The Best Answer
All vegetables contain some "simple sugars," etc... Tomatoes allowed on this diet (4HB p 74) contain 4 g sugar per 149 gram serving, and two of those grams are fructose. Coconut water contains 6 g sugar per 240 g, and as such has less sugar than tomatoes or peas or even coconut itself, that is also allowed on this diet (per TF, "A little coconut is totally fine but I wouldn't eat it as an entree." link below). More importantly, even if a food (tomatoes, coconut water, peas) contains fructose, eating it is not the same as eating fructose. Coconut water is fine in moderation.