Invert the filter for an attribute

[Silberfischchen]

Hello together I need a solution for the following problem. Normally, I filter into attributes and get the products that match the attribute value.
Example cellphone: Black, 64G Memory 16Mpixel Cam
Ok, that's easy.

But I also need the other way around. I am planning a shop with spices and spices. Because of food intolerances, I need an attribute to a reversal so that everything is displayed but not what I clicked in the filter. For example gluten.

How do I proceed there or does someone know a module? Can not be that I'm the first one of a filter to negate.

[Aheadworks · Accepted solution]

It's likely you can add a reverse attribute to your products, for example 'gluten-free product' and use the same order of filtering...