Citrinin: A Kidney Toxin With an Unexpected Supplement Source
Citrinin is a kidney-toxic mycotoxin produced by several Penicillium, Aspergillus and Monascus species. It frequently appears alongside ochratoxin A because the producing fungi and the affected commodities overlap. Its most distinctive source is red yeast rice, a supplement in which the producing organism is deliberately cultured.
Mainly dietary
Citrinin is the mycotoxin most likely to have entered through a supplement cupboard rather than a food or a building. Red yeast rice is the source people rarely think to check.
Which fungi produce citrinin
The species from which citrinin was first isolated, and a common contaminant of stored cereals.
Produces both citrinin and ochratoxin A, which is why the two are so often detected together.
Cultured deliberately to produce red yeast rice. Citrinin is an unwanted secondary metabolite of that fermentation.
Several produce citrinin, including species common on stored commodities.
Where exposure comes from
A urine panel confirms that a compound reached you. It cannot say by which route. These are the realistic possibilities, which is what a result has to be read against.
Produced by fermenting rice with Monascus purpureus, which can generate citrinin alongside the intended monacolins. Levels vary widely between products and several jurisdictions now set limits.
Wheat, barley, oats, rye and rice contaminated by Penicillium during damp storage.
Some fermentation processes involve species capable of producing citrinin.
Penicillium is among the most common indoor moulds on damp material, so an environmental contribution is plausible though generally smaller than dietary intake.
How it affects the body
Citrinin concentrates in the kidney, where the proximal tubule is the principal target. Renal handling explains the organ specificity: the same filtration and reabsorption that concentrate the compound expose those cells to the highest levels.
The dominant mechanism is mitochondrial. Citrinin disrupts electron transport and increases membrane permeability, reducing ATP production and generating reactive oxygen species, which in turn drives oxidative damage and apoptosis in tubular cells.
Co-exposure with ochratoxin A is common and is not merely additive. Experimental work indicates the two interact, with combined nephrotoxicity exceeding what either produces alone at the same doses, which is a reason to read the two results together.
Documented health effects
Nephrotoxicity is the established effect, demonstrated consistently across animal species, with proximal tubule damage and impaired concentrating ability.
The two frequently co-occur and appear to potentiate one another, which matters because panels often report both.
Evidence is mixed. Some laboratory systems show DNA damage while others do not, which is part of why the carcinogenicity classification remains inconclusive.
Embryotoxic effects are reported in animal studies at doses well above typical dietary exposure.
Cancer classification: IARC Group 3, not classifiable as to carcinogenicity in humans
How it is measured
The informative urinary marker is dihydrocitrinone, the principal human metabolite, rather than citrinin itself. Panels that measure only the parent compound understate exposure, so it is worth checking which your laboratory reports.
Citrinin and ochratoxin A are commonly measured on the same panel because they share producing organisms and affected commodities, and reading them together is more informative than reading either alone.
The wider question of what these panels can and cannot establish is covered in the guide to mycotoxin urine testing.
Reading a citrinin result
Before considering environmental sources, check the supplement cupboard. Red yeast rice is taken specifically for its monacolin content and is an under-recognised citrinin source, so it is the first thing worth ruling out on a positive result.
Then account for cereal intake, particularly stored grains and rice. Citrinin is a storage-related contaminant, so the relevant variable is how the commodity was kept rather than what it was.
A citrinin result alongside a raised ochratoxin A is worth taking more seriously than either alone, given the evidence that the two potentiate each other in the kidney.
If you are holding a panel and want each value explained, the free lab report interpreter reads mycotoxin results alongside ERMI and HERTSMI-2 building scores and the inflammatory markers used in biotoxin illness, and explains what each one indicates.
Frequently asked questions
What is dihydrocitrinone and why is it measured instead of citrinin?
Dihydrocitrinone is the main metabolite humans produce from citrinin, and it is excreted in urine more reliably than the parent compound. A panel measuring only citrinin itself can understate exposure, so it is worth confirming which your laboratory reports.
Does red yeast rice contain citrinin?
It can. Red yeast rice is made by fermenting rice with Monascus purpureus, which produces citrinin as an unwanted secondary metabolite alongside the monacolins the supplement is taken for. Levels vary widely between products and several jurisdictions set limits, so it is the first source to check on a positive result.
Why do citrinin and ochratoxin A appear together?
They share producing organisms, notably Penicillium verrucosum, and the same stored commodities. That co-occurrence matters because experimental evidence indicates the two potentiate each other in the kidney rather than simply adding together.
Is citrinin dangerous?
It is an established kidney toxin in animal studies, targeting the proximal tubule through mitochondrial disruption and oxidative stress. Human outcome data are limited, and IARC places it in Group 3, not classifiable as to carcinogenicity. The practical concern is chronic low-level intake, particularly alongside ochratoxin A.
Screening for Biotoxin Effects
A mycotoxin result describes what your body is clearing. The Visual Contrast Sensitivity test measures something different, a neurological effect associated with biotoxin exposure, which gives a second and independent data point. Free, in your browser, about 15 minutes.