Immunoglobulin G

ProteinProteinBest with a meal

What is it

Immunoglobulin G (IgG) is the most abundant antibody class in human and mammalian blood. In supplements it is typically a bovine serum-derived IgG concentrate used for gut and immune support.

Evidence for 2 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Functional GI symptoms (IBS-D, chronic loose stools)

Limited Evidence

Small trials of serum-derived bovine immunoglobulin (SBI) have reported symptom improvement in some patients with diarrhea-predominant IBS and HIV-associated enteropathy. Sample sizes are modest.

Gut barrier support

Limited Evidence

Mechanistic and small clinical studies suggest binding of bacterial antigens in the lumen may reduce inflammatory markers, though benefits on hard clinical outcomes remain to be confirmed.

How it works

Oral bovine IgG concentrates work mostly inside the gastrointestinal tract. They bind to microbial antigens, lipopolysaccharide, and other gut irritants, reducing local inflammatory signaling and supporting mucosal barrier function. Very little intact IgG is absorbed into systemic circulation; most acts within the lumen and is then digested or excreted.

Dosage

Supplement IgG products commonly provide 1.2 to 5 g of serum-derived bovine immunoglobulin per day. There is no RDA. Clinical studies in functional GI symptoms have used doses around 2.5 to 5 g daily.

When and how to take it

Usually taken with meals, once or twice daily. Acts locally in the gut so consistent dosing matters more than time of day.

2 commercial forms

Compare the main delivery options and what they’re best suited for.

Serum-derived bovine immunoglobulin (SBI)

The most common research-grade form.

Acts locally in the gut; minimal systemic absorption.

Colostrum-derived IgG

Different source; typically lower IgG concentration than SBI.

Comes alongside other colostrum components such as lactoferrin and growth factors.

Safety

Generally well tolerated in clinical trials. Mild bloating or constipation has been reported. Considered a medical food in some U.S. categories.

Who should be cautious

Avoid if you have known severe allergy to beef or bovine protein. Pregnancy and breastfeeding data are limited; check with a clinician.

Interactions

No significant interactions reported.

Food sources

Bovine colostrum

Amount
varies by product
%DV
—

Frequently asked questions

Does oral IgG raise my blood antibody levels?⌄

No meaningfully. Oral IgG is not absorbed intact into the bloodstream in adults; it works inside the gut.

Is IgG supplement the same as IVIG?⌄

No. IVIG is a prescription intravenous human-derived immunoglobulin used for serious immune disorders. Oral bovine IgG supplements are a different product with different uses.

References

Immunoglobulin G on Wikidata — Wikidata link

Immunoglobulin G on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Immunoglobulin G (PubMed search) — PubMed link

Track Immunoglobulin G with Pilora

Set up dose reminders, check interactions, and join the community in the Pilora iPhone app.

Coming to App Store
Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.