How do we know that cold "remedies" work? My sister swears by Zicam. "Our colds are gone so much faster when we use it". What exactly does that mean? Now, don't get me wrong. I'm not knocking my sister here. She's pretty darn smart but...
How long does a cold last? Not like that is a precise measurement. Think about it.
There is no precise measurement. "My colds lasted 33.5 hours, but with Zicam they last 21.4". Laboratory tested. Colds last different lengths of time for all sorts of different reasons. Maybe the positive energy created in your brain by applying Zicam regularly causes your body to generate more antibodies and kick the cold quicker. Maybe if you were convinced that vodka tonics with lime were the trick, they also would do it.
So let's extend that. I take a variety of supplements. Glucosamine/condroitin for my joints. I have crappy knees, I'll blame rugby but it's most likely just that I have crappy knees. I take a supplement. If I stop taking the supplement I think that my knees start to hurt more. Do they actually? I don't know. Maybe I just notice it and blame it on the lack of supplement. The rest of what I take I take because I have been told it is healthy. Vitamin C, Omega 3 oils, multivitamin, stuff for my eyes because my family has a history of AMD. Does any of it do any good? Beats the heck out of me. But I (semi)faithfully shovel it into myself (almost every morning and hope that I am going to live longer and better because of it. Sort of like my sister's Zicam.