Individual nutrients matter little. It is the network that matters. It is possible that the loss of the GULO gene has been adequately compensated by network changes, and thus the requirements for vitamin C may be less than in those animals of roughly our size who make grams of C per day. Metabolism is the most sensitive and specific way to decide the question – not external or internal symptoms.
Based on data from animals about our size that make their own vitamin C, the mutation in the GULO gene has left us probably about 10 grams short of the vitamin C per day we would have made if we still had this gene. Fortunately, we can make up for this by dosing about 1/2 gram every waking hour.
One hundred milligrams of vitamin C per day may be enough to maintain body pools of vitamin C, but it does not provide the regular over-dosing that the circulatory system may need to be fit and healthy, scavenging heavy metals, and keeping lipoprotein(a) from acting as a pesky surrogate. At least Rath’s and Pauling’s view makes biological sense.
The government’s view is that the amount of vitamin C that is needed is merely enough to maintain pools.
But some functions of C require circulation and are not complete without excretion. An example is heavy metal chelation. To see this going on in ordinary individuals, we may need mass spec with attogram sensitivities. To see this in those suffering from lead, mercury, or cadmium intoxication, we probably do not need such sensitive tools.
One hundred milligrams of vitamin C a day does not provide the large amount needed during severe stress (vitamin C must be titrated up to meet the severity of the stresses the body is under), as during wound healing (amazingly high dose vitamin C is not even a part of the medical establishment’s wound healing protocol and neither is acidification of the wound), as during infections (and our overly stressful reaction to them) in the blood stream, and the large amount that the urinary system may need to keep everything as soluble as possible, particularly when some people, due to numerous nutrient deficiencies (magnesium, vitamin C and vitamin K, among others), are excreting their calcium-rich liquified bone extract, along with copious quantities of phosphate from bone, and oxalate, the latter a product of oxidized vitamin C, a sign of poor antioxidant status inside cells (of which low vitamin C is but an example).