What Is VIP (Vasoactive Intestinal Peptide)? A Research Guide
Vasoactive intestinal peptide (VIP) is a 28-amino acid signaling peptide that nerve and immune cells make throughout the body, especially in the gut, brain and pancreas. It relaxes smooth muscle, widens blood vessels, drives fluid secretion in the intestine and helps regulate immune responses. Despite the name, it is not limited to the intestine, and it was first described in the gut only because that is where researchers first looked. This guide explains what VIP is, how it acts, what a “normal VIP level” means, what human studies have and have not shown, and what to check when sourcing it for laboratory work.
TL;DR
- VIP is a naturally occurring 28-amino acid neuropeptide that acts through two receptors, VPAC1 and VPAC2, found in many body systems.
- Its established roles include smooth muscle relaxation, blood flow, gut and pancreatic secretion, immune modulation and circadian signaling.
- In clinical medicine, a blood VIP test is used mainly to help diagnose a rare tumor called a VIPoma; a normal result is under 75 pg/mL.
- Human trials of VIP analogs have been mixed and are not a basis for personal use. Peppy&Me supplies VIP for laboratory research use only.
- For research buyers, lot-specific third-party testing (purity, mass accuracy, endotoxins, sterility, heavy metals) matters more than any label claim.
What VIP is and where it comes from
VIP belongs to the secretin/glucagon superfamily of peptides. It is made in central and peripheral neurons and in immune cells, and it is concentrated in the gastrointestinal tract and the pancreatic islets, according to a 2019 review of VIP physiology. The body does not make it as a finished 28-residue chain. It is cleaved from a precursor of roughly 9 kb, called prepro-VIP, and processed into the mature peptide with an amidated C-terminus (the same review describes this processing).
That amidated end matters to anyone working with the synthetic version. A research-grade VIP has to reproduce the correct sequence and terminal modification, which is why mass accuracy is one of the first things a certificate of analysis should confirm.
Why it is called “intestinal”
The name reflects its history. VIP was isolated from gut tissue and observed to widen blood vessels (hence “vasoactive”). Later work found it in the brain, lungs, immune cells and elsewhere, so a more accurate description today is a broadly distributed neuropeptide with a particularly strong presence in the gut.
How VIP works in the body
VIP acts as both a neurotransmitter and a neuroendocrine releasing factor. It signals by binding to two G-protein-coupled receptors, VPAC1 and VPAC2, which appear across multiple organ systems (PMC review, 2019). Because the same receptors sit in tissues as different as the intestinal wall, the airways and immune cells, a single peptide can influence very different processes.
The same review summarizes the main functions it regulates:
- Contraction and relaxation of smooth muscle
- Secretion in several organs
- Blood flow
- Immune responses
- Circadian rhythms
- Glucose metabolism
In the gut specifically, VIP promotes anion and water secretion, and in the pancreas it promotes fluid and bicarbonate secretion. That secretory role explains why too much VIP produces severe watery diarrhea, as described below.
Vasodilation and smooth muscle
The original observation still holds: VIP relaxes smooth muscle. In blood vessels this means dilation and increased flow. In airways it means relaxation of bronchial muscle, which is why respiratory researchers have studied VIP and its analogs for decades.
Immune and nervous system signaling
Immune cells both produce VIP and respond to it, and the peptide is generally described as an immune-calming signal rather than an immune stimulant. In the nervous system it functions as a neuromodulator, and it participates in circadian timing. These are active research areas, and much of the evidence comes from cell and animal models rather than human trials.
What is a normal VIP level?
A common question is what a “normal VIP level” is. In clinical practice, VIP is measured in blood, and the test exists mostly for one reason. According to UCSF Health, the test measures VIP in the blood primarily to help diagnose a vipoma, and normal values are below 75 pg/mL (22.2 pmol/L), though ranges can vary slightly among laboratories.
VIPoma: the condition behind the test
A VIPoma is a rare pancreatic neuroendocrine tumor that secretes excess VIP. The MSD Manual Professional Edition describes its characteristic picture as watery diarrhea, low potassium (hypokalemia) and absent stomach acid (achlorhydria), often grouped as WDHA syndrome. Diagnosis first requires demonstrating secretory diarrhea. Only then are serum VIP levels measured, ideally during a symptomatic episode.
Treatment is also well defined. Localized tumors are treated with surgical resection, while octreotide or lanreotide usually controls the diarrhea in metastatic disease (same MSD reference). That is the clearest established clinical story for VIP: a hormone-secreting tumor, a blood test, and standard therapy. It has no connection to supplementation.
Anyone with persistent watery diarrhea, dizziness or muscle weakness should see a physician such as a gastroenterologist or endocrinologist. A VIP level is not something to interpret on your own.
What human research shows so far
The therapeutic literature around VIP is genuinely interesting, but it is early and mixed. Three examples show the range.
Inhaled VIP and the airways
In a 1984 study of inhaled VIP, Barnes and Dixon reported that it protected humans against histamine-induced bronchoconstriction, without changes in heart rate or blood pressure after inhalation. Later work examined inhaled VIP agonists for respiratory conditions such as asthma and sarcoidosis, with the expectation that local delivery would limit systemic side effects. These are research directions, not established treatments.
Aviptadil in critical COVID-19
Aviptadil is a synthetic VIP analog. In a 2022 randomized controlled trial in patients with critical COVID-19 respiratory failure, intravenous aviptadil did not meet its primary endpoint, although subgroup analysis suggested possible survival improvements. A subgroup signal is a reason for further study, not a finding of benefit.
