5 years ago, I was having persistent lower back pain. It took a while, but I stumbled on first one, then several articles on the side effects sucralose (splenda) sweetener has with one's kidneys, stating it can even cause internal scarring. All of the beverages I used, used sucralose. I decided to get some larger containers of bottled water and a few of those small bottles of water flavoring and I got some stevia sweetener to make my own beverages. Within 4 weeks my back pain was gone. I have been using the water and flavoring since. I just use distilled water on it's own, or with a measure of soluble fiber at work as I can drink it at any temperature with no bad taste. As far as the Coke goes, It seems like different sweeteners have an affinity for some flavors, and not so for others.
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"Any sufficiently advanced technology is indistinguishable from magic."
— Arthur C. Clarke