Acidic foods don’t test positive for Covid

15 July 2021
What was claimed

Tomatoes, raspberries, blackberries and lemons produce positive lateral flow test results for Covid-19.

Our verdict

These foods break the lateral flow devices creating a fake “positive” result. This doesn’t tell us anything about whether the tests are reliable when used correctly.

A number of Facebook posts have claimed that tomatoes, raspberries, blackberries and lemons produce positive lateral flow test results for Covid-19.

This isn’t true.

The photos in both posts show pictures of fruit accompanied by a completed lateral flow test with two lines next to areas marked “C” and “T”. These lines indicate a positive result for Covid-19. Any other result is either negative or invalid. One of the posts shows a lemon with a positive result, which it claims is evidence of the tests producing multiple false positives, while the other shows ‘positive’ results next to a tomato, a raspberry and a blackberry.

However, as we’ve established before, foods high in acid break lateral flow tests, causing it to appear like a positive result. The fact that these tests can effectively be broken with fruit does not make them inaccurate or unreliable for use in the general population. 

Lateral flow tests are unlikely to give a false positive result if used correctly.

We have previously fact checked, among others, claims that kiwi fruit, Coca Cola, ketchup, fruit squash, strawberries, grapes, oranges and diluted cordial have incorrectly produced “positive” results. 

Using food and drinks on lateral flow tests has been in the news after reports that pupils are attempting to get time off school by using liquids like lemon juice to create false positive results.

This article is part of our work fact checking potentially false pictures, videos and stories on Facebook. You can read more about this—and find out how to report Facebook content—here. For the purposes of that scheme, we’ve rated this claim as false because foods high in acid break lateral flow tests and create a fake “positive” result.

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