it doesn't help decreasing your anxiety, but it gives you an energy,concentration and focus that is very helpful. You will certainly have better conversations with people as you can focus more on what people say to you and how you could respond to that, also you react quicker and more impulsive to what others say so that you say things that you otherwise only think but would be too afraid of to tell out loud.
I always drink one in the morning when I arrive at school.