A Facebook post suggests that a number of foods and drinks can deliver a “positive” Covid-19 result on a lateral flow test.
This is true, insofar as the acidity in some foods can break a test and cause a second line to appear, as if the test were positive. This doesn’t mean that the foods contain the Covid virus, however, or that the tests are unreliable when used correctly on people.
The photo shows what appear to be a citrus fruit, a tomato, a grape, a strawberry, a bottle of Kia Ora squash, a bottle of Tesco orange squash and a bottle of Heinz tomato ketchup, each one beside a completed lateral flow test.
A caption says “my cousin done this and all of them are positive apart from a grapefruit.”
A positive result creates two lines next to the areas marked “C” and “T” on the lateral flow test. Any other result is either negative or invalid.
It is not easy to tell from the photo whether all the tests do have two lines, but even if they do, this doesn’t mean that the tests are not reliable for their intended purpose.
Lateral flow tests are very unlikely to give a false positive result if used correctly. However, we have checked claims in the past about how samples from a kiwi fruit, Coca-Cola and oranges have incorrectly created “positive” results.