I have recently started my pre-pre-op diet and I have a totally irrational aversion to powdered drink mixes, to the point that I have put off having the surgery because that was a requirement. I was told about a Protein drink from bipro that is an unflavored product. I have used it several times now and I don't have any trouble with it at all. I make smoothies and mix it with Vitamin Water in a whisk bottle. It really is unflavored!!!! I ordered it from their website and it took about a week to get to me. www.biprousa.com. It is also on Amazon, but it is the same price and ships from the manufacturer, so would be just the same as ordering it direct.