I took 12 grams for much of about 10 years from age 27 to 37. Myself and the only two others I know of who took more than 10 grams a day for more than a week or two noticed a decrease in libido. Fast-forward 10 more years and at age 47 I seem to have Parkinson's. Then I remembered Dr Pauling's videos from about 1981 and on seem to show him displaying two symptoms of Parkinsons: weak voice, trembling hands, and head nodding just a tad more than you would expect. After some researching, I see that more than 2 grams a day causes copper to shift from the protein-bound state to free copper, and that the protein-bound state is needed to protect the part of the brain that is damaged in Parkinson's. The protein-bound state is needed to protect the brain from iron toxicity. If not, then the iron damages dopamine producing cells, which is directly related to libido. As a side note, my own research into how much vitamin C animals produce (and primates and guinea pigs need) would convert to 0.5 to 2 grams a day for a human. The biggest error in saying 10 grams a day is that it is based on body weight, but body weight is not the correct measure in converting nutrition and toxicity, but caloric intake, which is lower for larger animals. Anyway, I notice absolutely no Parkinson's in Dr Cathcart's videos, which tells me he probably did not take daily high doses on a regular basis.