No, cyanocobalamin is not made from human waste. It is produced through bacterial fermentation in large industrial vats, using sugar-based nutrients as feedstock. The claim that it comes from sewage or human feces is a persistent myth with no basis in how the vitamin is actually manufactured.
This misconception likely stems from the fact that bacteria are involved in production, and some people conflate “bacteria” with “sewage.” In reality, the process is closer to how beer or yogurt is made: carefully selected microorganisms are fed specific nutrients in a controlled environment, and they produce vitamin B12 as a metabolic byproduct.
How Cyanocobalamin Is Actually Made
Commercial vitamin B12 is produced through bacterial fermentation in stainless steel vats that can hold over 100,000 liters. The two main bacterial species used are Pseudomonas denitrificans and Propionibacterium freudenreichii. The latter is classified as GRAS (generally recognized as safe) and is the same type of bacterium used in Swiss cheese production.
These bacteria are fed a carefully formulated growth medium. The primary carbon source is sucrose or beet molasses, which contains about 44% sucrose along with amino acids like glutamate. The medium also includes small amounts of cobalt (a mineral at the center of every B12 molecule) and other trace nutrients. There is no sewage, no human waste, and no animal-derived material in standard B12 fermentation.
The fermentation runs for 7 to 10 days. Even at massive scale, yields are relatively low, which is one reason B12 supplements can be expensive to produce. After fermentation, it takes roughly two more weeks to go from raw bacterial broth to purified cyanocobalamin, using a series of steps including precipitation, chromatography, and crystallization.
Why It’s Called “Synthetic”
Cyanocobalamin is often labeled synthetic because it doesn’t exist in nature in significant amounts. The two forms of B12 your body actually uses are methylcobalamin and adenosylcobalamin. Cyanocobalamin is a stabilized version: a cyanide group (in a tiny, harmless quantity) is attached to the cobalamin molecule, making it more shelf-stable and cost-effective for supplements. Once you ingest it, your body strips off the cyanide group and converts it into the active forms it needs.
The word “synthetic” here doesn’t mean it’s assembled from chemicals in a lab the way aspirin is. The bacteria do the heavy lifting of building the complex B12 molecule, which has 63 carbon atoms and requires about 30 enzymatic steps to assemble. No purely chemical synthesis is practical at industrial scale. The “synthetic” label refers to the final stabilization step where the cyanide group is added, and to the fact that the process is engineered rather than harvested from food.
Purity Standards for the Final Product
Pharmaceutical-grade cyanocobalamin must meet strict purity requirements set by the United States Pharmacopeia (USP). The finished product must contain at least 96% pure cyanocobalamin, with total impurities capped at 3%. Individual impurity types, which are minor structural variants of the B12 molecule, are each limited to 0.5% to 2% depending on the specific compound. Any trace impurity below 0.1% doesn’t even need to be reported.
These standards exist precisely because cyanocobalamin goes through extensive purification after fermentation. The bacterial broth is processed through multiple extraction and filtration stages to isolate the vitamin from everything else in the culture medium. What ends up in your supplement bottle bears no resemblance to the fermentation vat it originated in, just as refined sugar bears no resemblance to a sugar beet field.
Where the Myth Comes From
The “human waste” claim appears to have originated from a few loosely connected facts that got distorted through repetition online. First, B12-producing bacteria do naturally live in the human gut, but those bacteria aren’t harvested for supplement production. Second, early B12 research in the 1940s and 1950s involved studying bacterial activity in many environments, including sewage, because researchers were trying to understand which organisms produced the vitamin. That research phase has nothing to do with modern manufacturing.
Some versions of the claim also confuse cyanocobalamin production with the entirely separate process of reclaiming phosphorus or other nutrients from wastewater, which is a real but unrelated area of environmental engineering. The vitamin B12 in supplements comes from purpose-built fermentation facilities, primarily in China, where the majority of the world’s supply is now produced. These are pharmaceutical manufacturing plants, not sewage treatment facilities.
What the Bacteria Are Actually Fed
If you’re curious about the specific ingredients, the fermentation medium reads more like a baking recipe than anything alarming. A typical formulation for industrial B12 production includes beet molasses (130 grams per liter), additional sucrose, betaine (a naturally occurring compound found in beets and spinach), ammonium sulfate as a nitrogen source, magnesium sulfate, zinc sulfate, and a tiny amount of cobalt chloride. The cobalt is essential because it sits at the molecular core of every B12 molecule.
The bacteria consume these sugars and nutrients, grow, and produce B12 as part of their normal metabolism. The vitamin is then extracted, purified, and crystallized into the red powder that eventually gets pressed into tablets or dissolved into liquid supplements. Every step of this process is performed under controlled, sterile conditions designed to maximize both yield and purity.