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Mycotoxins
There are unsubstantiated claims about the health effects of mycotoxins in coffee. We sought to understand how communities respond to such claims by analyzing posts and comments in r/Coffee, a large online community of coffee enthusiasts.
flowchart TD
A["Screened all public comments in r/Coffee<br/>Mar 2008 – July 2025<br/>(n = 5,591)"]
B["Excluded<br/>(n = 4,726)"]
C["Included<br/>35 posts → 865 comments"]
D["Analysis Plan<br/>• Thematic coding<br/>• Engagement (upvotes)<br/>• Content (explanations, sources)"]
A --> C
A --> B
C --> D
style A fill:#1f2937,color:#fff,stroke:#4ade80,stroke-width:2px
style B fill:#7f1d1d,color:#fff,stroke:#f87171
style C fill:#064e3b,color:#fff,stroke:#34d399
style D fill:#1e3a8a,color:#fff,stroke:#60a5fa
Study Overview
| Step |
Description |
Count |
| Screened |
All public comments in r/Coffee (Mar 2008 – Jul 2025) |
5,591 |
| Excluded |
Did not contain mycotoxin-related terms |
4,726 |
| Included posts |
Posts containing “mycotoxin” or variants |
35 |
| Unique comments |
Comments analyzed |
865 |
Analysis Framework
| Domain |
Description |
| Thematic coding |
Refuting, questioning, or concurring with misinformation |
| Engagement |
Measured via upvotes |
| Content type |
Explanation vs citation vs neither |
| Category |
Count |
| Total comments |
865 |
| Indirectly address topic |
585 |
| Directly address topic |
130 |
| Stance |
Count |
% |
| Refuting |
99 |
76% |
| Questioning |
8 |
6% |
| Concurring |
23 |
18% |
Content Type by Stance
| Content Type |
Refuting |
Questioning |
Concurring |
| Explanations of Manufacturing |
63 |
0 |
0 |
| Anecdotes |
0 |
0 |
9 |
| Outside sources |
19 |
0 |
2 |
Engagement
By stance
| Group |
Median |
IQR |
Interpretation |
| Refuting |
4 |
2–5 |
Higher engagement |
| Supporting |
2 |
1–2 |
Lower engagement |
By content type
| Content |
Median |
IQR |
| Explanation |
3.5 |
2–9 |
| Citation only |
2 |
1–5 |
| Both |
4 |
1.5–9.5 |
| Neither |
3 |
2–7 |
Key Findings
| Finding |
Interpretation |
| Majority of comments refute misinformation |
Community tends to challenge false claims |
| Explanatory comments perform best |
Narrative + reasoning drives engagement |
| Manufacturing knowledge is key |
Domain-specific expertise used in refutation |
| Citations alone less effective |
Context matters more than references alone |
Limitations
| Limitation |
Impact |
| Single subreddit (r/Coffee) |
Limited generalizability |
| Manual coding |
Potential subjectivity |
| Small sample of relevant posts |
Reduced statistical power |
Conclusions
-
Most visible refutations used narratives. Refuting comments received the most upvotes when they included an explanation with sources cited: 4 [1.5–9.5] versus 2 [1–5] when they did not include a narrative.
-
Choice of sources. Refuting comments cited manufacturing processes demonstrating that coffee, in general, does not have appreciable levels of ochratoxin A or aflatoxins. Supporting comments cited sources discussing the potential dangers of those mycotoxins.
-
Auto-regulation. Comments providing explanations or citing sources received more engagement than those that did not. These findings suggest that some online communities may effectively self-correct misinformation, highlighting opportunities for collaboration between domain experts and engaged lay communities.
-
Limitations. One social media community may not adequately represent the relevant population; comments were manually coded; the total number of relevant comments was small.
In r/Coffee, misinformation about mycotoxins was challenged through domain-specific explanations and the citation of academic and governmental sources.
Mucuna pruriens.
See this notebook for an analysis of online discussions about the use of Mucuna pruriens, a plant that contains L-DOPA and is used in the treatment of Parkinson’s disease.