First off - don't get angry at her! Colic is hard. You are both tired, irritable and at your wits end trying to get some peace. It's easy to turn on each other rather then face the problem together.
I'm guessing she has very recently given birth too so will be a mass of hormones which are not always logical. It's a big change for you too but you are not under the same torrent of hormonal pressures.
You might be right - there is no evidence - but that doesn't mean you are right. The colic will only last a few weeks (though I know it seems forever, I've been there!) and giving up onions, garlic and curry for those few short weeks if it appeases your DW is a small price to pay, IMHO.
You can say, 'I don;t think there is evidence for this, but if it will make you happy then I will do it' , basoically, I will make this compromise for us, becasue I want us to work toghether to solve problems not turn against one another - your understanding and commitment at this time is crucial.
From your compromise ask her to try one for you - I heartily recommend Colief www.colief.com/. It worked the day we gave it to DS but ask to give it a day or two.
Working together is an essential lesson. Life throws harder lessons that this at couples and only the ones who work together stay together.