Serum Bovine Immunoglobulin (SBI)

Also called serum-derived bovine immunoglobulin/protein isolate, SBI, bovine IgG.

Best grade C across 5 graded outcomes Other Last checked Oct 21, 2026

The short answer

From 7 sources

Serum bovine immunoglobulin is an IgG-rich protein isolate from cattle serum. In a 103-person HIV diarrhea trial it did no better than placebo over 4 weeks, and other studies are small, uncontrolled or report within-group changes (grade D). It stays in the gut rather than being absorbed. Most trials list authors from SBI makers.

Every graded outcome on this page

5 rows · line = participants

Grade CDaily unformed stools and GI symptomsDiarrhean 103
Grade DGut damage and inflammation markersGut barriern 103
Grade DIBS-D symptoms and quality of lifeIBSn 30
Grade DDiarrhea from chronic norovirus after organ transplantNorovirus diarrhean 14
Grade DBowel movements and gut absorption in HIV enteropathyDiarrhean 8
2 more graded outcomes, in the evidence chapter

Key facts

What it is: A protein isolate from bovine serum that is rich in immunoglobulin G (IgG)⁵
Absorption: Bovine IgG appeared in stool but not in blood after repeated doses in 42 healthy adults⁵
HIV diarrhea: Stools improved equally with SBI and placebo over a 4-week blinded phase in 103 people²
IBS-D: A 6-week pilot reported within-group symptom improvements at 5 and 10 g/day, without placebo comparisons in the abstract¹
Funding: The cited IBS-D, HIV and absorption trials include authors from the maker Entera Health; a 2024 COVID-19 pilot lists authors from another supplier, Proliant^1,2,5,7

What it is

Serum bovine immunoglobulin is a protein isolate from cattle blood serum, rich in IgG antibodies, taken by mouth for gut conditions.

How it works

Proposed

SBI's antibodies are proposed to bind bacterial products in the gut and reduce gut inflammation and leakiness. In healthy adults its IgG stayed in the gut and was not detected in blood. In people with HIV, markers of gut damage (I-FABP, zonulin) and IL-6 fell over 24 weeks of open-label use.^3,4,5

Forms

Form

The form on this page
Form	Elemental %	Absorption (human data)	GI tolerance	Studied for
Serum-derived bovine immunoglobulin/protein isolate (SBI)	Varies⁵Not applicable (protein isolate rich in IgG; no elemental fraction)	Bovine IgG was found in stool but not in blood after repeated doses in healthy adults; blood essential amino acids rose after a single dose.⁵	Well tolerated at up to 5 g twice daily in 103 people with HIV, with 2 withdrawals for possibly related adverse events.²	IBS-D, HIV-associated diarrhea and enteropathy

What the human research says

Human trials only, one row per outcome. The form line shows what each trial actually tested. Grades follow our evidence-grading policy.

Trial map

5 graded outcomes, largest study first

5 graded outcomes: 3 improved, 1 mixed, 1 no effect. The largest, a 2017 randomized trial of 103 people on daily unformed stools and GI symptoms, found no effect.

By sizeTable

1Daily unformed stools and GI symptoms

No effect · Grade C · RCT, 103 people, 2017

Adults with HIV on suppressive treatment and chronic unexplained diarrhea (USA)

Dose, result and source

Every graded outcome on this page, largest study first
Outcome	Found	People	Study	Who was studied
Daily unformed stools and GI symptoms	No effect	103	Grade C · RCT, 2017	Adults with HIV on suppressive treatment and chronic unexplained diarrhea (USA)
Gut damage and inflammation markers	Improved	103	Grade D · RCT, 2019	Adults with HIV on suppressive treatment and chronic diarrhea (USA)
IBS-D symptoms and quality of life	Mixed	30	Grade D · RCT, 2013	Adults with diarrhea-predominant IBS (Canada)
Diarrhea from chronic norovirus after organ transplant	Improved	14	Grade D · Observational, 2026	Adult solid-organ transplant recipients treated for norovirus (USA, 2020–2024)
Bowel movements and gut absorption in HIV enteropathy	Improved	8	Grade D · Open-label trial, 2013	Adults with HIV enteropathy (USA)

Every graded row

5 rows

Form tested

Showing 5 of 5 outcomes. Human trials only.

Grade CDaily unformed stools and GI symptomsDiarrheaNo effectRCT
n 103 · 2017

No effect Unformed stools fell from about 4 to under 2 a day by week 4 in every group, including placebo, and GI symptoms did not differ between SBI and placebo. Health-status scores improved in both SBI groups. Two people withdrew for adverse events possibly linked to SBI.

