# Three Compounds, Three Answers to the Same Question > Three Routes Compared — Research Peptide Fundamentals — A side-by-side comparison of three research peptides and one coenzyme on the only axis that decides an oral product: what the human evidence says about the route. Research Peptide Fundamentals, sorted by absorption. **COMPARISON / ABSORPTION** Sorted not by what each one is studied for, but by whether anything is known about what happens when it is swallowed. ## The short version Three compounds appear on this site and they give three different answers to one question: can the molecule be studied by mouth, and what evidence supports that route? BPC-157 gives no answer at all, because nobody in these sources has published the human oral study. Semaglutide gives a hard-won yes, at the cost of extensive molecular and formulation engineering while most swallowed material is still lost. NAD+ gives an answer that belongs in a different category, because its oral precursors are not peptides and the chemistry that lets them through does not transfer. The useful lesson is that route evidence and effect evidence are separate. A compound can have a large trial record and still say nothing about its own tablet. A compound can have a plausible mechanism and no measured absorption anywhere. Reading a product claim well means asking which of the two is being shown. ## The route table The table below sorts the three on the axis that decides whether an oral product is a serious proposition. It is compressed on purpose; the expanded version of every cell sits on the compound pages. | Compound | Molecule | Oral form | Oral evidence | Maturity | | --- | --- | --- | --- | --- | | BPC-157 | Short peptide | None | No human study; route test favoured injection [5] | Preclinical, a few pilots [2] | | Semaglutide | Engineered GLP-1 analogue | Approved tablet | Low absorption; enhancer required | Large trials, all injected [9][10][11] | | NAD+ | Coenzyme, not a peptide | Supplement only | Precursors raise blood NAD+ [14][17] | Biomarker yes, outcomes no [13] | Three readings of it are worth spelling out. The BPC-157 row says no human study rather than no effect, and the difference matters: the published route test compared intramuscular against intragastric delivery in a rodent ulcer model and favoured the injection [5], which is suggestive and is not a human absorption measurement. The semaglutide formulation depends on a co-formulated enhancer and a strict fasting rule; the precise absorption figure belongs to approved product information outside this site's composed reference list and is not repeated here. The NAD+ row records a genuine oral result in a molecule that is not a peptide, so it belongs in the table as a contrast rather than as a precedent. Read the third column and the fourth column together. An approved oral form and a measured bioavailability are two different facts, and only one compound here has both. ## Three different reasons the mouth is hard The three compounds fail, succeed and sidestep the oral barrier for reasons that do not resemble each other. BPC-157 faces the barrier in its plainest form. It is a short unmodified peptide with no protective modification, no absorption enhancer and no formulation programme behind it. The pharmacokinetic characterisation that does exist found it breaking down rapidly into small fragments entering ordinary amino-acid metabolism [3], which is exactly what a peptide does when the digestive system wins. Semaglutide faced the same barrier and was rebuilt around it. An altered amino acid blocks an enzyme that would cut it. A fatty di-acid chain binds albumin and slows clearance. An absorption enhancer in the tablet addresses the gastric wall. A fasting rule protects the enhancer's work. Several interventions produce a narrow but real oral pathway. NAD+ never meets the peptide barrier because it has no peptide bonds to cut. Its oral problem is uptake of the intact coenzyme, and the field's answer was to give smaller precursors instead and let the body assemble the molecule internally [14][17]. Those are three genuinely different engineering situations. Treating them as one category, which the word peptide encourages, is how a reader ends up believing that because one tablet exists, others are plausible. ## Evidence maturity is not evidence of absorption It is worth separating two things that get conflated constantly. Semaglutide has the deepest evidence base here by a wide margin: a 68-week weight trial [11], a cardiovascular outcome trial in 17,604 adults [10], a kidney outcome trial in 3,533 people with type 2 diabetes and chronic kidney disease [9], and a head-to-head against tirzepatide in 751 adults with obesity [8]. Every one of those tested the weekly injection. Depth of evidence for a molecule is not evidence for a route. NAD+ has the opposite shape. Its route evidence is clean and its outcome evidence is not. Blood NAD+ rises dose-dependently on oral precursors [14][17], and the 2025 review of human clinical evidence still concluded that efficacy in ageing remains limited and tissue data sparse [13]. BPC-157 has neither shape. Its animal record is broad and its human record is three pilot studies [2], and no bioavailability figure exists for any route a person swallows. A reader who keeps those two axes apart will not be surprised by much in this field. ## What the table cannot tell anyone The table sorts evidence. It does not authorise anything. It does not say that an oral or sublingual product is safe, effective or worth trying, and this site does not say that about any product or any format. It does not convert an absent study into a negative finding, and the BPC-157 row is deliberately worded as an absence rather than a refutation. It does not carry doses, because study doses belong on the compound pages where the trial that used them is named, and nowhere near a recommendation. What it does is put the route question where it belongs, which is first. A compound with no measured absorption by the route being sold has an unanswered question at the front of everything else that might be claimed about it, and no amount of mechanism detail behind that question closes it. --- An independent reading desk on what survives the trip from mouth to bloodstream, selling nothing, prescribing nothing and endorsing no capsule, spray or protocol.