Recommendation of fizzy drink intake

Answer 1

None at all. From a purely medical perspective, fizzy drinks (I'm guessing this is the British term for what Americans would call "soda" or "soft drinks") have no nutritional value whatsoever, and contain a large amount of sugar. The high phosphoric acid content of Coke and Coke-like products aren't going to be doing your teeth (and possibly your bones) any favors. The calories in Coke will replace those that could have better been accomodated by fruits and vegetables- and if it doesn't replace what you would've been eating, you'll be taking in excess empty calories, which can lead to obesity. Diet versions of beverages aren't really much better- studies following those trying to lose weight amongst those drinking diet and non-diet beverages found no difference in weight loss between the two groups. While most artificial sweetners are recognized as generally being safe, very high quantitities have shown risks in animal studies. With no benefit to sodas, there seems little reason to take any sort of small but significant risk. There are no health benefits to consuming soda and quite a number of detriments. The optimal number of soft drinks per day is zero.