Design: RCT, n = 103, 2017
Population: Adults with HIV on suppressive treatment and chronic unexplained diarrhea (USA)
Form: SBI
Dose: 2.5 or 5 g twice daily vs placebo
Duration: 4-week blinded phase, then 20 weeks open
Source: Reference 2 · PubMed 29210625 (opens PubMed)

Grade DGut damage and inflammation markersGut barrierImprovedRCT
n 103 · 2019

Improved By week 24, I-FABP and zonulin (gut damage markers) and IL-6 fell from baseline; CD4 counts rose 26 cells/µL in those with the lowest baseline counts.

Design: RCT, n = 103, 2019
Population: Adults with HIV on suppressive treatment and chronic diarrhea (USA)
Form: SBI
Dose: 2.5 or 5 g twice daily
Duration: 24 weeks (4 weeks vs placebo, then 20 weeks open)
Source: Reference 3 · PubMed 31139758 (opens PubMed)

Grade DIBS-D symptoms and quality of lifeIBSMixedRCT
n 30 · 2013

Mixed Within the 10 g/day group, abdominal pain, loose stools, bloating, gas and urgency fell from baseline; the 5 g/day group improved on fewer symptoms. Quality of life did not change. The abstract reports within-group changes, not comparisons with placebo.

Design: RCT, n = 30, 2013
Population: Adults with diarrhea-predominant IBS (Canada)
Form: Serum-derived bovine immunoglobulin/protein isolate (SBI)
Dose: 5 or 10 g/day vs placebo
Duration: 6 weeks
Source: Reference 1 · PubMed 24833942 (opens PubMed)

Grade DDiarrhea from chronic norovirus after organ transplantNorovirus diarrhea12 of 14 improved; no control groupObservational
n 14 · 2026

Improved 12 of 14 improved clinically and 8 of 14 fell below three bowel movements a day; 8 of the 10 alive at 90 days had no relapse.

Design: Observational, n = 14, 2026
Population: Adult solid-organ transplant recipients treated for norovirus (USA, 2020–2024)
Form: Serum-derived bovine immunoglobulin (medical food)
Dose: Not stated in the abstract
Duration: Median 4.5 days to improvement; 90-day follow-up
Source: Reference 6 · PubMed 42525503 (opens PubMed)

Grade DBowel movements and gut absorption in HIV enteropathyDiarrheaImprovedOpen-label trial
n 8 · 2013

Improved All eight participants reported much better symptoms with fewer bowel movements a day; gut absorption tests and duodenal immune cells were also reported to improve.

Design: Open-label trial, n = 8, 2013
Population: Adults with HIV enteropathy (USA)
Form: SBI
Dose: 2.5 g twice daily
Duration: 8 weeks
Source: Reference 4 · PubMed 23660579 (opens PubMed)

Human study outside the graded table: COVID-19

1 note

Open-label pilot; the abstract does not give the number of participants, so it is not graded here.

Mild-to-moderate COVID-19 (2024): Adults randomised 2:1 to SBI 5 g twice daily plus standard care or standard care alone for 2 weeks: more reported no symptoms at week 2 (74.2% vs 43.6%), with no difference in IL-6. Four authors work for Proliant Health & Biologicals, an SBI supplier, which is listed as the funder.⁷

What the numbers add up to

Each point is worked out from the data and the sources numbered on this page, with the arithmetic shown under it. It adds no new data and is not medical advice.

Placebo did as well

In the largest trial, 103 people with HIV diarrhea, stools improved just as much on placebo during the 4-week blinded phase; later gains came without a placebo group.^2,3

Maker-run research

The IBS-D, HIV diarrhea and absorption studies list authors from Entera Health, which makes SBI.^1,2,5

Studied doses

Doses used in research, shown against the official limits. They describe the studies, not a recommendation for you.

Studied doses in research, not advice. These are amounts used in research, not personal advice. Your clinician or pharmacist can say what fits you.

Doses studied in human trials

Doses studied in human trials ranged from 5 to 10 g/day: 5 or 10 g/day for 6 weeks (IBS-D), and 2.5 or 5 g twice daily for 4 to 24 weeks (HIV-associated diarrhea). A safety study gave up to 10 g twice daily for 2 weeks.^1,2,3,5

Interactions and safety

Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.

Interactions

0 agents

None found in our sources.

Check with what you take

Kept on this device only

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Most cited:

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Starting from one medicine? The interaction checker rates how serious each pair is, on a curated list of 19 entries for 11 medicines. This cabinet has no severity rating: it lists every interaction row our supplement pages cite.

Who should be careful

4 groups

Beef allergy: SBI is made from bovine (cattle) serum protein.⁵
Pregnancy and breastfeeding: No pregnancy or breastfeeding data were found: the cited trials enrolled adults only, and LactMed has no SBI entry.^1,2,5
Children: The cited trials enrolled adults only, so dosing and safety in children are not established here.^1,2,5
Medicines: No drug-interaction studies were found, and LiverTox and LactMed have no SBI entry. IgG was not detected in blood in healthy adults, but that does not rule out effects in the gut.⁵

Reading the label, and the cost per dose

Compare any product you already have by the amount it delivers, not by capsule count or front-of-pack weight.

