Vac-Yeast Is a Food

Foods aren’t drugs

Foods can be vaccines. It’s an exciting idea at a basic scientific level, but the best part is that it means vaccines can be regulated as foods. It means vaccine development can be democratized. In the inspirational words of Chef Gusteau in the movie Ratatouille:

Great cooking is not for the faint of heart. You must be imaginative! You must try things that may not work. You must not let anyone define your limits because of where you come from. What I say is true: anyone can cook. But only the fearless can be great.

The first objection I hear from some scientific colleagues comes along the lines of “you’re not fooling anyone with this food thing - we all know vaccines are drugs.” While it’s true that all previous vaccines have been marketed with the intent of preventing disease - a regulatory bright line that makes them drugs - that doesn’t mean that all future vaccines can only be considered drugs.

My colleagues are missing the point made in my carrageenan post, where I illustrate the fact that a given ingredient can simultaneously exist as a food in some products and a drug in other products. Another example is artemisinin, which is separately marketed either as an FDA-approved anti-malarial drug or as a food supplement product. We all know artemisinin is a drug, but that doesn’t mean it can’t also be a food. A third example is vitamin C - that fact that it exists as an FDA-approved injection drug used for treating scurvy doesn’t automatically turn limes and multivitamins into drugs.

The bright line is that food products only become drugs if the manufacturer makes marketing claims indicating that the product is intended to prevent or treat disease. Foods can be advertised as having general effects on normal healthy bodily structures and functions, they just can’t be advertised with the intent of treating disease.

An important point is that the food versus drug distinction is focused on manufacturer intent, as revealed by marketing claims. At the consumer level, people are free to read medical literature and choose foods they hope might treat a specific disease. If you know you have vitamin A deficiency, you’re allowed to go buy some carrots with the explicit intent of curing yourself of the disease. You could also choose to eat Golden Rice (a food product intentionally engineered to provide vitamin A). The law also allows physicians and scientists to advise patients and the general public that carrots and Golden Rice are known cures for vitamin A deficiency. At a marketing level, it’s only the manufacturer whose hands are tied.

In the Discussion section of our vaccine beer manuscript, we draw an analogy to spinach - which contains an Investigational New Drug (IND) called zeaxanthin. If you wanted to test the hypothesis that the zeaxanthin in spinach can prevent a form of blindness called macular degeneration (which extensive scientific literature suggests is possible) you would need to alert the FDA with an IND application before your spinach product could go into controlled clinical trials. The IND filing would make the specific spinach product being used in the clinical trial a not-yet-approved drug. Spinach on supermarket shelves would still just be spinach. A food manufacturer could also lawfully sell a GMO spinach strain engineered to have ten times more zeaxanthin [1], so long as the super-spinach food product doesn’t carry the marketing claim that the added zeaxanthin is intended to prevent macular degeneration. The point is that foods - including foods with ingredients known to have possible disease-fighting effects - are regulated differently than drugs.

A challenging marketing question is whether the word “vaccine,” all by itself, can only be construed as an intent to prevent or treat disease. The Merriam-Webster’s definition of the word vaccine describes a methodology that can have various possible intents:

A preparation that is administered (as by injection) to stimulate the body's immune response against a specific infectious agent or disease.

A definition from the National Cancer Institute also describes multiple possible intents:

A substance or group of substances meant to cause the immune system to respond to a tumor or to microorganisms, such as bacteria or viruses. A vaccine can help the body recognize and destroy cancer cells or microorganisms.

The word “or” in the definitions highlights the fact that infectious agents aren’t the only possible target for vaccines, and it highlights the fact that infectious agents aren’t necessarily synonymous with disease. Viruses often cause disease, but infections can also be asymptomatic. In the case of the BK polyomavirus (BKV) vaccine beer [2] I drank, my consumer intent reflected a hope for general health benefits. Although BKV infection is widely described in scientific literature as “asymptomatic” or “harmless” in healthy individuals, the virus can sometimes cause diseases of the kidneys, bladder, gut, brain, and cardiovascular system in immunosuppressed people. I also worry that BKV may be modifying normal bodily structure/function in other ways we simply haven’t figured out yet. The BKV vaccine project was essentially just a philosophical “no thanks” to BKV as a general health proposition - as opposed to a specific intent to prevent or treat any particular disease. It could be broadly described as a way of supporting the normal healthy functions of my immune system. This is a general-health structure/function claim can be found on approximately 25,000 food product labels.

In summary, having the term “BKV vaccine” on the label isn’t claiming an intent for therapeutic efficacy for any particular disease - the intent is simply to inform consumers about the presence of a specific component of the food product that could have possible health effects (including hypothetical hazards). It’s no different from telling people limes contain vitamin C.

In the vaccine beer manuscript, we report the first commercial sales food-grade vaccine-yeast products. The starting goal wasn’t to be scalable or profitable - the major initial aim is to satisfy specific aspects of food and drug law. As described in detail in Appendix B (reproduced verbatim below), if the first appearance of a substance is on the FDA IND track then it can never later be marketed as a food supplement product - it can only ever be considered a drug. The initial sales of the yeast as a food (to a set of customers with expertise in vaccine design) secures its status as a product that any company can sell as a general health food product even if, in parallel, it goes through clinical trials as a possible disease-preventing drug in the future.

When I imagine future sales to less expert customers, I start to worry that omitting the word “vaccine” from the product label could make some consumers think we’re trying to furtively sneak vaccines into the food supply. That’s the exact opposite of what we’re trying to do. The goal of this work is to promote open source vaccine development in a way that will increase everybody’s freedom of choice. Tricking people into doing things absolutely is not on the agenda.

