But start much lower and increase gradually over days, week and months. Some can tolerate much less at first, which might increase over time. A watery bowel-movement is the sure sign it was too much, take less the next dose again. Bowel-tolerance can fluctuate, with diseases it naturally goes up. Above 100 g per day in some, like cancer. Upto 50 g per day, in my case, due to rhinitis.
There is also an individual limit for each separate dose, in my case at 10 g. So in case of diseases, where one needs higher intake despite low tolerance, more frequent doses than the usual 3, down to every 20 minutes in the case of an acute cold, for example, can be employed to increase intake despite low tolerance.
Linus Pauling gave the wide range of usually 6-18 g, or more a day as therapeutic window of vitamin C, due to biochemical individuality. Which was exactly my experience, too, the first year. Improvements of walking disability, and a 2 years persisting skin-rush on my back, started to commence only, after reaching above 6 g/d.
Without having to because tolerating acidity, I also used a high magnesium containing mineral water (1g of Mg per liter) and mainly for potassium its bicarbonate form. So I also got about 6.6 g/d of bicarbonate between the two. Mixed in water the ascorbic acid, therefore about 13 g of it was actually consumed as mineral ascorbate. And 12 g as ascorbic acid only, in my case.
Vitamin C in my experience, is a rare nutrient which can be dosed high, without needing co-factors (of course, always test for deficiencies of other nutrients, where you can; I therefore did supplement all the electrolytes in high doses, and which might actually be the co-factor for high vitamin C). Other than all B-vitamins needing each other, or vitamin D3, which at least may need magnesium, vitamin A and K.
