Are there any foods that are harmless when eaten alone yet are dangerous or toxic when eaten together with another otherwise innocuous food?

There can obviously be problems if you combine acidic foods with basic foods. I'm looking more for pairings that cause some sort of chemical reaction that produces a toxin and/or some pharmacological product.

This question is motivated by some claims that have been made over on Cooking.SX. For example, it is claimed that the combination of crab and persimmon is toxic.

I could have sworn that I had seen a similar question asked either here or on Cooking.SX, however, I couldn't seem to find it after doing a search.

  • 1
    A common story in Belgium and the Netherlands is that you should not mix tonic and baileys, because it would form a stone in your stomach, which is not the case (link is in dutch). – johanvdw Sep 22 '11 at 19:48
  • like a 2-part poison – ratchet freak Sep 23 '11 at 1:02
  • @ESultanik - I suggest you make your question about a specific claim, we can't provide answers where the answers are just a list of "possible claims" – going Sep 23 '11 at 4:50
  • Note: please don't make this a list question. – Sklivvz Sep 23 '11 at 7:55
  • @Sklivvz: Now that there are two answers, how should I deal with this? Should I edit the question to only ask about the crab/persimmon combination? I intended this question to have a simple "yes/no" answer (i.e., any single counter-example is sufficient). – ESultanik Sep 23 '11 at 11:59


One example that springs to mind is the combination of certain species of mushrooms and alcoholic beverages. The mushrooms contain metabolites which inhibit one of the enzymes involved in breaking down ethanol, leading to a buildup of the aldehyde ethanal, which is unpleasant.

The ink cap--Coprinus atramentarius (Bulliard ex Fries) Fries--is responsible for poisoning when ingested with alcohol


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    +1, although it could certainly be argued that alcohol doesn't qualify as harmless when eaten alone – David Hedlund Sep 23 '11 at 11:48

One common claim I was told as a child is that it is unhealthy to eat fish and leafy vegetables (like spinach), due to the formation of nitrosamines. This seems to be more of a theoretical risk than an actual cause of illness, although I did find one paper linking fish and high-nitrate vegetables to liver cancer.

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