin®/asafoetida preparations in functional-dyspepsia populations have reported improvements in GI symptoms, and a 2025 randomized trial additionally reported improvements in Bergen Insomnia Scale scores alongside microbiome changes. These findings provide preliminary clinical support for a gut–brain-axis rationale, but the studies were small, involved industry participation, and were conducted in dyspepsia populations. Direct evidence that UltraFlora® Night Rest & Digest improves sleep in healthy adults is not established.

What Is a Postbiotic?

Probiotics are live beneficial microorganisms. Prebiotics are the dietary fibers that feed them. Postbiotics are bioactive preparations derived from probiotic bacteria — in this case, produced by heat-treating Bifidobacterium longum CECT7347 (ES1), which inactivates the organism while preserving biologically active cell-wall components and metabolites. The resulting preparation is shelf-stable and does not require refrigeration or live-culture handling. Postbiotic research is an active and evolving area of gut-health science, and the evidence base for specific heat-treated strains is still accumulating.

What the Evidence Does — and Does Not — Establish

Asafin® (Asafetida Oleo-Gum-Resin Extract) — 250 mg

• HUMAN RCT Mala KN, et al. (PMID: 30224930) — Randomized, double-blind, placebo-controlled study in 43 adults with moderate-to-severe nonulcer functional dyspepsia comparing Asafin® 250 mg twice daily (500 mg/day total) versus placebo for 30 days. Asafin® significantly improved validated dyspepsia symptom scores and quality-of-life measures versus placebo; approximately 81% of Asafin® participants showed improvement in overall scores and quality of life, and 66% were reported symptom-free at study end, with improvements including bloating and postprandial fullness. Important applicability limitation: the trial used a total daily dose of 500 mg Asafin® — twice the 250 mg provided by one capsule of UltraFlora® Night Rest & Digest at the labeled one-capsule regimen. This dose gap means findings from this trial should not be assumed to apply directly to this product at its standard dose. Authors were affiliated with Akay Flavours & Aromatics, the developer of Asafin®.
• HUMAN RCT Das SS, et al. (PMID: 41054174) — Randomized, double-blind, placebo-controlled study in 62 participants with functional dyspepsia symptoms comparing an asafoetida oleo-gum-resin formulation at 250 mg/day versus placebo for 14 days. The trial reported improvements in early satiety, bloating, and heartburn, along with microbiome changes. Importantly, sleep was assessed using the Bergen Insomnia Scale and showed improvement at day 14 — directly relevant to the nighttime positioning of this formula. Applicability and funding context: this was a small 62-participant, 14-day study in a functional-dyspepsia population, not a general healthy-sleeper population. The 250 mg/day studied dose is numerically the same as the amount of Asafin® listed in one UltraFlora® capsule, although formulation equivalence and finished-product efficacy should not be assumed. The study was funded by Akay Natural Ingredients, the developer of the formulation, and several investigators were affiliated with the company. These findings are promising but require independent replication before they can be considered established evidence.

Heat-Treated B. longum ES1 (HT-ES1) Postbiotic — 25 mg

• HUMAN RCT Andresen V, et al. (PMID: 38630015) — Randomized, double-blind, placebo-controlled trial in 200 adults with diarrhea-predominant IBS (IBS-D) comparing live B. longum CECT7347, heat-treated CECT7347 (HT-ES1), and placebo over 12 weeks. Both the live and heat-treated ES1 preparations significantly reduced IBS Symptom Severity Scores versus placebo. These findings support biological and clinical activity of HT-ES1 in the specific IBS-D population studied. They should not be extrapolated to mean that UltraFlora® Night Rest & Digest treats IBS-D: the finished product was not evaluated in this trial, and this formula is not labeled for IBS management.
• MIXED EVIDENCE PMID: 39599737 — Randomized, double-blind, placebo-controlled pilot study in 60 healthy adults with mild-to-moderate digestive symptoms receiving HT-ES1 for 8 weeks. GI symptom changes were minimal and did not reach clinical significance, although microbiome compositional changes were observed, including increases in Faecalibacterium and Anaerobutyricum. This study does not establish a meaningful digestive-symptom benefit for HT-ES1 in otherwise healthy adults. The microbiome findings are hypothesis-generating but do not constitute clinical evidence of benefit.

