Description:
A quick search on the web about the health benefits (OR DETRIMENTS) of soy will quickly lead you to choose some other liquid to put in your smoothies.
I do not promote the consumption of cow's milk (or soy milk), but I also do not force my food choices on others.
If you prefer cow's milk, then by all means, use cow's milk.
The main thing is to research the health benefits (OR LACK THEREOF) of a food before adding it (OR NOT ADDING IT) to your diet.