How to read the label

1 checks

Not the same as colostrum

SBI is made from cattle blood serum, not from colostrum (first milk); the trials here tested only the serum-derived isolate.^1,2,5

Have the bottle? Photograph its Supplement Facts panel and see each line, serum bovine immunoglobulin (sbi) included, beside the doses and forms the trials used in Label X-Ray.

Cost per studied dose, without the sales pitch

Your numbers, no product data

Price paid ($)Servings per containerSBI per serving (mg)

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Frequently asked questions

Short answers to common questions; the numbers link to the sources below.

Common questions

8 answers

Does serum bovine immunoglobulin help IBS?

A 6-week pilot in IBS-D reported symptom improvements within the 5 and 10 g/day groups, but the abstract does not show a difference from placebo.¹

Does SBI help diarrhea?

In 103 people with HIV and chronic diarrhea, stools improved equally with SBI and placebo over 4 weeks.²

Is SBI safe?

It was well tolerated at up to 5 g twice daily for 24 weeks; 2 of 103 people withdrew for adverse events possibly linked to it.²

How much SBI was studied?

5 or 10 g a day in the IBS-D pilot and 2.5 or 5 g twice daily for 4 to 24 weeks in the HIV trials; a safety study in healthy adults used up to 10 g twice daily for 2 weeks.^1,2,5

Does SBI interact with medicines?

No interaction studies were found. Its IgG stayed in the gut in healthy adults, but interaction data are simply lacking.⁵

Is SBI safe during pregnancy or breastfeeding?

It has not been studied: all cited trials enrolled adults outside pregnancy, and LactMed has no entry for it.^1,2,5

Is SBI absorbed into the blood?

No. In healthy adults, bovine IgG was found in stool but not in blood after repeated doses.⁵

Is SBI the same as colostrum?

No. SBI is made from cattle blood serum, not milk, although both colostrum and SBI contain IgG.⁵

Sources

7 sources: trial abstracts, NIH fact sheets and reference databases. Numbers in the text link here.

Sources cited on this page

7 sources

1Evaluation of serum-derived bovine immunoglobulin protein isolate in subjects with diarrhea-predominant irritable bowel syndrome.RCT Clin Med Insights Gastroenterol, 2013 · PMID 24833942
2Evaluation of oral serum-derived bovine immunoglobulins in HIV-infected patients with chronic idiopathic diarrhea.RCT HIV Clin Trials, 2017 · PMID 29210625
3Serum Bovine Immunoglobulins Improve Inflammation and Gut Barrier Function in Persons with HIV and Enteropathy on Suppressive ART.RCT Pathog Immun, 2019 · PMID 31139758
4Oral serum-derived bovine immunoglobulin improves duodenal immune reconstitution and absorption function in patients with HIV enteropathy.Open-label trial AIDS, 2013 · PMID 23660579
5Absorption and safety of serum-derived bovine immunoglobulin/protein isolate in healthy adults.PK study Clin Exp Gastroenterol, 2016 · PMID 27980432
6Clinical Experience of Oral Serum-Derived Bovine Immunoglobulin in Solid Organ Transplant Recipients Diagnosed With Norovirus Infection.Observational Clin Transplant, 2026 · PMID 42525503
7Serum-derived bovine immunoglobulin treatment in COVID-19 is associated with faster resolution of symptoms: A randomized pilot clinical trial.RCT J Med Virol, 2024 · PMID 39390688

What changed

Every dated change to this page: what changed, who made it and why.

Change log

4 entries

Dated changes to this page
Date	Change	Who and why
Oct 21, 2026summary, key facts, evidence, research notes, who should be careful, related, FAQ	Added a 2026 transplant norovirus case series (PMID 42525503) as a clinical-use row and a 2024 COVID-19 open-label pilot (39390688) as a research note (participant count not in the abstract). Searched PubMed for newer meta-analyses or larger trials: none. Checked LiverTox and LactMed: no SBI entries; no published drug interactions found, now stated on the page. Split pregnancy, breastfeeding and children notes; added three FAQs and three related links.	Writer: Kymata Health EditorialTrigger: A–Z page audit
Oct 17, 2026FAQ	Independent review: reworded the colostrum FAQ to stay within what the cited source supports.	Writer: Kymata Health EditorialTrigger: review
Oct 17, 2026all	First draft. Every PMID checked against NCBI E-utilities esummary (title and year taken from the record) and abstracts read for every cited row.	Writer: Kymata Health EditorialTrigger: new page
Oct 17, 2026all	Adversarial review pass: every evidence row's numbers machine-checked against its PubMed abstract, retraction and erratum flags checked for all PMIDs, unverified country and affiliation details removed, and claims not supported by the cited abstracts reworded or dropped.	Writer: Kymata Health EditorialTrigger: review

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