My dog has a strong reaction to Athletic Greens. Has anyone else experienced this?

Hi! Whenever my husband uses Athletic Greens one of our senior chihuahuas is so scared. He will instantly whimper, hide and shiver. Like he’s scared of it. It has nothing to do with the sounds of the container because sometimes it’s a packet. Once the AG1 is opened and hits the air he knows. He can literally be in another room and will realize. My husband tried to hide it and put it in his smoothie while my dog and I were in another room. I knew he was using it because my dog who was in my lap out of no where was sniffing the air and whimpering. Anyway, AG1 is no longer allowed because our dog is simply terrified of it. I just wonder why – I tried looking up the ingredients but I don’t see anything that stands out. We can make smoothies with anything else no issues. Has anyone else experienced this with their dog?