Safety signals
The same trial’s published safety data are a useful reminder of VIP’s pharmacology. Side effects included mild-to-moderate diarrhea and hypotension. The hypotension was managed with pressors, and no unanticipated drug-related serious adverse events were recorded. Both effects follow directly from what VIP does: it relaxes vessels and drives gut secretion. They were observed under hospital monitoring, which is very different from unsupervised use.
Why VIP is not an approved consumer product
People often ask why a compound this well studied is sold as a research material rather than a medicine. The answer is largely economic. FDA approval requires large financial investment, multi-phase clinical trials and commercial backing. Naturally occurring or hard-to-patent compounds, VIP among them, offer little exclusivity to recoup that cost, so sponsors have fewer reasons to fund the full program, even while scientific interest continues.
The practical result is that VIP is not an FDA-approved product for any personal use, and this site makes no claims that it treats, prevents or cures any condition. Peppy&Me lists it for laboratory research only, and buyers must be authorized individuals aged 21 or older.
Sourcing VIP for research: what to check
With 28 amino acids, an amidated terminus and sensitivity to handling, VIP is not a peptide where quality can be assumed. A researcher evaluating any supplier can use the same short checklist.
| What to check | Why it matters for VIP |
|---|---|
| Purity (HPLC) | Confirms that the main peak is the target peptide and shows how much truncated or related sequence is present |
| Mass accuracy (mass spectrometry) | Verifies the molecular weight matches the expected 28-residue sequence |
| Endotoxin testing | Matters for any cell-based or in vivo work where contamination can distort results |
| Sterility | Needed to protect cultures and prevent confounding growth |
| Heavy metals | Rules out residues from synthesis and manufacturing |
| Lot and batch traceability | Lets you tie a result in your notebook to a specific, documented lot |
The key phrase is lot-specific. A generic certificate that does not match the vial in your hands says very little. For a walkthrough of how to read assay results and ask the right questions about any peptide, see our guide to quality checks and evidence gaps.
Handling and measurement
Lyophilized peptides are typically stored cold and protected from light and moisture, and reconstituted material is handled with care to avoid repeated freeze-thaw cycles. Your protocol and the supplier’s documentation should govern the details. Accurate reconstitution math also matters in research, and the dose calculator and peptide glossary on Peppy&Me are built to support concentration planning and handling background for laboratory work.
Perspective: how we think about VIP
We see a lot of curiosity about VIP that outruns the evidence, and we would rather close that gap than profit from it. VIP is a legitimate, well-characterized molecule with a clear physiological role and a few intriguing research threads. It is also a peptide whose human data are narrow, whose pharmacology (vasodilation, secretion, blood pressure effects) demands respect, and whose regulatory status is research-only.
So our approach is simple. We publish what the literature supports, we label our materials for laboratory use, and we put the documentation in front of the buyer: third-party testing for purity, mass accuracy, endotoxins, sterility and heavy metals, with traceable lot and batch numbers and QR-based access to the lot’s certificate. If a claim cannot be sourced, we do not make it. Researchers should expect the same discipline from any supplier they use.
— Peppy&Me
Where to find VIP for laboratory research
If your work calls for VIP, Peppy&Me lists it on its VIP (Vasoactive Intestinal Peptide) product page, with lot documentation, account-based order tracking and same-day shipping on orders placed before 2 PM. Members can also use the built-in dose calculator and the peptide glossary when planning handling and concentrations. You can browse related materials in the research compounds catalog, and businesses interested in building their own line can look at the private label partnership program.
All products are sold for laboratory research use only, not for human consumption, diagnosis or treatment.
FAQ
What does VIP do for the body?
VIP is a signaling peptide that regulates smooth muscle tone, blood flow, gut and pancreatic secretion, immune responses, circadian rhythms and glucose metabolism. It does this mainly by binding VPAC1 and VPAC2 receptors. These are physiological roles of the body’s own VIP, not proven benefits of taking it as a product.
What is a normal VIP level?
For a clinical blood test, normal values are generally below 75 pg/mL (22.2 pmol/L), and ranges vary slightly by laboratory. The test is used mostly to help diagnose a VIPoma. Results should be interpreted by a physician in the context of symptoms.
Who should not take VIP?
VIP is not approved for personal use, and Peppy&Me does not sell it for human consumption. Because it relaxes blood vessels and increases gut secretion, trials have recorded hypotension and diarrhea. Anyone with a health concern should speak with their physician rather than seek out research materials.
Where can I buy VIP peptide for research?
Authorized researchers aged 21 or older can order laboratory-grade VIP from Peppy&Me. Look for lot-specific third-party testing, traceable batch numbers and clear research-use-only labeling from any supplier you consider.
Sources
- Recent advances in vasoactive intestinal peptide physiology (PMC, 2019)
- Vasoactive intestinal peptide test, UCSF Health
- Vipoma, MSD Manual Professional Edition
- The Use of IV Vasoactive Intestinal Peptide (Aviptadil) in critical COVID-19 (PubMed, 2022)
- Aviptadil trial safety data (PMC)
- Vasoactive Intestinal Peptide Inhaled Agonists (PMC, 2013)
- Effect of inhaled vasoactive intestinal peptide on histamine-induced bronchoconstriction (PubMed, 1984)