Taken together: HT-ES1 shows significant IBS-D symptom reduction in a disease population (PMID: 38630015) but minimal GI symptom benefit in healthy adults (PMID: 39599737). The population context is critical when evaluating applicability to any individual patient.

Poolzyme® (Proprietary Digestive Enzyme Blend) — 200 mg

• BIOCHEMICAL FUNCTION Poolzyme® is a blend of five enzymes — Lactase, Protease, Amylase, Lipase, and Cellulase — each of which catalyzes the breakdown of a specific class of dietary substrate: lactose/dairy, proteins, starches, fats, and plant cell-wall fibers respectively. These enzymatic functions are biochemically established. Whether this proprietary blend at these doses produces clinically meaningful improvements in digestive symptoms in healthy adults depends on enzyme activity units, meal composition, GI transit conditions, and the individual’s digestive baseline — and has not been independently verified here from a human RCT specific to this formulation.

Milk Thistle (Silybum marianum) Seed Extract — 80 mg

• REVIEW Milk thistle and its primary active constituent silymarin have been extensively studied in liver-related contexts — hepatitis, cirrhosis, and toxic liver injury — generally at silymarin doses of 140–800 mg/day. That liver-focused literature does not establish that the 80-mg milk-thistle seed extract dose in UltraFlora® Night Rest & Digest improves nighttime digestion or sleep. The inclusion of milk thistle at this dose reflects general liver-support positioning; it is not supported by a clinical evidence base specific to the formula’s nighttime digestive indication.

What Is Not Established

• That HT-ES1 produces meaningful GI symptom benefit in healthy adults — the pilot RCT in that population showed minimal symptom change (PMID: 39599737).
• That the Asafin® findings from a 500 mg/day trial (PMID: 30224930) apply to the 250 mg/day one-capsule regimen in this product.
• That the sleep improvement observed in the 2025 asafoetida RCT (PMID: 41054174) generalizes beyond the 62-person functional-dyspepsia population studied, or that formulation equivalence between the studied preparation and Asafin® in this finished product can be assumed.
• That taking digestive enzyme supplements at a specific time of day produces superior outcomes compared with other timing — no direct comparative timing trials were identified.
• That the 80-mg milk-thistle extract dose in this formula produces measurable hepatoprotective or digestive benefit.
• That UltraFlora® Night Rest & Digest as a finished combination product produces any specific clinical outcome — it has not been independently evaluated in published human clinical trials.

Supplement Facts

Serving Size: 1 Capsule  |  Servings per Container: 30

**Daily Value not established.

Other Ingredients: Capsule [hydroxypropylmethylcellulose, water, sorbitol, silicon dioxide, and sodium copper chlorophyllin (color)], microcrystalline cellulose, magnesium stearate (vegetable), and silicon dioxide.

Finished-Product Evidence Note

UltraFlora® Night Rest & Digest as a specific finished product has not been independently evaluated in published human clinical trials. The evidence discussed above applies to individual ingredients studied in various forms, doses, and populations. Ingredient-level evidence does not establish that this finished combination product produces any specific clinical outcome.

Dosing Directions

Per current Metagenics label directions: take one capsule daily with the evening meal. A second capsule may be taken with another main meal if needed, or as directed by a healthcare practitioner. Do not exceed the recommended dose without healthcare provider guidance.

Safety and Precautions

The following safety information reflects current Metagenics label warnings and standard pharmacist guidance:

• Discontinue use and consult a healthcare provider if stomach discomfort occurs.
• Do not use if you have a current peptic ulcer or duodenal ulcer.
• Consult a healthcare provider before use during pregnancy or breastfeeding.
• Consult a healthcare provider before use if you are taking antidiabetic medication.
• This product is formulated for occasional digestive discomfort in adults. It is not intended to diagnose, treat, cure, or prevent any disease, including chronic gastrointestinal conditions, liver disease, or sleep disorders.
• Keep out of reach of children. Store in a cool, dry place.

About Metagenics®

Metagenics® is a practitioner-distributed supplement brand with over 40 years in the clinical nutrition space, manufactured in GMP- and NSF-certified facilities with extensive third-party quality testing. As with all supplement products, quality certifications address manufacturing standards — not clinical efficacy of the finished product.

