A vial of standardized human stool now sells for several thousand dollars per dose. This is not a laboratory curiosity: since 2022, the FDA has approved two treatments based on human gut microbiota — Rebyota in November 2022, then Vowst in April 2023 — to prevent relapses of Clostridioides difficile infections, a bacterium responsible for 15,000 to 30,000 deaths per year in the United States according to the Centers for Disease Control and Prevention. These two products are manufactured from stool samples of healthy voluntary donors, purified, standardized, and packaged like any other medication.

Medicine gains something real from this. Patients exhausted by repeated cycles of antibiotics that worsen the problem they are supposed to solve now have access to an effective treatment. Clinical trials show protection rates exceeding 70% against relapses, where standard antibiotics often failed. But this approval has also opened a question that American law—and global law—has not properly settled for a century: at what point does a fragment of the human body cease to be a donation and become a product?

The Essentials

  • The FDA approved two treatments based on standardized human microbiota in 2022-2023 to prevent relapses of C. difficile infections, a bacterium that kills 15,000 to 30,000 Americans per year.
  • Rebyota (Ferring Pharmaceuticals) and Vowst (Seres Therapeutics / Nestlé Health Science) are the first two commercial products derived from human stool donations, with catalog prices around $9,000 to $10,000 per treatment.
  • Patents already cover donor selection procedures, purification protocols, and pharmaceutical formulations — without donors themselves receiving legally structured compensation.
  • The precedent of blood plasma in the United States — where remuneration has created a two-tiered market dependent on the most precarious populations — is the reference scenario to avoid for microbiota.
  • Alternative regulatory frameworks exist: France and several European countries maintain free stool donations within a public hospital model, with comparable efficacy.

Intestinal Bacteria Against C. difficile: How It Works

Clostridioides difficile colonizes the colon when normal intestinal flora has been destroyed, often by antibiotics. The bacterium produces toxins that cause severe diarrhea, sometimes fatal in elderly and immunocompromised people. The problem is that the antibiotics prescribed to treat the infection — notably vancomycin and metronidazole — destroy the microbiota again, creating a cycle of relapses that affects 25 to 30% of patients after a first episode, and up to 60% after multiple episodes.

Fecal microbiota transplantation (FMT) rests on a simple principle: reintroduce into the impoverished colon a healthy bacterial ecosystem, taken from a carefully selected donor, so that this ecosystem regains dominance over C. difficile. Studies published in the New England Journal of Medicine as early as 2013 showed cure rates exceeding 90% with this method, well above vancomycin. The problem then was the absence of a clear regulatory framework: hospitals performed artisanal FMTs, sometimes using stool from relatives, with minimal standardization.

This is exactly the gap that Ferring and Seres filled. Rebyota is a rectal suspension of purified human microbiota. Vowst is an oral capsule containing purified bacterial spores from human stool. Both products require rigorously selected donors, tested for dozens of pathogens, with strict exclusion protocols. Securing the donation was necessary: in 2019, two immunocompromised patients died after receiving FMTs contaminated with extended-spectrum beta-lactamase-producing E. coli, in a poorly regulated clinical trial setting, according to an FDA report.

When Donation Becomes Product, and Product Becomes Patent

The transformation is both therapeutic and economic. Vowst sells for approximately $9,000 for a complete treatment, according to pricing data published by Seres Therapeutics. Rebyota is in the same range. These prices reflect the real cost of donor selection and screening, industrial processing, quality controls, and cold chain logistics. But they also reflect commercial margins and, most importantly, the value attached to patents.

These patents do not cover the bacteria themselves — American law has forbidden patenting natural human genetic sequences since Association for Molecular Pathology v. Myriad Genetics (2013) — but the processes: algorithms for donor selection, purification methods, pharmaceutical formulations, administration protocols. The human donation itself cannot be patented. What surrounds it can.

This legal distinction is elegant on paper. It becomes less comfortable when one realizes that the economic value of the product depends entirely on the availability of donors, and that these donors see no legally structured compensation. Some microbiota banks, like OpenBiome in the United States, paid their donors approximately $40 per donation before their partial closure in 2023 — a symbolic sum compared to the final product’s selling price. The question is not only moral. It is structural: what guarantees a stable supply of quality donors if the sector remains in this ambiguity?

The Plasma Precedent, or How a Market Can Capture a Donation

The United States has already constructed a response to this question for blood plasma. And this response is instructive, not necessarily in the right direction.

Human plasma is the raw material for a pharmaceutical industry worth $45 billion per year globally, according to estimates from the International Plasma Fractionation Association. In the United States, unlike Europe, plasma donors are compensated — between $30 and $150 per donation depending on centers and frequency. This system has allowed the United States to produce approximately 70% of the world’s fractionated plasma. It has also created a very particular geography of donation: plasma collection centers are concentrated in low-income neighborhoods, near university campuses and areas of precarity. Studies published in PLOS Medicine have documented donors who donate twice a week — the regulatory maximum — to supplement insufficient incomes, with measurable effects on their serum protein levels.

American plasma has become, in the terms of the 2011 Nuffield Council on Bioethics report, a system of “remuneration disguised as indemnification” that has created structural dependence of global supply chains on America’s precarious populations. Europe, which prohibits remuneration for blood and plasma donations, is chronically dependent on American imports for plasma-derived medications.

