But apparently, that is the main ingrediant. From the website:
Beer shampoo, really? For volume, softness and shine we proudly serve our tremendously effective pub-inspired shampoo. Cynthia Sylvia Stout is made with organic vegan stout beer from a local brewery, which contains protein to give your hair weight, smoothness and gloss. It's excellent for hair that tends to go frizzy in damp or humid environments. Cynthia smells delicious, just like a brandy, stout and lemon cocktail and even makes curly hair unbelievably shiny and bouncy once again. Give your thirsty hair a drink of this.