It is important to avoid a deficiency of vitamin C rather than supplementing above optimal, according to Dr. Fiona Harrison of Vanderbilt University. Her research has focused mainly on the damage vitamin C deficiency can do, not the benefits huge amounts of supplementation can have. “Changes in the brain can be slowed down with adequate vitamin C,” Harrison told The Korea Times at the Plaza Hotel, Tuesday. “We use mouse models that have specific genetic manipulations, so that we can control vitamin C levels in the brain.” She found that mice with low brain vitamin C levels develop signs of Alzheimer’s disease earlier, causing learning and memory problems, and other changes in the brain that would not be seen until many months later. “This could be relevant to humans,” she said. “Our studies do not show that vitamin C can cure Alzheimer’s and they are all pre-clinical, but it does seem to show that deficiency can speed the onset of learning and memory problems.” She explained that in the United States, statistics show that if the onset of Alzheimer’s could be slowed by five years, the number of diagnoses of cases could be cut by 50 percent. She added that vitamin C deficiency speeds up the onset of other related diseases. “Everybody ages and loses speed of processing in the brain, and changes occur, such as oxidative stress,” she said. “This happens in normal aging, but more and more of an extent in diseases.” Harrison, who is fascinated by vitamin C and its role in human health, also stressed that while it doesn’t seem possible to have too much vitamin C, none of her research supports the use of high dosages. “We have specialized transporters in the intestines that carry vitamin C into the blood,” she explained. “Any unused vitamin C is excreted, but in specific medical cases, like those who are prone to kidney stones, it could be damaging.” Harrison noted that other studies seem to have proven that it is difficult to see the benefit of supplements. “Because we’re limited by the transporters as to how much we can take at a time, there seems to be no point in taking too much,” she said. She said that it is difficult to assess exactly what the optimal amount of vitamin C would be, but in a study in which she used a specific transporter for the brain and varied it using genetic manipulation, the decrease was 20 to 30 percent of normal brain levels with 500 milligrams, which was enough to help learning and memory. “Anything more may not be worth taking,” she said. And while her studies have yet to be peer-reviewed, she uses a specific mouse model with two mutations, which helps express the beta amyloid protein and the pathology associated with it. Beta amyloids are peptides that are the main component of the amyloid plaque found in the brains of Alzheimer’s patients. “We use large numbers of mice so that we can be as confident as we can be in our statistics, and we’re very careful in our methods,” she said. Harrison hopes to expand her studies into prenatal development. “Vitamin C is crucial throughout development,” she said. “Aging starts as soon as we’re conceived so I’m also interested in the role of vitamin C in the brain then.”

밴더빌트 대학의 피오나 해리슨 박사는 지난 3월 25일 플라자 호텔에서 열린 ‘제4회 비타민 C 국제 심포지엄’에서 비타민 C의 과량 섭취보다 섭취 부족을 방지하는 것이 더 중요하다고 밝혔다. 해리슨은 비타민 C의 충분한 섭취가 뇌의 변화를 늦출 수 있다고 하였다. 연구팀은 특정한 유전자가 조작된 마우스 모델을 사용하여 뇌에서 비타민 C의 수준을 조절할 수 있도록 하였으며, 뇌에서 낮은 비타민 C 수준을 가지는 마우스는 학습과 기억의 문제를 일으키는 알츠하이머의 징후를 더 일찍 나타낸다는 것을 밝혀냈다. 그녀는 이 연구가 모두 전임상시험이며, 비타민 C가 알츠하이머를 치료한다는 것을 의미하는 것은 아니지만 비타민 C의 결핍은 학습과 기억력 관련 문제의 발병을 가속화시킬 수 있는 것으로 보이며 이는 인간과도 관련이 있을 수 있다고 주장했다. 반면, 과량의 비타민 C 섭취는 체내에 존재하는 비타민 C 수송체에 의해 그 흡수가 제한되기 때문에 이에 대한 효능은 없다고 말했다. 비타민 C의 적정 섭취량이 얼마인지 정하는 것은 곤란하지만, 뇌에 특정 수송체를 사용하고 유전자 조작을 한 연구에서 적정량이라고 알려진 500mg의 20~30%를 섭취했을 때 뇌 기능의 감소가 일어났고, 이 정도 섭취량이 학습과 기억력을 돕기에 충분하다고 말했다. 그녀의 연구는 아직 검토 중인 단계이지만 두 가지 마우스 변이 모델을 사용하였고, 연구의 신뢰성을 위해 많은 수의 마우스를 사용하였으며 매우 신중하게 연구를 수행했음을 강조했다. 해리슨은 비타민 C는 발달 과정에서 매우 중요하다고 말하며 태아 발달에까지 그녀의 연구를 확장시키기를 희망했다.