The fact that the word vaccine is intended to describe an ingredient can be emphasized by referring to the emerging product category, in general, as “vac-foods” — where vac stands for “vaccine antigen-containing.” The possible vaccine antigen would be listed as a bioengineered component of the food product. My sense is that this compromise approach should be readily intelligible to consumers, while also lowering the hackles of scientific colleagues and regulators. We all know that familiar vaccines are drugs, but maybe we can all agree that vac-foods are foods [3].

This is a controversial new area of legal interpretation, and I’m not a lawyer. Comments - especially constructive criticism or cautions - are most welcome [4].

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Footnotes

[1] GMO tomatoes engineered to produce a class of drugs called anthocyanins are marketed as a food with a range of possible general health benefits.

[2] Grapes, apples, and honey don’t have enough maltose to trigger the production of the vaccine antigen. All you beer-haters out there will have to develop your own expression systems. Or you could learn to love beer? It built the pyramids! How bad could it be.

[3] In the surprising event that courts eventually rule the category name “Vac-Yeast” an impermissible disease claim, manufacturers could resort to a category name like “Immune Support Yeast” (with the expressed antigen simply listed as a bioengineered component). I like this market approach a lot less, because it risks tricking consumers into accidentally drinking vaccines. But it’s good to know there’s technically a backup plan that only uses a permissible general health structure/function claim.

[4] In response to reader comments, I extensively revised this post several times during the last week of December 2025 and again in April 2026. Thanks, readers!

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Song of the day: With apologies to Uncle Byron, who didn’t like war metaphors, I say again: Viruses. Must. Die.

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Appendix B. Marketing and regulatory considerations

In order for an ingredient to be marketed as food in the US, it must be Generally Recognized As Safe (GRAS), as defined by federal statute 21 CFR § 170.30(b) and (c)(1).

General recognition of safety through experience based on common use in food prior to January 1, 1958, shall be based solely on food use of the substance prior to January 1, 1958, and shall ordinarily be based upon generally available data and information. An ingredient not in common use in food prior to January 1, 1958, may achieve general recognition of safety only through scientific procedures… General recognition of safety through scientific procedures shall be based upon the application of generally available and accepted scientific data, information, or methods, which ordinarily are published, as well as the application of scientific principles, and may be corroborated by the application of unpublished scientific data, information, or methods.

Food manufacturers may choose to notify the Food and Drug Administration (FDA) of a self-conducted GRAS determination, but the law does not require formal notification (FDA, 2017).

Saccharomyces cerevisiae yeast have served as a foundational food ingredient for millennia. In recent years, American consumers have quietly embraced genetically modified (GMO) yeast as a commercial beer ingredient (Kramer, 2023). The FDA has acknowledged GRAS notifications for a number of GMO yeast products.

BKV VP1 is frequently shed in human urine, and various cultures have historically engaged in the routine practice of drinking urine (Savica et al., 2011). Although the proposed health benefits of urophagia are unproven, urine and its constituent components are not known to be allergenic or toxic. Furthermore, chronic infections with BKV, and its close relative JCV, are highly prevalent and both viruses have been reported to asymptomatically inhabit human gut mucosa (Shadbash et al., 2024). Recombinant VLPs composed of JCV VP1 have been tested as an experimental injection vaccine and the vaccine was well tolerated (Ray et al., 2015; Sospedra et al., 2014). We are not aware of any evidence indicating that eating VP1 as a food ingredient might be allergenic, toxic, or in other ways harmful.

The VP1 expression plasmid used in this work, pGustiv, encodes a formaldehyde dehydrogenase 1 (FDH1) gene as a selectable marker. The FDH1 sequence is derived from Candida maltosa, a yeast species that is non-pathogenic, commonly found in fermented dairy products, and used for industrial production of animal feed (de Melo Pereira et al., 2022; Mauersberger et al., 1996). As detailed in the Supplemental Methods section, residual levels of formaldehyde in the finished vaccine beer are well within levels declared safe in World Health Organization guidance (WHO, 2005).

The pGustiv plasmid encodes a variant of enhanced green fluorescent protein (GFP) that is useful for confirming the co-expression of vaccine antigens of interest. Dietary GFP has been shown to be safe in animal models (Han et al., 2015; Richards et al., 2003) and online videos depict home hobbyists drinking and sharing beer made from yeast expressing GFP, with no apparent adverse effects. A Phase I clinical trial (NCT009794131) concluded that a therapeutic virus expressing GFP is safe for use in humans (Jaime et al., 2012).

These scientific considerations support the determination that yeast carrying the pGustiv expression plasmid are a GRAS food.

In the future, academic groups or commercial entities may wish to file Investigational New Drug (IND) applications covering formal research investigations into the possible therapeutic efficacy of food vaccines. US law allows GRAS ingredients to be marketed as food products, so long as they were marketed as a food or dietary supplement prior to any IND applications. FDA guidance states:

Generally, the dietary supplement definition excludes ingredients that are approved as new drugs, licensed as biologics, or authorized for clinical investigation under an investigational new drug application (IND) that has gone into effect, unless the ingredient was previously marketed as a dietary supplement or as a food (FDA, 2024).

To establish a documented example of vaccine yeast being marketed as a food product, Remy LLC sold yeast slurries as food products for personal use to two customers who happen to be professional research scientists with expertise in virology and vaccine development. Both customers are former employees of the FDA. Remy LLC did not make any claims of therapeutic effects or possible structure/function health benefits. The customers have not reported any adverse effects.

References

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FDA. (2017). Guidance for Industry: Regulatory Framework for Substances Intended for Use in Human Food or Animal Food on the Basis of the Generally Recognized as Safe (GRAS) Provision of the Federal Food, Drug, and Cosmetic Act. https://www.fda.gov/regulatory-information/search-fda-guidance-documents/guidance-industry-regulatory-framework-substances-intended-use-human-food-or-animal-food-basis

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