Eight-week dietary trial finds different urinary mycotoxin patterns

Researchers analysed samples from a randomized dietary trial

An analysis published in npj Science of Food on 18 September 2026 found different urinary mycotoxin patterns after an eight-week vegan or meat-rich dietary intervention. Researchers at the University of Freiburg examined samples from healthy adults who had eaten omnivorous diets before joining the trial. Of 65 participants who completed the study, two were excluded because of implausible mycotoxin data. The final analysis included 32 participants assigned to the vegan group and 31 to the meat-rich group.

After a one-week mixed-diet run-in, the vegan group excluded animal foods, while the meat-rich group was instructed to eat at least 150 g of meat daily; fish did not count toward that requirement. The vegan group was encouraged to choose whole foods. Participants selected their own foods within the protocol, received nutritional support and were not supplied with meals. The intervention compared diets with similar energy intake.

Creatinine-adjusted results differed for four toxins

The researchers measured six mycotoxins in morning spot urine collected at baseline and after eight weeks. They reported concentrations in micrograms per litre of urine and, separately, concentrations adjusted for creatinine in micrograms per gram of creatinine. Values below each toxin's detection limit were assigned half that limit for statistical analysis.

At week eight, the creatinine-adjusted median deoxynivalenol concentration was 7.15 µg/g creatinine in the vegan group and 2.85 µg/g in the meat-rich group (p = 0.004). The corresponding medians were 0.45 versus 0.20 µg/g for ochratoxin A (p = 0.003) and 1.34 versus 0.49 µg/g for zearalenone (p = 0.001). T-2 toxin showed the opposite pattern: 3.44 µg/g in the vegan group and 5.15 µg/g in the meat-rich group (p = 0.047).

For concentrations reported per litre of urine without creatinine adjustment, the week-eight comparison was significant for T-2 toxin, which was higher in the meat-rich group. The unadjusted endpoint comparisons for deoxynivalenol, ochratoxin A and zearalenone were not statistically significant.

The analysis of changes over time gave a different T-2 result

Mixed models using the repeated measurements found significant diet-by-time interactions for creatinine-adjusted deoxynivalenol, ochratoxin A and zearalenone. The T-2 toxin model did not find a significant interaction or a significant between-group difference at week eight, despite the significant endpoint comparison in the simpler analysis.

Some models used log transformations and excluded outliers to obtain normally distributed residuals. The authors did not adjust for multiple testing and identify the resulting higher chance of false-positive findings as a limitation. Many measurements were below detection limits: for example, aflatoxin was below its limit in 57 of 63 week-eight samples, while fumonisin was below its limit in 61.

Food records did not give a clear account of individual sources

Participants kept weighed food diaries, generally for three days at each assessment. The researchers examined associations between food-group intake and urinary concentrations. Further plots and regression analyses suggested possible associations of vegetable intake with creatinine-adjusted deoxynivalenol and ochratoxin A, but the authors call for caution because of the modest sample size.

The paper notes that the food groups contained many different products, spices were incompletely recorded and some diaries covered only two days. Food records did not necessarily cover every day immediately before urine collection. The authors could not explain the higher T-2 toxin values in the meat-rich group.

The authors distinguish exposure patterns from health outcomes

Creatinine adjustment is an important uncertainty in comparisons of these diets. The paper discusses how meat and fish intake, and differences in muscle mass, may affect urinary creatinine. The study did not include long-term vegans, and the authors considered large changes in fat-free mass unlikely over eight weeks. However, neither 24-hour urine collection nor adjustment for urine specific gravity was available.

The authors state that the laboratory reference ranges reported in the paper are not safety thresholds and that direct health outcomes were not assessed. They call for larger, well-designed randomized studies to investigate exposure and any possible health effects. Their conclusion also states that the findings are not intended to discourage plant-forward diets and calls for efforts to reduce mycotoxin exposure regardless of dietary choice.