Selected Key Studies

1. HUMAN RCT Mala KN, Thomas J, Syam DS, Maliakel B, Krishnakumar IM. Safety and Efficacy of Ferula asafoetida in Functional Dyspepsia: A Randomized, Double-Blinded, Placebo-Controlled Study. 2018. PMID: 30224930. DOI: 10.1155/2018/4813601.
   n = 43 adults with nonulcer functional dyspepsia; Asafin® 250 mg twice daily (500 mg/day) vs. placebo, 30 days. Significant improvement in validated dyspepsia symptom scores and QOL. Total daily dose is double the one-capsule UltraFlora® regimen; formulation equivalence should not be assumed. Authors affiliated with Akay Flavours & Aromatics.
2. HUMAN RCT Das SS, et al. Ferula asafoetida oleo-gum resin alleviates dyspepsia symptoms through modulation of microbiome-gut-brain axis: A randomized, double-blind, placebo-controlled study. Medicine. 2025. PMID: 41054174. DOI: 10.1097/MD.0000000000044590.
   n = 62 adults with functional dyspepsia symptoms; 250 mg/day asafoetida formulation vs. placebo, 14 days. Improvements in GI symptoms, microbiome parameters, and Bergen Insomnia Scale scores. The 250 mg/day studied dose is numerically the same as the amount of Asafin® listed in one UltraFlora® capsule; formulation equivalence and finished-product efficacy should not be assumed. Funded by Akay Natural Ingredients; investigator affiliations with Akay present. Small sample, short duration, requires independent replication.
3. HUMAN RCT Andresen V, et al. Heat-inactivated Bifidobacterium longum CECT 7347 (ES1) for diarrhea-predominant irritable bowel syndrome. PMID: 38630015.
   Double-blind RCT, n = 200 adults with IBS-D, 12 weeks. Both live and heat-treated ES1 significantly reduced IBS Symptom Severity Scores vs. placebo. Supports clinical activity of HT-ES1 in IBS-D; does not establish efficacy for the finished product or for healthy adults without IBS-D.
4. MIXED EVIDENCE Pilot RCT of heat-treated B. longum ES1 in healthy adults with mild-to-moderate digestive symptoms. PMID: 39599737.
   Double-blind pilot RCT, n = 60 healthy adults, 8 weeks. Minimal GI symptom changes; microbiome shifts noted (increased Faecalibacterium and Anaerobutyricum). Does not establish meaningful digestive-symptom benefit for HT-ES1 in healthy adults.

Frequently Asked Questions

When should I take UltraFlora® Night Rest & Digest?

Per current Metagenics label directions, adults should take one capsule daily with the evening meal. A second capsule may be taken with a separate main meal if needed, or as directed by a healthcare practitioner.

Does this product contain melatonin or sedatives?

No. The formula does not contain melatonin, diphenhydramine, valerian, or other sedative ingredients. Its positioning as a nighttime formula relates to the gut–brain axis rationale and evening-meal timing, not direct sedation.*

What is the difference between a probiotic and a postbiotic?

Probiotics are live beneficial microorganisms. Postbiotics are bioactive preparations derived from those organisms. The heat-treated B. longum ES1 in this formula is a postbiotic: the organism has been inactivated by heat treatment, preserving biologically active components while producing a shelf-stable, non-live preparation that does not require refrigeration.

Is this appropriate if I have a diagnosed GI condition?

If you have a diagnosed gastrointestinal condition — such as IBS, IBD, GERD, gastroparesis, peptic ulcer, or liver disease — please consult your physician or gastroenterologist before adding any digestive supplement to your regimen. This product carries a specific label contraindication against use with a current peptic or duodenal ulcer. It is formulated for occasional digestive discomfort in otherwise healthy adults, not for managing diagnosed conditions.

Why does the article note industry funding for the Asafin® trials?

At Khang Pharmacy, we report funding sources and investigator conflicts of interest for every study we cite — not because industry funding invalidates research, but because it is a relevant factor when evaluating evidence strength, particularly for small early-stage trials that have not yet been independently replicated. Both Asafin® trials involve the ingredient developer, Akay. We present their findings transparently alongside that context so you can weigh the evidence as a fully informed patient.

Reviewed by: Dai Tran, PharmD, MBA, B.S.  View full bio →

CEO & Lead Pharmacist, Khang Pharmacy • CA/MN/TX Licensed Pharmacist

Clinical Insights Series • APhA Immunization Certified • 10+ Years Clinical Experience

Khang Pharmacy | 2451 S King Rd., Ste A1, San Jose, CA 95122 | (408) 622-8068 | www.khangpharmacy.com