The syrup just makes it taste better and supplies more minerals. I use 1 tablespoon to 1/2 gallon juice mixture. The old book probably would have you add 3-5 tablespoons to this much, but I think 1 tablespoon is enough.
There was a MD that cured every patient with red star yeast. Today this would be a very, very expensive method, but I believe the old guy was correct in what he did.