Microbiota is not there yet. But the conditions for a similar trajectory are in place. The market is growing fast: beyond C. difficile, clinical trials are exploring FMT for Crohn’s disease, ulcerative colitis, certain cancers treated with immunotherapy, and even neuropsychiatric pathologies via the gut-brain axis. If these indications are confirmed, demand for qualified donors will grow significantly. “Super-donor” profiles, whose microbiota produces significantly superior therapeutic results, are already identified in the literature. These rare individuals represent a biological resource with high economic value that law has not yet learned to characterize.

What the Europeans Are Doing, and What It Teaches

France, the Netherlands, Belgium, and several Nordic countries have developed FMT programs within a public hospital framework, modeled on free blood donation. In France, the National Agency for the Safety of Medicines and Health Products (ANSM) has regulated FMT as an “advanced therapy medicinal product,” subject to hospital authorization, with non-compensated volunteer donors. Published clinical results are comparable to American studies.

This model has an underestimated economic virtue: it neutralizes the incentive to relax donor selection criteria under demand pressure. A center that pays its donors has a commercial interest in recruiting more; a hospital center without a commercial budget has an interest in maintaining strict standards to avoid incidents. Safety and ethics converge here with good regulatory risk management.

The European model has its limits. It is difficult to scale. Hospital microbiota banks struggle to meet growing demand, and geographical access remains unequal. But these limits are a matter of organization and public funding, not irreversible. What is more difficult to undo is a commercial market already established with patents and established actors.

The question of irreversibility deserves to be posed frontally. In platform economics as in pharmaceutical economics, network effects and sunk costs create lock-ins. Once two industrial players hold process patents and donor networks, rebuilding an alternative model costs much more than building it from the start. Decisions made between 2022 and 2028 — during the market’s opening window — condition the options available in 2035. It is the logic of precedent that makes this moment particularly important.

Questions That Law Has Not Settled

The intellectual property of human living matter is not a new subject. The decision Moore v. Regents of the University of California (1990) had already decided it, brutally: John Moore, whose cells had been used to develop a lucrative leukemia drug, had no property rights over his own cells once removed. He could have sued his doctor for failure to inform, but not claimed a share of the profits.

This jurisprudence has never been overturned. It applies, in fact, to microbiota donors today. A donor whose bacterial profile proves exceptionally effective cannot claim rights over the derived product. This outcome may seem unjust, but the problem is not only moral: it is practical. If donors are neither proprietors nor compensated, and if remuneration remains symbolic and unregulated, the sector risks reproducing the imbalances of plasma — a supply dependent on the economic precarity of a segment of the population.

Several regulatory approaches are discussed in bioethics literature and in preliminary work by the World Health Organization. The first is the “common good” model: human microbiota would be treated as a shared resource, not patentable in its essential dimensions, with regulated access and compulsory licenses for validated therapeutic indications. The second is a system of transparent and capped compensation, analogous to what exists for certain egg donations in Europe, which recognizes the real cost of donation without creating distorting financial incentives. The third is the extension of the benefit-sharing model developed in the Convention on Biological Diversity for plant genetic resources — an imperfect but existing framework.

None of these approaches is simple to implement. All are preferable to the absence of framework, which is precisely the current state in the United States.

Microbiota in Twenty Years: A Resource or a Common Good?

Market projections for microbiota-based therapies vary depending on assumptions about clinical validation of new indications, but several specialized firms, including Grand View Research, estimated the global market at around $800 million in 2023, with projected annual growth of 15 to 20% if ongoing trials on Crohn’s disease and oncology confirm preliminary results. Over a ten-year horizon, this represents a potential market of several billion dollars.

This growth is conditional. It depends on trial replication, regulatory approval for new indications, and the ability of manufacturers to secure a supply of quality donors. This last point creates the link between therapeutic progress and ethical questions: the more effective the therapies become, the greater the pressure on donors will be, and the greater the risk of the market paying to attract precarious profiles increases.

There is a different path. It passes through public policies that support hospital microbiota banks, intellectual property frameworks that recognize donor contributions, and public-private partnerships that allow industrial scale-up without abandoning the principles of altruistic donation. This path is more politically demanding, but it is accessible: several European countries have already shown it is practicable.

Microbiota medicine will continue to advance. Data published in Nature Medicine and the New England Journal of Medicine document real, measurable advances for patients who had no other options. The question that remains open is not whether these therapies work, but who will produce the human raw materials that make them possible, under what conditions, and with what rights. Answering this question before the market closes it is a political decision, not a medical one.

Sources

  1. Nature Medicine — https://www.nature.com/nm/
  2. FDA — Approval of Rebyota (November 2022) and Vowst (April 2023): https://www.fda.gov
  3. Centers for Disease Control and Prevention — epidemiological data on Clostridioides difficile
  4. New England Journal of Medicine — van Nood et al., 2013 — FMT clinical trial vs. vancomycin
  5. Nuffield Council on Bioethics — Human Bodies: Donation for Medicine and Research, 2011
  6. PLOS Medicine — studies on physiological effects of repeated plasma donations in the United States
  7. International Plasma Fractionation Association — global fractionated plasma market estimates
  8. Association for Molecular Pathology v. Myriad Genetics, 569 U.S. 576 (2013) — United States Supreme Court
  9. Moore v. Regents of the University of California, 51 Cal. 3d 120 (1990) — California Supreme Court
  10. National Agency for the Safety of Medicines and Health Products (ANSM) — French regulatory framework for FMT
  11. Grand View Research — microbiota therapy market projections, 2023