It's also logical. GLUT2 is a passive transporter and relies on diffusion. You will always have a bunch more glucose than vitamin C, so it will outcompete it.
The same transporter is used for both, as they are very similar - GULO gene transforms glucose to C.
There is a special C transporter SVCT1/2, a pump, that that doesn't suffer from this, but requires Mg/Ca for activation and is a lot less distributed than GLUT2. But then, eating modern fruit simple doesn't have much of it, and even that is lost around the conditions used. That's why no animal on the planet delegated vitamin C production to the plants, the amounts are far from enough for satisfactory workings of the body (except us, GULO mutants), alas high enough so you don't disintegrate (scurvy).
This might be one of the reasons why sugar diminishes the immunity (to be more precise, phagocytic index
) by around 50% several hours after eating it. Don't ask for study, there is Google Schoolar et al.
> your intake on fruit seem quite extreme
That means nothing to me nor anybody seriously researching this stuff. I rely on interpreting science documents. My or researcher interpretations might be wrong, but it's still the best we know so far. Contrary to that, unquantifiable "advices" like don't be extreme or that of moderation are best to left unsaid and all it does is tell me that person simply doesn't know anything about the topic and should be completely ignored.
> unquantifiable "advices" like don't be extreme or that of moderation are best to left unsaid
That wasn't meant to be advice, just my general, nonprofessional, take on nutrition recommendation until I am convinced otherwise. Which I gladly am, because I find human biology (esp. the metabolism) more and more interesting the more I know about it.
I only remember reading that vitamin c in its ascorbic acid form is the predominant way it is transported into the cells (by SVCT1,2 pathways) and DHA transports contribute only a way minor amount.
> This might be one of the reasons why sugar diminishes the immunity by around 50% several hours after eating it
Interesting, I'll try to find some reading material about that.
DHA is valuable transport since it doesn't require prerequisites and is ubiquitous, also SVCT doesn't transport DHA which you have tones of given that C is among other things ROS scavenger. Can't remember now the details, but I remember reading a paper where it was determined that DHA transport is substantial. Logically fallows that if you have to recycle C, its all you got, since you can't produce C.
Regarding immunity claim, here is something to get you started (50% claim):
> Oral 100-g portions of carbohydrate from glucose, fructose, sucrose, honey, or orange juice all significantly decreased the capacity of neutrophils to engulf bacteria as measured by the slide technique.
I am curious where you got that consuming sugar inhibits vitamin c absorption. I couldn't find any studies or research that supports this take.